Patent Publication Number: US-8972092-B2

Title: Control apparatus for unmanned autonomous operating vehicle

Description:
BACKGROUND 
     1. Technical Field 
     An embodiment of the invention relates to a control apparatus of an unmanned autonomous operating vehicle, particularly to an apparatus for controlling an operating vehicle to autonomously run about in an operating area to perform an operation using a mounted operating machine. 
     2. Background Art 
     Conventionally, there are proposed a variety of unmanned autonomous operating vehicles that autonomously runs in operating areas to perform operations using mounted operating machines such as lawn-mowing blades, as taught, for example, by International Publication No. WO 2005/074362. 
     In the reference, a magnetic sensor attached to a front end of an operating vehicle detects the intensity of a magnetic field of an area wire laid along a border of an operating area to recognize the operating area, and a mounted operating machine including lawn-mowing blades and installed with an electric motor is driven to perform the operation in the recognized operating area. 
     The motor of the vehicle in the technique stated in the reference is supplied with power from a mounted battery. In order to charge the battery, a charging device is disposed on the area wire and when the remaining battery level is decreased, the vehicle is controlled to follow the area wire by the aid of the magnetic sensor to return to the charging device along the area wire. 
     SUMMARY 
     There are varous types of operating areas. In one case, an operating area is divided into main areas and sub areas and those areas are connected through narrow passages. The operation is regularly performed in the main areas and it may suffice if the operation is performed once in a while in the sub areas. The same can be said when the operation is intended to be performed in a certain part of one operating area. 
     Meanwhile, the vehicle disclosed in the reference is configured to detect the area wire and follow the area wire to return to the charging device when the remaining battery level is decreased as mentioned above. In this case, if the operating area is divided by different area wires, it is necessary to install the charging devices for the respective divided areas, disadvantageously. 
     An object of an embodiment of the invention is therefore to overcome the foregoing drawback by providing a control apparatus for an unmanned autonomous operating vehicle having an electric motor that is mounted on a vehicle body and supplied with power from a battery to drive an operating machine to perform an operation, which apparatus can control the vehicle so as not to perform the operation in a certain part, with the simple structure. 
     In order to achieve the object, the embodiment of the invention provides in the first aspect an apparatus for controlling an unmanned autonomous operating vehicle having an electric motor supplied with power from a battery for operating an operating machine, prime movers for driving wheels, and magnetic sensors for detecting intensity of a magnetic field of an area wire, the vehicle being controlled to run about in an operating area defined by the area wire through wheels driven by the prime movers to perform an operation using the operating machine and to return to a charging device installed on the area wire so as to charge the battery, wherein the improvement comprises: a turn-back portion formed by bending the area wire at an appropriate position and again bending the area wire to return in a same direction with a predetermined space so as to divide the operating area into a plurality of parts; and a running controller adapted to control the vehicle to be prohibited from going across the turn-back portion. 
     In order to achieve the object, the embodiment of the invention provides in the second aspect a method for controlling an unmanned autonomous operating vehicle having an electric motor supplied with power from a battery for operating an operating machine, prime movers for driving wheels, and magnetic sensors for detecting intensity of a magnetic field of an area wire, the vehicle being controlled to run about in an operating area defined by the area wire through wheels driven by the prime movers to perform an operation using the operating machine and to return to a charging device installed on the area wire so as to charge the battery, wherein the improvement comprises the step of: controlling the vehicle to be prohibited from going across a turn-back portion formed by bending the area wire at an appropriate position and again bending the area wire to return in a same direction with a predetermined space so as to divide the operating area into a plurality of parts. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
       The above and other objects and advantages will be more apparent from the following description and drawings in which: 
         FIG. 1  is a side view of a control apparatus for an unmanned autonomous operating vehicle according to an embodiment of the invention; 
         FIG. 2  is a plan view of the vehicle shown in  FIG. 1 ; 
         FIG. 3  is a block diagram showing input and output of devices mounted on the vehicle shown in  FIG. 1 ; 
         FIG. 4  is a plan view showing an operating area where the vehicle shown in  FIG. 1  is to be run; 
         FIG. 5  is a block diagram showing the configuration of the charge ST (station) shown in  FIG. 4 ; 
         FIG. 6  is an explanatory view showing a charging process at the charge ST shown in  FIG. 5 ; 
         FIG. 7  is an explanatory view showing a magnetic field of an area wire embedded in the operating area shown in  FIG. 4 ; 
         FIG. 8  is a flowchart showing the operation of the apparatus shown in  FIG. 1 , i.e., the operation in the case of applying a running trajectory ( 1 ) shown in  FIG. 4 ; 
         FIG. 9  is a flowchart showing the operation of the apparatus shown in  FIG. 1 , i.e., the operation in the case of applying a running trajectory ( 2 ) shown in  FIG. 4 ; and 
         FIG. 10  is a flowchart showing the operation of the apparatus shown in  FIG. 1 , i.e., the operation in the case of applying a running trajectory ( 3 ) shown in  FIG. 4 . 
