Patent Publication Number: US-2020301436-A1

Title: Autonomous travel vehicle and route generation method thereof

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     This application claims the benefit of priority to Japanese Patent Application No. 2019-051457 filed on Mar. 19, 2019. The entire contents of this application are hereby incorporated herein by reference. 
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to an autonomous travel vehicle and a route generation method thereof, and in particular, an autonomous travel vehicle that performs an exhaustive travel in an outer circumferential region based on outer circumferential data, and a route generation method thereof. 
     2. Description of the Related Art 
     The autonomous travel vehicle travels autonomously in accordance with a route plan from a travel start position to a travel end position. The autonomous travel vehicle is used for a device required to travel evenly in a specific region, for example, a cleaning robot and a ball collecting machine in a driving range. 
     In the case of the cleaning robot, the autonomous travel vehicle executes instruction reproduction travel. During the instruction reproduction travel, the autonomous travel vehicle travels based on a traveling route instructed in advance by a worker. 
     The instruction reproduction travel includes, as an example, a copy travel in which all the traveling routes are instructed by the worker operation in advance and the autonomous travel vehicle reproduces the traveling routes as they are. 
     The instruction reproduction travel includes, as an example, an exhaustive travel in which an outer circumference is instructed by a user operation and the autonomous travel vehicle creates and executes an exhaustive route plan in the outer circumference (see International Publication No. 2018/043180), for example. 
     In the case of the exhaustive travel of the autonomous travel vehicle, if the exhaustive route plan is created and executed using the same outer circumferential data, the generated route is always constant. Therefore, in the case of a cleaning machine, wheel marks remain on the floor surface. In the case of a ball collecting machine on a golf course, the lawn or grass where the wheel passes is rutted or shaved. 
     International Publication No. 2018/043180 discloses a route creation method with which a traveling route is changed for each execution of autonomous traveling or each predetermined number of times. 
     However, in the case of a towing vehicle such as a ball collecting machine or a four-wheel vehicle, the minimum turning radius is large, and hence an untraveled area (which is an area that should be traveled but has not actually been traveled) always occurs when the vehicle body is rotated by 180 degrees. Then, it is conceivable to create a route along which the vehicle repeatedly travels while shifting a plurality of lap routes. In this case, since the turn-around portions of the lap routes overlap a plurality of times, it is assumed that a portion of the lawn or grass is damaged. 
     SUMMARY OF THE INVENTION 
     Preferred embodiments of the present invention reduce or prevent overlapping travel areas while reducing an untraveled area in an autonomous travel vehicle that performs an exhaustive travel. 
     Hereinafter, a plurality of aspects of preferred embodiments of the present invention will be described. These aspects may be combined in any manner where necessary. 
     An autonomous travel vehicle according to an aspect of a preferred embodiment of the present invention plans and travels an autonomous traveling route in a designated region, and includes a main body, a route generator, and a travel controller. 
     The main body has a conveyor. 
     The route generator generates an autonomous traveling route along which the autonomous travel vehicle reciprocates a plurality of times in a main direction in the designated region. 
     The travel controller moves the main body along the autonomous traveling route by controlling the conveyor. 
     The route generator generates an autonomous traveling route including a plurality of lap routes coupled while being shifted in a sub direction intersecting the main direction in the region. 
     Turn-around positions in the main direction of the lap routes include at least one set of turn-around positions shifted from each other. 
     The autonomous travel vehicle travels on an autonomous traveling route in the region. The autonomous traveling route is including the plurality of lap routes coupled while being shifted in the sub direction intersecting the main direction. Therefore, the untraveled area is able to be reduced even if the autonomous travel vehicle has a large minimum turning radius. Furthermore, since the turn-around positions in the main direction of the respective lap routes include at least one set of turn-around positions shifted from each other, overlapping travel areas at the turn-around positions are reduced. 
     A turn-around position of a last lap route in the region may be on a travel direction innermost side in the main direction among a plurality of turn-around positions. The autonomous travel vehicle reduces the untraveled area in the last lap route. 
     A turn-around position of a first lap route in the region may be on the travel direction innermost side in the main direction among a plurality of turn-around positions. 
     The autonomous travel vehicle reduces the untraveled area in the first lap route. 
     The shift of the turn-around position may be equal to or greater than the wheel width of the conveyor. 
