Patent Publication Number: US-6711469-B2

Title: Robot system, robot apparatus and cover for robot apparatus

Description:
This is a continuation of application Ser. No. 09/869,256, filed Jun. 26, 2001 now U.S. Pat. No. 6,505,098, which is a 371 of PCT/JP00/07592, filed Oct. 27, 2000. 
    
    
     TECHNICAL FIELD 
     The present invention relates to a robot system, a robot apparatus and a cover for a robot apparatus, and is preferably applied, for example, to a pet robot. 
     BACKGROUND 
     There halve recently been developed and on sale quadruped-walking type pet robots which resemble dogs or cats which are to be kept as pets in general households. 
     Such a pet robot is equipped with software such as emotion models which are modeling of real animals&#39; emotions to generate emotions such as “joy” and “anger” in response to user&#39;s spurring such as “patting” and “striking” as well as a surrounding condition, so that the pet robot can autonomously act on the basis of the emotions. 
     By the way, for a reason to find fun in individuality of such an entertainment robot, it has recently been desired to make an appearance of a robot freely changeable, for example, by fitting a cover such as clothes/costume on the robot. 
     However, it is fearful that motions of the robot may be hindered or vent holes formed in a main body surface of the robot may be covered when the robot is clothed in a cover which is made without taking external forms and movements of movable members into consideration. It causes a problem that a control member cannot control adequately under such circumstances, which causes a trouble. 
     In addition, even in such a pet robot with a cover which is made with taking external forms and movements of movable members into consideration, if control is not performed with taking a mass distribution and the like of the cover into consideration, the pet robot may not correctly and smoothly act, for example, it does not walk with good balance. 
     Furthermore, considering that a pet robot can wear a cover, not only its appearance can be changeable but also if it can perform different actions depending on the appearance, it is considered that such a pet robot will be capable of giving higher emotions of intimacy and satisfaction to users, which improve an amusement property in the pet robot. 
     DISCLOSURE OF THE INVENTION 
     This invention has been achieved in view of the above points and is to propose a robot system, a robot apparatus and cover for the robot apparatus which can get rid of irregular covers to prevent occurrence of trouble, and a robot system, a robot apparatus and a cover for the robot apparatus which can improve an amusement property. 
     In order to solve such a problem, in a robot system comprising a robot apparatus and a cover in this invention, a predetermined authenticating pattern is formed on a cover and the robot apparatus is provided with an authenticating means for authenticating the cover on the basis of the authenticating pattern on the fitted cover. As a result, the robot system is capable of detecting an irregular cover when such a cover is fitted over a robot, which can realize a robot system capable of getting rid of irregular covers and previously preventing troubles in the robot. 
     Furthermore, the present invention provides a robot apparatus equipped with an authenticating means for authenticating a fitted cover on the basis of a predetermined authenticating pattern formed on a cover which is detachably fitted. As a result, the robot apparatus is capable of detecting an irregular cover when such a cover is fitted, which can realize a robot apparatus capable of getting rid of irregular covers and previously preventing troubles in the robot. 
     Furthermore, the present invention provides a cover for a robot apparatus with a predetermined authenticating pattern. As a result, a fitting robot apparatus can detect an irregular cover on the basis of the authenticating pattern when such a cover is fitted, which can getting rid of irregular covers and can realize a cover for a robot apparatus capable of previously preventing troubles in the robot. 
     Further, a robot system in the present invention provides a cover with an information holding means for holding inherent information, and a robot apparatus with an information detecting means for detecting the inherent information held by the information holding means on the cover and a control means for changing motion manifesting patterns as occasion demands on the basis of the detected inherent information. As a result, the robot system is capable of reflecting the inherent information obtained from the cover on the motion manifesting patterns of the robot apparatus as occasion demands when the cover is fitted over the robot apparatus. Thus, the robot system can act with an individuality for each cover, thereby making it possible to realize a robot system which can remarkably improve an amusement property. 
     Furthermore, the present invention provides a cover to be detachably fitted over a robot apparatus with an information holding means for holding inherent information corresponding to the cover, which allows the robot apparatus to change motion manifesting patterns as occasion demands on the basis of the inherent information held by the information holding means when the cover is fitted over the robot apparatus. As a result, when the covers is fitted over the robot apparatus, the inherent information obtained from the above described cover can be reflected on the motion manifesting patterns of the robot apparatus as occasion demands. Thus, the robot apparatus can act with an individuality for each cover, thereby making it possible to realize a cover capable of remarkably improving an amusement property in a robot apparatus. 
     Furthermore, the present invention provides a robot apparatus with an information detecting means for detecting inherent information corresponding to the cover from the cover when the cover is detachably fitted, and a control means for changing motion manifesting patterns on the basis of the detected inherent information as occasion demands. As a result, the robot apparatus can reflect the inherent information obtained from the cover on the motion manifesting patterns for the robot apparatus as occasion demands. Thus, the robot apparatus can act with an individuality for each cover, thereby making it possible to realize a robot apparatus capable of remarkably improving an amusement property. 
     Furthermore, the present invention provides a robot apparatus which has movable members and performs predetermined actions by moving the movable members, a cover to be detachably fitted over the robot apparatus, and a control means which is installed in the robot apparatus for driving and controlling the movable members. The control means detects an amount of influence on motions due to the cover by driving the movable members when the cover is fitted over the robot apparatus, and the motion manifesting patterns are changed on the basis of the detection result as occasion demands. As a result, in the robot system, the robot apparatus can previously prevent trouble in its performances even there are covers of various shapes and structures and materials, because the motion manifesting patterns for the robot apparatus are changed by moving the movable members after the cover is fitted over the robot apparatus. Thus, the different kinds of covers can be fitted over the robot apparatus, thus making it possible to realize a robot system capable of remarkably improving an amusement property. 
     Furthermore, the present invention provides the robot apparatus which has movable members and performs predetermined motions by moving the movable members, with a control means for detecting an amount of influence on the motions due to the cover by moving the movable members when the cover is detachably fitted and for changing the motion manifesting patterns on the basis of the detection result as occasion demands. As a result, the robot apparatus can previously prevent trouble in its performances even there are covers of various shapes and structures and materials, because the motion manifesting patterns for the robot apparatus are changed by moving the movable members after the cover is fitted over the robot apparatus. Thus, the different kinds of covers can be fitted over the robot apparatus, thus making it possible to realize a robot system capable of remarkably improving an amusement property. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a perspective view showing a configuration of a robot system in a first embodiment. 
     FIG. 2 is a block diagram showing an internal configuration of the pet robot in the first embodiment. 
     FIG. 3 is a schematic perspective view showing configurations of a robot side concavo-convex pattern and a cover side concavo-convex pattern. 
     FIG. 4 is a sectional view descriptive of fitting between the robot side concavo-convex pattern and the cover side concavo-convex pattern. 
     FIG. 5 is a perspective view and a sectional view showing another embodiment. 
     FIG. 6 is a sectional view showing another embodiment. 
     FIG. 7 is a perspective view showing another embodiment. 
     FIG. 8 is a schematic diagram showing a configuration of a pet robot system in a second embodiment. 
     FIG. 9 is a schematic diagram showing a configuration of the pet robot shown in FIG.  8 . 
     FIG. 10 is a block diagram showing an internal configuration of the pet robot. 
     FIG. 11 is a block diagram showing internal configurations of a main body side interface member and a cover side interface member. 
     FIG. 12 is a schematic diagram descriptive of processing by a controller in the second embodiment. 
     FIG. 13 is a schematic diagram descriptive of data processing by a emotion and instinct model section. 
     FIG. 14 is a schematic diagram descriptive of data processing by the emotion and instinct model section. 
     FIG. 15 is a schematic diagram descriptive of data processing by the emotion and instinct model section. 
     FIG. 16 is a state transition diagram of a limited automaton in an action determining mechanism section. 
     FIG. 17 is a posture transition diagram in a posture transition mechanism section. 
     FIG. 18 is a flow chart descriptive of a cover fitting processing procedure. 
     FIG. 19 is a schematic diagram showing a configuration of a pet robot system in a third embodiment. 
     FIG. 20 is a schematic diagram descriptive of a growth model in the third embodiment. 
     FIG. 21 is a schematic diagram descriptive of processing by a controller in the second embodiment. 
     FIG. 22 is a schematic diagram showing a probability automaton. 
     FIG. 23 is a conceptional diagram showing a first growth factor list and a first growth factor counter table. 
     FIG. 24 is a conceptional diagram showing a second growth factor list and a second growth factor counter table. 
     FIG. 25 is a flow chart descriptive of a growth step control processing procedure. 
     FIG. 26 is a schematic diagram showing a configuration of a pet robot system according to another embodiment. 
     FIG. 27 is a schematic diagram showing a configuration of a pet robot system in a fourth embodiment. 
     FIG. 28 is a schematic diagram showing a configuration of pet robot shown in FIG.  27 . 
     FIG. 29 is a block diagram showing an internal configuration of the pet robot. 
     FIG. 30 is a block diagram showing internal configurations of a main body side interface member and a cover side interface member. 
     FIG. 31 is a table showing 22 parameters for walking-control. 
     FIG. 32 is a schematic diagram showing standard walking postures. 
     FIG. 33 is a schematic diagram descriptive of movements of one leg member unit. 
     FIG. 34 is a schematic diagram descriptive of parameters. 
     FIG. 35 is a timing chart showing phase relationship of the parameters in various kinds of walking styles. 
     FIG. 36 is a schematic diagram descriptive of barycenter locations before and after fitting a cover. 
     FIG. 37 is a flow chart descriptive of a calibration processing procedure in the fourth embodiment. 
     FIG. 38 is a schematic diagram showing a configuration of a pet robot system in a fifth embodiment. 
     FIG. 39 is a flow chart descriptive of a calibration processing procedure in the fifth embodiment. 
     FIG. 40 is a schematic embodiment showing a pet robot system according to a sixth embodiment. 
     FIG. 41 is a block diagram showing an internal configuration of the robot system shown in FIG.  40 . 
     FIG. 42 is a schematic diagram descriptive of cover information. 
     FIG. 43 is a block diagram descriptive of processing by a controller in the sixth embodiment. 
     FIG. 44 is a conceptional diagram showing a probability automaton. 
     FIG. 45 is a table descriptive of state transition diagram. 
     FIG. 46 is a table showing the relation between an angle of incline of a canopy with respect to an optical axis of a distance sensor and an output characteristic of the distance sensor. 
     FIG. 47 is a characteristic curvilinear graph showing the relation between an angle of incline of the canopy with respect to an optical axis of the distance sensor and the output characteristic of the distance sensor. 
     FIG. 48 is a table showing the relation between colors of the canopy and output characteristics of the distance sensor. 
     FIG. 49 is a characteristic curvilinear graph showing the relation between the colors of the canopy and the output characteristics of the distance sensor. 
    
