Patent Publication Number: US-2022219330-A1

Title: Transport system

Description:
TECHNICAL FIELD 
     The present invention relates to a transport system that transports objects. 
     BACKGROUND ART 
     Nowadays, robots have been widely used in daily life. For example, Patent Literature 1 discloses a robot that transports objects such as food and drink to users. The robot has a tray on which an object is placed. The robot moves to a user with an object placed on the tray to transport it to the user. It is not easy for transport systems using such a robot to transport many objects at a time. When transporting an object, the speed of the robot is greatly limited to prevent adverse effects (e.g. vibrations or toppling) on the object during transport. 
     Examples of a system for transporting objects are food service carts disclosed in Patent Literatures 1 and 2. These food service carts can accommodate many objects (e.g. food and drink to be served to users) at a time. They are provided with a lifter inside them to facilitate taking out objects from them. The food service carts are adapted to allow objects housed therein to be taken out through a certain doorway. Patent Literature 4 discloses a wheelchair provided on one side with a housing rack having a lifting function to allow the user of the wheelchair to serve trays of food and drink smoothly. 
     CITATION LIST 
     Patent Literature 
     
         
         Patent Literature 1: Publication of Chinese Patent Application No. 108527378 
         Patent Literature 2: Publication of Japanese Utility Model No. S58-18749 
         Patent Literature 3: Japanese Utility Model Application Laid-Open No. S62-203781 
         Patent Literature 4: Japanese Patent No. 5903449 
       
    
     SUMMARY OF INVENTION 
     Technical Problem 
     Multi-functionality of robots are of interest to many people, and a variety of their use in daily life have been developed. As described above, use of robots in various situations of transporting objects such as food and drink have been studied. In particular, robots can be employed usefully in situations of transporting many objects, taking out the objects from a housing and passing them to a user at a destination. To cause a robot to execute such useful operations, it is necessary to control the robot precisely. For example, various processing is needed, such as detailed recognition of objects and positioning for allowing a hand unit of the robot, such as an end effector, to perform a holding operation. Such processing is not easy or simple to execute in most cases. 
     The present invention was made to address the above problem, and an object of the present invention is to provide a transport system capable of transporting object appropriately. 
     Solution to Problem 
     To solve the above problem, according to the present invention, a manipulator apparatus having a hand unit for holding an object and a housing apparatus in which a plurality of objects are housed are configured to be capable of moving in a state in which they are coupled together, and the object is brought to a predetermined specific position in the housing apparatus so that the object is accessible for the hand unit. This configuration enables the hand unit of the manipulator apparatus to hold the object by simple control. 
     More specifically, according to the present invention, there is provided a transport system comprising a manipulator apparatus having a hand unit capable of holding an object and a housing apparatus having a housing unit capable of housing a plurality of said objects, wherein the manipulator apparatus is configured to be capable of controlling the position of the hand unit relative to a manipulator body unit that constitutes a main body of the manipulator apparatus, and the housing apparatus is configured to bring the objects housed in the housing unit one by one to a specific position in the housing apparatus accessible for the hand unit. The manipulator apparatus and the housing apparatus are configured to be capable of moving as a unit in a state in which the manipulator body unit and the housing apparatus are coupled with each other. The specific position is set as a known position relative to the manipulator body unit in the state in which the manipulator body unit and the housing apparatus are coupled with each other to make the manipulator apparatus and the housing apparatus integral. 
     Advantageous Effects of Invention 
     The present invention can provide a transport system that can achieve favorable transport of an object. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         FIG. 1  is a diagram illustrating the general structure of a transport system. 
         FIG. 2  is a first diagram illustrating the general structure of a robot included in the transport system. 
         FIG. 3  is a second diagram illustrating the general structure of the robot included in the transport system. 
         FIG. 4  is a third diagram illustrating the general structure of the robot included in the transport system. 
         FIG. 5  is a diagram illustrating joint axes in the robot. 
         FIG. 6  is a diagram illustrating the general configuration of a housing apparatus included in the transport system. 
         FIG. 7  is a diagram illustrating the general configuration of a housing rack included in the housing apparatus illustrated in  FIG. 6 . 
         FIG. 8  is a diagram illustrating the structure of a chain included in the housing rack illustrated in  FIG. 7 . 
         FIG. 9  is a diagram illustrating the structure of a tray rest included in the housing rack illustrated in  FIG. 7 . 
         FIG. 10  is a diagram specifically illustrating a portion of the housing rack. 