     In the autonomous travel vehicle, since the shift of the turn-around position is sufficiently large, overlap of the lap routes at the turn-around positions hardly occurs. 
     In route generation after the first time, the route generator may set the main direction of a lap route with respect to the region at an angle different from the main direction of a lap route created last time. 
     In the autonomous travel vehicle, since the angles of the main direction of the lap routes are different in the respective route generations, overlapping travel areas with the route generated last time are reduced. 
     In route generation after the first time, the route generator may shift a lap route in the sub direction and/or the main direction with respect to a lap route created last time. 
     In the autonomous travel vehicle, since the lap routes are shifted in the respective route generations, overlapping travel areas are reduced. 
     In route generation after the first time, the route generator may set the width in the sub direction of the lap route to a length different from the width in the sub direction of the lap route created last time. 
     In the autonomous travel vehicle, since the widths in the sub direction of the lap routes are different in the respective route generations, overlapping travel areas with the route generated last time are reduced. 
     In order to generate the plurality of lap routes, the route generator may divide the region into  2 N (N is a natural number) main direction routes in the sub direction so as to be in a long strip shape in the main direction, determine a travel order in the main direction routes as a first, an N+1-th, a second, and an N+2-th, and set travel directions of the main direction routes from the first to a N-th and from the N+1-th to a  2 N-th so as to be opposite to each other. 
     In the autonomous travel vehicle, the route generation by the route generator can be achieved with a small calculation amount. 
     A method according to another aspect of a preferred embodiment of the present invention is a route generation method for an autonomous travel vehicle that plans and travels an autonomous traveling route in a designated region, including generating a route along which the autonomous travel vehicle reciprocates a plurality of times in the main direction in the designated region, the route being an autonomous traveling route including a plurality of lap routes coupled together while being shifted in the sub direction. 
     Turn-around positions in a main direction of the respective lap routes include at least one set of turn-around positions shifted from each other. 
     According to the route generation method, the autonomous travel vehicle travels on an autonomous traveling route including a plurality of lap routes coupled together while being shifted in the sub direction intersecting the main direction in the region. Therefore, the untraveled area is able to be reduced even if the autonomous travel vehicle has a large minimum turning radius. Furthermore, since the turn-around positions in the main direction of the respective lap routes include at least one set of turn-around positions shifted from each other, overlapping travel areas at the turn-around positions are reduced or prevented. 
     The autonomous travel vehicle that performs an exhaustive travel and the route generation method thereof according to a preferred embodiment of the present invention, it is possible to reduce overlapping travel areas while reducing untraveled area. 
     The above and other elements, features, steps, characteristics and advantages of the present invention will become more apparent from the following detailed description of the preferred embodiments with reference to the attached drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a schematic plan view of a driving range. 
         FIG. 2  is a schematic perspective view of a ball collecting and discharging machine. 
         FIG. 3  is a schematic perspective view of the ball collecting and discharging machine. 
         FIG. 4  is a block diagram illustrating an overall configuration of a controller. 
         FIG. 5  is a schematic plan view of the ball collecting and discharging machine. 
         FIG. 6  is a schematic plan view illustrating turn-around traveling of the ball collecting and discharging machine. 
         FIG. 7  is a flowchart illustrating a control operation of a manual operation instruction mode of exhaustive travel. 
         FIG. 8  is a flowchart illustrating details of steps of creating a ball collecting route travel schedule. 
         FIG. 9  is a schematic view illustrating in a stepwise manner a state in which a ball collecting route is created in a traveling region. 
         FIG. 10  is a schematic view illustrating in a stepwise manner a state in which the ball collecting route is created in the traveling region. 
         FIG. 11  is a schematic view illustrating in a stepwise manner a state in which the ball collecting route is created in the traveling region. 
         FIG. 12  is a schematic view illustrating in a stepwise manner a state in which the ball collecting route is created in the traveling region. 
         FIG. 13  is a schematic plan view illustrating the ball collecting route in the traveling region. 
         FIG. 14  is a schematic plan view illustrating a lap route of the ball collecting route. 
         FIG. 15  is a schematic plan view illustrating the lap route of the ball collecting route. 
         FIG. 16  is a schematic plan view illustrating a position relationship between turn-around routes of the lap route. 
         FIG. 17  is a schematic plan view of the present preferred embodiment of the present invention in which a turn-around position is shifted. 