     
    
    
     DESCRIPTION OF EMBODIMENT 
     A control apparatus of an unmanned autonomous operating vehicle according to an embodiment of the present invention will now be explained with reference to the attached drawings. 
       FIG. 1  is a side view of a control apparatus for an unmaned autonomous operating vehicle according to an embodiment of the invention,  FIG. 2  is a plan view of the vehicle shown in  FIG. 1 ,  FIG. 3  is a block diagram showing input and output of devices mounted on the vehicle shown in  FIG. 1  and  FIG. 4  is a plan view showing an operating area where the vehicle shown in  FIG. 1  is to be run. 
     As shown in  FIGS. 1 and 2 , symbol  10  indicates an unmanned autonomous operating vehicle. The vehicle  10  has a vehicle body  12  and wheels  14 . The body  12  includes a chassis  12   a  and a frame  12   b  attached to the chassis  12   a , while the wheels  14  include right and left front wheels  14   a  of a relatively small diameter that are fixed on the forepart of the chassis  12   a  through a stay  12   a   1 , and right and left rear wheels  14   b  of a relatively large diameter that are directly attached to the chassis  12   a.    
     Blades (rotary blades; operating machine)  16  for mowing lawn are attached in the center or thereabout of the chassis  12   a , and an electric motor (hereinafter called the “operating motor”)  20  is installed above the blades  16 . The blades  16  are connected to the operating motor  20  to be driven and rotated thereby. 
     The blades  16  are also connected to a blade height adjustment mechanism  22  to be manually manipulated by an operator (user). The blade height adjustment mechanism  22  is equipped with a screw (not shown) to be manually turned by the operator for adjusting the height of the blades  16  from a contacting ground GR. 
     Two electric motors (prime movers; hereinafter called the “running motors”)  24  are attached to the chassis  12   a  of the vehicle  10  to the rear of the blades  16 . The running motors  24  are connected to the right and left rear wheels  14   b  to operate them so that the rear wheels  14   b  are rotated in the normal (forward running) direction or reverse (backward running) direction independently of each other to make the vehicle  10  run on the ground GR. In other words, the front wheels  14   a  serve as the free wheels while the rear wheels  14   b  serve as the driven wheels. The blades  16 , operating motor  20 , running motors  24 , etc., are covered by the frame  12   b.    
     A charging unit (including an AC/DC converter)  26  and battery  30  are accommodated at the rear of the vehicle  10  and two charging terminals  32  are attached to the frame  12   b  at the front of the vehicle  10  to protrude forward to be connectable with the charging device. Each of the terminals  32  has a contact point  32   a  on a side facing the other contact point  32   a.    
     The terminals  32  are connected to the charging unit  26  through wiring and the charging unit  26  is connected to the battery  30  through wiring. The operating and running motors  20 ,  24  are connected to the battery  30  through wiring to be supplied with power therefrom. The wiring is not illustrated in  FIGS. 1 and 2 . 
     Thus, the vehicle  10  is constituted as a four-wheel, unmanned, electric autonomous operating vehicle (lawn-mowing vehicle) that is, for instance, about 600 millimeters long, 300 millimeters wide and 300 millimeters high. 
     A front end of the vehicle  10  is installed with two, i.e., right and left magnetic sensors (magnetism detector)  34 . The frame  12   b  is attached with a contact sensor  36 . When the frame  12   b  comes off from the chassis  12   a  upon having contact with an obstacle and such, the contact sensor  36  outputs an ON signal. 