         FIG. 11  is a functional block diagram of the transport system. 
         FIG. 12  is a first flow chart of an object transport process executed in the transport system. 
         FIG. 13  is a second flow chart of an object transport process executed in the transport system. 
     
    
    
     MODE FOR CARRYING OUT THE INVENTION 
     A transport system according to an embodiment is constituted by a combination of a manipulator apparatus having a hand unit capable of holding an object and a housing apparatus capable of housing a plurality of objects. The hand unit of the manipulator apparatus may be of any type, so long as it is capable of holding an object. For example, a mechanism configured to hold an object between a plurality of fingers may be employed as the hand unit. Alternatively, the hand unit may be configured to hold an object by aspiration or suction. The manipulator apparatus includes a manipulator body unit that constitutes the main body of the manipulator apparatus and the hand unit, and the manipulator apparatus is configured to be capable of controlling the position of the hand unit relative to the manipulator body unit. Therefore, it is possible to position the hand unit relative to the object and to move the object held by the hand unit. The mechanism used to move the hand unit relative to the manipulator body unit is not limited to any particular mechanism. For example, this mechanism may be a system that moves the hand unit by a link mechanism composed of a plurality of links or an arm mechanism having a plurality of joints. 
     The manipulator apparatus may be constructed as, for example, a robot including a robot main body constituting the manipulator body unit, a first arm unit having a first hand unit constituting a first example of the aforementioned hand unit, the first arm unit being configured to be capable of controlling the position of the first hand unit relative to the robot main body, and a second arm unit having a second hand unit constituting a second example of the aforementioned hand unit, the second arm unit being configured to be capable of controlling the position of the second hand unit relative to the robot main body. The manipulator apparatus may include a further (third or more) arm unit. 
     The housing apparatus can house a plurality of objects in its housing unit. The housing apparatus is configured to bring the objects housed in it to a specific position one by one. This specific position is a position in the housing apparatus accessible for the hand unit. Thus, an object brought to the specific position can be held by the hand unit, and then the object held by the hand unit can be moved to a desired position by position control performed by the hand unit and the manipulator body unit. 
     The transport system having the above-described construction is configured such that the manipulator body unit and the housing apparatus are coupled with each other so that the manipulator apparatus and the housing apparatus can move integrally as a unit. Thus, the manipulator apparatus and the housing apparatus can move together to a place to which an object is to be transported with a plurality of objects housed in the housing unit, and one, some, or all of the objects housed therein can be taken out by the manipulator apparatus at that place. 
     In the transport system, the specific position is set as a known position relative to the manipulator body unit in the state in which the manipulator apparatus and the housing apparatus are coupled integrally as described above. In consequence, when the operation of holding an object is performed, the positional relationship of the manipulator apparatus and the housing apparatus is fixed. Hence, the object to be held is always positioned at the known position (or the specific position) as seen from the manipulator body unit. This helps simplification of the position control of the hand unit by the manipulator apparatus. Specifically, since the relative positional relationship of the specific position is known, it is not necessary to recognize (or determine) the position of the object specifically when holding it by the hand unit, or the processing of recognizing the position of the object can be made simpler. This leads to a reduction of the operation load in the process of taking out objects from the housing unit one by one. In consequence, this system can achieve favorable transport of objects. 
     In the following, a specific embodiment of the present invention will be described with reference to the drawings. In should be understood that the dimensions, materials, shapes, relative arrangements, and other features of the components that will be described in connection with the embodiment are not intended to limit the technical scope of the present invention only to them, unless particularly stated. 
     &lt;Configuration of Transport System  1 &gt; 
     The general configuration of a transport system according to an embodiment will be described with reference to  FIG. 1 . The transport system  1  includes a robot  10  corresponding to the manipulator apparatus according to this disclosure and a housing apparatus  95 . The robot  10  has a robot main body  30 , two arm units  50  attached to the robot main body  30 , a pelvis unit  16  included in the robot main body  30 , and a leg unit  35  attached to the pelvis unit  16  and extending downward. Details of the robot  10  will be described later. To the end of each arm unit  50  is attached a hand unit  60  used to hold an object. The housing apparatus  95  has a housing rack  70  corresponding to the housing unit according to this disclosure and a truck  90 . The truck  90  has a pedestal  91  (see  FIG. 6  mentioned later), and the robot  10  is mounted on the pedestal  91 . Thus, the robot  10  and the housing apparatus  95  integrally constitute a transport system  1 . 