    
     BEST MODE FOR CARRYING OUT THE INVENTION 
     Embodiments of the present invention will be described in detail with reference to the accompanying drawings. 
     (1) First Embodiment 
     (1-1) Configuration of a Robot System in this Embodiment 
     In FIG. 1, reference numeral  1  denotes a robot system as a whole preferred as the embodiment, which comprises a pet robot  2  and a cover unit  3  to be fitted over the pet robot  2 . 
     The pet robot  2  is formed by coupling leg member units  11 A through  11 D with front right, front left, rear right, and rear left portions of a body member unit  10  and connecting a head member unit  12  and a tail member unit  13  to a front end and a rear end of the body member unit  10 , as apparent from FIG.  1 . 
     In this case, as shown in FIG. 2, the body member unit  10  contains a controller  20  which controls entire motions of the pet robot  2 , a battery  21  which functions as a power source for the pet robot  2 , a heat sensor  22 , a cooling fan  23  which is disposed so as to be placed under a vent hole  10 A (FIG. 1) formed in a top surface of the body member unit  10  and so on. 
     Further, disposed on the head member unit  10  at predetermined locations are a microphone  24  which is used as “ears” of the pet robot  2 , a CCD (charge coupled device) camera  25  which is used as “eyes,” a touch sensor  26 , and a speaker  27  which is used as a “mouth” and so on. 
     Furthermore, actuators  28 A through  28   n  which have degree og freedom are disposed in joints parts of the leg member units  11 A through  11 D, coupled parts of the leg member units  11 A through  11 D and the body member unit  10 , a coupled part of head member unit  12  and the body member unit  10 , a coupled part of the tail member unit  13  and the body member unit  10 , and so on. 
     The microphone  24  on the head member unit  12  gathers order sounds such as “walk,” “lie down” or “chase a ball” which are given in a form of musical scales from a user with a sound commander (not shown) and sends out the audio signal S 1  thus obtained to the controller  20 . Furthermore, the CCD camera  25  picks up a surrounding condition and sends out the image signal S 2  thus obtained to the controller  20 . 
     Furthermore, the touch sensor  26  which is disposed on a top of the head member unit  12  as apparent from FIG. 2 detects a pressure received from the user by a physical spurring such as “patting” or “striking” and sends out the detection result as a pressure detection signal S 3  to the controller  20 . 
     Furthermore, the heat sensor  22  on the body member unit  10  detects heat in the body member unit  10  and sends out a detection result as a heat detection signal S 4  to the controller  20 . 
     The controller  20  judges presence or absence of an order or physical spurring from the user, surrounding conditions and the like on the basis of the audio signal S 1 , the image signal S 2 , the pressure detection signal S 3 , the heat detection signal S 4  and the like which are respectively given from the microphone  24 , the CCD camera  25 , the touch sensor  26 , the heat sensor  22  and the like. 
     On the basis of the judgement result and a control program which is stored preliminarily in a memory  20 A, the controller  20  determines a next action and sends out control signals S 5 A through S 5   n  to required actuators  28 A through  28   n  on the basis of the determination result to drive the actuators, thereby allowing the pet robot to take actions such as swinging of the head member unit  12  up, down, left and right, movement of a tail  13 A of the tail member unit  13  and walking by driving the leg member units  11 A through  11 D. 
     At this time, the controller  20  gives a predetermined audio signal S 6  to the speaker  27  as occasion demands to allow it to give sounds based on the above described audio signal S 6  to outside, and turns on or off or flickers LEDs (light emitting diode) (not shown) disposed at locations of eyes of the pet robot  2 . 
     Accordingly, the pet robot  2  is configured to be capable of autonomously acting dependently on presence or absence of an order and physical spurring from the user, and on the basis of the surrounding conditions, the control program and the like. 
     On the other hand, a cover unit  3  (FIG. 1) is made of material having predetermined hardness such as synthetic resin, and has internal form and size nearly the same as a form and a size of the top portion of the body member unit  10  of the pet robot  2 . 
     Furthermore, formed in a front end of the cover unit  3  is a notch  3 A so as to fit a neck at with which the body member unit  10  and the head member unit  12  of the pet robot  2  are coupled, and formed on the top of the cover unit  3  are a plurality of screw holes  3 B so as to be placed at the same positions as a plurality of tapped holes  10 B formed at predetermined locations of the body member unit  10  of the pet robot  2 . 
     Accordingly, the robot system  1  is configured to allow the cover unit  3  to be fitted over the pet robot  2  in a fixed condition by fitting the cover unit  3  over the body member unit  10  of the pet robot  2  and tightening screws  4  into the tapped holes  10 B of the body member unit  10  of the pet robot  10  through the screw holes  3 B of the cover unit  3 . 
     Furthermore, formed on the top of the cover unit  3  is a vent aperture  3 C so as not to cover the vent hole  10 A of the body member unit  10  of the pet robot  2  and formed around a lower end of the cover unit  3  are notches  3 D so as to fit the joint portions of the leg member units  11 A through  11 D and of the tail  13 A of the tail member unit  13  of the pet robot  2 . 
     Accordingly, the robot system  1  is configured to be capable of allowing heat which is exhausted through the vent hole  10 A of the body member unit  10  of the pet robot  2  to be exhausted outside through the vent aperture  3 C of the cover unit  3  and preventing the cover unit  3  from interfering with the leg member units  11 A through  11 D and the tail  13 A when the pet robot  2  moves the leg member units  11 A through  11 D and the tail  13 A. 
     In addition to the configuration described above, in this robot system  1 , a concavo-convex pattern (hereinafter referred to as a robot side concavo-convex pattern)  31  having a predetermined form is formed on a base member  30  having a predetermined height at a predetermined location of the body member unit  10  of the pet robot  2 , as shown in FIGS. 1,  3  and  4 (A). 
     Furthermore, a concavo-convex pattern (hereinafter referred to as a cover side concavo-convex pattern)  32  which has an inverted form of the concavo-convex form of the robot side concavo-convex pattern  31  and consists of a concave portion  32 B and a convex portion  32 A to fit with a convex portion  31 A and a concave portion  31 B respectively of the robot side concavo-convex pattern  31  is formed on the cover unit  3  so as to fit the robot side concavo-convex pattern  31 . 
     In case of this embodiment, the concavo-convex form of the cover side concavo-convex pattern  32  has been registered as an industrial design so that people without the license cannot utilize the concavo-convex form of the cover side concavo-convex pattern  32 . 
     Accordingly, the robot system  1  is configured to fit the robot side concavo-convex pattern  31  with the cover side concavo-convex pattern  32  as shown in FIG.  4 (B) and allows the cover unit  3  to be fitted correctly over the pet robot  2  at a stage to fit the cover unit  3  over the pet robot  2  when the cover unit  3  is a regular cover unit, and on the contrary, when the cover unit  3  is an irregular cover unit, the robot side concavo-convex pattern  31  is not fit with the cover side concavo-convex pattern  32 , unlike FIG.  4 (B) and as a result, the cover unit  3  can not correctly be fitted over the pet robot  2 . 
     In case of this embodiment, the robot side concavo-convex pattern  31  is disposed at both sides of the vent hole  10 A of the body member unit  10  of the pet robot  2  as shown in FIG.  1 . In the body member unit  10  of the pet robot  2 , the above described tapped holes  10 B are formed in the vicinities of the robot side concavo-convex pattern  31  as pairs consisting of two tapped holes each laterally sandwiching the corresponding robot side concavo-convex pattern  31  as shown in FIG.  4 (A). 
     Furthermore, the screws  4  which are used to fix the cover unit  3  to the pet robot  2  are selected so that a length L of a portion which is to be screwed into the body member unit  10  of the pet robot  2  is shorter than a sum of a height H 1  of the convex portion  31 A of the robot side concavo-convex pattern  31  and a height H 2  of the convex portion  32 A of the cover side concavo-convex pattern  32 , as shown in FIG.  4 (C). 
     Accordingly, the robot system  1  does not allow the screws  4  to be screwed into the tapped holes  10 B of the pet robot  2  through the screw holes  3 B of the cover unit  3  as shown in FIG.  4 (C) when the cover unit  3  is an irregular cover unit, thereby making it impossible to fix the irregular cover unit  3  to the pet robot  2 . 
     (1-2) Operation and Effect in this Embodiment 
     In the robot system  1  which has the above described configuration, the robot side concavo-convex pattern  31  is fitted with the cover side concavo-convex pattern  32  at a stage to fit the cover unit  3  over the pet robot  2  when the cover unit  3  is a regular cover unit, so that the above described cover unit  3  can be fitted correctly. On the contrary, when the cover unit  3  is an irregular cover unit, the robot side concavo-convex pattern  31  does not fit the cover side concavo-convex pattern  32 , so that the above described cover unit  3  can not be fitted correctly. 
     Accordingly, the robot system  1  is capable of excluding irregular cover units  3  and providing a result to effectively prevent the pet robot  2  from being troubled due to the use of the irregular cover unit  3  when only those who manufacture the cover unit  3  in compliance with a standard for the pet robot  2  are permitted to use the cover side concavo-convex pattern  32 . 
     The above described configuration is adapted to form the cover side concavo-convex pattern  32  having the predetermined form of the registered design on the cover unit  3  and the robot side concavo-convex pattern  31  having the inverted form of the concavo-convex form of the above described cover side concavo-convex pattern  32  on the pet robot  2  so as to fit the cover side concavo-convex pattern  32 , thereby making it possible to realize a robot system which is capable of preventing the irregular cover unit  3  from being fitted over the pet robot  2  effectively and preventing the robot from being troubled by excluding irregular covers. 
     (1-3) Other Embodiments 
     Note that, in the aforementioned embodiment, the present invention is applied to the quadruped walking type pet robot  2  configured as shown in FIG.  1 . The present invention, however, is not limited to this and applicable widely to other various kinds of robots such as toys and dolls (hereinafter, it is the same in the following second to sixth embodiments). 
     Further, though the robot side concavo-convex pattern  31  is formed in the base member  30  in the above described embodiment, the present invention is not limited to this and it is possible, for example, to dispose a boss  40  for fixing the cover unit  3  to the pet robot  2 , to form a concavo-convex pattern  41  having a predetermined form on a top end surface of the boss  40  and to form a corresponding concavo-convex pattern  42  on the cover unit  3  so as to fit the concavo-convex pattern  41  as shown in FIGS.  5 (A) and  5 (B). 
     Further, though cubic patterns (the cover side concavo-convex pattern  32  and the robot side concavo-convex pattern  31 ) are formed as the authenticating pattern on the cover unit  3  and the authenticating means on the pet robot  2  in the above described embodiment, the present invention is not limited to this and it is possible, for example, to form a planar pattern (a pattern of a color or reflectance) on the cover unit  3  as an authenticating pattern and to dispose a CCD camera or the like on the pet robot  2  as the authenticating means so that the controller  20  (FIG. 2) of the pet robot  2  judges whether or not the cover unit  3  is irregular on the basis of the authenticating pattern of the cover unit  3  photographed by the CCD camera and makes the pet robot  2  inoperative when the cover unit  3  is irregular. 
     Furthermore, it is possible to form the authenticating pattern on the cover unit  3  using an electrically conductive material such as an electrically conductive paint and form an electrode on the pet robot  2  as the authenticating means so that the authenticating pattern on the cover unit  3  is detected electrically. 
     Furthermore, it is possible, for example, to form a predetermined concavo-convex pattern (ether linearly or two-dimensionally)  43  on the cover unit  3  as an authenticating pattern and arrange a plurality of touch sensors  44  (ether linearly or two-dimensionally) at corresponding locations of the pet robot  2  as shown in FIG. 6 so that the controller  20  of the pet robot  2  judges whether or not the cover unit  3  is irregular on the basis of which touch sensors  44  in the authenticating pattern (concavo-convex pattern  44 ) on the cover unit  3  are pressed and makes the pet robot  2  inoperative when the cover unit  3  is irregular. 
     Though the concavo-convex pattern having the form of the registered design (cover side concavo-convex pattern  32 ) is used as the authenticating pattern on the cover unit  3  in the above described embodiment, the present invention is not limited to this and forms other than the registered form can be used widely as the cover side concavo-convex pattern  32  so far as the forms can technically or legally restrict use of the concavo-convex pattern of the cover unit  3  only to specific persons. 
     In this case, it is possible to use a concavo-convex pattern  45  which is formed by embossing characters of a registered trademark or the like as the authenticating pattern on the cover unit  3 , for example, as shown in FIG.  7 . 
     Furthermore, through the present invention uses the cover unit  3  which is made of synthetic resin having predetermined hardness and is formed as shown in FIG. 1, and the present invention is not limited to this and can use other kinds of materials as a material of the cover and also other different shapes for the cover can be applied so that impressions of the pet robot  2  can be changed preferably. 
     (2) Second Embodiment 
     (2-1) Configuration of Robot System  50  in this Embodiment 
     FIG. 8 shows a robot system  50  according to a second embodiment, and a predetermined cover part (hereinafter, referred to as a cover unit)  52  can cover a whole surface of a pet robot  51  by detachably being fit over the pet robot  51 . 
     The pet robot  51  is actually composed by coupling leg member units  54 A through  54 D with front right, front left, rear right, rear left portions of a body member unit  53 , and connecting a head member unit  55  and a tail member unit  56  to a front end and a rear end of the body member unit  53  respectively. 
     A cooling fan (not shown) is disposed in the body member unit  53 , and an air exhaust port  53 AX and an air suction port  53 BX (FIG. 9) are formed on a top surface  53 A and a bottom surface  53 B for the cooling fan. Accordingly, the pet robot  51  is configured to be capable of lowering an internal temperature of the body member unit  53  by exhausting air, which has been sucked with the air suction port  53 BX, through the body member unit  53  from the air exhaust port  53 AX to outside while the cooling fan is driven. 
     Furthermore, disposed on a bottom surface  53 B of the body member unit  53  is an interface member (hereinafter referred to as a main body side interface member)  58  on which a connector part  57  is composed of a connector half  57 A and an engaging mechanism part  57 B as shown in FIG.  9 . 
     On the other hand, as shown in FIG. 8, the cover unit  52  is formed by a cover main body  52 A which has the same shape as a real dog and is made of synthetic fibers. And disposed at a predetermined location on the back surface of the cover main body  52 A is an interface member (hereinafter referred to as a cover side interface member)  60  on which a connector part  59  is composed of a connector half  59 A and an engaging mechanism part  59 B which are to be connected to the connector half  57 A and the engaging mechanism part  57 B of the main body side interface member  58  disposed on the body member unit  53 . 
     To fit the cover unit  52  actually over the pet robot  2 , the cover main body  52 A of the cover unit  52  is fitted so as to cover a whole surface of the pet robot  2 , and then by connecting the connector part  59  of the cover side interface member  50  to the connector part  57  of the main body side interface member  58 , the connector halves  57 A and  59 A are electrically connected to each other and the engaging mechanism parts  57 B and  59 B are connected mechanically. 
     (2-2) Internal Configuration of Pet Robot System 
     In the robot system  50  shown in FIG. 10, accommodated in the body member unit  53  of the pet robot  51  are a controller  70  which controls entire motions of the pet robot  51 , a battery  71  which functions as a driving power source of the pet robot  51 , an internal sensor member  74  which consists of a battery sensor  72  and a heat sensor  73 , the main body side interface member  58  which consists of a coupling sensor  80  and the connector part  57 , and an information reading member  75  which reads out a control program stored in a recording medium (not shown) which is inserted from outside. 
     Disposed at predetermined locations in a head member unit  55  are a microphone  76  which is used as “ears”, a CCD (charge coupled device) camera  77  which is used as “eyes”, a touch sensor  78 , a speaker  79  which is used as a “mouth” and so on. 
     Furthermore, actuators  54 AA 1  to  54 AA K ,  54 BA 1  to  54 BA K ,  54 CA 1  to  54 CA K ,  54 DA 1  to  54 DA K ,  55 A 1  to  55 A L  and  56 A 1  to  56 A M  are disposed in joint parts of leg member units  54 A to  54 D, coupling parts of the leg member units  54 A to  54 D and the body member unit  53 , a coupling part of the head member unit  55  and the body member unit  53 , a coupling part of a tail member unit  56  and the body member unit  53 , etc. 
     The microphone  76  of the head member unit  55  gathers order sounds such as “walk,” “lie down” and “chase a ball” which are given in form of musical scales from a user with a sound commander (a commander which gives sounds in form of musical scales different dependently on operation contents) which is not shown and sends out an obtained audio signal S 10  to the controller  70 . The CCD camera  77  picks up an image of surrounding conditions and sends out an obtained image signal S 11  to the controller  70 . 
     Furthermore, the touch sensor  78  is disposed on the top of the head member unit  55  as apparent from FIG. 8, and detects pressures applied from the user by physical spurring such as “patting” and “striking,” and sends out a detection result as a pressure detection signal S 12  to the controller  70 . 
     Furthermore, the battery sensor  72  of the body member unit  53  detects a residual amount of the battery  71  at a plurality of steps and sends out a detection result at each step as a battery residual amount detection signal S 13  consecutively to the controller  70 . 
     Furthermore, the heat sensor  73  of the body member unit  53  detects an internal temperature of the pet robot  51  and sends out a detection result as a heat detection signal S 14  to the controller  70 . 
     Furthermore, the main body side interface member  58  of the body member unit  53  is composed of the coupling sensor  80  and the above described connector part  57  which is composed of the connector half  57 A and the engaging mechanism part  57 B. The coupling sensor  80  detects coupling conditions of the cover unit  52  with the cover side interface member  60  and sends out a detection result as a cover detection signal S 15  to the controller  70 . 
     On the basis of the audio signal S 10 , the image signal S 11 , the pressure detection signal S 12 , the battery residual amount detection signal S 13 , the heat detection signal S 14  and the cover detection signal S 15  and the like which are given from the microphone  76 , the CCD camera  77 , the touch sensor  78 , the battery sensor  72 , the heat sensor  73  and the coupling sensor  80 , the controller  70  judges surrounding conditions and whether or not the user made an order, spurring and the like. 
     On the basis of a judgment result and the control program which has been input, the controller  70  determines a next action, and allows the pet robot to take actions such as swinging the head member unit  55  up, down, left and right, moving the tail member unit  56 , walking with the leg member units  54 A through  54 D by driving actuators  54 AA 1  to  54 AA K ,  54 BA 1  to  54 BA K ,  54 CA 1  to  54CA   K ,  54 DA 1  to  54 DA K ,  55 A 1  to  55 A L  and  56 A 1  to  56 A M  which are required from the determination result. 
     At this time, the controller  70  gives a predetermined audio signal S 16  to the speaker  79  as occasion demands, thereby allowing the speaker to output sounds to outside on the basis of the above described audio signal S 16 , and turns on or off or flickers LEDs (light emitting diode) which are not shown and disposed at locations of “eyes” of the pet robot  51 . 
     The pet robot  51  is capable of acting autonomously on the basis of surrounding conditions and the control programs, as described above. 
     In the cover unit  52 , on the other hand, the cover side interface member  60  which is built in a cover main body  52 A comprises an information storage member  81  and the above described connector part  59 , and the above mentioned connector part  59  is composed of the connector half  59 A and the engaging mechanism part  59 B. The engaging mechanism part  59 B in the cover side interface member  60  is configured so as to be fitted detachably to the engaging mechanism part  57 B in the main body side interface member  58 . 
     The information storage member  81  in the cover side interface member  60  comprises, for example, a non-volatile memory such as a ROM (random access memory) which preliminarily stores information representing a manufacturer ID, information representing a manufacturing license such as a product ID, a lot number and the like determined by the manufacturer, and enciphered information for authenticating a cover unit and so on (hereinafter referred to as cover setting information D 1 ), for each cover number allocated to a type of the cover unit  52 . 
     Furthermore, preliminarily stored in the recording medium to be inserted into the information reading member  75  disposed in the body member unit  53  is program information (hereinafter referred to as performance information) D 2  for determining performances of the pet robot  51  according to the contents of the cover setting information D 1  for the above described each cover number. 
     When the cover side interface member  60  is coupled with the main body side interface member  58 , the connector half  59 A and the engaging mechanism part  59 B disposed on the connector part  59  of the above described cover side interface member  60  are connected electrically and mechanically to the corresponding connector half  57 A and engaging mechanism part  57 B disposed on the connector part  57  of the main body side interface member  58 . 
     Concretely speaking, the main body side interface member  58  and the cover side interface member  60  are configured as shown in FIG.  11 . 
     In the main body side interface member  58 , connecting terminals A 1  to A 4  for a grounding line L 1 , a power source line L 2 , a measurement line L 3  and a signal line L 4  are exposed on the connector half  57 A of the connector part  57 , and an end of a load resistor R 1  which has the other end connected to ground is connected between the connecting terminal A 3  and the coupling sensor  80  on the measurement line L 3 . 
     In the cover side interface member  60 , connecting terminals A 5  to A 8  for a ground line L 5 , a power source line L 6 , a measurement line L 7  and a signal line L 8  are exposed on the connector part  59 , a load resistor R 2  is disposed on the measurement line L 7  which is drawn from the power source line L 6 , and ends of the above described load resistor R 2  are connected to the information storage member  81  and the connecting terminal A 7 . 
     When the connector half  59 A disposed on the connector part  59  of the cover side interface member  60  is actually connected to the connector half  57 A disposed on the connector part  57  of the main body side interface member  58 , the connecting terminals A 1  to A 4  for the ground line L 1 , the power source line L 2 , the measurement line L 3  and the signal line L 4  on the connector half  57 A are brought into contact with and conductive to the corresponding connecting terminals A 5  to A 8  for the lines L 5  to L 8  on the connector half  59 A. 
     At this time, the coupling sensor  80  in the main body side interface member  58  detects a voltage value of the load resistor R 2  on the measurement line L 7  connected to the power source line L 6  in a condition where the connector halves  59 A and  57 A conductive to each other, between the cover side interface member  60  and the main body side interface member  58 , thereby judging a coupling condition of the main body side interface member  58  with the cover side interface member  60  (an “H” level in a coupling condition or an “L” level in a separated condition). 
     As a result, the controller  70  reads out the cover setting information D 1  stored in the information storage member  81  in the cover side interface member  60  only when the coupling sensor  80  obtains an affirmative result, reads out the performance information D 2  from the recording medium inserted into the information reading member  75  in the body member unit  53  on the basis of the above described cover setting information D 1  and determines an action of the pet robot  51  on the basis of the performance information D 2 , thereby driving the actuators  54 AA 1  to  56 A M  which are required for the determined action and allowing the speaker  79  to output sounds as occasion demands. 
     When the cover unit  52  is fitted, the pet robot  51  is capable of autonomously changing actions with the individuality according to the cover setting information D 1  stored in the information storage member  81  in the cover side interface member  60  of the above described cover unit  52  and the performance information D 2  read out from the recording medium inserted into the information reading member  75  in the body member unit  53  on the basis of the above described cover setting information D 1 . 
     (2-3) Manifestation of Actions Dependent on Emotions and Instincts of Pet Robot  51   
     The pet robot  51  is configured not only to autonomously act in accordance with the surrounding conditions, the control program and the like, but also to change actions as if it were a real animal which has natural “emotions and instincts.” 
     That is, the pet robot  51  has three “emotion expressions” of “joy,” “sadness” and “anger” as well as three “instinct expressions” of “appetite,” “curiosity” and “desire for movement.” Preliminarily stored in a memory of the controller  70  are action and motion models consisting of various kinds of control parameters and control programs as bases of actions and motions related to four items of “walking condition,” “motion,” “action” and “sound” for each “emotion expression” and each “instinct expression.” 
     Now, description will be made of processing performed by the controller  70  to generate the actions of the pet robot  51 . 
     As shown in FIG. 12, functions of the controller  70  for processing to generate actions of the pet robot  51  can be classified into a sensor input processing section  90  which recognizes a specific external condition, a emotion and instinct model section  91  which expresses conditions of the emotions and instincts by accumulating recognition results of the above described sensor input processing section  90 , an action determining mechanism section  92  which determines a succeeding action on the basis of the recognition results of the above described sensor input processing section  90 , a posture transition mechanism section  93  which allows the pet robot  51  to actually manifest actions on the basis of the determination result of the above described action determining mechanism section  92  and an expression result of the emotion and instinct model section  91 , and a control mechanism section  94  which drives and controls the actuators  54 AA 1  to  56 A M . 
     In this case, the sensor input processing section  90  recognizes the specific conditions on the-basis of the audio signal S 10 , the image signal S 11 , the pressure detection signal S 12 , the battery residual amount detection signal S 13 , and the heat detection signal S 14  which are respectively supplied from the microphone  76 , the CDD camera  77 , the touch sensor  78 , the battery sensor  72 , and the heat sensor  73 , and sends out the recognition result as a condition recognition information D 5  to the emotion and instinct model section  91  and the action determining mechanism section  92 . 
