Abstract:
Only when a wall side and the vicinity of an obstacle are cleaned, a side brush is operated and the cleaning is carried out, and when any other place than the wall side and the vicinity of the obstacle is cleaned, the side brush is maintained in a stoppage state. When a place such as the wall side or the vicinity of the obstacle in which dust is easy to accumulate is cleaned, the side brush is operated to enhance the dust collecting property. When any other place than the wall side or the vicinity of the obstacle is cleaned, the side brush is stopped to suppress power consumption and generation of a noise. A judgment processing portion detects based on a detection signal from an obstacle detecting portion that a cleaner is approaching a wall or an obstacle. In response to such detection, the judgment processing portion instructs a travel steering portion to carry out immediate rotation and change of a travel direction, or travel along a wall side. Also, the judgment processing portion instructs a side brush driving portion to drive a side brush only in the rotation and in the wall side travel, and to stop the side brush in straight advance travel.

Description:
[0001]     This application claims priority under 35 U.S.C. §119 of Japanese Patent Application No. 2004-207861 filed Jul. 14, 2004.  
       BACKGROUND OF THE INVENTION  
       [0002]     1. Field of the Invention  
         [0003]     The present invention relates to a cleaner, and more particularly to a self-propelled vacuum cleaner including auxiliary dust collecting means such as a side brush in addition to dust collecting means such as a dust collecting port or a suction nozzle.  
         [0004]     2. Description of the Related Art  
         [0005]     In recent years, a so-called self-guided, self-propelled vacuum cleaner having a microcomputer and various sensors mounted therein has been developed and come into wide use.  
         [0006]     Normally, dust collecting means such as a suction nozzle or a brush is provided in a bottom portion of a main body of a self-propelled vacuum cleaner of this sort. During a self-guided, self-propelled operation, occasional travel positions are measured based on rotational frequencies of wheels and a travel direction. In addition, an obstacle located forward in the travel direction is detected by contact type or non-contact type sensing means, and the travel direction is changed accordingly to avoid the obstacle. Note that in addition to the method utilizing the self-contained navigation (technique for measuring a travel position based on rotational frequencies of wheels and a travel direction) as described above, the technique based on the inertial navigation using a gyroscope can be used for the measurement of the travel position.  
         [0007]     As regards such a self-propelled vacuum cleaner, a cleaner has been developed in which auxiliary dust collecting means such as a rotating brush is provided in addition to dust collecting means such as a suction nozzle or a brush. With this cleaner, during the cleaning, the auxiliary dust collecting means such as the rotating brush is operated, thereby enhancing the dust collecting property in a travel path.  
         [0008]     JP 7-322977 A discloses a technique for reducing a rotational frequency of a side brush when the brush is cleaning along the wall or when a self-propelled movement direction is reversed. According to this technique, it is possible to prevent a side brush from scratching a wall, a carpet, or the like when the brush is cleaning along the wall or when the self-propelled movement direction is reversed.  
         [0009]     However, in such a conventional self-propelled vacuum cleaner, there arises a problem that an electric power is consumed and a large noise is generated all the more because the side brush is usually rotating during the cleaning. In addition, the side brush is effective to collect the dust, for example, near the wall or around obstacles which is hardly collected by the main collecting means. However, there is a possibility that when the self-propelled vacuum cleaner travels in a place which does not have many obstacles such as a center of a room, the side brush scatters the dust about rather than collects the dust. Moreover, the possibility that the side brush catches a feeder cord or the like becomes higher.  
       SUMMARY OF THE INVENTION  
       [0010]     It is an object of the present invention to provide a self-propelled vacuum cleaner which is capable of effectively suppressing power consumption and noise generation while maintaining a high dust collecting property, and of preventing a side brush from scattering dust, tangling a cord, or the like as much as possible.  
         [0011]     A main feature of the present invention is that a side brush is operated only when necessary such as when the cleaner is cleaning along the wall or around obstacles. Thus, the dust collecting property is enhanced in a place in which the dust is hardly collected or in a place in which the dust is easy to accumulate. The excessive power consumption, the generation of the noise, the scattering of the dust, the tangling of the cord, and the like by the side brush are suppressed in any place other than those places.  
         [0012]     An aspect of the present invention is characterized by a cleaner, including: dust collecting means; a side brush; obstacle detecting means for detecting an obstacle; and brush control means for controlling drive of the side brush based on detection results obtained by the obstacle detecting means. Here, when an obstacle is detected by the obstacle detecting means, the brush control means starts to drive the side brush, and when the obstacle detecting means does not detect an obstacle, the brush control means stops driving the side brush.  