         FIG. 18  is a schematic plan view of a conventional example in which the turn-around position is not shifted. 
         FIG. 19  is a schematic plan view illustrating the ball collecting route in the traveling region according to a second preferred embodiment of the present invention. 
         FIG. 20  is a schematic plan view illustrating the ball collecting route in the traveling region according to a third preferred embodiment of the present invention. 
         FIG. 21  is a schematic plan view illustrating the ball collecting route in the traveling region according to a fourth preferred embodiment of the present invention. 
         FIG. 22  is a schematic plan view illustrating the ball collecting route in the traveling region according to a fifth preferred embodiment of the present invention. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     1. First Preferred Embodiment 
     A ball collecting and discharging machine  1  will be described with reference to  FIGS. 1 to 3 .  FIG. 1  is a schematic plan view of a driving range.  FIGS. 2 and 3  are schematic perspective views of the ball collecting and discharging machine. 
     In the present preferred embodiment, the ball collecting and discharging machine  1  is used in a driving range  2  (an example of ball collecting and discharging section). This is because a large number of golf balls B are scattered in a short period of time in the driving range  2 , and it is necessary to collect and reuse scattered golf balls B. 
     The driving range  2  includes a ball scattered area  3 , in which the plurality of golf balls B are scattered, and a ball discharging site  7 , in which the collected golf balls B are discharged. In this preferred embodiment, the ball scattered area  3  is turfed. The ball discharging site  7  is a groove provided in the ball scattered area  3 . The golf balls B delivered to the ball discharging site  7  are sent to a collection pool by discharged water. 
     The ball collecting and discharging machine  1  is a device that collects and discharges balls by performing instruction reproduction travel in the driving range  2 . The term “instruction reproduction travel” is a travel based on a route having been instructed in advance by the worker, and includes, for example, a copy travel, which is to travel on the traveling route itself having been instructed in advance by the worker, and an exhaustive travel in which the controller determines an autonomous traveling route within a frame having been instructed in advance by the worker. 
     The ball collecting and discharging machine  1  includes a main body  11 , a storage  13 , and a controller  15 . 
     The main body  11  includes a conveyor  21 , and a ball collector and discharger  23  capable of collecting the golf balls B and discharging the golf balls B. Specifically, the conveyor  21  is a device that causes the ball collecting and discharging machine  1  to travel. The conveyor  21  includes, for example, a travel motor ( FIG. 4 ) provided in the main body  11 , and wheels  33 . 
     The ball collecting and discharging machine  1  includes a GNSS (Global Navigation Satellite System) receiver  35  provided in the main body  11 . The GNSS receiver  35  acquires information (position information) on a current position of the ball collecting and discharging machine  1  on the ground. As a result, the ball collecting and discharging machine  1  is capable of traveling outdoors while grasping its own position. 
     The ball collecting and discharging machine  1  may include a geomagnetic sensor (not illustrated) provided in the main body  11 . The geomagnetic sensor measures an orientation of geomagnetism at the position of the ball collecting and discharging machine  1  (the main body  11 ) in the driving range  2 . Due to this, it is possible to measure the direction in which the ball collecting and discharging machine  1  (the main body  11 ) is facing in the driving range  2 . 
     In addition, a pair of the GNSS receivers  35  may be provided in the main body  11 . For example, the pair of GNSS receivers  35  are arranged side by side on a predetermined axis (e.g., an axis parallel or substantially parallel to the straight-traveling direction of the ball collecting and discharging machine  1 ) of the main body  11 . Due to this, the orientation (direction) of the main body  11  in the driving range  2  can be calculated from two coordinate values (combination of latitude and longitude) obtained from the pair of GNSS receivers  35  (Moving Baseline method). As a result, by calculating the direction using the coordinates obtained by the GNSS receivers  35 , the direction of the ball collecting and discharging machine  1  can be easily measured (calculated) without performing calibration for each place of use. 
     The ball collector and discharger  23  includes a ball collector  24  to collect the golf balls B and a ball discharger  25  to discharge the golf balls B. The ball collector  24  performs a publicly known technique and includes a pickup rotor  24   a  that rotates along with the travel of the main body  11 . It is to be noted that the ball collector  24  may have a configuration in which the pickup rotor  24   a  rotates by a ball collector motor (not illustrated). The ball discharger  25  performs a publicly known technique and has a ball discharger motor  25   a  ( FIG. 4 ) and a ball discharging gate  25   b  driven by the ball discharger motor  25   a.    