     If it is assumed in this embodiment that the direction of travel of the truck  90  in the transport system  1  (namely, the frontward direction of the robot  10 ) is the positive direction of the X axis, the leftward direction of the truck  90  (or the robot  10 ) is the positive direction of the Y axis, and the anti-gravity direction (i.e. the direction opposite to the gravity) of the truck  90  (or the robot  10 ) is the positive direction of the Z axis, the X axis is the roll axis, the Y axis is the pitch axis, and the Z axis is the yaw axis. In consequence, rotation about the X axis is roll rotation (or leftward or rightward rotation), rotation about the Y axis is pitch rotation (or frontward or rearward rotation), and rotation about the Z axis is yaw rotation. In the context of this embodiment, the upward direction is the positive direction of the Z axis or the anti-gravity direction, and the downward direction is the negative direction of the Z axis or the direction of gravity. The leftward and the rightward directions refer respectively to the leftward and the rightward directions seen from the truck  90  (or the robot  10 ); the positive direction of the Y axis is the leftward direction, and the negative direction of the Y axis is the rightward direction. 
     &lt;Structure of Robot  10 &gt; 
     The general structure of the robot  10  will be described next with reference to  FIGS. 2 to 4 .  FIG. 2  is a front view of the robot  10 , and  FIG. 3  is a rear view of the robot  10 .  FIG. 4  is a diagram illustrating the robot  10  in a partially disassembled state. In these drawings, the robot  10  is illustrated without its body cover to make its interior structure visible. The robot  10  is a humanoid robot, which has a body that mimics the human bone structure. The body is the bone structure of the upper body of the robot  10 , which constitutes the robot main body  30  illustrated in  FIG. 2 . The robot main body  30  is mainly composed of a spine unit  14  extending along the Z axis in  FIG. 2 , bone units  14   a  to  14   d  made of metal plates, which will be described later, a hipbone unit  15  coupled to the spine unit  14  to support it, and a pelvis unit that supports the hipbone unit  15  and to which the leg unit  35  is connected. The arm units  50  and the leg unit  35  are attached to this robot main body  30 . To the spine unit  14  is connected a neck unit  13  of the robot  10 , on the top of which a head unit  11  is mounted. The head unit  11  may be provided with a camera that captures images of its environment. The head unit  11  and the spine unit  14  are connected via the neck unit  13  in such a way as to allow roll, pitch, and yaw rotations of the head unit  11  relative to the spine unit  14 . 
     The robot  10  is provided with drive units  20  for driving the right and left upper bodies of the robot  10  respectively. The drive unit  20  includes an actuator used to rotate the arm unit  50  of the robot  10  in pitch and roll directions on the shoulder of the robot  10 . As illustrated in  FIG. 4 , a front collarbone unit  14   a  and a back collarbone unit  14   b  are connected to the spine unit  14  at the location of the shoulder of the robot  10  respectively on the front and the back of the robot  10 . Moreover, a front breastbone unit  14   c  and a back breastbone unit  14   d  are connected to the spine unit  14  at the location of the breast (below the shoulder) of the robot  10  respectively on the front and the back of the robot  10 . These bone units  14   a  to  14   d  and the spine unit  14  form spaces on the right side and the left side of the spine unit  14  in the upper body of the robot  10 . The two drive units  20  are housed respectively in the right and left spaces and connected to the bone units  14   a  to  14   d . Thus, the two drive units  20  are provided inside the robot  10 . Since the bone units  14   a  to  14   d  are made of metal plates, the drive units  20  are attached to the spine unit  14  relatively elastically. The drive units  20  are also connected to the hipbone unit  15 . The hipbone unit  15  is supported by the pelvis unit  16 . 
     In the upper body structure of the robot  10  configured as above, various drive axes are defined as illustrated in  FIG. 5 . Among them, drive axes relating to the head unit  11  include a head roll axis, a head pitch axis, and a head yaw axis. Actuators are provided for the respective axes so that the head unit  11  can rotate in the roll, pitch, and yaw directions relative to the neck unit  13 . Drive axes relating to the hipbone unit  15  include a waist roll axis, a waist pitch axis, and a waist yaw axis. Actuators are provided for the respective axes so that the upper body of the robot  10  can rotate in the roll, pitch, and yaw directions relative to the hipbone unit  15 . Drive axes relating to the arm unit  50  include a shoulder roll axis, a shoulder pitch axis, a shoulder yaw axis, an elbow pitch axis, a wrist roll axis, a wrist pitch axis, and a wrist yaw axis (seven axes in total). Actuators are provided for the respective axes so that the arm unit  50  of the robot  10  can rotate in the roll, pitch, and yaw directions at the shoulder, in the pitch direction at the elbow, and in the roll, pitch, and yaw directions at the wrist. As will be understood from the above structure, the arm unit  50  of the robot  10  has a structure mimicking the human arm. The arrangement and the structure of the actuators for the respective axes are known in the art, and therefore they will not be described specifically in this disclosure. 