         [0013]     In addition, it is possible to adopt a configuration that the detection results obtained by the obstacle detecting means reveal that a distance to an obstacle is equal to or smaller than a first predetermined value, the brush control means judges that an obstacle is present and drives the side brush, and when the detection results obtained by the obstacle detecting means reveal that the distance to the obstacle is beyond the first predetermined value, the brush control means judges that no obstacle is present and stops driving the side brush.  
         [0014]     Further, when the cleaner according to the present invention further includes self-propelled movement means, it is possible to adopt a configuration that when the detection results obtained by the obstacle detecting means reveal that the distance to the obstacle is equal to or smaller than a second predetermined value, the self-propelled movement means changes a travel direction of the cleaner while the brush control means drives the side brush.  
         [0015]     It is also possible to adopt a configuration that after the self-propelled movement means changes the travel direction of the cleaner, the brush control means stops driving the side brush. More specifically, when the detection results obtained by the obstacle detecting means reveal that the distance to the obstacle becomes equal to or larger than a third predetermined value after the self-propelled movement means changes the travel direction of the cleaner, the brush control means stops driving the side brush.  
         [0016]     Moreover, when the cleaner according to the preset invention further includes self-propelled movement means, it is possible that the brush control means drives the side brush and the self-propelled movement means maintains the distance to the obstacle based on the detection results obtained by the obstacle detecting means.  
         [0017]     According to the present invention, only when places such as near the wall and around obstacles are cleaned where the dust is easy to accumulate, the side brush is operated and the cleaning using the side brush is carried out. Thus, the dust collecting property in those places can be enhanced. In addition, when a place other than those places is cleaned, since the operation of the side brush is stopped, the excessive power consumption and the noise generation by the side brush are suppressed. Also, the scattering of the dust and the tangling of the cord by the side brush are prevented.  
         [0018]     Consequently, according to the present invention, it is possible to provide the cleaner which is capable of suppressing the scattering of the dust and the tangling of the cord while suppressing the excessive power consumption and the generation of the noise, and of effectively cleaning places such as near the wall and around obstacles where the dust is easy to accumulate. 
     
    
     BRIEF DESCRITION OF THE DRAWINGS  
       [0019]     The above and other objects and novel features of the present invention will be more perfectly clear when the following description of preferred embodiments is read with reference to the accompanying drawings, in which:  
         [0020]      FIG. 1  is a perspective view of a main portion of a cleaner according to an embodiment of the present invention;  
         [0021]      FIG. 2  is a bottom view of the cleaner according to the embodiment of the present invention;  
         [0022]      FIG. 3  shows a functional block of the cleaner according to the embodiment of the present invention;  
         [0023]      FIGS. 4A, 4B , and  4 C are diagrams explaining a construction of a rotational frequency detecting portion of the cleaner according to the embodiment of the present invention;  
         [0024]      FIG. 5  shows an example of an operation for cleaning a rectangle-shaped room by the cleaner according to the embodiment of the present invention;  
         [0025]      FIG. 6  is a flow chart in an along-wall travel mode of the cleaner according to the embodiment of the present invention;  
         [0026]      FIGS. 7A, 7B ,  7 C, and  7 D illustrate a wall detecting operation in the along-wall travel mode of the cleaner according to the embodiment of the present invention;  
         [0027]      FIGS. 8A, 8B ,  8 C, and  8 D illustrate how to turn a corner of a wall in the along-wall travel mode of the cleaner according to the embodiment of the present invention;  
         [0028]      FIGS. 9A, 9B ,  9 C, and  9 D illustrate how to turn a corner of a wall in the along-wall travel mode of the cleaner according to the embodiment of the present invention;  
         [0029]      FIG. 10  is a flow chart of a random travel mode of the cleaner according to the embodiment of the present invention;  
         [0030]      FIGS. 11A, 11B ,  11 C, and  11 D illustrate a method of calculating a rotation angle in the random travel mode of the cleaner according to the embodiment of the present invention;  
         [0031]      FIGS. 12A and 12B  illustrate a method of calculating a rotation angle in the random travel mode of the cleaner according to the embodiment of the present invention;  
         [0032]      FIG. 13  is another flow chart in the random travel mode of the cleaner according to the embodiment of the present invention;  
         [0033]      FIG. 14  shows an example of a cleaning operation in a rectangle-shaped room of the cleaner according to the embodiment of the present invention; and  
         [0034]      FIGS. 15A, 15B ,  15 C, and  15 D illustrate a cleaning operation carried out along an obstacle or the like in the random travel mode of the cleaner according to the embodiment of the present invention. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0035]     Hereinafter, an embodiment of the present invention will be described with reference to the accompanying drawings.  
         [0036]      FIG. 1  is a perspective view of a cleaner  100  according to an embodiment of the present invention, and  FIG. 2  is a bottom view of the cleaner  100  according to the embodiment of the present invention.  