     Concretely, the sensor input processing section  90  always checks the audio signal S 10  which is given from the microphone  76 , and when detecting spectrums of which musical scales are the same as an order sounds which are output as spectrums of the audio signal S 10  from the sound commander in accordance with an order such as “walk,” “lie down,” and “chase a ball”, it recognizes that the order was given informs the emotion and instinct model section  91  and action determining mechanism section  92  of the recognition result as the condition recognition information D 5 . 
     Further, the sensor input processing section  90  always checks image signals S 11  which are given from the CCD camera  77 , and when detecting from an image based on the image signal S 11 , for example, “something red” or “a flat surface which is vertical to the ground and is higher than a predetermined height”, it recognizes that “there is a ball” or “there is a wall” and informs the emotion and instinct model section  91  and the action determining mechanism section  92  of the recognition result as the condition recognition information D 5 . 
     In addition, the sensor input processing section  90  always checks pressure detection signals S 12  which are given from the touch sensor, and when detecting on the basis of the pressure detection signal S 12 , pressure which has a threshold not lower than a predetermined value and is given for a short time (for example, less than two seconds), recognizes that it was struck (scolded), and on the contrary when detecting pressure which has a threshold not higher than a predetermined value and is given for a long time (for example, more than two seconds), recognizes that it was patted (praised) Then, the sensor input processing section  90  informs the emotion and instinct model section  91  and the action determining mechanism section  92  of the recognition result as the condition recognition information D 5 . 
     Furthermore, the sensor input processing section  90  always checks the battery residual amount detection signals S 13  which are given from the battery sensor  72 , and when recognizing that the amount of energy in the battery  11  is getting low, it informs the emotion and instinct model section  91  and the action determining mechanism section  92  of the recognition result as the condition recognition information D 5 . 
     Furthermore, the sensor input processing section  90  always checks the heat detection signals S 14  which are given from the heat sensor  73 , and when recognizing that the temperature inside the pet robot  51  is higher than a predetermined temperature, it informs the emotion and instinct model section  91  and the action determining mechanism section  92  of the recognition result as the condition recognition information D 5 . 
     Furthermore, the sensor input processing section  90  recognizes the presence or absence of the cover unit  52  and the various setting information set in the cover unit  52  on the basis of the cover detection signal S 15  which is given from the coupling sensor  80  in the main body side interface member  58 , the cover setting information D 1  read out from the information storage member  81  in the cover side interface member  60 , and the performance information D 2  read out with the information reading member  75  in the body member unit  53 , and informs the emotion and instinct model section  91  and the action determining mechanism section  92  of the recognition result as the condition recognition information D 5 . 
     The emotion and instinct model section  91  has control parameters for a basic emotion group  100  consisting of emotion units  100 A to  100 C adopted as a plurality of independent emotion models and a basic desire group  51  consisting of desire units  101 A to  101 C adopted as a plurality of independent desire models in the memory  70 A of the controller  70  as shown in FIG.  13 . In the basic emotion group  100 , the emotion unit  100 A expresses an emotion of “joy,” the emotion unit  100 B expresses an emotion of “sadness” and the emotion unit  100 C expresses an emotion of “anger.” 
     The emotion units  100 A to  100 C represent intensities of the emotions, for example, by 0 to 100 levels and change the intensities of the emotions from time to time on the basis of the condition recognition information D 5  which is supplied. Accordingly, the emotion and instinct model section  91  expresses the emotions of the pet robot  51  by combining the intensities of the emotion units  100 A to  100 C which are changed from time to time, thereby modeling changes of the emotions with time. 
     In the basic desire group  101 , the desire unit  101 A expresses a desire of “appetite,” the desire unit  101 B expresses a desire of “curiosity” and the desire unit  101 C expresses a desire of “desire for motion.” 
     Similar to the emotion units  100 A to  100 C, the desire units  101 A to  51 D represents the intensities of the desires, for example, by 0 to 100 levels and change the intensities of the desires from time to time on the basis of the condition recognition information D 5  which is supplied. Accordingly, the emotion and instinct model section  91  expresses conditions of the instincts of the pet robot  51  by combining the intensities of the desire units  101 A to  101 C which are changed from time to time, thereby modeling changes of the instincts with time. 
     In this way, the emotion and instinct model section  91  changes the intensities of the emotion units  100 A to  100 C and the desire units  101 A to  101 C respectively on the basis of the condition recognition information D 5 . The emotion and instinct model section  91  determines the emotions by accumulatively combining the changed intensities of the emotion units  100 A to  100 C, determines conditions of the instincts by accumulatively combining the changed intensities of the desire units  101 A to  101 C, and sends out the determined conditions of the emotions and the instincts to the action determining section  92  as the emotion and instinct condition information D 6 . 
     By the way, when the emotion units  100 A to  100 C desired out of the basic emotion group  100  are combined so as to restrain or stimulate each other and an intensity of one of the combined emotion units  100 A to  100 C is changed, an intensity of the other emotion unit is changed correspondingly, whereby the emotion and instinct model section  91  realizes a pet robot with natural emotions and instincts. 
     When the “joy” emotion unit  101 A is combined with the “anger” emotion unit  100 B so as to restrain each other as shown in FIG. 14, the emotion and instinct model section  91  enhances an intensity of the “joy” emotion unit  100 A when the pet robot is praised by the user and naturally lowers an intensity of the “anger” emotion unit  100 B as the intensity of the “joy” emotion unit  100 A is enhanced even when the condition recognition information D 5  which changes the intensity of the “anger” emotion unit  100 B is not supplied. Similarly, when an intensity of the “anger” emotion unit  100 B is enhanced, the emotion and instinct model section  91  lowers an intensity of the “joy” emotion unit  100 A naturally as the intensity of the “anger” emotion unit  100 B is enhanced. 
     By combining the “sadness” emotion unit  100 B with the “anger” emotion unit  100 C so as to stimulate each other, the emotion instinct model section  91  enhances an intensity of the “anger” emotion unit  100 C when the pet robot is struck by the user and naturally enhances an intensity of the “sadness” emotion unit  100 B as the intensity of the “anger” emotion unit  100 C is enhanced even when the condition recognition information D 5  which changes the intensity of the “sadness” emotion unit  100 B is not supplied. Similarly, when an intensity of the “sadness” emotion unit  100 B is enhanced, the emotion and instinct model section  91  enhances an intensity of the “anger” emotion unit  31 C naturally as the intensity of the “sadness” emotion unit  100 B is enhanced. 
     When the desire units  101 A to  101 C desired out of the basic desire units  101  are combined so as to restrain or stimulate each other as in the case-where the emotion units  100 A to  100 C are combined and an intensity of one of the combined desire units  101 A to  101 C is changed, an intensity of the other desire unit is also changed correspondingly, whereby the emotion and instinct model section  91  realizes the pet robot  51  with natural instincts. 
     In FIG. 15, action information D 7  having contents of a current action or a past action of the pet robot  51  itself, for example, “having walked for a long time” is supplied to the emotion and instinct model section  91  from an action determining mechanism member  92  disposed at a later stage, and even when an identical condition recognition information D 5  is given, the emotion and instinct model section  91  generates the different emotion and instinct condition information D 6  in accordance with the action of the pet robot  51  represented by the above described action information D 7 . 
     Concretely speaking, as shown in FIG. 15, intensity increase-decrease functions  105 A to  105 C which generate intensity information D 8 A to D 8 C for enhancing and lowering intensities of the emotion units  100 A to  100 C on the basis of the action information D 7  representing actions of the pet robot  51  and the condition recognition information D 5  are disposed at stages preceding to the emotion units  100 A to  100 C so that the emotion and instinct model section  91  enhances and lowers the intensities of the emotion units  101 A to  100 C dependently on the intensity information D 8 A to D 8 C which is output from the intensity increase-decrease functions  105 A to  105 C. 
     The emotion and instinct model section  91  enhances an intensity of the “joy” emotion unit  10 A, for example, when the pet robot salutes the user and is patted, that is, when the action information D 7  representing salutation to the user and the condition recognition information D 5  representing the patting on the head are given to the intensity increase-decrease function  105 A, whereas the emotion and instinct model section  91  does not change an intensity of the “joy” emotion unit  100 A even when the pet robot is patted during doing a task, that is, even when the action information D 7  representing the middle of the task and the condition recognition information D 5  representing the patting are given to the intensity increase-decrease function  105 . 
     As described above, the emotion and instinct model section  91  determines intensities of the emotion units  100 A to  100 C while referring not only to the condition recognition information D 5  but also to the action information D 7  representing the current or past action of the pet robot  51 , thereby being capable of avoiding arising of an unnatural instinct, for example, the enhancing of an intensity of the “joy” emotion unit  100 A, for example, when the pet robot is patted on the head simply for fun during doing a task. 
     By the way, as to the desire units  101 A to  101 C, the emotion and instinct model section  91  also enhances and lowers intensities of the desire units  101 A to  101 C on the basis of the condition recognition information D 5  and the action information D 7  which are supplied. 
     As described above, the intensity increase-decrease functions  105 A to  105 C are functions which generate and output the intensity information D 8 A to D 8 C in accordance with the parameters set in advance when the condition recognition information D 5  and the action information D 7  are input, thereby being capable of letting the pet robots  51  have individualities, for example, a pet robot  51  liable to be angry and a pet robot  51  having a joyful character by setting the above mentioned parameters at different values for the individual pet robots  51 . 
     In FIG. 12, the action determining mechanism section  92  determines a next motion on the basis of the condition recognition information D 5  and the emotion and instinct condition information D 6 , and sends out the contents of a determined motion to the posture transition mechanism section  93  as action command information D 9 . 
     Concretely speaking, as shown in FIG. 16, the action determining mechanism section  92  uses an algorithm referred to as a limited automaton  110  having a limited number of states which expresses a history of the condition recognition information D 5  supplied in the past as a motion state (hereinafter referred to as a state) and determines the next action by transition of the above described state into another state on the basis of the condition recognition information D 5  currently supplied and a state at this time. The action determining mechanism section  92  determines a motion referring not only to the current condition recognition information D 5  but also to the past condition recognition information D 5  by shifting a state each time when the condition recognition information D 5  is supplied and determining a motion dependently on the shifted state. 
     Accordingly, a state ST 1  of “chasing a ball” is shifted to a state ST 5  of “standing,” for example, when the condition recognition information D 5  of “lost sight of a ball” is supplied, whereas a state ST 2  of “lie down” is shifted to a state ST 4  of “standing” when the condition recognition information D 5  of “get up” is supplied. It will be understood that a motion is identical but states are different between these states ST 4  and ST 5  due to different histories of the past condition recognition information D 5 . 
     Actually, the action determining mechanism section  92  shifts a current state to a next state when detecting a predetermined trigger. Concrete examples of the trigger is that a motion at a current state has been performed for a fixed period of time and that an intensity of a desired unit out of intensities of the emotion units  100 A to  100 C and the desire units  101 A to  101 C represented by the specific condition recognition information D 5  and the emotion and instinct condition information D 6  supplied from the emotion and instinct model section  91  has exceeded a predetermined threshold value. 
     At this time, the action determining mechanism section  92  selects a state as a transition destination on the basis of whether or not the predetermined threshold value is exceeded by an intensity of a unit desired out of the emotion units  100 A to  100 C and the desire units  101 A to  101 C represented by the emotion and instinct condition information D 6  supplied from the emotion and instinct model  91 . Accordingly, the action determining mechanism section  92  is configured to make transition to a different state dependently on intensities of the emotion units  100 A to  100 C and the desire units  101 A to  101 C even when an identical condition recognition information D 5  is input. 
     Accordingly, the action determining mechanism section  92  generates action command information D 9  for allowing the pet robot to take a motion of “hand lending” in response to a palm stretched toward the eyes and sends out the information D 9  to the posture transition mechanism section  93 , when the action determining mechanism section  92  detects a palm stretched out toward the eye, on the basis of the supplied condition recognition information D 5 , detects an intensity of the “anger” emotion unit  100 C which is not higher than a predetermined threshold value on the basis of the emotion and instinct condition information D 6  and detects the battery voltage which is not lower than a predetermined threshold value (that is, “the pet robot is not hungry) on the basis of the condition recognition information D 5 . 
     Furthermore, the action determining mechanism section  92  generates the action command information D 9  to allow the pet robot to take a motion of “licking a palm” and sends out the information to the posture transition mechanism section  93 , when the action determining mechanism section  93  detects a palm stretched out toward the eyes, detects an intensity of the “anger” emotion unit  100 C which is not higher than the predetermined threshold value and detects “the pet robot is hungry,” that is, the battery voltage which is lower than the predetermined threshold value. 
     Furthermore, the action determining mechanism section  92  generates the action command information D 9  to allow the pet robot to take a motion of “looking aside in a huff” and sends out the information to the posture transition mechanism section  93 , when the action determining mechanism section  92  detects a palm stretched out toward the eyes and an intensity of the “anger” emotion unit  100 C which is not lower than the predetermined threshold value. It does not matter whether or not “the pet robot is not hungry,” that is, whether or not the battery voltage is not lower than the predetermined threshold value. 
     On the basis of intensities of units desired out of the emotion units  100 A to  100 C and the desire units  101 A to  101 C represented by the emotion and instinct condition information D 6  supplied from the emotion and instinct model section  91 , the action determining mechanism section  92  determines parameters for actions to be taken at a state of a transition destination, for example, walking speed, speeds and magnitudes to move hands and feet, a pitch and a volume of a sound to be given and so on, generates the action command information D 9  corresponding to the above described parameters for the actions and sends out the information to the posture transition mechanism section  93 . 
     Since the information recognition information D 5  which is given from the sensor input processing section  90  has contents which are different depending on timings of inputs into the emotion and instinct model section  91  and the action determining mechanism section  92 , the condition recognition information D 5  is input into both the emotion and instinct model section  91  and the action determining mechanism section  92 . 
     The controller  70  generates the emotion and instinct condition information D 6  of “joy” with the emotion and instinct model section  91  and supplies the emotion and instinct condition information D 6  to the action determining mechanism section  92 , for example, when the information recognition information D 5  representing “being patted on the head” is supplied. However, when the information recognition information D 5  representing “there is a hand in front of the eyes” is supplied in this condition, the controller  70  generates the action command information D 9  of “willing to lend a hand” in the action determining mechanism section  42  on the basis of the above described emotion and instinct condition information D 6  of “joy” and the information recognition information D 5  of “there is a hand in front of the eyes,” and sends out the action command information D 9  to the posture transition mechanism section  43 . 
     In FIG. 12, the posture transition mechanism section  93  generates posture transition information D 10  for transition of a current posture to a next posture on the basis of the action command information D 9  supplied from the action determining mechanism section  92  and sends out the posture transition information D 10  to the control mechanism section  94 . In this case, a posture to which a current posture can be shifted is determined dependently, for example, on physical forms of the pet robot  51  such as forms and weights of a body, hands and feet, coupling conditions of parts and mechanisms of the actuators  54 AA 1  to  56 A M  such as bending directions and angles of joints. 
     The postures to which the current posture can be shifted are classified into those to which the current posture can be shifted directly and others to which the current posture cannot be shifted directly. For example, the pet robot  51  with four feet can shift from a posture where it is lying with hands and feet largely thrown out to a lie-down posture, but not to a standing posture. This transition requires two steps of motions of taking a lie-down posture once with the hands and feet drawn near the body and then a motion of standing up. Furthermore, there is a posture which cannot be taken safely. For example, the four-footed pet robot easily falls down when it tries to raise both forefeet in a standing posture. 
     Therefore, the posture transition mechanism section  93  in which postures to which transition is possible are preliminarily registered sends out the above described action command information D 9  supplied from the action determining mechanism section  92  to the control mechanism section  94  as the posture transition information D 10  with no modification when the action command information D 9  represents a posture to which direct transition is possible. However, in the case of a direct transition is impossible, the posture transition mechanism section  93  generates the posture transition information D 10  which represents transitions to another possible posture and then to a target posture, and sends out the information to the posture transition mechanism section  94 . Accordingly, the pet robot  51  is capable of avoiding an unreasonable attempt to take a posture to which transition is impossible or an event of falling down. 
     Concretely speaking, the posture transition mechanism section  93  is configured to preliminarily register postures which the pet robot  51  is capable of taking and possible transition between two postures. 
     The posture transition mechanism section  93  uses an algorithm referred to as a directed graph  111  which expresses postures which the pet robot  51  is capable of taking with nodes NODE 1  to NODE 5 , in which the two postures between which transition is possible, that is, the nodes NODE 1  to NODE 5  are connected to each other with the directed arcs ARC 1  to ARC 10  for example, as shown in FIG.  17 . 
     When the action command information D 9  is supplied from the action determining mechanism section  92 , the posture transition mechanism section  93  searches for a path from a current node NODE 1  to NODE 5  to a next node NODE 1  to NODE 5  following a direction of the directed arc ARC 1  to ARC 10  by connecting a node NODE 1  to NODE 5  corresponding to a current posture to a node NODE 1  to NODE 5  corresponding to a posture to be taken next indicated by the action command information D 9  and consecutively records nodes NODE 1  to NODE 5  existing on the searched path, thereby planning posture transition. Accordingly, the pet robot  51  is capable of taking a motion directed by the action determining mechanism section  92  while avoiding an unreasonable attempt to take posture to which transition is impossible and an event of falling down. 
     When the action command information D 9  of “sit down” is supplied at the node NODE 2  which represents the current posture of “lie down,” for example, the posture transition mechanism section  93  gives posture transition information D 10  of “sit down” to the posture control mechanism section  94  utilizing a fact that direct transition is possible from the node NODE 2  representing a posture of “lie down” to the node NODE 5  representing a posture of “sit down.” 
     On the contrary, when the action command information D 9  of “walk” is supplied, the posture transition mechanism section  93  plans posture transition by searching for a path from the node NODE 2  of “lie down” to the node NODE 4  of “walk,” generates as a result the posture transition information D 10  which makes an order of “stand up” and then an order of “walk,” and sends out the information to the control mechanism section  94 . 
     In FIG. 12, the control mechanism section  94  generates a control signal S 20  for driving the actuators  54 AA 1  to  56 A M  on the basis of the posture transition information D 10 , sends out the control signal S 10  to the actuators  54 AA 1  to  56 A M  for driving the above described actuators  54 AA 1  to  56 A M , thereby allowing the pet robot  51  to take a desired action. 
     (2-4) Cover Fitting Processing Procedure RT 1   
     When the cover unit  52  is actually fitted, the controller  70  in the pet robot  51  enters a cover fitting processing procedure RT 1  shown in FIG. 11 from step SP 0 , and while monitoring a detected condition of the coupling sensor  80  in the main body side interface member  58  on the body member unit  53  at step SP 1 , the controller  70  proceeds to step SP 2  where the controller  70  judges whether or not the cover side interface member  60  in the cover unit  52  has been connected electrically and mechanically on the basis of a detection result of the above described coupling sensor  80 . 
     At the step SP 2 , the controller  70  waits for an affirmative result, proceeds to step SP 3  where the controller  70  reads out the cover setting information D 1  from the information storage member  81  in the cover side interface member  80  on the cover unit  52  and decodes an enciphered information included in the above described cover setting information D 1  at step SP 4 . 
     Successively, the controller  70  extracts a cover number included in the cover setting information D 1  at step SP 5  and proceeds to step SP 6  where the controller  70  reads out the performance information D 2  corresponding to the above described cover number with the information reading member  75  in the body member unit  53 . 
     The controller  70  then proceeds to step SP 7  where the controller  70  decodes enciphered information included in the performance information D 2 , which is read out with the information reading member  75  and at step SP 8 , judges whether or not the cover unit  52  fitted over the pet robot  51  is a regular cover on the basis of decoded results at the steps SP 4  and SP 7 . 
     When an affirmative result is obtained at the step SP 8  which represents that the cover unit  52  has been authenticated as a regular cover to be fitted over the pet robot  51 , the controller  70  proceeds to step SP 9  where the controller  70  monitors an on/off condition of the touch sensor  78  on the basis of spurring by the user and proceeds to step SP 10  only when detecting spurring such as “patting” and “striking”. 
     At the step SP 10 , the controller  70  determines a current emotion condition by accumulatively combining intensities of emotions such as “being patted” and “being struck” (the emotion units  100 A to  100 C described above in FIG.  13 ). 
     The controller  70  thereafter proceeds to step SP 11  where the controller  70  determines next action contents and sound contents dependently on the current emotion condition, selects action contents and sound contents suitable for the determined action contents and sound contents, out of the performance information D 2  corresponding to a type of the cover unit  52  (that is, the cover number) at step SP 12 , and then proceeds to step SP 13 . 
     On the contrary, when a negative result is obtained at the step S 8  which indicates that the cover unit  52  has not been authenticated as a regular cover to be fitted over the pet robot  51 , the controller  70  proceeds to step SP 14  where the controller  70  reads out an audio signal indicating an irregular cover, outputs sounds based on the audio signal from the speaker  79 , and proceeds to the step SP 13 . 
     While monitoring a detection condition of the coupling sensor  80  in the main body side interface member  58  at the step SP 13 , the controller  70  proceeds to step SP 15  where the controller  70  judges whether or not the cover side interface member  60  in the cover unit  52  has been connected electrically and mechanically on the basis of the detection result of the coupling sensor  80 . 
     When an affirmative result is obtained at the step SP 14 , the controller  70  proceeds to step SP 16  to terminate the above described cover fitting processing procedure RT 1  while moving the pet robot  51  autonomously in accordance with the above described action contents having an individuality and the sound contents corresponding to the cover unit  52 , which are determined at the step SP 12 . 
     When a negative result is obtained at step SP 15  which indicates that the cover unit  52  has been detached from the pet robot  51  by the user or the cover side interface member  60  of the cover unit  53  has been, disconnected from the main body side interface member  58  of the pet robot  51  due to some external cause regardless of a user&#39;s intention, in contrast, the controller  70  returns once again to the step SP 1  to repeat the processings as described above. 
     (2-5) Operations and Effects in this Embodiment 
     When the user fits a desired cover unit  52  over the pet robot  51  in the robot system  50 , the user first electrically and mechanically connects the cover side interface member  60  of the cover unit  52  to the main body side interface member  58  of the body member unit  53 . 
     Successively, it is judged whether or not the cover unit  52  is a regular cover on the basis of the cover setting information D 1  stored by the information storage member  81  in the cover unit  52  and when an affirmative result is obtained, the performance information D 2  corresponding to the above described cover setting information D 1  is read out from the information reading member  75  in the body member unit  53 . 