     A housing box is provided in the center or thereabout of the vehicle  10  to house a board  40  on which an Electronic Control Unit (ECU; Controller)  42  including a microcomputer having a CPU, ROM, RAM, etc., is installed. The board  40  is also installed in the vicinity of the ECU  42  with a Yaw sensor (angular velocity sensor)  44  that produces an output or signal indicative of angular velocity (yaw rate) generated about a z-axis in the center of gravity of the vehicle  10  and with a G sensor (acceleration sensor)  46  that produces an output or signal indicative of an acceleration G acting on the vehicle  10  in the X, Y and Z (three-axis) directions. 
     A wheel speed sensor  50  is installed near the rear (driven) wheel  14   b  to produce an output or signal representing a wheel speed thereof A lift sensor  52  is installed between the chassis  12   a  and frame  12   b  to output an ON signal when the frame  12   b  is lifted from the chassis  12   a  by the operator or the like. 
     A current/voltage sensor  54  is installed at the battery  30  to produce an output or signal indicative of SOC (State Of Charge) of the battery  30 . The vehicle  10  is installed with a main switch  56  and emergency stop switch  60  to be manipulated by the operator. 
     The outputs of the foregoing magnetic sensors  34 , contact sensor  36 , Yaw sensor  44 , G sensor  46 , wheel speed sensor  50 , lift sensor  52 , current/voltage sensor  54 , main switch  56  and emergency stop switch  60  are sent to the ECU  42 . 
     The upper surface of the frame  12   b  of the vehicle  10  is widely cut away and a display  62  is installed therein. The display  62  is connected to the ECU  42  to show a mode of the vehicle&#39;s status such as an operating mode in response to a command sent from the ECU  42 . 
     Next, the explanation will be made on the operating area  70  where the vehicle  10  is to be run. As shown in  FIG. 4 , the operating area  70  has a substantially-rectangular shape and a lower portion (in the drawing) is greatly concaved inwardly so that a zone  1  (main area) on the left side and a zone  2  (sub area) on the right side are formed. The zones  1 ,  2  are interconnected by a narrow passage. 
     The operating area  70  is defined by an area wire (electric wire)  72  that is embedded (laid) along a border of land L and a charge ST (station)  74  is provided on the area wire  72 . The charge ST  74  is disposed with an ST coil  76 . A magnetic field radiated from the ST coil  76  forms a charging device detecting area  76   a  of a circle with center at the charge ST  74  with a radius of about one meter. Thus, the charge ST (charging device)  74  is disposed with the coil  76  radiating a magnetic field that forms the charging device detecting area  76   a  around the charge ST  74 . 
     As shown in  FIG. 5 , the charge ST  74  has a charging device  84  connected to a commercial power source  80  through a socket  82 , and a charging terminal  86  that is connected to the charging device  84  and connectable to the contact points  32   a  of the charging terminals  32  of the vehicle  10  through its contact points. The charging terminal  86  is shown in  FIG. 6  (the contact points thereof are not illustrated). 
     The charging device  84  has an AC/AC converter  84   a , an Electronic Control Unit (ECU)  84   b  that includes a microcomputer similarly to the ECU  42  and controls the operation of the AC/AC converter  84   a , and a signal generator  84   c  that supplies alternating current to the area wire  72  and ST coil  76  to generate signals. 
     Alternating current coming from the commercial power source  80  through the socket  82  is appropriately stepped down by the AC/AC converter  84   a  of the charging device  84  and, when the vehicle  10  is returned and connected to the charge ST  74  through the charging terminals  32  and  86 , the current is sent to the vehicle  10  to charge the battery  30  through the charging unit  26 . 
     As shown in  FIG. 4 , the area wire  70  is bent at an appropriate position, i.e., a position near the narrow passage connecting the zone  1  to the zone  2 , and again bent to return in the same direction with a predetermined space (direction) w. In other words, a turn-back portion  72   a  is formed at the area wire  70 , whereby the operating area  70  is divided into a plurality of zones, i.e., two (right and left) zones in the illustrated example. As described later, in this embodiment, when the vehicle  10  is run about to perform the operation, the vehicle  10  is prohibited from going across the turn-back portion  72   a  so as not to perform the operation in a certain part (zone  2 ) of the operating area  70 . 