     As an alternative preferred embodiment, the ball collector and discharger  23  may include a ball storage amount detector (not illustrated). When the storage amount of the balls exceeds the threshold value in the storage amount detector, the balls become ready to be discharged. Specifically, the storage amount detector is, for example, a weight sensor measuring the weight of the stored golf balls B or a photoelectric sensor detecting the height of the upper surface of the stored golf balls B. 
     The storage  13  is provided in the controller  15  in this preferred embodiment. The storage  13  is a portion of or an entirety of a storage region of a storage device of a computer system defining the controller  15 , and stores various types of information related to the ball collecting and discharging machine  1 . The storage  13  stores a ball collecting route travel schedule  101  and a ball discharging route travel schedule  103 , for example, as will be described later. 
     The controller  15  is a computer system including a CPU, a storage device (RAM, ROM, hard disk drive, SSD, or the like) and various types of interfaces. The controller  15  performs these various types of controls related to the ball collecting and discharging machine  1 . 
     The configuration of the controller  15  will be described in detail with reference to  FIG. 4 .  FIG. 4  is a block diagram illustrating an overall configuration of the controller. All or some of functional blocks of the controller  15  described below may be implemented by a program executable by a computer system defining the controller  15 . In this case, the program may be stored in a memory and/or the storage. All or some of the functional blocks of the controller  15  may be implemented as a custom IC such as an SoC (System on Chip). 
     The controller  15  may be defined by a single computer system or may be defined by a plurality of computer systems. When the controller  15  is defined by a plurality of computer systems, for example, functions carried out by a plurality of functional blocks can be executed by allocating the functions to the plurality of computer systems at any ratio. 
     The controller  15  includes a travel controller  51 . The travel controller  51  controls the travel motor  31 . The travel controller  51  receives a travel command from a travel command calculator  53  (described later). The travel controller  51  receives a travel command from a traveling route instructor  37  in an instructed travel mode. The traveling route instructor  37  is, for example, an operator that operates the ball collecting and discharging machine  1 , such as a steering wheel. That is, the travel controller  51  receives the operation of the worker through the traveling route instructor  37 . 
     The controller  15  includes the travel command calculator  53 . The travel command calculator  53  outputs a travel command to the travel controller  51 . Data provided to the travel command calculator  53  is the ball collecting route travel schedule  101  in an exhaustive travel mode and the ball discharging route travel schedule  103  in a copy travel mode. The travel controller  51  calculates a target rotation speed of the travel motor  31 , and outputs, to the travel motor  31 , drive power to rotate the travel motor  31  at the target rotation speed. 
     The controller  15  includes a ball discharging controller  58 . The ball discharging controller  58  controls the ball discharger motor  25   a.    
     The controller  15  includes a position acquirer  55 . The position acquirer  55  acquires position information acquired by the GNSS receiver  35 . As a result, the controller  15  can grasp which position in the ball scattered area  3  the ball collecting and discharging machine  1  is moving. Specifically, the position acquirer  55  receives absolute coordinates (latitude/longitude) of the current location obtained by RTK (Real Time Kinematic) positioning. 
     The controller  15  includes a ball collecting route travel schedule generator  57 . The ball collecting route travel schedule generator  57  creates the ball collecting route travel schedule  101  described above. The ball collecting route travel schedule  101  is a schedule in which the ball collecting and discharging machine  1  travels evenly (as if “filling”) in a traveling region TA. The traveling region TA is a region in which the ball collecting and discharging machine  1  travels in a travel environment. 
     When the manual operation instruction mode is executed, the ball collecting route travel schedule generator  57  receives position information having been input from the position acquirer  55  at a predetermined length of time (e.g., every control cycle in the controller  15 ). Due to this, the ball collecting route travel schedule generator  57  acquires a point sequence of a plurality of pieces of position information, and determines the traveling region TA based on the acquired point sequence of the plurality of pieces of position information. 
     Next, the ball collecting route travel schedule generator  57  creates the ball collecting route travel schedule  101  in the traveling region TA, and stores the same in the storage  13 . 