     As a result, the pet robot  51  is capable of changing conditions of a emotion and/or an instinct in an individual style in a predetermined changing state determined on the basis of the performance information D 2  when user&#39;s spurring or an external stimulus is given while the pet robot  51  is taking an autonomous action. 
     An intensity of the “anger” emotion is enhanced at a rate higher than usual, for example, when the cover unit  52  has an aggressive appearance like a fierce animal or a reptile, whereas an intensity of “joy” emotion is enhanced at a rate higher than usual when the cover unit  52  has a lovely appearance like a cherished stuffed toy. 
     As a result, the pet robot  51  is capable of recognizing the patting on the head by the user as a “disagreeable thing” and manifesting a emotion corresponding to the disagreeable thing when the cover unit  52  has the aggressive appearance, whereas the pet robot  51  is capable of recognizing the patting on the head by the user as a “joyful thing” and manifesting a emotion corresponding to the joyful thing when the cover unit  52  has the lovely appearance. 
     Furthermore, an intensity of the desire of “appetite” desire is enhanced at a rate higher than usual and/or an intensity of the desire of “desire for motion” is enhanced at a rate lower than usual when the cover unit  52  is a relatively heavy. When the cover unit  52  has a relatively light, on the other hand, an intensity of the desire of “appetite” is enhanced at a rate lower than usual and/or an intensity of the desire of “desire for motion” is enhanced at a rate higher than usual. 
     As a result, the pet robot  51  having the cover unit  52  which is a relatively heavy is capable of executing actions to appeal a desire for charging the battery  71  taking residual amount change of the battery  71  quicker than usual into consideration, thus showing to the user the appetite emotion like a real animal. Together with and/or instead of this action, the pet robot  51  is capable of taking a motion with less amount of motion as a residual amount of the battery  71  is reduced by reducing the amount of motion as the residual amount of the battery  71  gets low. 
     Furthermore, the pet robot  51  is capable of securing a crime preventive property by preventing use of a cover unit  52  prepared illegally by a third party since the enciphered information is included in the cover setting information D 1  which is stored in the information storage member  81  of the cover unit  52  so that the pet robot  51  judges whether or not the cover unit  52  attached to the pet robot  51  is the regular cover unit, on the basis of the above described enciphered information. 
     The configuration described above makes it possible to realize the robot system  50  having a remarkably enhanced amusement property since the information storage member  81  which stores the cover setting information D 1  relating to the cover unit  52  is disposed in the cover unit  52 , the performance information D 2  matched with the above described cover setting information D 1  is selectively read out of the performance information D 2  set for kinds of the cover unit  52  and stored in the information storage member  75  in the body member unit  53  when the cover unit  52  is fitted over the pet robot  51 , and emotions and instincts of the pet robot  51  are changed in accordance with predetermined changing conditions determined on the basis of the performance information D 2  so that performance information D 2  is reflected on making actual motions and actions of the pet robot  51  in individual styles. 
     (2-6) Other Embodiments 
     Note that, though the present invention is applied to the robot system  50  having a basic configuration of the quadruped walking type pet robot  51  configured as shown in FIG. 8 in the embodiments described above, the present invention is not limited by the embodiments and the present invention is applicable widely to robot apparatuses having other various configurations so far as the robot apparatus manifests predetermined motions (walking, light emission, sounding and so on). 
     Further, though the cover unit  52  which is composed of the cover main body  52 A made of synthetic fibers having a shape like a surface skin of a real dog is used as a cover to be detachably fitted over the robot apparatus as shown in FIG. 8 in the above described embodiments, the present invention is not limited by the embodiments and shapes like surface skins of other animals (cat, raccoon dog, horse, monkey, human or the like) may be made of other various kinds of materials (fur, textile, ceramic, synthetic resin, metal and so on). 
     Further, though the cover main body  52 A which is made of a monolithic molding of synthetic fiber having a form like a surface skin of an animal is used as the cover main body  52 A to form the cover unit  52 , the present invention is not limited to this and a plurality of cover parts  137  which are made of metal corresponding to parts of the pet robot  51  may be used separately as shown in FIG.  26 . In this case, the plurality of cover parts  137  consist of a head part  1370 A, a body part  1370 B, leg parts  137 C and shank parts  137 D, and the above described cover side interface member  60  is disposed in the body part  137 B. In addition, various kinds of material (synthetic fibers, fur, textile, ceramic, synthetic resin, and so on) other than metal are widely usable to form the cover parts  137 . 
     Further, though the controller  70  used as a control means in the body member unit  53  of the pet robot  51  is configured to determine the performance information D 2  corresponding to the cover number in the above described cover setting information D 1  on the basis of the cover setting information (inherent information) D 1  allocated to the above described cover unit  52  when the cover unit  52  is fitted over the pet robot  51  in the above described embodiments, the present invention is not limited to this and control means having various configurations may be used so far as the control means is capable of changing motion manifesting patterns on the basis of the cover setting information D 1  as occasion demands. 
     Further, though the cover setting information D 1  includes information about the cover number and the manufacturing license, the cover setting information may include information related to a type, a form, a material, a mass distribution, hardness and a heat conductivity of the cover unit as well as information related to an individuality, motions and actions of the cover unit. In this case, the controller  70  disposed as control means in the body member unit  53  of the pet robot  51  may be configured to determine actions of the pet robot  51  on the basis of only the cover setting information D 1  read out with the information reading member (information reading means)  75  and drive the actuators  54 AA 1  through  56 A M  which are required in relation to determined actions and allow the speaker  79  to give sounds as occasion demands. 
     Further, though an individuality is imparted by storing the cover number as the inherent information in the above described embodiments, the present invention is not limited by the embodiments and numbers and parameters defining a walking pattern, an action pattern and contents of motions suitable for a kind of animal represented by a cover (for example, hopping in case of a kangaroo or slow walking in case of a bear) may be stored as the inherent information dependently on the shapes of covers (for example, a kangaroo, a bear or a rabbit). 
     Further, though the cover side interface member  60  disposed in the cover unit  52  and the main body side interface member  58  disposed in the pet robot  51  are used as means for connecting the cover electrically and mechanically to the robot apparatus when the cover is fitted over the robot apparatus in the above described embodiments, the present invention is not limited by the embodiments and other means having various configurations may be used so far as the means can impart an individuality to each shape of cover unit  52  and detachably connect the cover to the robot apparatus. 
     Further, though the information storage member  81  is disposed in the cover unit  52  as the information storing means (memory) and the inherent information corresponding to the cover unit  3  is stored in the above described information storage member  81  in the above described embodiments, the present invention is not limited by the embodiments and a characteristic item corresponding to the inherent information (a mark, a bar code, a predetermined concavo-convex pattern, a protruding end having a special form or the like) may be disposed at a location to connect the pet robot  51  without disposing the information storage member  81  in the cover unit  52  so that the inherent information can be recognized by reading the characteristic item at the location to connect the pet robot  51 . Furthermore, as storing means, in addition to a non-volatile memory which stores the inherent information, a passive element such as a resistor, and magnetism may store inherent information, and a light emitting pattern of a light emitting diode (LED) may be used as inherent information. 
     Further, though the connector halves  57 A and  59 A and engaging mechanism parts  57 B and  59 B are connected between the connector part  59  of the cover side interface member  60  and the connector part  57  of the main body side interface member  58  so that the coupling sensor  80  in the connector part  57  of the main body side interface member  58  detects a connected condition between the cover unit  52  and the pet robot  51  on the basis of a voltage value obtained by way of the load resistor R 2  in the connector part  59  of the cover side interface member  60  and the connector part  57  of the main body side interface member  58  in the above described embodiments, the present invention is not limited by the embodiments and other various methods may be used to detect the connected condition between the cover unit  52  and the pet robot  51 . 
     It is possible, for example, to dispose a distance detecting member (not shown) in either the connector part  57  of the main body side interface member  58  or the connector part  59  of the cover side interface member  60  so that the controller  70  detects a connected condition between the connector parts  57  and  59  on the basis of changes of distance information obtained as a detection result of the above described distance detecting member, or to dispose a light amount detecting member (not shown) in the connector part  57  of the main body side interface member  58  so that the controller  70  detects the connected condition between the connector parts  57  and  59  on the basis of a light amount change obtained as a detection result of the above described light amount detecting member. 
     Further, though the controller  70  disposed as information detecting means in the body member unit  53  of the pet robot  51  determines the performance information D 2  corresponding to a type of the above described cover unit  52  on the basis of the cover setting information D 1  (inherent information) given from the cover unit  52  and determines actions of the pet robot  51  on the basis of the above described performance information D 2  in the above described embodiments, the present invention is not limited by the embodiments and form information included in the cover setting information D 1  may be judged so that parts of the pet robot  51  move free from interference due to the cover unit, or a mass distribution in the cover setting information D 1  is judged so that the pet robot  51  moves with good balance. 
     Further, though contents of the cover setting information D 1  allocated to each cover unit  52  are not reflected on the performance information D 2  when the cover side interface member  60  of the cover unit  52  is not connected to the main body side interface member  58  in the body member unit  53  of the pet robot  51  in the cover fitting processing procedure RT 1  shown in FIG. 18 in the above described embodiments, the present invention is not limited by the embodiments and some or all of actions and motions of the pet robot  51  may be restrained when the cover side interface member  60  of the cover unit  52  is not connected to the main body side interface member  58  in the body member unit  53  of the pet robot  51 . 
     Furthermore, though the information reading member  75  disposed as information reading means reads out the performance information D 2  from a recording medium (not shown) inserted from outside and sends out the information to the controller  70  in the body member unit  53  of the pet robot  51  in the above described embodiments, the present invention is not limited by the embodiments and a receiving device may be used as the information reading means to receive and download the performance information D 2  transmitted from outside. 
     (3) Third Embodiment 
     (3-1) Configuration of Robot System  120  according to this Embodiment 
     FIG. 19 where the same reference numerals are applied to parts corresponding to parts in FIG. 8 shows a pet robot system  120  according to a third embodiment. The pet robot system  120  has the same configuration as the pet robot system  50  (FIG. 8) except that a pet robot  121  has a function of changing motions and actions as if the real animal “grew”, in accordance with a history of operation inputs such as spurring and orders given with a sound commander from a user and histories of own actions and motions. 
     Concretely speaking, prepared for the pet robot  121  in this pet robot system  120  are four “growth steps” of “baby period,” “child period,” “young period” and “adult period.” Preliminarily stored in a memory  122 A (FIG. 19) of a controller  122  (FIG. 10) are action and motion models consisting of various kinds of control parameters and control programs to be used as bases of actions and motions related to four items of “walking condition,” “motion,” “action” and “sound” for each “growth step.” 
     At an initial stage, the controller  122  controls actuators  54 AA 1  to  56 A M  and a sound output according to action and motion models for “baby period” so that “walking condition” is made “tottering walk” by narrowing steps, “motion” is made “simple” motions like “walk,” “stand up” and “lie down,” “action” is made a monotonous action consisting of an identical action which is repeated and “sound” is made a “low and short” sounds by lowering an amplification ratio of an audio signal S 16 . 
     At this time, the controller  122  always monitors and counts generation of a plurality of predetermined factors related to “growth” (hereinafter referred to as growth factors) such as strengthening learning consisting of order inputs using a sound commander, sensor inputs by way of a touch sensor  78  such as “patting” and “striking,” and the number of successes in predetermined actions and motions, sensor inputs by way of the touch sensor  78  other than “patting” and “striking,” and predetermined actions and motions such as “playing with a ball.” 
     When a total value of accumulative frequencies of the growth factors (hereinafter referred to as a total experience value of the growth factors) exceeds a predetermined threshold value, the controller  122  modifies the action and motion models for “baby period” into action and motion models for “child period” at a higher growth level (at which actions and motions are harder and more complicated) on the basis of the accumulative frequencies of the growth factors. 
     Thereafter, the controller  122  controls the actuators  54 AA 1  to  56 A M  and a sound output from the speaker  79  according to the action and motion models for “child period” so that “walking condition” is made walking “with a little firm steps” by enhancing rotating speeds of the actuators  54 AA 1  to  56 A M , “motion” is made “a little upgraded and complicated” motions by increasing the number of motions, “action” is made a motion “with a little purpose” by determining a next action by referring to a preceding action and “sound” is made “a little long and loud” sounds by prolonging the audio signal S 16  and enhancing an amplification ratio of the signal. 
     Each time the total experience value of the growth factors exceeds each of a threshold value predetermined for each “young period” and “adult period,” the controller  122  similarly modifies the action and motion models into action and motion models for “young period” or “adult period” at a higher growth level, gradually enhances the rotating speeds of the actuators  54 AA 1  to  56 A M , prolongs the audio signal S 16  according to above described action and motion models, enhances the amplification ratio of the audio signal S 16  to be given to the speaker  79  and changes rotating amounts of the actuators  54 AA 1  to  56 P M  for a single motion. 
     As a result, the pet robot  121  changes stepwise “walking condition” from “tottering walk” to “firm walking,” changes “motion” from “simple” to “upgraded and complicated,” changes “action” from “monotonous” to “action with a purpose” and changes “sound” from “low and short” to “long and loud” as the pet robot  121  has ascended “growth step” (that is, “growth step” changes from “baby period” to “child period,” from “child period” to “young period” and from “young period” to “adult period”). 
     The pet robot  122  is configured to “grow” at the four steps of “baby period,” “child period,” “young period” and “adult period” dependently on external inputs as well as histories of actions and motions of the pet robot itself as described above. 
     In case of this embodiment, a plurality of action and motion models are prepared for “growth steps” of “child period,” “young period” and “adult period” as shown in FIG.  20 . 
     Actually prepared as the action and motion models for “child period” are action and motion models (Child  1 ) which provide a “rude” character manifesting quick and rough actions and motions, and action and motion models (Child  2 ) which provide a “gentle” character manifesting smooth and slow actions and motions. 
     Furthermore, prepared as action and motion models for “young period” are action and motion models (Young  1 ) which provide an “irritated” character manifesting actions and motions which are quicker and rougher than those of the “rough” character in “child period,” action and motion models (Young  2 ) which provide an “ordinary” character manifesting actions and motions slower and smoother than those of the “irritated” character, and action and motion models (Young  3 ) which provide a “gentle” character manifesting actions and motions slower and smaller in amounts than those of the “ordinary” character. 
     Furthermore, prepared as action and motion models for “adult period” are action and motion models (Adult  1 ) which provide an “aggressive” character manifesting motions quicker and rougher than those of the “irritated” character of “young period” and hardly movable in accordance with user&#39;s orders, action and motion models (Adult  2 ) which provides a “little rough” character liable to manifest smoother and slower actions and motions in accordance with user&#39;s orders, action and motion models (Adult  3 ) which provide a “little gentle” character manifesting smoother and slower actions and motions in smaller amounts and always moving in accordance with user&#39;s orders, and action and motion models (Adult  4 ) which provide a “gentle” character manifesting much slower actions and motions in smaller amounts and always moving in accordance with user&#39;s orders. 
     When upgrading “growth step,” the controller  122  selects a action model and/or a motion model out of action and motion models for a next “growth step” on the basis of the accumulative frequency of each growth factor, and modifies the used action and motion models with the selected action and motion models. 
     On and after “child period,” action and motion models at a current “growth step” can be shifted only to specific action and motion models connected by the arrows in FIG. 20 at a next “growth step.” When the action and motion models (Child  1 ) manifesting the “rough” actions and motions has been selected at “child period,” for example, the model cannot be shifted to the action and motion model (Young  3 ) which manifests “gentle” actions and motions at “young period.” 
     The pet robot  121  is configured to change also “character” along with “growth” dependently on a history of inputs such as spurring and orders from the user, and a history of actions of the pet robot itself as if the pet robot was a real animal which grows and has its character dependently on breeding manner of an owner. 
     (3-2) Processing by Controller  122   
     Now description will be made of processing which is performed by the controller  122  for generating actions of the pet robot  121 . 
     As shown in FIG. 21 where the same reference numerals are applied to parts corresponding to those of FIG. 12, functions of the controller  122  which performs processing for generating actions of the pet robot  121  can be classified into a sensor input processing section  130  which recognizes specific conditions, a emotion and instinct model section  131  which expresses the emotion and instinct conditions on the basis of the recognition result by the sensor input processing section  130 , an action determining mechanism section  132  which determines a successive action on the basis of a result recognized by the sensor input processing section  130 , an action generating mechanism section  133  which allows the pet robot  121  to actually manifest actions on the basis of a result determined by the action determining mechanism section  132  and a growth step control mechanism section  133  which controls the “growth steps” of the pet robot  121 . 
     In this case, the sensor input processing section detects and recognizes surrounding and own conditions, and the presence and absence of spurring and orders from a user, on the basis of the audio signal S 10 , the image signal S 11 , the pressure detection signal S 12 , the battery residual amount detection signal S 13  and the heat detection signal S 14  which are given from the microphone  76 , the CDD camera  77 , the touch sensor  78 , the battery sensor  72 , and the heat sensor, and also recognizes the presence and absence of the cover unit  52  and various setting information set for the cover unit  52 , on the basis of the cover detection signal S 15  which is supplied from the coupling sensor  80  in the main body side interface member  58 , the cover setting information D 1  read out from the information storage member  81  in the cover side interface member  60 , and the performance information D 2  read out with the information reading member  75  in the body member unit  53 . Then, the sensor input processing section informs the emotion and instinct model section  131  and the action determining mechanism section  132  of the recognition result as the condition recognition information D 20 . 
     Then, the emotion and instinct model section  131  decides emotions and instincts of the pet robot  121  of this time and sends out the decided emotion and instinct conditions as emotion and instinct condition information D 21  to the action determining mechanism section  132 , as in the case of the emotion and instinct model section  91  described in the second embodiment in FIG.  12 . 
     When the condition recognition information D 20  is given from the condition recognizing mechanism section  130  or when the current action has been performed for a fixed period of time, the action determining mechanism section  132  determines a next action such as “stand up” “lie down” or “walk” on the basis of the emotion and instinct condition information D 21  which is given from-the emotion and instinct model section  131  and a control parameter for an “action” of action and motion models which is preliminarily designated by the growth step control mechanism section  134  out of the control parameters for “action” of the action and motion models which are stored in the memory  122 A. 
     Concretely speaking, the action determining mechanism section  132  uses, as means for determining a next action, an algorithm referred to as a probability automaton which expresses conditions using nodes NODE 0  to NODE n  and determines transition to be made from the node NODE 0  to any of the nodes NODE 1  through NODE n  with a probability on the basis of transition probabilities P 1  through P n  which are set for arcs ARC 1  through ARC n  with which the nodes NODE 0  through NODE n  are connected to each other, as shown in FIG.  22 . 
     The transition probabilities P 1  through P n  for the arcs ARC 1  through ARC n  are preliminarily set as control parameters related to “actions” and stored in the memory  122 A for each action and motion model at each “growth step.” 
     When the condition recognition information D 20  is given from the condition recognizing mechanism section  130  or when the pet robot has been in the current condition (node NODE 0 ) for a fixed period of, for example, the action determining mechanism section  132  determines a next condition (nodes NODE 1  through NODE n ) with the probability automaton on the basis of the transition probabilities P 1  through P n  for the arcs ARC 1  through ARC n  which are control parameters related to “actions” of the action and motion models selected at that time and informs the emotion and instinct model section  131 , the action generating mechanism section  133  and the growth step control mechanism section  134  of actions for transition to the above described condition as action determining information D 22 . 
     The action generating mechanism section  133  has, in the memory  122 A of the controller  122 , various kinds of control parameters and necessary control programs for “walking condition,” “motion” and “sound” of each action and motion model correspondingly to each action and motion model at each “growth step” described above. 
     When the action determination information D 22  is given from the action determining mechanism section  132 , the action generating mechanism section  133  makes a concrete action plan for executing actions determined by the action determining mechanism section  132  on the basis a various kinds of control parameters and necessary control programs for the action and motion models preliminarily designated by the growth step control mechanism section  134 , out of the various kinds of control parameters and necessary control programs for “walking condition,” “motion” and “sound” of the action and motion models which are stored in the memory  122 A. The action plan is calculated actually as numerical values representing the number of rotations of the actuators  54 AA 1  through  56 A M  which are required to execute the action. 
     The action generating mechanism section  133  generates a control signal S 20  for the required actuators  54 AA 1  through  56 A M  on the basis of this driving plan, and drives and controls corresponding actuators  54 AA 1  through  56 A M  on the basis of the control signal S 20 , thereby allowing the pet robot  121  to execute the actions determined by the action determining mechanism section  131 . 
     When the condition recognizing mechanism section  130  recognizes some condition on the basis of the audio signal S 10 , the image signal S 11 , the pressure detection signal S 12 , the battery residual amount detection signal S 13  and the heat detection signal S 14  which are given from the microphone  76 , the CCD camera  77 , the touch sensor  28 , the battery sensor  72  and the heat sensor  73 , the condition recognizing mechanism section  130  informs the growth step control mechanism section  134  of the condition as condition recognition information D 23 . 
     The condition given from the condition recognizing mechanism section  130  to the growth step control mechanism section  134  is not only the specific conditions which are supplied to the action determining mechanism section  132  as described above but also inputs using the touch sensor  78  which do not correspond to “patting” or “striking.” 
     Further, the growth step control mechanism section  134  has, in the memory  122 A, a list (hereinafter referred to as a first growth factor list)  135 A of the above described growth factors which are to be used as reference factors for enhancing “growth step” out of various kinds of conditions based on the condition recognition information D 23  given from the condition recognizing mechanism section  131  as shown in FIG.  23 (A) and a countertable (hereinafter referred to as a first growth factor countertable)  136 A such as that shown in FIG.  23 (B) for counting accumulative frequencies of the growth factors. 
     When the condition recognition information D 23  is given from the condition recognizing mechanism section  130 , the growth step control mechanism section  134  judges on the basis of the first growth factor list  135 A whether or not a condition obtained on the basis of the condition recognition information D 23  is a growth factor, and when the above described condition is a growth factor, the growth step control mechanism section  134  increases a corresponding count value (experience value) by one in the first growth factor countertable  136 A. 