     As illustrated in  FIG. 1 , the leg unit  35  is attached to the pelvis unit  16  and extending downward. The leg unit  35  is configured to support the above-described upper structure of the robot  10 . Specifically, the leg unit  35  includes an upper leg link unit  31  and a lower leg link unit  32 . The lower leg link unit  32  is fixed to the pedestal  91  of the truck  90 . Thus, the robot main body  30  and the housing apparatus  95  are coupled via the leg unit  35 . The upper leg link unit  31  and the lower leg link unit  32  are connected by a knee joint unit  33  having an actuator in such a way as to be capable of rotating in the pitch direction. The upper leg link unit  31  and the pelvis unit  16  are connected by an under-waist joint unit  34  having an actuator in such a way as to be capable of rotating in the pitch direction. The height of the upper body structure of the robot  10  can be changed by cooperative pitch rotations of the knee joint unit  33  and the under-waist joint unit  34  while maintaining its posture. 
     &lt;Structure of Housing Apparatus&gt; 
     The general structure of the housing apparatus  95  will be described next with reference to  FIGS. 6 and 7 .  FIG. 6  is a diagram illustrating the general structure of the housing apparatus  95 , and  FIG. 7  is a diagram illustrating the general structure of the housing rack  70  provided in the housing apparatus  95 . The housing apparatus  95  includes the housing rack  70  and the truck  90 . It is possible to arrange a plurality of trays in the housing rack  70  along the vertical direction (or the Z axis direction) one above another, as illustrated in  FIG. 6 . The trays are objects to be held by the hand units  60 . The trays may be arranged in the housing rack  70  with food and drink to be served to users placed thereon. The truck  90  has four drive wheels  92 . The truck  90  also has a bumper  93  on its front side to reduce the impact upon collision. The housing rack  70  is provided on the front portion of the upper surface of the truck  90 , and the pedestal  91  is provided on the rear portion of the upper surface of the truck  90  to serve as a place on which the robot  10  is disposed behind the housing rack  70 . 
     Next, the housing rack  70  will be described with reference to  FIG. 7 . The housing rack  70  has a pair of base members  71  mounted on the truck  90  and extending along the X axis. The housing rack  70  also has four support columns  72  fixed on the base members  71  and extending along the Z axis. Two pairs of supporting columns  72  among the four support columns  72  that respectively define YZ planes are used to construct two lift devices. More specifically, the housing rack  70  has a lift device constructed in a first YZ plane and another lift device constructed in a second YZ plane spaced from the first YZ plane along the X axis, both of which are mounted on the pair of base members  71 . Trays to be held are placed in such a way that the ends of each tray rest on a tray rest  80  of one lift device and a tray rest  80  of the other lift device. Thus, the trays housed in the housing rack  70  are arranged one above another along the vertical direction. 
     The lift devices of the housing rack  70  will now be described below. Since the two lift devices of the housing rack  70  have the same structure, only one of them will mainly be described. One lift device has an actuator  74  provided on the lower portion of one of the support columns  72 . The actuator  74  is used to move up and down a plurality tray rests  80  that are arranged one above another between one support column  72  and the other support column  72 . The output shaft of the actuator  74  is connected to a lower rotary shaft  75   a  via a transmission mechanism (e.g. gears) not shown in the drawings, the lower rotary shaft  75   a  being extending between the lower portions of the two support columns and rotatably supported thereon. To the lower rotary shaft  75   a  are attached two sprockets  76   a  for the respective support columns. There is also provided an upper rotary shaft  75   b  extending between the upper portions of the two support columns  72  and rotatably supported thereon. To the upper rotary shaft  75   b  are also attached two sprockets  76   b  for the respective support columns. Chains  77  are wrapped around the lower sprockets  76   a  and the upper sprockets  76   b  for the two columns  72 . With this structure, the drive force of the actuator  74  is transmitted to the lower rotary shaft  75   a  and then to the upper rotary shaft  75   b  by the chains  77 . There is also provided flat guide plates  73  extending in the vertical direction along the respective support columns. 