         [0037]     Referring to  FIG. 1 , reference numeral  1  designates a bumper;  2 , an obstacle detecting sensor;  3 , a dust collecting box; and  4 , a fan motor for a dust collecting operation.  
         [0038]     The bumper  1  doubles as a contact type sensor such as a switch for detecting, when an obstacle or the like unexpectedly contacts the cleaner  100 , the unexpected contact. The bumper  1  functions as a sensor for carrying out a stoppage, a back operation, or the like of the cleaner  100  when, for example, a leg or the like of someone suddenly touches the cleaner  100 .  
         [0039]     The obstacle detecting sensor  2  is a non-contact type sensor such as an ultrasonic sensor for detecting an obstacle. Several sets of obstacle detecting sensors  2  are mounted to a side face of a main body of the cleaner  100  with a transmission portion and a reception portion as one set. The obstacle detecting operation is carried out such that an obstacle detection signal is generated from the transmission portion, and the obstacle detection signal reflected by the obstacle is received by the reception portion.  
         [0040]     Referring to  FIG. 2 , reference numeral  5  designates a side brush, and reference numeral  6  designates a driving wheel. The two driving wheels  6  are disposed in a left-hand side and a right-hand side of the cleaner  100 , respectively. Also, reference numeral  7  designates a dust collecting port;  8 , an auxiliary wheel; and  9 , an arm for supporting the side brush  5 .  
         [0041]     The dust collecting port  7  is a suction port for sucking dust or the like. The side brush  5  is mounted to a tip of the arm  9  projecting from the bottom surface of the main body of the cleaner  100 . The side brush  5  is mounted so that a head of the side brush  5  projects at least from a peripheral surface of the main body of the cleaner  100 . As regards the side brush  5 , there are known several side brushes such as a cup type brush and a rod type brush. In this embodiment, the rod type brush is used as the side brush  5 . The rod type brush is adapted to rotate at the head of the arm  9  with its one end as a center.  
         [0042]     Note that the cleaner  100  may be provided with such a mechanism that a stopper etc. stop an operation of the rod type brush in an arm lower portion. As a result, when the cleaner  100  travels with the side brush  5  being unused, an unnecessary part such as a cord is prevented from being tangled round the side brush  5 . It is supposed that in this embodiment, the cleaner  100  has such a mechanism (not shown in  FIG. 2 ) installed therein.  
         [0043]     The travel direction of the cleaner  100  is changed to a left-hand or right-hand side depending on the difference in rotational frequency between the left-hand driving wheel and the right-hand driving wheel. Note that the change of the travel direction may also be carried out by steering the cleaner using the direction guidance wheel in addition thereto.  
         [0044]      FIG. 3  is a functional block diagram of the cleaner  100  according to this embodiment. In  FIG. 3 , reference numeral  11  designates a side brush driving portion for driving the side brush  5 ;  12 , the stopper described above;  13 , a time measuring timer;  14 , an obstacle detecting portion including an obstacle detecting sensor;  15 , a judgment processing portion for carrying out the processing, the judgment, and the control for the individual portions;  16 , a travel steering portion including a motor and the like; and  17  designates a rotational frequency detecting portion for detecting an operation of the travel steering portion  16 .  
         [0045]     Operations of the respective portions in this embodiment will hereinafter be described with reference to  FIG. 3 .  
         [0046]     The obstacle detecting portion  14  outputs a detection signal to the judgment processing portion  15  in response when the reception portion of any one of the obstacle detecting sensors  2  receives the obstacle detection signal. Still when the obstacle detection signal reflected by the obstacle is received and is then amplified by an amplifying circuit, and the level of the resultant signal exceeds a certain threshold, the obstacle detecting portion  14  outputs the detection signal. Thus, the sensitivity for the obstacle detection can be changed through the tuning of a circuit constant of the amplifying circuit, or the change of the threshold.  
         [0047]     The judgment processing portion  15  carries out the detection of the presence or absence of an obstacle, and the calculation for a distance to the obstacle based on the detection signal or the like inputted thereto. More specifically, the judgment processing portion  15  carries out the detection of the presence or absence of an obstacle based on the reception of the detection signal from a certain reception portion, and carries out the calculation for the distance to the obstacle based on a time difference between the obstacle detection signal output timing and the detection signal checking timing.  
         [0048]     The judgment processing portion  15  inputs an instruction to request to drive or stop the side brush  5  to the side brush driving portion  11  in correspondence to the results of the detection of the obstacle or the calculation for the distance to the obstacle. The side brush driving portion  11  carries out the control for the side brush  5  in accordance with the individual instruction inputs. Note that when stopping the side brush  5 , the side brush driving portion  11  simultaneously operates the stopper  12 .  