     The operation of detecting the operating area  70  will be explained. Upon power supply from the signal generator  84   c , a magnetic field is generated around the area wire  72 . The intensity of the magnetic field varies depending on the entire length of the area wire  72  and also varies depending on a distance d from the area wire  72  as shown in  FIG. 7 . 
     The intensity of the magnetic field of the area wire  72  is detected by the magnetic sensors  34  attached to the vehicle  10  and sent to the ECU  42 . Based on the detected values, the ECU  42  detects a position of the subject vehicle (autonomous operating vehicle  10 ) with respect to the area wire  72  (i.e., whether the subject vehicle is positioned inside or outside the operating area  70 ) and the distance of the subject vehicle from the area wire  72  (i.e., from the border of the operating area  70 ). 
     More specifically, as shown in  FIG. 7 , when the subject vehicle is moved from the inside of the operating area  70  to the outside thereof in a direction indicated by an arrow a, as the distance from the area wire  72  is reduced (as the subject vehicle is moved closer to the area wire  72 ), the intensity of the magnetic field is gradually increased on a positive side and afterward, decreased. When the subject vehicle is positioned on the area wire  72 , the intensity becomes zero. Subsequently, when the distance from the area wire  72  is again increased, the intensity exhibits the similar characteristics on a negative side. Also when the subject vehicle is moved from the inside of the operating area  70  to the outside thereof in a direction indicated by an arrow b, the characteristics similar to the above pattern are exhibited. 
     In  FIG. 4 , the predetermined space w at the turn-back portion  72   a  of the area wire  72  is determined based on the intensity of the magnetic field of the area wire  72 . Specifically, in order to avoid a situation where the magnetic fields at two close points of the area wire  72  are canceled out and become undetectable, the predetermined space w is appropriately set, e.g., set to 200 millimeters. 
     The operation of the vehicle  10  will be explained. The height of the blades  16  is manually adjusted by the operator through the blade height adjustment mechanism  22  in accordance with a growing condition of the lawn in the operating area  70 . When the main switch  56  is switched on so that the ON signal is outputted, the ECU  42  starts to be operated and enters the operating mode to mow the lawn. 
     In the operating mode, the ECU  42  calculates a power supply control value with which a vehicle speed detected from the output of the wheel speed sensor  50  becomes a predetermined value and supplies the calculated value to the running motors  24  through a driver  24   a  to make the vehicle  10  run about. Further, the ECU  42  calculates a power supply control value with which rotational speeds of the blades  16  become a predetermined value and supplies the calculated value to the operating motor  20  through a driver  20   a  to operate the blades  16  to perform the operation. 
     To be more specific, in the operating mode, the ECU  42  makes the vehicle  10  run about randomly (or in accordance with an operation pattern) to perform the operation within the operating area  70 . When determining that the vehicle  10  has moved out of the operating area  70  based on the outputs of the magnetic sensors  34 , the ECU  42  changes a running direction detected based on the output of the Yaw sensor  44  by a predetermined angle so that the vehicle  10  comes back to the inside of the operating area  70 . 
     Since the right and left rear (driven) wheels  14   b  are configured so that they are driven by the running motors  24  to rotate in the normal and reverse directions independently or separately from each other, when the motors  24  are rotated in the normal direction at the same speed, the vehicle  10  is run straight, whilst when they are rotated in the normal direction at different speeds, the vehicle  10  is turned toward a side of lower rotational speed. When one of the motors  24  is rotated in the normal direction and the other is rotated in the reverse direction, since the rear wheels  14   b  are rotated in the same direction as the associated motor&#39;s rotation, the vehicle  10  is turned at the same position (which is so-called pivot turn). 
     Thus, in the operating mode, the ECU  42  makes the vehicle  10  run about within the operating area  70  while changing the running direction thereof randomly whenever the vehicle  10  reaches the area wire  72 , and drives the blades  16  to perform the operation. 