     Further, the growth step control mechanism section  134  has, in the memory  122 A, a list (hereinafter referred to as a second growth factor list)  135 B of the above described growth factors which are to be used as reference factors for enhancing “growth step” as to actions obtained on the basis of the action determination information D 22  given from the action determining mechanism section  132  as described above as shown in FIG.  24 (A) and a countertable (hereinafter referred to as a second growth factor countertable)  136 B such as that shown in FIG.  24 (B) for counting accumulative frequencies of these growth factors. 
     When the action determination information D 22  is given from the action determining mechanism section  132 , the growth step control mechanism section  134  judges on the basis of the second growth factor list  135 B whether or not the actions obtained on the basis of the above described condition recognition information D 20  is a growth factor, and when the above described action is a growth factor, the growth step control mechanism section  134  increases a corresponding count value (experience value) by one in the second growth factor countertable  136 B. 
     When the count value is increased in the first or second growth factor countertable  136 A or  136 B as described above, the growth step control mechanism section  134  increases a count value by one in a counter (hereinafter referred to as a total experience value counter) provided separately from the first and second growth factor countertables  136 A and  136 B for judging whether or not “growth step” is to be enhanced and then judges whether or not a count value of the total experience value counter has reached a count value preliminarily set as a condition to terminate a current “growth step.” 
     When the count value of the total experience value counter has reached the count value preliminarily set as the condition to terminate the current “growth step,” the growth step control mechanism section  134  determines action and motion models at a next “growth step” to which transition is to be made from the current action and motion models on the basis of count values in the first and second growth factor countertables  136 A and  136 B, and informs the action determining mechanism section  132  and the action generating mechanism section  133  of the determination result. At an initial condition, the growth step control mechanism section  134  informs the action determining mechanism section  132  and the action generating mechanism section  133  of orders so as to select the action and motion models for “baby period.” 
     As a result, the action determining mechanism section  132  selects a control parameter for “action” of the designated action and motion model on the basis of information from the growth step control mechanism section  134 , thereafter determining actions next to the current actions of the pet robot  121  using this control parameter as described above. 
     Further, the action generating mechanism section  132  selects various kinds of control parameters and necessary control programs for “walking condition,” “motion” and “sound” of the designated action and motion models on the basis of information from the growth step control mechanism section  134 , thereafter driving and controlling the actuators  54 AA 1  through  56 A M  and the sound output using the various kinds of control parameters and the necessary control programs. 
     The controller  122  generates actions of the pet robot  121  so as to be capable of acting autonomously while enhancing “growth step” as occasion demands as described above. 
     (3-3) Growth Step Control Processing Procedure RT 2   
     The growth step control mechanism section  134  controls “growth step” of the pet robot  121  in accordance with a growth step control processing procedure RT 2  shown in FIG.  25 . 
     After power is turned on, the growth step control processing mechanism section  134  starts the growth step control procedure RT 2  at step SP 20  and judges whether or not the condition recognition information D 23  has been given from the condition recognizing mechanism section  130  at succeeding step SP 21 . 
     When a negative result is obtained at the step SP 21 , the growth step control mechanism section  134  proceeds to step S 22  and judges whether or not the action determination information D 22  has been given from the action determining mechanism section  132 . When a negative result is obtained at the step SP 22 , the growth step control mechanism section  134  returns to the step SP 21  and repeats a loop of steps SP 21 -SP 22 -SP 21  until an affirmative result is obtained at the step SP  21  or SP 22 . 
     When the affirmative result is obtained at the step SP 21 , the growth step control mechanism section  134  proceeds to step SP 23  and judges whether or not a condition obtained on the basis of the condition recognition information D 23  given from the condition recognizing mechanism section  130  is a growth factor. 
     The growth step control mechanism section  134  returns to the step SP 21  when a negative result is obtained at the step SP 23 , whereas the growth step control mechanism section  134  proceeds to step SP 24  when an affirmative result is obtained, and increases a corresponding count value in the first growth factor list  135 A and a count value in the total experience value counter, by one respectively. 
     Successively, the growth step control mechanism section  134  proceeds to step SP 25  and judges whether or the count value in the total experience count value has reached a count value which is preliminarily set as a terminating condition of a current “growth step.” 
     The growth step control mechanism section  134  returns to the step SP 21  when a negative result is obtained at the step SP 25 , whereas the growth step mechanism section  134  proceeds to step SP 26  when an affirmative result is obtained, determines action and motion models at a next “growth step” to which the action and motion models are shifted, informs the action determining mechanism section  132  and the action generating mechanism section  133  of the determination result, and returns to the step SP 21 . 
     When an affirmative result is obtained at the step SP 22 , the growth step control mechanism section  134  proceeds to step SP 27  and judges whether or not the actions obtained on the basis of the action determining information D 22 , given from the action determining mechanism section  132  is a growth factor. 
     The growth step control mechanism section  134  returns to the step SP 21  when a negative result is obtained at the step SP 27 , whereas the growth step control mechanism section  134  proceeds to step SP 24  when an affirmative result is obtained, increases a corresponding count value in the second growth factor list  135 B and a count value in the total experience value counter, by one respectively, proceeds to the step SP 25  and executes processings similar to those which have been described above. 
     (3-4) Operations and Effects of Third Embodiment 
     To fit a desired cover unit  52  over the pet robot  121  in the robot system  120  which has the above described configuration, the user connects the cover side interface member  60  of the cover unit  52  electrically and mechanically to the main body side interface member  58  of the body member unit  53 . Then, it is judged on the basis of the cover setting information D 1  read out of the information storage member  81  in the above described cover unit  52  whether or not the cover unit  52  is a regular cover unit, and the performance information D 2  corresponding to the above described cover setting information D 1  is read out from the information reading member  75  in the body member unit  53  when an affirmative result is obtained. 
     As a result, the pet robot  121  is capable of changing transition rates of action and motion models at “growth step” of the pet robot  121  in an individual style in a predetermined changing condition determined on the basis of the performance information D 2  when user&#39;s spurring or an external stimulus is given while the pet robot  121  is acting autonomously. 
     The transition rate of the action and motion model at “growth step” is lower than usual when the cover unit  52  has a childish appearance like that of an animation character or a cherished stuffed toy, whereas the transition rate of the action and motion models at “growth step” is higher than usual when the cover unit  52  has an intelligent appearance like that of a police dog. 
     As a result, the pet robot  121  can act and move as if it were a real animal which stays in “baby period” and “child period” for rather a long time in case of a cover unit  52  manifesting a childish appearance, whereas the pet robot  121  is capable of acting and moving as if it were a real animal which is at a process of “young period” or “adult period” soon reached in case of a cover unit  52  manifesting an intelligent appearance. 
     The configuration described above makes it possible to realize the robot system having a remarkably enhanced amusement property, because the information storage member  81  which stores the cover setting information D 1  related to the above described cover unit  52  is disposed in the cover unit  52 , the performance information D 2  suitable for the above described cover setting information D 1  is selectively read out of the performance information D 2  set for a type of the cover unit  53  with the information reading member  75  in the body member unit  53  when the above described cover unit  52  is fitted over the pet robot  121 , and an upgrading rate of a growth step of the pet robot  121  is changed in a predetermined changing condition determined on the basis of the above described performance information D 2  so that the performance information D 2  is reflected on making actual motions and actions of the pet robot  121  in individual styles. 
     (3-5) Other Embodiments 
     Note that, in the aforementioned embodiment, through the present invention is applied to the robot system  120  which comprises the pet robot  121  using the growth models as shown in FIG. 20, the present invention is not limited thereto and may be applied to other kinds of robot system which comprises a robot apparatus using other type of growth models. 
     Further, in the aforementioned embodiment, though the growing speed is changed in accordance with the appearance of the cover unit  53 , the present invention is not limited thereto and growth models may be changed dependently on the appearance of the cover unit  53 . 
     (4) Fourth Embodiment 
     (4-1) Configuration of Robot System in this Embodiment 
     In FIG. 27, reference numeral  140  represents a pet robot system as a whole in this embodiment which is configured to cover a whole surface of a pet robot  141  with a predetermined cover part (hereinafter referred to as a cover unit)  142  by detachably fitting the cover unit  142  over the above described pet robot  141 . 
     The pet robot  141  is actually composed by coupling leg member units  144 A through  144 D with front right, front left, rear right, rear left portions of a body member unit  143 , and connecting a head member unit  145  and a tail member unit  146  to a front end and a rear end of the body member unit  143 . 
     A cooling fan (not shown) is disposed in the body member unit  143 , and an air exhaust port  143 AX and an air suction port  143 BX (FIG. 2) are formed in a top surface  143 A and a bottom surface  143 B so as to be placed under and above the cooling fan. Accordingly, the pet robot  141  is configured to be capable of lowering an internal temperature of the above described body member unit  143  by exhausting air sucked from the air suction port  143 BX, through the body member unit  143  from the air exhaust port  143 AX to outside as the cooling fan is driven. 
     Furthermore, disposed on a bottom surface  143 B of the body member unit  143  is an interface member (hereinafter referred to as a main body side interface member)  148  on which a connector part  147  is composed of a connector half  147 A and an engaging mechanism part  147 B as shown in FIG.  28 . 
     On the other hand, as shown in FIG. 27, the cover unit  142  is formed by a cover main body  142 A made of synthetic fibers resembling a surface skin of a real dog, and disposed at a predetermined location on the back surface of the above described cover main body  142 A is an interface member (hereinafter referred to as a cover side interface member)  150  on which a connector part  149  is composed of a connector half  149 A and an engaging mechanism part  149 B so as to fit the connector half  147 A and the engaging mechanism part  147 B of the main body side interface member  148  disposed on the body member unit  143 . 
     To fit the cover unit  142  actually over the pet robot  141 , the cover main body  142 A of the cover unit  142  is fitted so as to cover a whole surface of the pet robot  141 , the connector halves  147 A and  149 A are electrically connected to each other and the engaging mechanism parts  147 B and  149 B are connected mechanically by connecting the connector part  149  of the cover side interface member  150  to the connector part  147  of the main body side interface member  148 . 
     (4-2) Concrete Configurations of Pet Robot  141  and Cover Unit  142   
     In a robot system  1  shown in FIG. 29, accommodated in a body member unit  143  of a pet robot  1141  are a controller  160  which controls motions of the pet robot  141 , the main body side interface member  148  which consists of a coupling sensor  161  and a connector part  147 , an information reading member  162  which reads out control programs stored in a recording medium (not shown) which is to be inserted from outside, an acceleration sensor  163 , an angular velocity sensor  164  and a battery (not shown) which functions as a power source for the pet robot  161 . 
     The acceleration sensor  163  of the body member unit  143  detects accelerations in directions of three axes (X-axis, Y-axis and Z-axis) in a unit of several dozens of milliseconds and sends out the detection result as an acceleration-detection signal S 30  to the controller  160 . Furthermore, the angular velocity sensor  164  detects rotating angular velocity in directions of three angles (angle R, angle P and angle Y) in a unit of several dozens of milliseconds and sends out the detection result as an angular velocity detection signal S 31  to the controller  160 . 
     Disposed at predetermined locations in the head member unit  145  are a microphone  165  which is used as “ears”, a CCD (charge coupled device) camera  166  which is used as “eye”, a distance sensor  167 , a touch sensor  168 , a speaker  169  which is used as a “mouth” and so on. 
     The microphone  165  in the head member unit  145  gathers order sounds such as “walk,” “lie down” or “chase a ball” which are given in form of musical scales from a user with a sound commander (a commander which gives sounds in form of musical scales different dependently on contents of operations) (not shown), and sends out the obtained audio signal S 32  to the controller  160 . 
     Further, the CCD camera  166  picks up an image of a front situation and sends out the obtained image signal S 33  to the controller  160 , and the distance sensor  167  composed of an infrared distance sensor or the like measures a distance to a front object and sends out a measurement result as a distance measurement signal S 34  to the controller  160 . 
     Furthermore, the touch sensor  168  is disposed on the head member unit  145  as apparent from FIG. 27, and detects pressures applied from the user by physical spurring such as “patting” and “striking,” and sends out the detection result as a pressure detection signal S 35  to the controller  160 . 
     Furthermore, actuators  144 AA 1  through  144 AA K ,  144 BA 1  through  144 BA K ,  144 CA 1  through  144 CA K ,  144 DA 1  through  144 DA K ,  145 A 1  through  145 A L  and  146 A 1  through  146 A M  as well as potentiometers  170 AA 1  through  170 AA K ,  170 BA 1  through  170 BA K ,  170 CA 1  through  170 CA K ,  170 DA 1  through  170 DA K ,  171 A 1  through  171   L ,  172 A 1  through  172 A M  are disposed in joint parts of leg member unit  144 A through  144 D, coupled parts of the leg member unit  144 A through  144 D and the body member unit  143 , a coupled part of the head member unit  145  and the body member unit  143 , and a coupled part of a tail member unit  146  and the body member unit  143 , etc. 
     The potentiometers  170 AA 1  through  170 AA K ,  170 BA 1  through  170 BA K ,  170 CA 1  through  170 CA K ,  170 DA 1  through  170 DA K ,  171 A 1  through  171   L  and  172 A 1  through  172 A M  detect rotating angles of output shafts of corresponding actuators  144 AA 1  through  144AA   K ,  144 BA 1  through  1   44BA   K ,  144 CA 1  through  144 CA K ,  144 DA 1  through  144 DA K ,  145 A 1  through  145 A L  and  146 A 1  through  146 A M , and send out the detection results as angle detection signals to the controller  160 . 
     Furthermore, the main body side interface member  148  of the body member unit  143  is composed of the coupling sensor  161  and the above described connector part  147  comprising the connector half  147 A and the engaging mechanism part  147 B. The coupling sensor  161  detects a coupling state of the main body side interface member  148  with the cover side interface member  150  of the cover unit  142  and sends out the detection result as a cover detection signal S 36  to the controller  160 . 
     The controller  160  judges surrounding conditions and whether or not user&#39;s order or spurring exists, on the basis of the audio signal S 32 , the image signal S 33 , the distance measurement signal S 34 , a pressure detection signal S 35 , the acceleration detection signal S 30 , the angular velocity detection signal S 31 , a cover detection signal S 36  and so on which are given from the microphone  165 , the CCD camera  166 , the distance sensor  167 , a touch sensor  168 , the acceleration sensor  163 , the angular velocity sensor  164  and the coupling sensor  161 . 
     On the basis of the judgment result and the control program which is input in advance, the controller  160  determines next actions, and allows the pet robot to take actions such as swinging the head member unit  145  up, down, left and right, moving the tail member unit  146 , walking with the leg member units  144 A through  144 D by driving the actuators  144 AA 1  to  144 AA K ,  144 BA 1  to  144 BA K ,  144 CA 1  to  144 CA K ,  144 DA 1  to  144 DA K ,  145 A 1  to  145 A L  and  146 A 1  to  146   M  which are required for actions from the determination result. 
     At this time, the controller  160  gives a predetermined audio signal S 37  to the speaker  169  as occasion demands, thereby allowing the speaker to output sounds based on the audio signal S 37  to outside, and turns on or off or flickers LEDs (light emitting diode) (not shown) which are disposed at locations of “eyes” of the pet robot  141 . 
     In this way, the pet robot  141  is capable of acting autonomously on the basis of surrounding conditions, the control programs and the like. 
     In the cover unit  142 , on the other hand, the cover side interface member  150  which is built in a cover main body  142 A is composed of an information storage member  173  and the above described connector part  149 , and the above mentioned connector part  149  is composed of the connector half  149 A and the engaging mechanism part  149 B. The engaging mechanism part  149 B in the cover side interface member  150  is configured so as to detachably engage with the engaging mechanism part  147 B in the main body side interface member  148 . 
     The information storage member  173  in the cover side interface member  150  is composed, for example, of a non-volatile memory such as a ROM (random access memory) in which information representing a manufacturer&#39;s ID, information representing a manufacturing license such as a product ID and a lot number determined by a manufacturer, setting information such as enciphered information for authenticating the cover unit (hereinafter referred to as cover setting information) D 1  are stored preliminarily for each cover number allocated to each kind of the cover unit  142 . 
     Furthermore, program information for determining performance of the pet robot  141  (hereinafter referred to as performance information) D 31  and information representing a mass distribution of each cover (hereinafter referred to as mass distribution information) D 32  which are set for each cover number described above according to contents of the cover setting information D 30  are stored preliminarily in a recording medium to be inserted into the information reading member  162  disposed in the body member unit  143 . 
     Furthermore, information related to a barycenter location of the pet robot in a standard posture of standing with all four legs stretched with no cover fitted (hereinafter referred to as initial barycenter location information) D 33  is preliminarily stored in the information reading member  162 . 
     When the cover side interface member  150  is coupled with the main body side interface member  148 , the connector half  149 A and the engaging mechanism part  149 B disposed on the connector part  149  of the above described cover side interface member  150  are connected electrically and mechanically to the connector half  147 A and engaging mechanism part  147 B respectively, which are disposed on the connector part  147  of the main body side interface member  148 . 
     Concretely speaking, the main body side interface member  148  and the cover side interface member  150  are configured as shown in FIG.  30 . 
     In the main body side interface member  148 , connecting terminals A 1  to A 4  for a grounding line L 1 , a power source line L 2 , a measurement line L 3  and a signal line L 4  are exposed on the connector half  147 A of the connector part  147 , and an end of a load resistor R 1  which has the other end connected to ground is connected between the connecting terminal A 3  and the coupling sensor  161  on the measurement line L 3 . 
     In the cover side interface member  150 , connecting terminals A 5  to A 8  for a ground line L 5 , a power source line L 6 , a measurement line L 7  and a signal line L 8  are exposed on the connector part  149 , a load resistor R 2  is disposed on the measurement line L 7  which is drawn from the power source line L 6 , and ends of the above described load resistor R 2  are connected to the information storage member  171  and the connecting terminal A 7 . 
     When the connector half  149 A disposed on the connector part  149  of the cover side interface member  150  is actually connected to the connector half  147 A disposed on the connector part  147  of the main body side interface member  148 , the connecting terminals A 1  to A 4  for the ground line L 1 , the power source line L 2 , the measurement line L 3  and the signal line L 4  on the connector half  147 A are brought into contact with and conductive to the connecting terminals A 5  to A 8  for the corresponding lines L 5  to L 8  on the connector half  149 A. 
     At this time, the coupling sensor  161  in the main body side interface member  148  detects a voltage value of the load resistor R 2  on the measurement line L 7  connected to the power source line L 6  by way of the connector halves  149 A and  147 A conductive to each other, between the cover side interface member  150  and the main body side interface member  148 , thereby judging a coupling condition of the main body side interface member  148  with the cover side interface member  150  (an “H” level in a coupling condition or an “L” level in a separated condition). 
     As a result, the controller  160  reads out the cover setting information D 30  stored in the information storage member  173  in the cover side interface member  150  only when the detection result of the coupling sensor  161  is affirmative, reads out the performance information D 31  from the recording medium inserted into the information reading member  162  in the body member unit  143  on the basis of the above described cover setting information D 30 , determines an action of the pet robot  141  on the above described performance information D 31 , and drives the actuators  144 AA 1  to  146 A M  which are required for the determined action, thereby allowing the speaker  169  to output sounds as occasion demands. 
     As described above, when the cover unit  142  is fitted, the pet robot  141  is capable of autonomously changing actions with the individuality according to the cover setting information D 30  stored in the information storage member  173  in the cover side interface member  150  of the above described cover unit  142  and the performance information D 31  stored in the recording medium which is read out with the information reading member  162  in the body member unit  143  on the basis of the above described cover setting information D 30 . 
     In addition to the configuration described above, the controller  160  corrects, at a stage to allow the pet robot  141  to act, an error of a location of the barycenter of the pet robot  141  (that is, modifies standard values of control parameters under influence due to the barycenter) before and after fitting the cover unit  142 , on the basis of the acceleration detection signal S 30 , the angular velocity detection signal S 31 , the image signal S 33 , the distance measurement signal S 34  and the like which are supplied from the acceleration sensor  163 , the angular velocity sensor  164 , the CCD camera  166  and the distance sensor  167 . 
     Description will be made below of processing performed by the controller  160 . First, various kinds of parameters for walking control of the pet robot  141  will be described. In case of the pet robot  141 , the walking control is carried out on the basis of a control program described with  22  parameters which are stored in the information reading member  22  of the body member unit  143  as shown in FIG.  31 . 
     These parameters consist of parameters for determining a standard walking posture, parameters for determining movements of the leg member units  144 A through  144 D and parameters for determining entire movements of a body. These parameters will be described below. 
     First, a center coordinate is set in the body member unit  143  of the pet robot  141  in a standard posture of standing with all the four legs stretched, as shown in FIG.  32 . When the center coordinate is set relative to an absolute coordinate system, the pet robot stoops with the leg member units  144 A through  144 D bent in a standard walking posture, whereby the above described center coordinate moves in an up-down direction and a back-forth direction in the absolute coordinate system. Values of movements are controlled with parameters of “body center x” and “body center z.” 
     In this standard walking posture, the body member unit  143  is not only translated but also inclined forward or backward and this inclination is controlled with a parameter of “body pitch.”Furthermore, grounding locations for the leg member unit  144 A through  144 D also influence walking in the standard walking posture. In order to reduce the number of parameters, an offset in an astride direction is set at an identical value for the front and rear leg member units  144 A through  144 D and controlled with a parameter of “all legs y.” 
     Furthermore, offsets in the back-forth direction of the front leg member units  144 A,  144 B and the rear leg member units  144 C,  144 D are controlled with parameters of “front legs z” and “rear legs z” respectively. These are the parameters for the standard walking posture. 
     On the other hand, control parameters used to control movements of the leg member units  144 A through  144 D are as described below. FIG. 33 shows simplified movements of one leg member unit  144 A to  144 D. 
     First, a parameter for determining a length of a walking step is determined as “step length.” Furthermore, a height and a time of raising the leg member units  144 A through  144 D at a swinging-leg time are controlled with parameters of “swing height” and “swing time” respectively. 
     “swing multi” is a parameter which represents a ratio of a grounding time to a swinging-leg time at one cycle of a leg, and this parameter controls the grounding time and the swinging-leg time of each of the leg member units  144 A through  144 D. This parameter can be used also as a parameter for controlling a rising manner of the leg member units  144 A through  144 D when transition processing from a crawl walking style (static walking) to a trot walking style (dynamic walking) or to a pace walking style (dynamic walking), for example, is performed with a different algorithm. 
     Walking safety and speed can be improved by adding relatively backward, forward, leftward and rightward translations or rotating movements such as rolling, pitching and yawing to movements of the body member unit  143  of the pet robot  141  at a walking time. These movements are controlled with parameters of “ample body x,” “ample body y” “ample body z,” “ample roll,” “ample pitch” and “ample yaw”. 
     “min. gain,” “shift” and “length” are parameters for determining control related to PID control gains of the actuators (servo motors)  144 AA 1  through  146 A M  which are used for walking motions of the pet robot  141 . A possibility to walk smoothly is obtained by giving such soft PID gains so as to absorb shocks at a grounding time with these parameters. Only a P gain out of the PID gains is actually controlled with the following equation: 
     