         [0049]     An output from the time measuring timer  13  is used for the purpose of measuring a certain time, preventing an infinite operation, and so forth by the judgment processing portion  15 . Note that a specific usage method will be described in detail later with reference to processing flow charts shown in  FIG. 6  and the like.  
         [0050]     The judgment processing portion  15  inputs an instruction for a forward movement, a backward movement, or a stop operation to the travel steering portion  16 . The travel steering portion  16  carries out the moving operation in accordance with the instruction input, and controls the motor for the left-hand and right-hand side driving wheels to change the travel direction of the cleaner  100  to the left-hand direction or the right-hand direction.  
         [0051]     The rotational frequency detecting portion  17  successively detects the rotating operations of both the left-hand and right-hand driving wheels in the travel steering portion  16  to output the detection results to the judgment processing portion  15 . The judgment processing portion  15  detects the rotational frequencies of the left-hand and right-hand driving wheels based on the detection results, calculates the moving speed of the cleaner  100  based on the detected rotational frequencies of the left-hand and right-hand driving wheels, and calculates an angle by which the travel direction of the cleaner  100  is changed based on the rotational frequency difference between the rotational frequencies of the left-hand and right-hand driving wheels.  
         [0052]     Referring now to  FIG. 4A , a rotational frequency of the driving wheels is calculated by using a magnet  20  and a magnetic flux sensor to detect the rotational frequency of a motor  21  and compute its rotational frequency in a rotational frequency encoder.  FIG. 4B  shows a waveform of an output from the magnetic flux sensor which is plotted along a time axis. The output from the magnetic flux sensor is changed between an H level and an L level in correspondence to the changing of the polarity of the magnet  20  between an N pole and an S pole.  FIG. 4C  shows a structure of the magnet  20  within a plane intersecting perpendicularly a rotating axis of the magnet  20 . The N pole and the S pole are alternately set in the magnet  20 .  
         [0053]     The judgment processing portion  15  measures a cleaner&#39;s own position of the cleaner  100  based on the data (the rotational frequencies of the left-hand and right-hand driving wheels and the rotational frequency difference therebetween) obtained in the manner as described above (self-contained navigation). Note that the judgment processing portion  15  may also detect a cleaner&#39;s own position by utilizing the inertial navigation using a gyroscope, an acceleration sensor, and the like.  
         [0054]     In the cleaner  100  according to this embodiment, after a power supply is turned ON, a cleaning operation based on an along-wall travel mode is carried out. After the cleaning operation based on the along-wall travel mode is completed, a cleaning operation based on a random travel mode is carried out.  
         [0055]      FIG. 5  shows an example of the cleaning operation when two obstacles exist in a rectangle-shaped room. In  FIG. 5 , a solid line portion indicates a cleaning operation path based on the along-wall travel mode, and a broken line portion indicates a cleaning operation path based on the random travel mode.  
         [0056]     Hereinafter, the cleaning operations in those two travel modes will be described in detail. Note that the operation such as the backward movement or the stop operation by the bumper switch is interruptedly carried out in each of the following travel modes, and an interruption operation is carried out for a predetermined time.  
         [0000]     [Along-Wall Travel Mode] 
         [0057]      FIG. 6  is a flow chart explaining the operation of the cleaner  100  according to this embodiment. Note that the cleaner  100  is placed in the vicinity of the wall so that its travel direction is directed toward the wall as a pre-preparation of the cleaner  100 .  
         [0058]     In Step S 101 , the power supply is turned ON to start the cleaning operation.  
         [0059]     In Step S 102 , the cleaner  100  carries out the self-propelled travel for a forward movement based on the self-guidance while carrying out the cleaning operation for collecting the dust. At this time, the side brush is held in a stop state. Note that during the self-propelled travel, the judgment processing portion  15  carries out the measurement of the cleaner&#39;s own position and grasps a shape of a room and positions of obstacles within the room (hereinafter referred to as “mapping”) based on output information from the rotational frequency detecting portion  17 . In the following operation, during the movement of the cleaner  100 , the mapping is carried out unless otherwise specified.  
         [0060]     In Step S 103 , the wall is detected. That is, as previously stated, a distance to the wall is detected based on the time difference between the output timing of the obstacle detection signal and the reception timing of the detection signal. When the distance to the wall is equal to or smaller than a specified value, the cleaner  100  judges that the cleaner  100  reaches a position very close to the wall, the operation proceeds to Step S 104 . On the other hand, when the distance to the wall is larger than the specified value, the operation returns back to Step S 102 .  