     Further, in the operating mode, the ECU  42  monitors the SOC of the battery  30  based on the output of the current/voltage sensor  54  and when the remaining battery level is decreased to a predetermined level, transitions to a return mode in which the vehicle  10  is returned to the charge ST  74  to charge the battery  30  by the charging device  84 . Running trajectories (or routes) ( 1 ) to ( 3 ) to follow in the operating mode and return mode are shown in  FIG. 4 . Note that those trajectories ( 1 ) to ( 3 ) are only examples and a variety of trajectories other than those can be applied in accordance with the situation. 
     Further, an entering direction of the vehicle  10  to the charge ST  74  is alternately changed between a CW (Clockwise) and CCW (Counterclockwise), as viewed from above of the operating area  70  (shown in  FIG. 4 ), whenever the vehicle  10  is returned. It is carried out by setting an appropriate flag in the RAM of the ECU  42 . 
     In the operating mode and return mode, when any of the contact sensor  36 , lift sensor  52  and emergency stop switch  60  produces the ON signal, the ECU  42  stops the operating and running motors  20 ,  24  to stop the operation and running of the vehicle  10 . 
       FIGS. 8 to 10  are flowcharts showing operations of the ECU  42 , i.e., operations (controls) corresponding to the running trajectories ( 1 ) to ( 3 ) shown in  FIG. 4 . 
       FIG. 8  is a flowchart corresponding to the running trajectory ( 1 ). The illustrated program applies the case where the operation is performed only in the zone  1 . 
     This program begins under a condition where the vehicle  10  has a connection with the charging device  84  at the charge ST  74  to charge the battery  30  (S 10 ). When the battery  30  has been fully charged, the vehicle  10  is run backward and turned about (S 12 , S 14 ), and the status is changed to the operating mode in which the vehicle  10  is run about within the operating area  70  randomly to mow the lawn (S 16 ). It is determined whether the remaining battery level of the battery  30  is decreased (i.e., becomes equal to or less than the predetermined level) (S 18 ) and until the remaining battery level is determined to have been decreased, the mowing operation is continued (S 16 , S 18 ). 
     In the operating mode, the ECU  42  operates the motors  24  to drive the wheels  14  to run about the vehicle  10  in the operating area  70 , while operating the motor  20  to drive the blades  16  to perform the operation. The ECU  42  determines the turn-back portion  72   a  of the area wire  72  as the inside, outside and inside of the operating area  70 , based on the outputs of the magnetic sensors  34 . 
     At that time, in the operating mode, the ECU  42  compares a time period that the vehicle  10  is determined to be in the outside of the operating area  70  with an appropriate threshold value. The comparison result is used to control the vehicle  10 , i.e., prohibit the vehicle  10  from going across the turn-back portion  72   a  so as not to perform the operation in the zone  2 . 
     When the remaining battery level is determined to be decreased to the predetermined level, the mowing operation is stopped, the running motors  24  are controlled to run the vehicle  10  straight (S 20 ), the area wire  72  is detected based on the outputs of the magnetic sensors  34 , and the vehicle  10  is moved out of the operating area  70  and stopped (S 22 ). 
     In the case of applying the trajectory ( 1 ), since the entering direction of the vehicle  10  when it is returned to the charge ST  74  is set as the CCW, the vehicle  10  is restarted to turn in counterclockwise (CCW) direction (S 24 ), and the above process is repeated until the area wire  72  is detected based on the outputs of the magnetic sensors  34  and it is confirmed that the vehicle  10  has come inside the operating area  70  (S 26 ). 
     Next, based on the detected magnetic field intensity of the area wire  72 , the operations of the running motors  24  are controlled to run the vehicle  10  on the area wire  72  (S 28 ). Specifically, based on the outputs of the magnetic sensors  34 , the ECU  42  controls amounts of power to be supplied to the running motors  24  using a feedback control law such as a proportional term so that a front portion of the vehicle  10  is slightly swung the right and left so that the front portion is positioned inside and outside the operating area  70  alternately, thereby controlling the vehicle  10  to run on or along the area wire  72 . 
     Next, it is determined whether the charge ST  74 , i.e., the charging device detecting area  76   a  is detected by detecting the magnetic field of low intensity generated from the ST coil  76  using the magnetic sensors  34  and comparing it with an appropriate threshold value (S 30 ). Whenever the result in S 30  is negative, the program returns to S 28  to repeat the foregoing process. 