     The structure of the chain  77  will now be described with reference to  FIG. 8 . The chain  77  is composed of a plurality of roller chains  77   a  that are connected by links  77   b ,  77   c . As illustrated in  FIG. 8 , the links  77   c  on one side of the chain  77  are flanged links on which the tray rests  80  are to be attached. Specifically, the flanged link  77   c  has a flange  77   cl  that is angled perpendicular to a flat portion that connects roller chains  77   a . The flange  77   cl  has a through hole  77   c   2 . The through hole  77   c   2  is used to attach the tray rest  80 . It is not necessary to provide the flanged links  77   c  on all the roller chains  77   a  of the chain  77 . It is preferred that the flanged links  77   c  be provided continuously along approximately half the circumference of chain  77 . 
     Next, the structure of the tray rest  80  will be described with reference to  FIG. 9 . The tray rests  80  are used to house a plurality of trays in the housing rack  70  by supporting the opposite ends of the trays on them. The tray rests  80  are arranged in such a way that one tray is supported by a pair of support rests  80  in the housing rack  70 . This pair of tray rests  80  corresponds to the table part according to this disclosure. The tray rest  80  has a table plate  81  on which an end of the tray is to be placed and a back plate  82  that is angled approximately perpendicular to the table plate  81 . The back plate  82  has through holes  86  near its both ends, which are used to attach the tray rest  80  to the chain  77 . Specifically, the tray rest  80  is attached to the two chains  77  with the through hole  86  near one end of the tray rest  80  being aligned with a through hole  77   c   2  of one chain  77  and with the through hole  86  near the other end of the tray rest  80  being aligned with a through hole  77   c   2  of the other chain  77 . To the back plate  82  are connected retaining plates  84  at locations below the through holes  86  provided near the ends of the back plate  82 . The retaining plates  84  and the back plate  82  are coplanar. The table plate  81  has a cut portion  83  having the same shape as the retaining plate  84 . When the tray rest  80  is being attached to the two chains  77 , the retaining plates  84  are located in such a way as to retain the chains  77 . This can prevent the chains  77  in the housing rack  70  from loosening, and therefore the chains  77  can transmit the driving force of the aforementioned actuator  74  reliably. 
     The tray rest  80  has guide portions  85  bent in a crank-like shape and extending from both ends of the back plate  82 . The guide portion  85  has a surface that is substantially parallel with the back plate  82  and spaced from the back plate  82  on the side opposite to the table plate  81 . In the state in which the tray rest  80  is being attached to the two chains  77 , the guide portions  85  are in surface contact with two side guide plates  73  disposed respectively along the two support columns  72  as illustrated in  FIG. 10 . The frictional force acting between the guide portions  85  and the guide plates  73  with their surface contact is small enough not to substantially affect driving of the chains  77  by the actuator  74 . The surface contact of the guide portions  85  and the guide plates  73  on both the ends of the tray rest  80  can prevent inclination of the tray rest  80  while the tray is moved up and down, thereby preventing food or drink on/in a dish, cup or other containers on the tray from spilling and preventing the containers from toppling over. 
     The operation of the housing rack  70  structured as above will now be described. As described above, the housing rack  70  has two lift devices, and the tray rests  80  attached to the respective lift devices are opposed to each other (see  FIG. 7 ). With this arrangement, a tray is placed with its ends supported on the tray rest  80  of one lift device and the opposed tray rest  80  of the other lift device (see  FIG. 6 ). As illustrated in  FIGS. 6 and 7 , the two lift devices of the housing rack  70  are spaced from each other by a distance slightly larger than the width of the tray. When a plurality of trays are to be housed in the housing rack  70 , the space between the lift devices may be utilized to slide the trays into the housing rack  70  from the direction of the Y axis.  FIG. 6  shows a state in which four trays are housed in the housing rack  70 . 
     When the hand units  60  of the robot  10  hold a tray housed in the housing rack  70  to take it out, the hand units  60  of the two arm units  50  hold the Y-axial ends of the tray and lift up the tray they hold. In order for the hand units  60  to do this operation, it is necessary that the tray to be held be the tray that is located uppermost in the housing rack  70  and that tray rests  80  that are not for the tray to be held (e.g. tray rests  80  on which another tray was being placed) are not located above the tray to be held. This is because if such tray rests  80  are located above the tray to be held, the tray held and lifted up by the hand units  60  may interfere with such tray rests  80 , whereby the tray may be prevented from being taken out smoothly. 