         [0061]     In Step S 104 , the rotating operation of the side brush  5  is started. In and after Step S 104 , the cleaning operation based on the along-wall travel is carried out while the side brush  5  is used.  
         [0062]     In Step  105 , the cleaner  100  travels forward while cleaning the room along the wall in a state in which the judgment processing portion  15  maintains a constant distance to the wall using the results of the output of a distance sensor. Note that when the cleaner  100  reaches a corner of the wall, the cleaner  100  changes its travel direction, and thereafter continues to carry out the along-wall cleaning similarly to the previous operation. Further, a distance to the wall is assumed to be a value determined by considering the distance to the wall, up to which the cleaner can clean the room using the side brush  5 .  
         [0063]     In Step S 106 , it is judged based on the mapping results and the measurement results of the cleaner&#39;s own position whether or not the cleaner  100  has made one lap in the room or the specified time has elapsed. Here, when it is judged in Step S 106  that the cleaner  100  has made one lap in the room, or when it is judged in Step S 106  based on a value in the time measuring timer  13  that the specified time has elapsed, the operation proceeds to Step S 107 . On the other hand, when it is judged in Step S 106  that the cleaner  100  has not made one lap in the room, or when it is judged in Step S 106  that no specified time has elapsed, the operation returns back to Step S 105  and the along-wall cleaning is continued.  
         [0064]     In Step S 107 , it is judged that the cleaning operation based on the along-wall travel is completed, and the rotation of the side brush  5  is stopped.  
         [0065]     The along-wall travel mode is completed through the above-mentioned operation, and the operation proceeds to the next random travel mode.  
         [0066]     Note that, the along-wall travel in Step S 105  will hereinafter be described with reference to  FIGS. 7A  to  7 D.  
         [0067]     Firstly, the operation at the beginning of the along-wall travel will be described with reference to  FIGS. 7A  to  7 D.  
         [0068]     When any one of the sensors  2  in  FIG. 7A  detects a wall during the straightly advancing operation, the cleaner  100  stops at a predetermined distance from the wall accordingly. Next, in  FIG. 7B , a rotation angle of the cleaner  100  is determined in correspondence to which sensor detects the wall, and the cleaner  100  rotates immediately by the rotation angle thus determined. As a result, the travel direction of the cleaner  100  is changed. After such rotation is completed, in  FIG. 7C , the travel direction of the cleaner  100  is determined as a direction parallel with the wall. Then, in  FIG. 7D , the forward movement operation is started in which the distance to the wall is kept constant while the detection results obtained by the sensor are used.  
         [0069]     Note that each of the predetermined distance and the constant distance shown in  FIGS. 7A and 7D , respectively, is a distance to which the cleaner  100  can approach the wall for cleaning by using the side brush  5  without colliding with the wall (this is also applied to the following description).  
         [0070]     In such a manner, the cleaner  100  cleans the room using the side brush  5  while traveling along the wall.  
         [0071]     Note that as can be seen by referring to  FIGS. 1 and 2 , since the side brush  5  is installed in a left-side lower portion of the main body of the cleaner  100 , when in this embodiment, the operation for cleaning the room along the obstacle, the wall, or the like is carried out using the side brush  5 , the control or the like for the rotation of the cleaner  100  is carried out so that the wall, the obstacle, or the like is located on the left-hand side with respect to the travel direction.  
         [0072]     Next, an explanation will be made with respect to an operation when the cleaner  100  reaches a corner of the wall.  
         [0073]     Firstly, an explanation will be made with respect to an operation when the cleaner  100  reaches a corner of a wall, and when the wall exists forward in the travel direction with reference to  FIGS. 8A  to  8 D. When in  FIG. 8A , any one of the sensors  2  detects the wall existing in front of the cleaner  100 , the cleaner  100  stops at a predetermined distance from the wall accordingly. Next, in  FIG. 8B , a rotation angle of the cleaner  100  is determined in correspondence to which sensor detects the wall, and the cleaner  100  rotates immediately by the rotation angle thus determined. As a result, the travel direction of the cleaner  100  is changed. After such rotation is completed, in  FIG. 8C , the travel direction of the cleaner  100  is determined as a direction parallel with the wall which exists in front of the cleaner  100  when the cleaner  100  approaches the corner of the wall. Then, in  FIG. 8D , the forward movement of the cleaner  100  is restarted in which the distance to the wall is held constant using the detection results obtained by the sensor  2 .  
         [0074]     Note that in  FIG. 8B , the cleaner  100  may also be equipped with a mechanism in which an arm is adapted to expand and contract so that the side brush  5  reaches even the inner part of the corner of the wall in order to rake the dust from the corner of the wall. In this case, for example, control is carried out such that the arm expands to the full in the middle of the rotation operation.  