     When the result in S 30  is affirmative, the running speed is decreased and the vehicle  10  is controlled to enter the charge ST  74  in the CCW direction, whereby the charging terminals  32  of the vehicle  10  are connected to the charging terminal  86  to charge the battery  30  (S 32 ). 
       FIG. 9  is a flowchart corresponding to the running trajectory ( 2 ) shown in  FIG. 4 . 
     This program also begins under a condition where the vehicle  10  has a connection with the charging device  84  at the charge ST  74  to charge the battery  30  (S 100 ). The vehicle  10  is run backward, and turn about (S 102 , S 104 ), and then run on the area wire  72  to follow a trajectory a to move to the zone  2  (S 106 ). 
     Next, it is determined whether the vehicle  10  has reached a desired point in the zone  2  (S 108 ). The desired point is set to a position that can be recognized based on the output of the wheel speed sensor  50  as where the vehicle  10  should reach after starting to run backward in S 102  and running a predetermined distance, for example. 
     Next, the vehicle  10  is controlled to turn about, enter the operating mode to run about within the operating area  70  randomly to mow the lawn, and continue the mowing operation until the remaining battery level is determined to have been decreased (S 110  to S 114 ). In the operating mode in S 112 , the ECU  42  prohibits the vehicle  10  from going across the turn-back portion  72   a  so as not to perform the operation in the zone  1 . 
     When the remaining battery level is determined to be decreased to the predetermined level in S 114 , the mowing operation is stopped, the running motors  24  are controlled to run the vehicle  10  straight (S 116 ), the area wire  72  is detected based on the outputs of the magnetic sensors  34 , and the vehicle  10  is moved out of the operating area  70  and stopped (S 118 ). 
     In the case of applying the trajectory ( 2 ), since the entering direction of the vehicle  10  when it is returned to the charge ST  74  is set as the CW, the vehicle  10  is restarted to turn in clockwise (CW) direction (S 120 ), and the above process is repeated until the area wire  72  is detected based on the outputs of the magnetic sensors  34  and it is confirmed that the vehicle  10  has come inside the operating area  70  (S 122 ). 
     Next, based on the detected magnetic field intensity of the area wire  72 , the operations of the running motors  24  are controlled to run the vehicle  10  on the area wire  72  to follow a trajectory  b  until the charge ST  74  is detected (S 124 ). In this embodiment, it is configured so that the return trajectory (route) b is set similarly to the outward trajectory (route) a. 
     Although the vehicle  10  can take a route on an upper side of the area wire  72  in  FIG. 4  (where the turn-back portion  72   a  is formed) to return to the charge ST  74 , it results in a longer running distance to the charging device  84 . Therefore, it is configured so that, when the vehicle  10  is moved to a distant zone (zone  1 ), the vehicle  10  is controlled to follow the same trajectory as that it took when it came. 
     When the charge ST  74  is detected, as shown in the drawing, the vehicle  10  is turned about (S 128 ). Then, the area wire  72  is detected and the vehicle  10  is moved out of the operating area  70  and stopped (S 130 ). The vehicle  10  is turned in the CCW direction until the area wire  72  is detected (S 132 , S 134 ). Subsequently, the vehicle  10  is controlled to enter the charge ST  74  in the CCW direction, whereby the charging terminals  32  of the vehicle  10  are connected to the charging terminal  86  to charge the battery  30  (S 136 ). Specifically, upon reaching the charging device detecting area  76   a , the vehicle  10  is turn about and run toward the area wire  72  to be guided to the charging device  84 . 
       FIG. 10  is a flowchart corresponding to the running trajectory ( 3 ) shown in  FIG. 4 . 
     The processes of S 200  to S 220  are conducted similarly to those of S 10  to S 30  in the  FIG. 8  flowchart (except for the turning direction). When the charge ST  74  is detected, similarly to S 128  to S 136  in the  FIG. 9  flowchart, the vehicle  10  is controlled to turn about (S 222 ), move out of the operating area  70  and stop (S 224 ), turn in the CCW direction until the area wire  72  is detected (S 226 , S 228 ), and enter the charge ST  74  in the CCW direction, whereby the charging terminals  32  of the vehicle  10  are connected to the charging terminal  86  to charge the battery  30  (S 230 ). 