     The system according to this embodiment is configured to control the position of the tray in the housing rack  70  such that the tray to be held satisfies the above condition. Details of this control will be described later. This position of the tray corresponds to the specific position according to this disclosure. This position will be referred to as the “tray holding position”. The tray holding position is a fixed position determined in advance in the housing rack  70 . As descried above, the truck  90  and the housing rack  70  mounted thereon constitute the housing apparatus  95 , and the robot  10  is fixed on the truck  90 . Thus, the housing apparatus  95  and the robot  10  integrally constitute the transport system  1 . In consequence, in this transport system  1 , the tray holding position is a known position relative to the robot main body  30  of the robot  10 . Therefore, when the holding operation is done by the hand units  60  of the two arm units  50  of the robot  10 , it is not necessary to recognize (or determine) the position of the tray specifically, or the processing of recognizing the position of the tray can be made simpler. This leads to a reduction of the operation load in the process of taking out trays from the housing rack  70  one by one by the robot  10 . In consequence, the control of the position of the hand units  60  by the robot  10  can be made simpler, and favorable transport of the trays can be achieved. 
     The transport system  1  including the robot  10  and the housing apparatus  95  configured as above can be moved by the truck  90  with the robot  10  to a destination of transport of the objects with a plurality of trays (or objects) being housed in the housing rack  70  of the housing apparatus  95 . After arriving at the destination, the transport system  1  can execute the operation of delivering the trays to a user(s) by holding and taking out the trays precisely with a simple position control of the hand units  60 . To enable the transport of trays by the transport system  1 , the robot  10  and the housing apparatus  95  are provided with respective control devices  10 A,  95 A. The control devices  10 A,  95 A are computers each having a calculation device and a memory. The control devices  10 A,  95 A execute certain control programs to perform the above-described transport process. The control devices  10 A and  95 A are electrically connected to each other, and signal communication is performed between these control devices when necessary to carry out the process of transporting the trays. 
     Functional parts implemented by executing the aforementioned control programs will now be described with reference to  FIG. 11 . The control device  10 A of the robot  10  has, as functional parts, a hand control part  101 , a posture control part  102 , and a recognition part  103 . The hand control part  101  is a functional part that controls opening and closing of the hand unit  60  of each arm unit  50 . In the system according to this embodiment, as described above, the tray to be held is always positioned at the predetermined tray holding position in the housing rack  70 . At this position, the tray is placed in a state in which it is supported on the tray rests  80  of the lift devices of the housing rack  70 . Thus, the tray positioned at the tray holding position is kept in a regular state. Therefore, the hand control part  101  may execute the opening and closing control of the hand units  60  to hold the tray immediately after the completion of position control of the hand units  60  by the posture control part  102  (which will be described below). 
     The posture control part  102  is a functional part that controls the posture of the robot  10 . In particular, the posture control part  102  executes the posture control for positioning the hand units  60  to hold the tray positioned at the tray holding position in the housing rack  70  and the posture control for taking out the tray after holding it. In this case also, the tray to be held is always positioned at the predetermined tray holding position in the housing rack  70 , and therefore, it is not necessary to specifically recognize the state and the position of the tray using a camera or other device and execute the posture control for the robot  10  based on the recognition, but the posture of the robot  10  may be controlled in such a way as only to bring the hand units  60  to the tray holding position. Therefore, the control by the posture control part  102  is simple. The recognition part  103  is a functional part that recognizes the presence of the tray to be held at the tray holding position. The processing of this recognition is executed based on a sensor signal sent from a detection part  953 , which will be described later. Control by the posture control part  102  is executed after the presence of the tray at the tray holding position is recognized by the recognition part  103 . 
     The control device  95 A of the housing apparatus  95  has, as functional parts, a movement control part  951 , an up and down control part  952 , and the detection part  953 . The movement control part  951  is a functional part that executes control relating to movement of the transport system  1  by the truck  90 . For example, to move the transport system  1  from a place at which trays are loaded into it to the destination of transport, the movement control part  951  controls steering and driving of the drive wheels  92  of the truck  90 . The truck  90  is equipped with a GPS device for determining the present location of the truck  90 , and the movement control part  951  may control the truck  90  based on a sensor signal of the GPS device. Alternatively, the movement control part  951  may control the truck  90  based on a control signal sent from an external device. 