         [0075]     Next, a description will be given with respect to the operation when the cleaner  100  reaches the corner of the wall as shown in  FIG. 9A . In this case, the cleaner  100  turns to the left in accordance with the control for holding a constant distance between an obstacle and the rear left portion of the cleaner  100 .  
         [0076]     Referring to  FIG. 9A , when a sensor  30  detects that the distance from the wall begins to become longer, in  FIG. 9B , the cleaner  100  turns to the left based on the distance to the obstacle detected by the sensor  30  so that the distance between the cleaner  100  and the wall is held constant, thereby changing the travel direction of the cleaner  100 . After that, after in  FIG. 9C , the change of the travel direction of the cleaner  100  is completed, in  FIG. 9D , the forward movement of the cleaner  100  is restarted in which the distance to the wall is held constant using the detection results obtained by the sensor  30 .  
         [0077]     In such a manner, the cleaner  100  carries out the cleaning operation using the side brush  5  while traveling along the wall.  
         [0000]     [Random Travel Mode] 
         [0078]     Next, the operation of the cleaner  100  during the random travel will be described with reference to a flow chart of  FIG. 10 .  
         [0079]     The operation proceeds from Step S 107  in the above-mentioned along-wall travel mode to Step S 201  shown in  FIG. 10 , thereby starting the random travel mode. Upon this shift, the travel direction of the cleaner  100  is changed so that the cleaner gets away from the wall as a pre-preparation. For example, the travel direction of the cleaner  100  is turned by 90°.  
         [0080]     In Step S 201 , the cleaner  100  carries out the self-propelled travel for a forward movement based on the self-guidance while carrying out the dust cleaning operation. At this time, the side brush  5  is in a stoppage state in Step S 107 . Note that though during such self-propelled travel, the cleaner  100  may travel using the results of the cleaner&#39;s own position check and the mapping work while the cleaner&#39;s own position check and the mapping work are carried out, in this embodiment, no mapping is carried out in the random travel mode.  
         [0081]     In Step S 202 , a wall, an obstacle, or the like is detected. When a distance to the obstacle or the like is equal to or smaller than a specified value, it is judged that the cleaner  100  will collide with the obstacle or the like, and the operation proceeds to Step S 203 . On the other hand, when the distance to the obstacle or the like is larger than the specified value, the operation returns back to Step S 201 .  
         [0082]     In Step S 203 , the operation for rotating the side brush  5  is started. In the operation in and after Step S 203 , the work for cleaning the room along the wall, around the obstacle, or the like is carried out while the side brush  5  is used.  
         [0083]     In Step S 204 , a rotation angle of the cleaner  100  is calculated to avoid the collision of the cleaner  100  with the obstacle or the like.  
         [0084]     In Step S 205 , the forward movement of the cleaner  100  is stopped, and the cleaner  100  is rotated by the rotation angle calculated in Step S 204 . As a result, the travel direction of the cleaner  100  is changed. Note that during such rotation, the cleaning operation and the rotation of the side brush are continued.  
         [0085]     In Step S 206 , the rotation of the cleaner  100  is completed at timing when the cleaner  100  is rotated by the above-mentioned rotation angle. After that, the forward movement of the cleaner  100  is started.  
         [0086]     In Step S 207 , the rotation of the side brush  5  is completed in correspondence to the completion of the operation for rotating the cleaner  100 . However, the cleaning operation is continuously carried out. Note that the control for operating the side brush  5  may also be carried out until the distance to the obstacle or the like becomes equal to or larger than the specified value. Alternatively, the control for stopping the side brush  5  after a lapse of a predetermined time may also be carried out after completion of the operation for rotating the cleaner  100 .  
         [0087]     In Step S 208 , it is judged based on the value in the time measuring timer  13  whether or not a specified time has elapsed. When it is judged that the specified time has elapsed, the operation proceeds to Step S 209 . On the other hand, when it is judged that no specified time has elapsed, the operation returns to Step S 201 , and the random travel mode is continued.  
         [0088]     Since in Step S 209 , the cleaning operations based on the two travel modes have been completed, all the operations are completed.  
         [0089]     Note that it is ideal that the collision of the cleaner  100  with an obstacle or the like can be avoided with the rotation angle calculated in Step S 204 . However, when the obstacle has a complicated shape, and so forth, a case may occur where the collision of the cleaner  100  with the obstacle cannot be avoided at the rotation angle. However, in this case as well, since a flow proceeds as follows: Step S 208 →Step S 201 →Step S 202 →Step S 203 , and the next rotation angle is instantaneously calculated, the avoidance of the collision of the cleaner  100  with the obstacle is compensated for.  