     Note that the programs of the  FIGS. 8 to 10  are repeated in the numerical order. As a result, the number of operations to be performed in the zone  2  can be reduced to a half of that in the zone  1 . 
     As stated above, the embodiment is configured to have an apparatus and method for controlling an unmanned autonomous operating vehicle ( 10 ) having an electric motor ( 20 ) supplied with power from a battery ( 30 ) for operating an operating machine ( 16 ), prime movers ( 24 ) for driving wheels ( 14 ), and magnetic sensors ( 34 ) for detecting intensity of a magnetic field of an area wire ( 72 ), the vehicle being controlled to run about in an operating area ( 70 ) defined by the area wire through wheels driven by the prime movers to perform an operation using the operating machine and to return to a charging device ( 74 ) installed on the area wire so as to charge the battery, characterized in that: a turn-back portion ( 72   a ) formed by bending the area wire at an appropriate position and again bending the area wire to return in a same direction with a predetermined space so as to divide the operating area into a plurality of parts; and a running controller ( 42 , S 16 , S 112 , S 206 ) adapted to control the vehicle to be prohibited from going across the turn-back portion. 
     With this, since the turn-back portion  72   a  is provided, it becomes possible to control the vehicle  10  so as not to perform the operation in a certain part of the operating area  70 . Further, since it is configured to only bend the area wire  72  locally and another device such as an additional charging device is not needed, the structure can be simple. 
     In the apparatus and method, the improvement further comprises: a charging device detecting area ( 76   a ) set to be used for detecting a position of the charging device, and the running controller controls the vehicle to turn about when the vehicle is determined to have reached the charging device detecting area and subsequently run toward the area wire to be guided to the charging device when the vehicle detects the intensity of the magnetic field of the area wire to return to the charging device ( 42 , S 124 -S 136 , S 218 -S 230 ). With this, in addition to the above effects, it becomes possible to shorten the running distance of the vehicle  10  when it is returned to the charging device  84  to charge the battery  30 . 
     In the apparatus and method, the running controller changes an entering direction of the vehicle to the charging device whenever the vehicle is returned to the charging device. With this, in addition to the above effects, it becomes possible to prevent many tracks or grooves from being formed on the area wire  72  by wheels  14  of the vehicle  10 . 
     In the apparatus and method, the predetermined space is determined based on the intensity of the magnetic field of the area wire. With this, in addition to the above effects, when the intensity of the magnetic field of the area wire  72  is detected to run on the area wire  72 , it becomes possible to avoid a situation where the magnetic fields at two close points of the area wire  72  are canceled out and become undetectable, so that the vehicle&#39;s running is not adversely affected. 
     In the apparatus and method, the prime movers ( 24 ) comprise electric motors to be supplied with power from the battery. With this, in addition to the above effects, it becomes possible to reduce the noise compared to a case that an engine is employed. 
     In the apparatus and method, the operating machine ( 16 ) comprises a lawn mower. With this, in addition to the above effects, in the mowing operation in which the operating area  70  is required to have the good appearance after the operation, it becomes possible to prevent many tracks or grooves from being formed on the area wire  72  by wheels  14  of the vehicle  10  and also avoid needlessly damaging the lawn. 
     In the apparatus and method, the vehicle has a charging terminal ( 32 ) at its front to be connectable with the charging device installed on the area wire. With this, it becomes possible to charge the battery  30  more easily. 
     In the apparatus and method, the charging device is disposed with a coil ( 76 ) radiating a magnetic field that forms the charging device detecting area around the charging device. With this, it becomes possible to detect the charging device (charge ST)  74 . 
     It should be noted that, in the foregoing, although the electric motor is applied as the prime mover, it may be an internal combustion engine or a hybrid of an engine and electric motor. 
     It should also be noted that, although the lawn-mowing blades are exemplified as the operating machine, but it should not be limited thereto and any machine can be applied if it is used for maintaining the appearance of the operating area. 
     Japanese Patent Application No. 2012-027636, filed on Feb. 10, 2012 is incorporated by reference herein in its entirety. 
     While the invention has thus been shown and described with reference to specific embodiments, it should be noted that the invention is in no way limited to the details of the described arrangements; changes and modifications may be made without departing from the scope of the appended claims.