       
         gain= g min+( g max− g min)×(1−sin(leg phase−shift))  (1)  
       
     
     “leg phase” has a [shift,+length] as a range of values. That is, the P gain has a value which changes from “g min” to “g max” while tracing a sine curve and a phase which is maximum at a location given by a parameter of “shift.” However, “g max” is preliminarily given and the phase is configured so that the leg member rises forward at 0[°], scratches the ground backward at 180[°] and returns to an initial position at 360[°]. 
     “L-R” and “F-H” are parameters which represent a ratio for one cycle of walking motion of a time from starting to swing each leg member unit  144 A to  144 D till starting swinging the left-front leg member unit  144 B or the right rear leg member unit  144 D, taking the right front leg member unit  144 A as a standard, as shown in FIGS. 34 and 35, and the ratios in case of the static walking (crawl walking style), a quasi-walking and the dynamic walking (trot walking style) are shown in FIGS.  35 (A),  35 (B) and  35 (C) respectively. 
     When loads imposed on grounding locations of the left, right front leg member units and the left, right rear leg member units  144 A through  144 D and direction vectors around the above described center coordinate of the pet robot  141  in the standard posture of standing with all the four legs stretched and with the cover unit  142  not fitted are represented by m FL , m FR , m RL , m RR  and r FL , r FR , r RL , r RR  respectively as shown in FIG.  36 (A), a vector R 0  representing a barycenter of the pet robot  141  is expressed by the following equation:                R   0     =           m   FR     *     r   FR       +       m   FL     *     r   FL       +       m   RR     *     r   RR       +       m   RL     *     r   RL             m   FR     +     m   FL     +     m   RR     +     m   RL                 (   2   )                         
     When a mass of the cover unit  142  is represented by M as shown in FIG.  36 (B), loads m FL ′, m FR ′, m RL ′, and m RR ′ imposed on the grounding locations of the left front, right front, left rear, right rear leg member units  144 A through  144 D with the cover unit  142  fitted over the pet robot  141  are in relationship expressed by the following equation: 
     