         [0090]     Next, a description will be given with respect to a method of calculating a rotation angle of the cleaner  100  ensuring the avoidance of the collision of the cleaner  100  with an obstacle or the like with reference to  FIGS. 11A  to  11 D. Note that in  FIGS. 11A  to  11 D, reference numerals  30  to  34  designate pairs of sensors (each including the transmission portion and the reception portion) of the obstacle detecting sensors  2  shown in  FIG. 2 .  
         [0091]     When an obstacle is detected in  FIG. 11A , a rotation angle of the cleaner  100  is calculated in  FIG. 11B , and the cleaner  100  is immediately rotated by the rotation angle thus calculated with the travel of the cleaner  100  being stopped in  FIG. 11C . As a result, the travel direction of the cleaner  100  is changed. After that, in  FIG. 11D , the cleaner  100  moves forward in a new travel direction. Thus, in the case shown in  FIGS. 11A  to  11 D, since the travel direction of the cleaner  100  is changed to the left-hand side with respect to the former travel direction, the collision of the cleaner  100  with the obstacle is avoided.  
         [0092]     In  FIG. 11A , the sensor pair  33  nearest the obstacle detects the obstacle. In  FIG. 11B , the direction which is obtained by adding a random angle based on random numbers to a fixed angle inherent in the sensor pair  33  is set as the new travel direction. Here, the reason for using the random angle is that a possibility, that a situation may arise in which the travel path of the cleaner  100  keeps to a certain travel path and thus the cleaner  100  cleans only the same place, is excluded by adding the random angle when the new travel direction is calculated. In  FIG. 11C , the cleaner  100  is rotated in a clockwise direction by an angle of “360° −(fixed angle+random angle)” in order to carry out the work for cleaning a place just near the obstacle using the side brush  5 .  
         [0093]     The fixed angle is set every sensor pair in consideration of the positions where the sensor pairs are disposed in the cleaner  100 . That is, even when the random angle is a value near zero, the fixed angle is set as such an angle that the travel direction of the cleaner  100  becomes a direction away from the wall as compared with the minimum avoidance direction shown in  FIG. 11B .  
         [0094]     Note that since the sensor pairs are mounted at intervals, an event in which the sensor pair  33  detects the obstacle may occur in a case where a distance between the sensor pair  33  and the obstacle is slightly shorter than that between the next sensor pair  32  on the right side of the sensor pair  33  and the obstacle as well as in a case where the distance between the sensor pair  33  and the obstacle is slightly shorter than that between the next sensor pair  34  on the left side of the sensor pair  33  and the obstacle.  
         [0095]      FIG. 12A  shows the case where the distance between the sensor pair  33  and the obstacle is slightly shorter than that between the sensor pair  34  and the obstacle, and  FIG. 12B  shows the case where the distance between the sensor pair  33  and the obstacle is slightly shorter than that between the sensor pair  32  and the obstacle.  
         [0096]     The above-mentioned fixed angle must be determined in consideration of the travel angle of the cleaner  100  with respect to the obstacle in such a manner. More specifically, a fixed angle shown in  FIG. 12B  is adopted as the fixed angle inherent in the sensor pair  33 . When the fixed angle inherent in the sensor pair  33  is set to this value, even if the random angle takes a value near zero, the possibility that the cleaner  100  collides with the obstacle is excluded. With this fixed angle, the collision of the cleaner  100  with the obstacle can be avoided even in the case shown in  FIG. 12A .  
         [0097]     This is also applied to the setting of the fixed angle for other sensor pairs. In addition, the foregoing can also be applied to the case where a course of the cleaner  100  is changed to the right-hand side with respect to the former travel direction in order to avoid the collision of the cleaner  100  with the obstacle. In such a manner, the fixed angles inherent in the respective sensor pairs are determined.  
         [0098]     Next, there is shown another operation form in the random travel mode. In this operation form, when it is judged that the cleaner  100  will collide with the obstacle or the like, in order to avoid the collision of the cleaner  100  with the obstacle or the like, the direction of the cleaner  100  is not changed, but the cleaning is carried out in which the side brush  5  is driven for a predetermined time or over a given distance while the cleaner  100  travels along the obstacle or the like.  
         [0099]      FIG. 13  shows a flow chart of this operation form. In  FIG. 13 , the operation from Step S 301  to Step S 308  is the same as that from Step S 201  to Step S 208  shown in  FIG. 10 . In the operation form shown in  FIG. 13 , when the operation proceeds from Step S 303  to Step S 304 , it is judged in Step S 309  whether or not the cleaning is carried out while the cleaner  100  travels along a wall, an obstacle, or the like.  