     The up and down control part  952  is a functional part that controls the up and down movement of the lift devices of the housing rack  70 . In particular, the up and down control part  952  controls the up and down movement of the lift devices so as to position a tray to be held at the tray holding position. The housing rack  70  is provided with a proximity sensor or the like (not shown), and the up and down control part  952  can detect the presence or absence of a tray on each tray rest  80 . The actuator  74  is provided with an encoder, and the up and down control part  952  can determine where each tray rest  80  is located based on a sensor signal of the encoder. The up and down control part  952  controls the up and down movement of the lift devices using these sensor signals. The detection part  953  is a functional part that detects the presence of the tray to be held (i.e. the upper most tray in the housing rack  70 ) at the tray holding position. Signals generated by detection executed by the detection part  953  is passed to the recognition part  103  of the control device  10 A. 
     Next, the tray transport process performed by the transport system  1  will be described with reference to  FIG. 12 .  FIG. 12  is a flow chart of the transport process. The execution of the transport process is triggered by a command to transport a plurality of trays to a certain destination sent to the transport system  1 . In the following description, it is assumed that a plurality of trays are being housed in the housing rack  70 . Firstly, in step S 101 , the movement control part  951  executes the processing of moving the transport system  1  to the destination. Information about the destination has already been supplied to the transport system  1 . 
     Then, in step S 102 , it is determined whether or not the tray to be held located uppermost is positioned at the tray holding position as the specific position. This determination is made by the recognition part  103  on the basis of the state of the trays in the housing rack  70  determined by the detection part  953 . If an affirmative determination is made in step S 102 , the process proceeds to step S 104 . If a negative determination is made in step S 102 , the process proceeds to step S 103 . In step S 103 , the up and down control part  952  executes a lifting process for the two lift devices in the housing rack  70 . Specifically, the up and down control part  952  controls driving of the actuator  74  so as to bring the uppermost tray to the tray holding position. In step S 104 , the posture control part  102  executes posing of the robot  10  to position the hand units  60  relative to the tray to be held. As described above, the housing apparatus  95  and the robot  10  in the transport system  1  are coupled integrally, and the tray holding position is a known position relative to the robot main body  30  of the robot  10 . Therefore, the posture control part  102  can do posing of the robot  10  easily and precisely. 
     After the hand units  60  are positioned relative to the tray by the aforementioned posing, the hand control part  101  executes the processing of holding the tray in step S 105 . Then, the hand control part  101  executes the processing of taking out the tray held by the hand units  60  from the housing rack  70 . In this taking-out process, the knee joint unit  33  and the under-waist joint  34  are used. It is possible to lift the tray held by the hand units  60  by cooperative operations of these joint units without changing the posture of the upper body of the robot  10 , in particular the posture of the arm units  50  that are holding the tray. This greatly contributes to stable taking-out of the tray. After the tray is taken out from the housing rack  70 , the upper body of the robot  10  is rotated in the yaw direction at the hipbone unit  15  by the actuator for the waist yaw axis provided in the hipbone unit  15  while keeping its posture. This also greatly contributes to stable taking-out of the tray. 
     In step S 106 , it is determined whether taking-out of the tray from the housing rack  70  has been completed. This determination may be made by the recognition part  103  on the basis of the state of the tray in the housing rack  70  detected by the detection part  953 . If an affirmative determination is made in step S 106 , the process proceeds to step S 107 . If a negative determination is made in step S 106 , the processing of step  102  onward is executed again. In step S 107 , the movement control part  951  executes the processing of moving the transport system  1  to a specific home place. Information about the home place may be prepared in advance. Alternatively, information about a place where loading of the housing apparatus  95  with objects to be transported next is performed may be supplied to the transport system  1  from an external device as information about the home place. 
     &lt;Modification&gt; 
     A modification of the object transport process performed by the transport system  1  will be described with reference to  FIG. 13 . In this modification, the housing apparatus  95  and the robot  10  in the transport system  1  are configured such that they can be coupled to and decoupled from each other, and the housing apparatus  95  and the robot  10  are configured to be cable of moving autonomously. For example, the truck  90  described in the above description of the embodiment is provided for each of the housing rack  70  and the robot  10  on their bottoms to enable the housing apparatus  95  and the robot  10  to move autonomously. In this case, the housing apparatus  95  is configured to implement the movement control part  951 , the up and down control part  952 , and the detection part  953  shown in  FIG. 11 , and the robot  10  is configured to implement a movement control part for controlling autonomous movement of the robot  10  in addition to the hand control part  101 , the posture control part  102 , and the recognition part  103 . Integration of the housing apparatus  95  and the robot  10  is achieved by coupling the trucks  90  of them to each other. This enables communication of information between the housing apparatus  95  and the robot  10 . After the integration, their autonomous movement may be performed under unified control executed by the movement control part  951  of the housing apparatus  95  or the movement control part of the robot  10 . 