       
         ( m   FL   ′+m   FR   ′+m   RL   ′+m   RR ′)= M+ ( m   FL   +m   FR   +m   RL   +m   RR )  (3)  
       
     
     Accordingly, a vector R 1  representing the barycenter location of the pet robot  141  with the cover unit  142  fitted is expressed by the following equation:                R   1     =           m   FR     *     r   FR       +       m   FL     *     r   FL       +       m   RR     *     r   RR       +       m   RL     *     r   RL             m   FR     +     m   FL     +     m   RR     +     m   RL                 (   4   )                         
     Accordingly, an error vector E of the barycenter location of the pet robot  141  before and after fitting the cover unit  142  is expressed by the following equation: 
     
       
           E=R   1   −R   0   (5)  
       
     
     By modifying the above described parameters related to walking so as to zero a value of the error vector E, the pet robot  141  can walk with good balance after the cover unit  142  is fitted, like the pet robot  141  before the cover unit  142  is fitted. 
     For example, in case of the error vector E=(0, 0, 5), that is, when the barycenter location of the pet robot  141  is shifted by 5 millimeters in a direction of the Z-axis after fitting the cover unit  142 , walking can be controlled so as to be stable by modifying the parameters (“body center z,” “front legs z” and “rear legs z”) related to walking. 
     (4-2) Calibration Processing Procedure RT 3  at Cover Fitting Time 
     When the cover unit  142  is actually fitted, the controller  160  in the pet robot  141  actually enters a calibration processing sequence RT 3  shown in FIG. 11 from step SP 30 , and while monitoring a state detected by the coupling sensor  161  in the main body side interface member  148  of the body member unit  143  at successive step SP 31 , proceeds to step SP 32  and judges whether or not the cover side interface member  150  in the cover unit  142  has been connected electrically and structurally, on the basis of a result detected by the above described coupling sensor  161 . 
     At this step SP 32 , the controller  160  waits until an affirmative result is obtained, proceeds to step SP 33 , reads out the cover setting information D 30  from the information storage member  173  in the cover side interface member  150  of the cover unit  142 , proceeds to successive step SP 34  and extracts a cover number included in the above described cover setting information D 30 . 
     Successively, the controller  160  reads out the mass distribution information D 32  corresponding to the above described cover number from the information reading member  162  in the body member unit  143  and reads out the initial barycenter location information D 33  set in the pet robot  141  at step SP 35 , and then proceeds to step SP 36 . 
     At this step SP 36 , the controller  160  calculates information related to the barycenter location of the pet robot  141  in the standard posture of standing with the cover unit  142  fitted and with all the four legs stretched (hereinafter referred to simply as barycenter location information) on the basis of the mass distribution information D 32  and the initial barycenter location information D 33  and proceeds to step SP 37 . 
     At this step SP 37 , the controller  160  judges whether or not the barycenter location information calculated after fitting the cover unit  142  is identical to the initial barycenter location information D 33 , proceeds to step SP 38  when a negative result is obtained, and while allowing the pet robot  141  to execute the standard postures (posture with all the four legs stretched, a sitting posture at a charging time or the like) and standard motions (walking motion, sitting motion or the like) on the basis of the performance information D 31  for a fixed period of time, analyzes the acceleration detection signal S 30 , the angular velocity detection signal S 31 , the image signal S 33  and the distance measurement signal S 34  supplied from the acceleration sensor  163 , the angular velocity sensor  164 , the CCD camera  166  and the distance sensor  167  respectively. 
     On the contrary, when an affirmative result is obtained at the step S 36  which indicates that the barycenter location of the pet robot  141  is not changed in the standard posture of standing with all the four legs stretched even before and after fitting the cover unit  142 , the controller  160  proceeds directly to step SP 39  to terminate the calibration processing procedure RT 3 . 
     Then, the controller  160  proceeds to step SP 40  and judges whether or not a balance state in the standard postures and the standard motions based on the performance information D 31  satisfies predetermined standard values on the basis of a analysis result of the detection signals S 30 , S 31 , S 33  and S 34  obtained from the sensors  163 ,  164 ,  166  and  167 . In this case, each standard value is calculated by the controller  160  for each of the standard postures and the standard motions on the basis of the above described initial barycenter location information D 33 . 
     When a negative result is obtained at this step SP 40  which indicates that a posture or motion which does not meet the standard value exists among the standard postures and the standard motions based on the performance information D 31 , the controller  160  proceeds to step SP 41 , calculates an error of the posture and/or motion which does not meet the standard value and proceeds to step SP 42 . 
     At this step SP 42 , the controller  160  calculates the error of the posture and/or the motion which does not meet the above described standard value and returns once again to the step SP 38  to repeat processing similar to those described above (such correction will hereinafter be referred to as correction by calibration) 
     When an affirmative result is obtained at the step SP 40  which indicates that all the standard postures and the standard motions on the basis of the performance information D 31  satisfy the standard values, on the other hand, the controller  160  proceeds directly to the step SP 39  to terminate the above described calibration processing procedure RT 3 . 
     Thereafter, the controller  160  is capable of allowing the pet robot  141  with the cover unit  142  fitted to execute autonomous actions and motions on the basis of the performance information D 31  while balancing the pet robot  141  in a state similar to that before fitting the above described cover unit  142 . 
     (4-3) Operations and Effects of Fourth Embodiment 
     When a cover unit  142  desired by the user is fitted over the pet robot  141  in the robot system  140  having the above described configuration, the pet robot  141  calculates the mass distribution information D 32  stored in the information reading member  162  in the body member unit  143  and the barycenter location information of the pet robot  141  in the standard posture after fitting the cover unit  142 , on the basis of the cover setting information D 30  obtained from the cover unit  142 . 
     When the barycenter location of the pet robot  141  before fitting the cover unit  142  is different from that after fitting the cover unit  142 , the controller  160  compares the postures and/or the motions of the pet robot  141  with those before fitting the cover unit  142  while allowing the pet robot  141  to take the standard postures and the standard motions based on the performance information D 31 , and when an error is made, the controller  160  corrects the error, whereby the controller  160  is capable of allowing the pet robot  141  to act and move autonomously with good balance after the cover unit  142  is fitted as in a state before fitting the cover unit  142 , even when the barycenter location of the pet robot  141  changes after fitting the cover unit  142 . As a result, the robot system  140  easily allows the cover units  142  having various mass distributions to be fitted over the pet robot  141 . 
     The robot system having the above described configuration is configured to calculate an error of a barycenter location of the pet robot  141  from that before fitting the cover unit  142  while allowing the pet robot  141  to take the standard postures and the standard motions and to correct the error (that is, perform the correction by calibration) after fitting the cover unit  142 , thereby being capable of preventing actions and motions of the pet robot  141  from being unbalanced even when cover units  142  having various mass distributions are fitted and making it possible to easily attach various kinds of cover units  142  to the pet robot  141  and realize the robot system which can remarkably improve an amusement property. 
     (5) Fifth Embodiment 
     (5-1) Configuration of Robot System  180  in Fifth Embodiment 
     FIG. 38 in which the same reference numerals are applied to parts corresponding to those in FIG. 27 shows a robot system  180  in the fifth embodiment. A pet robot  181  is configured as in the fourth embodiment described above, except that the mass distribution information D 32  of cover units  142  is not stored for each cover number of the cover units  142  in a recording medium which is to be inserted into an information reading member  162  (FIG. 28) disposed in a body member unit  143  of the pet robot  181  and the aforementioned calibration processing is performed without the mass distribution information D 32  of the pet robot  141 . 
     (5-2) Calibration Processing Procedure RT 2  at Cover Fitting Time 
     When the cover unit  142  is actually fitted, a controller  182  (FIG. 29) in the pet robot  181  enters the calibration processing procedure RT 4  shown FIG. 39 from step SP 50 , and at successive step SP 51 , the controller  182  analyzes an acceleration detection signal S 30 , an angular velocity detection signal S 31 , an image signal S 33  and a distance measurement signal S 34  which are supplied from an acceleration sensor  163 , an angular velocity sensor  164 , a CCD camera  166  and a distance sensor  167  respectively while allowing the pet robot  181  to execute standard postures and standard motions based on the performance information D 31  for a fixed period of time. 
     Successively, the controller  182  proceeds to step SP 52 , reads initial barycenter location information D 33  set in the pet robot  181  from the information reading member  162  in the body member unit  143  and proceeds to step SP 53 . 
     At this step SP 53 , the controller  182  judges whether or not balance states in the standard postures and the standard motions based on the performance information D 31  satisfy predetermined standard values, on the basis of analysis results of the detection signals S 30 , S 31 , S 33  and S 34  obtained from the sensors  163 ,  164 ,  166  and  167 . In this case, each standard value is calculated by the controller  182  for each of the standard postures and the standard motions on the basis of the above described initial barycenter location information D 33 . 
     When a negative result is obtained at this step SP 53  which indicates that a posture and/or a motion which does not satisfy the standard value exists among the standard postures and the standard motions based on the performance information D 31 , the controller  182  proceeds to step SP 54 , calculates an error of the posture and/or the action which does not satisfy the above described standard values and proceeds to step SP 55 . 
     At this step SP 55 , the controller  182  corrects the error of the posture and/or the motion which does not satisfy the standard values, returns once again to the step SP 51  and repeats correction processing by calibration similar to that described above. 
     When an affirmative result is obtained at the step SP 53 , on the other hand, which indicates that the standard values are satisfied by all the standard postures and the standard motions based on the performance information D 31 , the controller  182  proceeds directly to step SP 56  to terminate the above described calibration processing procedure RT 4 . 
     Thereafter, the controller  182  is capable of allowing the pet robot  181  with the cover unit  142  fitted to execute autonomous actions and motions on the basis of the performance information D 31  while balancing in a state which is the same as those before fitting the above described cover unit  142 . 
     (5-3) Operations and Effects of Fifth Embodiment 
     The pet robot system  180  having the above described configuration is configured to, when a user fits a desired cover unit  142  over the pet robot  181 , compare postures and motions of the pet robot  181  with those before fitting the cover unit  142  while allowing the pet robot  181  to take the standard postures and the standard motions based on the performance information D 31  and to correct an error if there is the error, thereby being capable of allowing the pet robot  181  to act and move autonomously with good balance after the cover unit  2  is fitted as before fitting the cover unit  142  even when the barycenter location of the pet robot  181  is changed after fitting the cover unit  142 . 
     As a result, the pet robot system  180  makes it possible to easily apply a cover unit  142  having various mass distributions to the pet robot  181 . 
     Furthermore, even a cover unit which is newly manufactured can easily be adapted to the pet robot  181  since it is unnecessary to preliminarily store information related to a mass distribution for each cover unit in the information reading member  162  in the body member unit  143 . 
     The pet robot system  180  having the above described configuration is configured to calculate an error of a barycenter location of the pet robot  181  from that before fitting the cover unit  142  while allowing the pet robot  181  to take the standard postures and the standard motions, and correct the error (that is, perform the correction by calibration) after the cover unit  142  is fitted, thereby being capable of preventing actions and motions of the pet robot  181  from being unbalanced even when the cover units  3  having various mass distributions are fitted and making it possible to easily apply various kinds of cover units  142  to the pet robot  181  and to realize the pet robot system which can remarkably improve an amusement property. 
     (5-4) Other Embodiments 
     Note that, though the present invention is applied to the quadruped walking type pet robot  141 ,  181  as shown in FIG. 27 in the above described embodiment, the present invention is not limited by the embodiments and is widely applicable to robot apparatuses having other various configurations so far as the robot apparatuses have movable members which manifests predetermined actions. 
     Further, though the cover unit  142  which is composed of the cover main body  142 A made of synthetic fibers having a form like a surface skin of a real dog is used as the cover detachably fitted over the pet robot  141 ,  181  as shown in FIG. 27 in the above described embodiments, the present invention is not limited by the embodiments and a cover of which the shape looks like a surface skin of another animal (cat, raccoon dog, horse, monkey, man or the like) may be made of other various kinds of materials (fur, textile, ceramic, synthetic resin, metal and so on). 
     Further, though a cover main body member  142 A composed of a one-piece molding of synthetic fibers which has a shape like a surface skin of an animal is applied as the cover main body member  142 A composing the cover unit  142 , the present invention is not limited by this cover main body member  142 A and cover parts made of metal (not shown) corresponding to portions of the pet robot  141  may be disposed separately. In this case, a plurality of cover parts consist of a head member, a body member, leg members and shank members, and the above described cover side interface member  150  is disposed in the body member. Various kinds of material in addition to metal (synthetic fibers, furs, textures, ceramics, synthetic resin or the like) may be widely used as materials for the cover parts. 
     Further, though the controller  160 ,  182  disposed in the body member unit  143  of the pet robot  141 ,  181  as control means determines the performance information D 31  corresponding to the cover number included in the above described cover setting information D 30  on the basis the cover setting information D 30  allocated to the above described cover unit  142  when the cover unit  142  is fitted over the pet robot  141 ,  181  in the fourth and fifth embodiments described above, the present invention is not limited by the embodiments and contents of the performance information D 31  may be changed on the basis of the cover setting information D 30 . 
     Further, though description has been made of a case in which information representing the cover number and the manufacturing license is applied as the cover setting information D 30 , the cover setting information may include information related to a kind, a form, a material, a mass distribution, hardness and a heat conductivity as well as information related to an individuality, motions and actions of the above described cover unit  142 . In this case, the controller  160 ,  182  as the control means for the pet robot  141 ,  181  may be configured to determine actions of the pet robot  141 ,  181  on the basis of only the cover setting information D 31  read out with the information reading member  165 , to drive the actuators  144 AA 1  through  146 A M  which are required for the determined actions and to allow the speaker  169  to give sounds as occasion demands. 
     Further, though the cover side interface member  150  and the main body side interface member  148  are configured as a means for connecting the cover unit  142  to the pet robot  141 ,  181  electrically and structurally when the cover unit  142  is fitted over the pet robot  141 ,  181  in the fourth and fifth embodiments described above, the present invention is not limited by the embodiments and other various configurations may be widely applied means so far as a cover unit can be detachably connected. 
     Though the information storage member  173  is disposed in the cover unit  142  and inherent information allocated to the cover unit  142  is stored in the above described information storage member  173  in the above described embodiments, the present invention is not limited by the embodiments and a characteristic item (mark, bar code, predetermined concavo-convex pattern or protruding end having a special form) corresponding to the inherent information is formed at locations for connection to the pet robot  141 ,  181 , without disposing the information storage member  173  in the cover unit  142 , so that the inherent information is recognized by reading the characteristic item at the locations for connection to the pet robot  141 ,  181 . Furthermore, usable as the storage means is not only a non-volatile memory which stores the inherent information but also a passive element such as a resistor or an element which magnetically stores the inherent information and a light emitting pattern of a light emitting diode (LED) may be used as the inherent information. 
     Further, as to the controller  160 ,  182  of the pet robot  141 ,  181  in the aforementioned fourth and fifth embodiments, the information reading member  162  reads out the performance information D 31  from a recording medium (not shown) inserted from the outside, and sends it to the controller  160 ,  182 , however, the present invention is not limited thereto and a receiving device may be used as an information reading means to receive and download the performance information D 31  which is given from the outside. 
     Further, in the aforementioned fourth and fifth embodiments, though the controller  182  which is disposed as the control means in the pet robot  141 ,  181  judges, on the basis of the analysis results of the detection signals S 30 , S 31 , S 33  and S 34  obtained from the acceleration sensor  163 , the angular velocity sensor  164 , the CCD camera  166  and the distance sensor  167  which are disposed as an error detection means, whether or not the standard values determined on the basis of the initial barycenter location information D 33  are satisfied by the standard postures and the standard motions, while allowing the pet robot  141 ,  181  to execute the standard postures and the standard motions based on the performance information D 31 , on the basis of cover setting information D 30  given from the cover unit  142 , the present invention is not limited by the embodiments and control means having other various configurations may be used so far as the controller  160 ,  182  is capable of detecting amounts of influences on actions of the component units (movable members)  143  through  146  due to the cover unit  142 . 
     In this case, though the amounts of influences on actions of the component units (movable members)  143  to  146  due to the cover unit  142  are calculated as the control error between before and after fitting the cover unit  142  using the above described sensors  163 ,  164 ,  166  and  167  and then the above described errors are corrected, the present invention is not limited by the embodiments and amounts of influences on motions of the component units (movable members)  143  through  146  after fitting the cover unit  142  may be detected using various kinds of sensors, for example, the potentiometers  170 AA 1  through  172 A M  and the touch sensor  168 . 
     Further, in the aforementioned fourth and fifth embodiments, though the standard values for the standard postures and the standard motions based on the performance information D 31  are set by the controller  160 ,  182  disposed as control means, on the basis of the initial barycenter location information D 33  set in the pet robot  141 ,  181 , the present invention is not limited by the embodiments and standard values for the standard postures and the standard motions based on the performance information D 31  may be preliminarily set for each cover unit  142 . 
     Further, in the aforementioned fourth and fifth embodiments, though the mass distribution information D 32  included in the cover setting information D 30  is judged on the basis of the initial barycenter location information D 33  to move the pet robot  141 ,  182  with good balance, the present invention is not limited thereto and each unit of the pet robot  141 ,  181  may be moved without influence due to the cover unit  142  by judging information about the forms of the entire pet robot  141 ,  181  and each unit, the movable range of each actuator  144 AA 1  to  146 A M , the link length, and the restricted degree of freedom, as long as when the cover unit  142  is fitted over the pet robot  141 ,  181 , the controller  160 ,  182  as control means drives each component unit (movable members)  143  to  146  to detect the amount of influence on motions after fitting the cover unit  142  and the motion manifesting pattern can be changed based on the detection result when occasion demands. 
     In this case, after the cover unit  142  is fitted, the controller  160 ,  182  may calculate the movable range of each actuator  144 AA 1  to  146 A M  on the basis of the detection result of degrees of the corresponding potentiometers  170 AA 1  to  172 A M  while allowing the pet robot  141 ,  181  to execute the standard postures and the standard motions and each actuator  144 AA 1  to  146 A M  may be moved within the movable range. 
     Further, the pet robot  141 ,  181  may be moved with good balance and each cover unit of the pet robot  141 ,  181  may be moved without influence due to a cover unit  142  by judging information about moment of inertia of each leg member unit  144 A to  144 D, focus characteristics and field degree of vision of the CDD camera  166 , listening characteristics of the microphone  165 , and touching characteristics of the touch sensor  168 . 
     Further, in the aforementioned fourth and fifth embodiments, though the controller  160 ,  182  in the body member unit  143  is used as a control means for driving the actuators (movable members)  144 AA 1  to  146 A M  so that the pet robot  141 ,  181  is in a predetermined posture and motion (motion pattern and walking pattern) when the cover unit  142  is fitter over the pet robot  141 ,  181 , the present invention is not limited thereto and the control means having other various configuration may be used as far as it can make the pet robot  141 ,  181  execute the predetermined postures and/or motions. 
     (6) Sixth Embodiment 
     (6-1) Configuration of Robot System in this Embodiment 
     In FIG. 40, a reference numeral  190  shows a robot system as a whole in this embodiment and this system is composed of a robot body  191  and a cover unit  192  which is to be attached to the robot body  191 . 
     In the robot body  191 , leg member units  194 A to  194 D are connected to the front right, front left, rear right, and rear left of a body member unit  193  and a head member unit  195  is connected to the front end of the body member unit  193 . 
     In this case, the body member unit  193  contains a controller  200  which controls the entire motions of the robot body  191 , a battery  201  which is a power supply to the robot body  191 , and an internal sensor member  204  which is composed of a battery sensor  202  and a heat sensor  203 . 
     In addition, disposed at the head member unit  195  are a CDD camera  205  which is used as actual “eyes” of the robot body  191 , a microphone  206  which is used as “ears”, an external sensor member  209  which is composed of a touch sensor  207  and a distance sensor  208 , a speaker which is used as a “mouth” and so on. 
     Further, actuators  211   1  to  211   n  having the degrees of freedom are disposed in joint parts of the leg member units  194 A to  194 D, the coupled parts of the leg member unit  194 A to  194 D with the body member unit  193 , and a coupled part of the head member unit  195  with the body member unit  193 . 
     The CDD camera  205  of the head member unit  195  photographs a surrounding situation and sends it out to the controller  200 . The microphone  206  gathers order sounds such as “walk”, “lie down”, and “chase a ball” which are given from a user in the form of sound scales with a sound commander (not shown), and sends out the obtained audio signal S 40 B to the controller  200 . 
     The touch sensor  207  is disposed on the top of the head member unit  195  as can be seen from FIG. 40, to detect pressures which is received from a user by physical spurring such as “patting” and “striking”, and sends out the detection result as a pressure detection signal S 40 C to the controller  200 . The distance sensor  208  measures a distance to a front object, and sends out the measurement result as a distance measurement signal S 40 D to the controller  200 . 
     Further, the battery sensor  201  detects/the residual amount of the battery  201  and sends out the detection result as a battery residual amount detection signal S 41 A to the controller  200 . The heat sensor  203  detects the heat inside the robot body  191  and sends out the detection result as the heat detection signal S 41 B to the controller  200 . 
     The controller  200  judges the surrounding situation and the internal situation of the robot body  193 , the order from the user, and the spurring from the user, on the basis of the image signal S 40 A, the audio signal S 40 B, the pressure detection signal S 40 C, and the distance measurement signal S 40 D (hereinafter, these signals are simply referred to as an external sensor signal S 40 ) which are supplied from the CDD camera  205 , the microphone  206 , the touch sensor  207 , and the distance sensor  208  in the external sensor member  209 , and the battery residual amount detection signal S 41 A and the heat detection signal S 41 B (hereinafter, these signals are simply referred to as an internal sensor signal S 41 ) which are given from the battery sensor  202  and the temperature sensor  203  in the internal sensor member  204 . 
     Then, the controller  200  determines next actions on the basis of the judgement result and control programs previously stored in a memory  200 A and drives actuators  211   1  to  211   n  required for the next actions to allow the robot body to take actions such as swinging of the head member unit  195  up, down, left and right, and walking by driving the leg member units  211   1  to  211   n . 
     Further, in this time, the controller  200  supplies a predetermined audio signal S 42  to the speaker  210  as occasion demands to give sounds based on the audio signal S 42  to outside. 
     As described above, the robot body  191  autonomously act on the basis of surroundings, internal situations, and order and spurring from a user. 
     On the other hand, the cover unit  191  is composed of a face cover member  200 A, a head cover member  200 B, a loins cover member  221 A, a flank cover member  221 B, a chest cover member  222 , and four pair of outside leg cover members  225 A to  225 D, inside leg cover members  226 A to  226 D and sole cover member  227 A to  227 D. 
     In this case, the face cover member  220  and the head cover member  221  can be fitted to the front and back of the head member unit  195  of the robot body  191 . The loins cover member  222  and the flank cover member  223  can be fitted to the top and bottom of the body member unit  193  of the robot body  191 . The chest cover member  222  can be fitted to the chest part of the body member unit  193  of the robot body  191 , and the outside leg cover member  225 A to  225 D, the inside leg cover member  226 A to  226 D, and the sole cover member  227 A to  227 D can be fit to the outside, inside, and bottom of the leg member unit  194 A to  194 D of the robot body  191 . 
     Therefore, holes  220 A,  220 B,  221 A 1 ,  221 A 2  of predetermined sizes are disposed at predetermined positions of the face cover member  220  and the head cover member  221  to fit the CCD camera  205 , the distance sensor  207 , the microphone  206  of the robot body  191 . Thereby, the face cover member  220  and the head cover member  221  does not obstruct the robot body  191  at the time of photographing surrounding situations, gathering sounds from outside and measuring a distance to a front object with the CDD camera  205 , the microphone  206 , and the distance sensor  208  through the holes  220 A,  220 B,  221 A 1 ,  221 A 2 . 
     Note that, in this embodiment, the hole  220 B of the face cover member  220  corresponding to the distance sensor  208  is covered with a translucent member (hereinafter, referred to as a canopy)  228 , which prevents the user from emotion strange due to the exposure of the distance measuring section of the distance sensor  208 . 
     In addition to this configuration, a non-volatile memory  230  such as an EEPROM (Electric Erasable Programmable ROM) is disposed in the head cover member  220  of the cover unit  192  in the robot system  190 . And this memory  230  stores information about a type of a cover for identifying the type of the cover unit  192 , information about an object bone type which represent a type of the robot body  191  to which the cover unit  192  can be attached, port information which represent which device is connected to each external terminal in the connector member  231  of the head cover member  220  which is described later, characteristic information which is predetermined correction information corresponding to characteristic which is previously set for each cover unit  192 , canopy information which consists of correction information for executing predetermined correction processing in accordance with optical characteristics of the canopy  228  of the cover unit  192 , and various information (hereinafter, referred to as cover information) about the cover unit  192  such as cover physical information including various correction information which is used for correcting parameters related to motions of the robot body  191  when the cover unit  192  is fitted. 
     Further, in the robot system  190 , the connector member (hereinafter, referred to as cover side connector member)  231  having a plurality of external connector terminals is disposed at predetermined position inside the head cover member  220 , and disposed at predetermined corresponding position of the robot body  191  is a connector member (hereinafter, referred to as a robot side connector member)  232  having a plurality of external terminals. When the head cover member  220  is attached to the robot body  192  in a predetermined condition, the cover side connector member  231  and the robot side connector member  23  are electrically connected so that the controller  200  in the robot body  191  can read out the cover information from the memory  230  of the head cover member  221  via the cover side connector member  231  and the robot side connector member  232 . 
     When the power is turned on, the controller  220  in the robot body  191  firstly accesses to the memory  230  in the cover unit  192  via the robot side connector member  232 . In the case where the controller  220  can not read out the cover information (for example, in the case where a cover unit is not fitted), it does not do anything, and on the contrary, in the case where the cover information can be read out, the controller  220  checks the type of the attached cover unit  192 , whether or not the cover unit  192  corresponds to the type of the robot body  191 , and what type of device is connected to each port of the cover side connector member  231 , on the basis of the read cover information, and also changes corresponding parameters on the basis of the canopy information and the cover physical information. 
     Then, the controller  220  of the robot body  191  controls actions of the robot body  191  in accordance with the parameters changed as described above. In this way, in the robot system  190 , the robot body  191  changes actions dependently on a type of the cover unit  192  attached to the robot body  191 . 
     (6-2) Processing by Controller  220   
     Next, the concrete processing by the controller  220  in the robot body  191  in this robot system  190  will be described. 
     The controller  220  executes aforementioned various processing in accordance with control programs stored in the memory  200 A. Processing by the controller  220  is functionally classified into a condition recognizing section  240 , a emotion and instinct model section  241  which determines emotions and instinct on the basis of the recognition result by the condition recognizing section  240 , an action determining section  242  which determines a next action on the basis of the recognition result by the condition recognizing section  240  and an output from the emotion and instinct model section  241 , and an action generating section  243  which makes the robot body  191  execute (manifest) the action based on the result determined by the action determining section  242 . 
     Hereinafter, the condition recognizing section  240 , the emotion and instinct model section  241 , the action determining section  242  and the action generating section  243  will be described in detail. 
     (6-2-1) Configuration of Condition Recognizing Section  240   
     The condition recognizing section  240  recognizes specific conditions on the basis of an external sensor signal S 40  from the external sensor member  209  (FIG.  41 ), an internal sensor signal S 41  from the internal sensor member  204  (FIG.  41 ), and informs the emotion and instinct model section  241  and the action determining section  242  of the recognition result as condition recognition information S 50 . 
     Actually, the condition recognizing section  240  always checks image signals S 40 A which are supplied from the CCD camera  205  (FIG. 41) of the external sensor member  209 , and when detecting, for example, “something round and red” or “an object” in an image based on the image signal S 40 A, recognizes that “there is a ball” or “there is an obstacle”, and informs the emotion and instinct model section  241  and the action determining section  242  of the recognition result. 
     Further, at this time, the condition recognizing section  240  obtains a distance to the object on the basis of a distance detection signal S 40 D which is given from the distance sensor  208  of the external sensor member  209 , and informs the emotion and instinct model section  241  and the action determining section  242  of the detection result. 
     In addition, the condition recognizing section  240  always checks audio signals S 40 B which are given from the microphone  206  (FIG.  41 ); and when recognizing the input of order such as “walk”, “lie down”, and “chase a ball” on the basis of the audio signal S 40 B, informs the emotion and instinct model section  241  and the action determining section  242  of the recognition result. 
     Further, the condition recognizing section  240  always checks pressure detection signals S 40 C which are given from the touch sensor  207  (FIG. 41) and when detecting on the basis of the pressure detection signal S 40 C pressure which has exceeded a predetermined threshold value and is applied for a short time (for example, less than two seconds), recognizes that “being struck (scolded)” and on the other hand, when detecting pressure of a large area which does not exceed the predetermined threshold value and is applied for a long time (for example, longer than two seconds), recognizes that “being patted (praised)” and informs the emotion and instinct model section  241  and the action determining section  242  of the recognition result. 
     Furthermore, the condition recognizing section  240  always checks heat detection signals S 41 B which are given from the heat sensor  203  (FIG. 41) of the internal sensor  204 , and when detecting heat which exceeds a predetermined temperature on the basis of the heat detection signal S 41 B, recognizes that “internal temperature has raised” and inform the emotion and instinct model section  241  and the action determining section  242  of the recognition result. 
     (6-2-2) Configuration of Emotion and Instinct Model Section  241   
     The emotion and instinct model section  241  has parameters which represent intensities of 6 kinds of emotions: “joy”, “sadness”, “surprised”, “horror”, “hatred” and “anger”. The emotion and instinct model section  241  successively updates the parameter for each emotion on the basis of the specific recognition result such as “being struck” and “being patted” which is given from the condition recognizing section  240  as the condition recognition information S 50 , the action determination information S 51  representing determined output actions which are given from the action determining section  242  which will be described later, passage time and so on. 
     Concretely, by taking the amount of change in the emotion which is calculated by a predetermined equation on the basis of a degree (previously set) of the output action based on the recognition result which is obtained based on the condition recognition information S 50 , and the action determination information S 51  with respect to the emotion, a degree of pressure and stimulation which are given from other emotions, and passage time, as ΔE[t], the parameter for the current emotion as E[t], and the coefficient which represents a rate of changing the emotion, on the basis of the recognition result and so on., as k e , the emotion and instinct model section  241  calculates the parameter E[t+1] for the emotions of a next cycle from the following equation. 
     