         [0100]     In Step S 309 , it is judged at first time whether or not a predetermined time has elapsed from the start of the along-wall travel mode. Also, it is judged from the next time on whether or not a predetermined time has elapsed from the last along-wall travel operation for the cleaning for the vicinity of the obstacle. Here, when it is judged in Step S 309  that the predetermined time has elapsed, the operation proceeds to Step S 310 . On the other hand, when it is judged in Step S 309  that no predetermined time has elapsed, the operation proceeds to Step S 304 . Note that when the mapping operation is carried out during the random travel mode, the control for carrying out operation for the cleaning for the vicinity of the obstacle may be made as follows. That is, the control for carrying out the along-wall cleaning operation for the cleaning for the vicinity of the obstacle is carried out at first time, and from next time, only after a lapse of the predetermined time, the operation is carried out. This control is made for each obstacle.  
         [0101]     In Step S 310 , the cleaning using the side brush  5  is carried out while the cleaner  100  travels forward along the wall, the obstacle, or the like, for a given time or over a predetermined distance while holding the distance to the obstacle or the like constant. Note that when the cleaner  100  reaches the corner or angle of the obstacle or the like, the direction is changed similarly to the cases of  FIGS. 8A  to  8 D and  FIGS. 9A  to  9 D which were described in the above-mentioned along-wall travel mode, and after that, the same along-wall cleaning is continuously carried out. Then, the operation proceeds to Step S 304 .  
         [0102]     Note that, in the foregoing, in the case shown in  FIGS. 9A  to  9 D, the travel direction of the cleaner  100  is changed after the cleaner  100  has passed the angle of the wall, and the cleaning operation is carried out using the side brush  5  while the cleaner  100  travels along the wall of the obstacle or the like. However, in Step S 310  in this embodiment, after completion of the operation for carrying out the cleaning while the cleaner  100  travels along the obstacle or the like, e.g., goes straight on after having passed the corner or angle of the wall, the operation may proceed to Step S 307 . In addition, a procedure may also be adopted in which after the change of the travel direction is completed in  FIG. 9C , the cleaner  100  moves backward once to clean a place just near the angle using the side brush  5 , and thus after the place is cleaned which has not been cleaned using the side brush  5  in the operation for turning the cleaner  100  to the left in  FIG. 9B , the forward movement of the cleaner  100  is restarted.  
         [0103]      FIG. 14  shows an example of the cleaning operations in the along-wall travel mode and the random travel mode when the cleaning operation is carried out in accordance with the operation flow shown in  FIG. 13 . In  FIG. 14 , the bold line indicates a state in which the cleaner  100  carries out the cleaning while traveling along an obstacle after having avoided the collision with the obstacle. Note that  FIG. 14  does not especially show a path in the along-wall travel mode and a path in the random travel mode distinguished from each other.  
         [0104]     A description will hereinafter be given with respect to the operation when the travel along the obstacle is started in Step S 310  with reference to  FIGS. 15A  to  15 D.  
         [0105]     When in  FIG. 15A , a sensor pair of the cleaner  100  detects an obstacle, the cleaner  100  is stopped at a predetermined distance from the obstacle. Next, in  FIG. 15B , the cleaner  100  is rotated immediately using the detection results obtained by the sensor pair to change the travel direction of the cleaner  100 . After that, in  FIG. 15C , after the rotation of the cleaner  100  is completed, the travel direction of the cleaner  100  is determined accordingly. Then, in  FIG. 15D , the cleaner  100  starts to move forward while keeping a constant distance to the wall using the detection results obtained by the sensor pair. After that, the cleaner  100  carries out the cleaning using the side brush  5  over a predetermined distance or for a given time while traveling along the obstacle.  
         [0106]     This embodiment has shown the form in which the cleaning operation proceeds from the along-wall travel mode to the random travel mode. However, the cleaning operation may not proceed to the random travel mode, but may proceed to a systematic travel mode in which the cleaner  100  carries out the cleaning while systematically traveling in accordance with a certain rule. In this case, however, for example, it is necessary to precisely carry out the mapping of the obstacle or the like and the check of the cleaner&#39;s own position as compared with this embodiment. In order to attain this, it is necessary to carry out the special control. As a result, the installation or the like of an extra hardware resource is required. Thus, there is a possibility that the inexpensiveness, the lightness, and the compactness are impaired. Moreover, the finite energy accumulated in a secondary battery is consumed.  
         [0107]     In addition, in the above-mentioned embodiment, the along-wall operation or the like is carried out using one of a plurality of obstacle detecting sensors. However, the stabilization of the along-wall operation or the like may be enhanced using two or more sensors.  
         [0108]     Note that the scope of the present invention is not intended to be limited to the above-mentioned embodiment. The embodiment of the present invention may be suitably and variously changed within the range of the technical idea shown in the appended claims.