     As illustrated in  FIG. 13 , the transport system  1  includes a processing apparatus. The processing apparatus is a server apparatus, which sends commands that are necessary in the object transport process to the housing apparatus  95  and the robot  10 . The processing apparatus, the housing apparatus  95 , and the robot  10  are electrically connected through a network so that they can communicate with each other. The transport system  1  may include another housing apparatus. 
     The processing apparatus receives a request for transport of an object (e.g. a tray on which food and drink is placed) from a user (the processing of step S 201 ). This request for transport includes information about the kind and the number of objects to be transported and the destination of transport. The processing apparatus receives the request for transport and sends a movement command to the housing apparatus  95  to cause it to move to the given destination after the requested object is loaded into the housing rack  70  (the processing of step S 202 ). At this time, the housing apparatus  95  and the robot  10  are in a separated state. After receiving the movement command, the housing apparatus  95  is loaded with the object to be transported in its housing rack  70  at a specific place and then moves to the destination as requested (the processing of step S 203 ). 
     While the housing apparatus  95  is moving in performing the above-described movement process, the housing apparatus  95  sends a movement request to the robot  10  to request it to move to the given destination of transport (the processing of step S 204 ). In other words, the housing apparatus  95  sends the movement request to the separated robot  10  so that the robot  10  can do the taking-out operation at the destination to which the housing apparatus  95  will transport the object. There may be cases where the robot  10  is doing the taking-out operation for a housing apparatus other than the housing apparatus  95  that has sent the movement request in step S 204 . In view of this, when receiving the movement request, the robot  10  executes the processing of determining whether it can fulfill the request in step S 205 . If it is determined that the robot  10  can do the taking-out operation, the robot  10  sends an answer indicating the acceptance of the request to the housing apparatus  95  in step S 206  and starts to move to the designated destination of transport (the processing of step S 207 ). Alternatively, the robot  10  may receive the movement request from the processing apparatus. 
     After the housing apparatus  95  and the robot  10  come to the destination of transport, the operation of coupling the trucks of them is performed in step S 208 , so that the housing apparatus  95  and the robot  10  are coupled into an integral state substantially the same as that illustrated in  FIG. 1 . Then, the processing of holding and taking out the object is performed to take out the object housed in the housing apparatus  95  by the robot  10  at the destination of transport (the processing of step S 209 ). The processing of step S 209  is substantially the same as the processing of steps S 102  through S 106  in  FIG. 12 . After the completion of the processing of taking out the object, the processing of decoupling the housing apparatus  95  and the robot  10  from each other is performed (the processing of step S 210 ), so that the housing apparatus  95  and the robot  10  become autonomously movable again. At the time when the decoupling is completed, the housing apparatus  95  sends a notification reporting the completion of the process relating to the transport request received in step S 201  to the processing apparatus (the processing of step S 211 ). 
     Thereafter, the housing apparatus  95  returns to a specific home place, where it waits for the next request sent from the processing apparatus (the processing of step S 212 ). Likewise, the robot  10  enters a standby state to wait for the next movement request for the taking-out operation (the processing of step S 213 ). The robot  10  in the standby state can accept a movement request sent from any housing apparatus  95  included in the transport system  1 . 
     By the above-described transport process, the robot  10  can be coupled to housing apparatuses  95  that require the operation of taking out objects one after another to provide the taking-out operation. Therefore, the rate of operation of the robot  10  can be enhanced, and the transport system  1  can achieve efficient transport of objects. Since the housing apparatus  95  is being separated from the robot  10  while moving to the destination of transport, the energy consumption in moving can be reduced. 
     REFERENCE SIGNS LIST 
     
         
           1 : transport system 
           10 : robot 
           10 A: control device 
           30 : robot main body 
           33 : knee joint unit 
           34 : under-pelvis joint unit 
           35 : leg unit 
           50 : arm unit 
           60 : hand unit 
           62 : first frame 
           65 : second frame 
           66 : slide member (slide part) 
           70 : housing rack 
           74 : actuator 
           77 : chain 
           80 : tray rest 
           81 : table plate 
           90 : truck 
           95 : housing apparatus 
           95 A: control device