       
           E[t+ 1]= E[t]+k   e   ×ΔE[t]   (6)  
       
     
     Then, the emotion and instinct model section  241  updates the parameter of the emotion by replacing the parameter for the current emotion E[t] with the calculated result. Note that, it is previously fixed that parameters for which emotions have to be updated for each recognition result and each output action. When the recognition result of “being struck” is made, for example, the parameter for the emotion “anger” is increased and the parameter for the emotion “joy” is decreased. In addition, when the recognition result of “being patted” is made, the parameter for the emotion “joy” is increased and the parameters of emotions “sadness” and “anger” are decreased. 
     Similarly to this configuration, the emotion and instinct model section  41  has parameters which represent intensities of five kinds of desires: “desire for movement”, “attachment”, “curiosity”, “appetite” and “sleep”. And the emotion and instinct model section  41  sequentially updates these parameters on the basis of recognition result from the condition recognizing section  240 , passage time, and the notify from the action determining section  242 . 
     Concretely, as to “desire for movement”, “attachment” and “curiosity”, by taking the amount of change in desire which is calculated by a predetermined equation on the basis of the output action of the robot body  191 , passage time, the a recognition result and so on., as ΔI[k], a parameter for the current desire as I[k], and a coefficient representing the intensity of the desire as k i , the emotion and instinct model section  241  calculates the parameter I[k+1] for the desire of a next cycle by the following equation. 
     
       
           I[k+ 1]= I[k]+k   i   ×ΔI[k]   (7)  
       
     
     Then, the emotion and instinct model section  241  updates the parameter for the desire by replacing the parameter I[k] of the desire with the calculated result. In this case, it is fixed that parameters of which desires have to be changed for the output action and the recognition result. For example, when the action deciding section  242  makes a notice of “did something”, the parameter for the desire “desire for movement” is decreased. 
     In addition, as to the desire “appetite”, by taking the residual amount of battery as B L , the emotion and instinct model section  241  calculates the parameter I[k+1] for the desire “appetite” on the basis of the battery residual amount detection signal S 42 A (FIG.  41 ), which is given via the condition recognizing section  240 , by a following equation. 
     
       
           I[k]= 100− B   L   (8)  
       
     
     Then, the emotion and instinct model section  241  updates the parameter for the desire “appetite” by replacing the parameter I[k] for the current appetite with the calculated result. 
     Furthermore, as to the desire “sleep”, the emotion and instinct model section  241  increases or decreases the parameter every fixed time with one day as one cycle. 
     Note that, the parameter for each emotion and each desire range from 0 to 100 and the coefficient k e , k i  are also individually set for each emotion and each desire. 
     (6-2-3) Configuration of Action Determining Section  242   
     The action determining section  242  decides a next action on the basis of the condition recognition information  50  which is given from the condition recognizing section  240 , the parameters for emotions and desires in the emotion and instinct model section  241 , the action model previously stored in the memory  200 A, passage time and so on., and outputs the decided result as action determination information S 51  to the emotion and instinct model section  241  and the action generating section  243 . 
     In this case, the action determining section  242 , as a means of determining a next action, uses an algorithm referred to as a probability automaton which probably decides, on the basis of transition probability P 0 ″ to P n ″ respectively set for arc ARC 0 ″ to ARC n ″ which connect between nodes (conditions) NODE 0 ″ to NODE n ″, which node NODE 0 ″ to NODE n ″, the same or another, one node NODE 0 ″ to NODE n ″ is shifted to, as shown in FIG.  44 . 
     More concretely, the memory  200 A stores, as action models, a state transition table  244  shown in FIG. 45 for each node NODE 0 ″ to NODE n ″ so that the action determining section  242  determines a next action on the basis of the state transition table  244 . 
     Here, in the state transition table  244 , input events (the recognition result from the condition recognizing section  240 ) which are used as transition conditions in the nodes NODE 0 ″ to NODE n ″ are written on the “input event” line in the order of priority, and more specific conditions are written on corresponding rows of “data name” and “data limit” lines. 
     As described above, the node NODE 100  defined by the state transition table  244  in FIG. 45 has condition for transition to the same or another node NODE 0 ″ to NODE n ″. For example, when the recognition result of “detected a ball” is given, the condition is that “size” of the ball given together with the recognition result has to be between 0 and 100 (0,1000)″, or for another example, when the recognition result of “detected an obstacle” is given, the condition is that “distance” to the obstacle given together with the recognition result has to be between 0 and 1000 (0,1000). 
     Further, even when the recognition result is not input in the node  100 , the node can be shifted to the same or another node NODE 0 ″ to NODE n ″ when the parameter for any emotion “joy”, “surprised”, or “sadness” out of emotions and desires in the emotion and instinct model section  241 , which are referred periodically by the action determining section  242 , is between 50 and 100 (50, 100). 
     In addition, in the state transition table  244 , some nodes NODE 0 ″ to NODE n ″ to which the node NODE 0 ″ to NODE n ″ can be shifted are written on a “transition destination node” line in a space for “transition probability to another node”, and the transition probabilities to the nodes NODE 0 ″ to NODE n ″ in the case where the conditions written in the “input event”, “data name” and “data limit” lines are all satisfied is written on the node NODE 0 ″ to NODE n ″ lines in the space for “transition probability to another node”, an action and motion which are output at this time are written on an “output action” row. Note that, the sum of the transition probability on each line in the space for “transition probability” is 100 [%]. 
     Therefore, the node NODE 100 ″ in this example can be shifted to “node NODE 120 ″ (node 120 )” at “probability of 30[%]” in the case where the following recognition results are given: “detected a ball” and the “size” of the ball is “between 0 and 1000 (0,1000)”, and at this time, the action and motion of “ACTION  1 ” are output. 
     The action model is formed so that each node NODE 0 ″ to NODE n ″ written in the state transition table  244  has many nodes to be shifted to. 
     Thus, when the condition recognition information S 50  is given from the condition recognizing section  240  or when the current actions have been performed for a fixed period of time, the action determining section  242  probably decides a next action and motion (action or motion written on the “output action” row) by using the state transition table  244  of the corresponding node NODE 0 ″ to NODE n ″ out of the action models stored in the memory  200 A, and outputs the determination result as action determination information S 51  to the emotion and instinct model section  242  and the action generating section  243 . 
     (6-2-4) Configuration of Action Generating Section  243   
     The action generating section  243  has a data file (hereinafter, referred to as motion file) for each action which is used to determine how much each actuator  211   1  to  211   n  is moved at the time of making the robot body  191  manifest various actions, and a data file for plural sounds (hereinafter, referred to sound file), in the memory  200 A. 
     The action generating section  243  reads out the corresponding motion file as occasion demands, from the memory  200 A on the basis of the action determination information S 51  which is given from the action determining section  242 , sends the driving signal S 52   1  to S 52   2  to the actuators  211   1  to  211   n  on the basis of the motion file and play the corresponding sound file, thus outputting the obtained audio signal S 42  to the speaker  210  (FIG.  41 ). 
     As a result, the required actuators  211 , to  211 , based on the driving signal S 52   1  to S 52   n  are driven and sounds based on the audio signal S 42  are output from the speaker  210 , thereby the robot body  191  manifests the actions and motions determined by the action determining section  242  as described above. 
     As described above, in the robot system  190 , the robot body  191  can autonomously act on the basis of surrounding and internal conditions, orders and spurring from a user, under the control of the controller  200 . 
     (6-3) Initial Setting Processing in Robot Body  190   
     Next, initial setting processing by the controller  200  of the robot body  191  in the robot system  190  will be described. 
     In this robot system  190 , after the power is turned on as described above, the controller  200  of the robot body  191  firstly read out cover information by accessing to the memory  230  of the cover unit  192 , and performs initial setting processing such as changing necessary parameters on the basis of the cover information. 
     In actual, in the case of the robot system  190 , the memory  230  of the face cover member  221  of the cover unit  192  stores, as the aforementioned characteristic information, the changing value for corresponding transition probabilities P 0 ″ to P n ″ (FIG. 44) in the corresponding state transition table  244  (FIG. 45) out of the state transition table  244  which is used for generating an action model, and the state transition table  244  for the nodes NODE 0 ″ to NODE n ″ of the action models. 
     The controller  200  of the robot body  191  changes corresponding transition probabilities P 0 ″ to P n ″ in a corresponding state transition table  244  on the basis of the characteristic information included in the cover information read out from the memory  230  of the cover unit  192 , and replaces the state transition table  244  for a corresponding node NODE 0 ″ to NODE n ″ with a new state transition table  244 . 
     In addition, the memory  230  of the cover unit stores an offset value to perform the offset correction on an output voltage of the distance sensor  208  (FIG. 41) as canopy information. 
     That is, in the case of measuring a distance to an object which is in front of the distance sensor  208 , via the canopy  228  (FIG.  40 ), a measurement error occurs due to an angle of incline of the canopy  228  with respect to the angle of incidence toward the distance sensor  208  as shown in FIG.  46  and FIG. 47, and the color of canopy as shown in FIG.  48  and FIG.  49 . Note that, in FIG.  46  and FIG. 48, the numbers on the most left line represent distances to an object to be measured, the numbers on the other lines represent output voltages of the distance sensor  208  for the angle of incline of the canopy  228  by taking the vertical condition to the optical axis of the distance sensor  208  as  0  degree. In addition, in FIG.  47  and FIG. 49, the ordinate represents output voltages from the distance sensor  208  and the abscissa represents distances to an object to be measured. 
     Therefore, in the robot system  190 , the memory  230  of the cover unit  192  stores offset values to perform the offset correction on an output voltage from the distance sensor  208  (FIG. 41) in correspondence with the angle of incline and the color of the canopy  208  of the cover unit  192 . 
     The controller  200  of the robot body  191  changes, on the basis of the canopy characteristic information included in the cover information which is read out from the memory  200 A of the cover unit  192 , the offset values for the distance measurement signal S 40 D of the time when the condition recognizing section  240  recognizes the distance to the front objet on the basis of the distance measurement signal S 40 D. 
     Further, the memory  230  of the cover unit  192  stores barycenter location information which represent the position of barycenter of the entire robot system  190  with the cover unit  192  fitted over the robot body  192 , motion information which represent moment of inertia of each movable unit at the time of fitting the cover unit  192 , and movable range information which represent the movable range of each movable unit at the time of fitting the cover unit  192 . 
     Then, the controller  200  of the robot body  192  changes parameters for walking-control described in FIG.  31  and other corresponding parameters, which are stored in the memory  200 A, on the basis of the barycenter location information out of the cover physical information included in the cover information read out from the memory  230  of the cover unit  192 . 
     As described above, in the robot system  190 , the parameters in the robot body  191  can be changed on the basis of the cover information stored in the memory  230  of the cover unit  192 , thereby the robot body  191  can manifest actions dependently on the cover unit  192  attached to the robot body  191 . 
     (6-4) Operations and Effects in the Embodiment 
     In the robot system  190  having the aforementioned configuration, the controller  200  reads out the cover information from the memory  230  of the cover unit  192  at the time of turning the power of the robot body  191  on, and changes required parameters on the basis of the cover information. 
     Therefore, the robot body  191  can manifest actions based on the cover unit  192  by storing the information corresponding to the shape, color and forms of the cover unit  192  as the cover information. 
     According to the aforementioned configuration, the memory  230  storing cover information corresponding to the forms of the cover unit  192  is disposed in the cover unit  192 , the controller  200  of the robot body  191  reads out the cover information at the time of turning the power on, and changes parameters to control actions an motions of the robot body  191  on the basis of the cover information, thereby the robot body  191  can manifest actions and motions according to the type of the cover unit  192 , which can remarkably improve the amusement property in the robot system. 
     INDUSTRIAL APPLICABILITY 
     The robot system, the robot apparatus and the cover for the robot apparatus can be applied to a robot system composed of a pet robot and a cover for a robot apparatus.