     The controller  15  includes a ball discharging route travel schedule generator  59 . The ball discharging route travel schedule generator  59  creates the ball discharging route travel schedule  103  based on the rotation amount and rotation direction of the steering wheel having been input from the traveling route instructor  37  in the instructed travel mode. The ball discharging route travel schedule  103  is a set of passing time in the instructed travel mode and passing point data corresponding to the passing time, and indicates the traveling route in which the ball collecting and discharging machine  1  autonomously moves at the time of execution of the reproduction travel mode. At the time of execution of the reproduction travel mode, the ball collecting and discharging machine  1  controls the travel motor  31  so as to reach the target position with reference to the target position indicated in the ball discharging route travel schedule  103 . In this preferred embodiment, the ball discharging route travel schedule  103  is a travel schedule of a ball discharging route (not illustrated), which is a copy traveling route having been instructed in advance by the worker, and at least a portion of the ball discharging route is in a vicinity of the ball discharging site  7 . 
     With the above configuration, the travel command calculator  53  calculates a control command (reproduction travel control command) for autonomous travel on the traveling route indicated in the ball collecting route travel schedule  101  or the ball discharging route travel schedule  103  as reproduction travel control at the time of execution of an autonomous travel mode, and outputs the control command to the travel controller  51 . The travel command calculator  53  calculates the reproduction travel control command based on the information stored in the schedule and the position information acquired from the position acquirer  55 . 
     Due to this, at the time of execution of the autonomous travel mode, the travel controller  51  is capable of autonomously moving the ball collecting and discharging machine  1  by controlling the travel motor  31  based on the reproduction travel control command. 
     The controller  15  includes a ball discharging instructor  39 . The ball discharging instructor  39  is, for example, an operation panel including a press button, and the ball discharging instructor  39  transmits, for example, the operation of the press button by the operator to the ball discharging controller  58 . 
     The ball discharging controller  58  receives a button operation from the ball discharging instructor  39  and converts the operation into a ball collecting instruction or a ball discharging instruction. The ball discharging controller  58  drives the ball discharging gate  25   b  by outputting the ball discharging instruction to the ball discharger motor  25   a.    
     Ball collecting conditions and ball discharging conditions are stored by the travel command calculator  53  in association with the ball collecting route travel schedule  101  and the ball discharging route travel schedule  103 , respectively. 
     At the time of execution of the autonomous travel mode, based on the ball discharging conditions associated with the ball discharging route travel schedule  103 , the ball discharging controller  58  controls the ball discharger motor  25   a  and opens the ball discharging gate  25   b.  Due to this, the ball collecting and discharging machine  1  is capable of autonomously executing the ball collecting work and the ball discharging work in accordance with the ball discharging conditions during autonomous traveling. 
     The controller  15  includes an autonomous traveling route travel schedule generator  61 . 
     If the position information of the start point and the end point is obtained, the autonomous traveling route travel schedule generator  61  calculates an optimal travel schedule, and creates an autonomous traveling route travel schedule. The route generation algorithm is publicly known and is not particularly limited. 
     In the autonomous traveling route travel mode, the travel command calculator  53  transmits a travel command to the travel controller  51  based on the autonomous traveling route travel schedule. 
     Although not illustrated, a sensor and a switch to detect the state of each device, and an information input device are connected to the controller  15 . 
     An encoder (not illustrated) is attached to an output rotation shaft of the travel motor  31 , for example. 
     Furthermore, a front detector and a rear detector (not illustrated) are attached to the main body  11 . These are laser range finders (LRF) having a detection range of 180° or more. The front detector and the rear detector may include TOF (Time Of Flight) cameras or the like. 
     With reference to  FIGS. 5 and 6 , the travel characteristics of the ball collecting and discharging machine  1  will be described.  FIG. 5  is a schematic plan view of the ball collecting and discharging machine.  FIG. 6  is a schematic plan view illustrating turn-around traveling of the ball collecting and discharging machine. 
     As mentioned above, the ball collector and discharger  23  is coupled to the conveyor  21  by a towing structure  26 , and the minimum radius at the time of rotation is large. Accordingly, when the ball collecting and discharging machine  1  performs turn-around traveling, as illustrated in  FIG. 6 , a large gap W is formed between the forward route and the return route. 
     One solution for the above problem is to create a traveling route connecting a plurality of lap routes to each other by shifting the lap routes laterally. 
     With reference to  FIG. 7 , the manual operation instruction mode of exhaustive travel will be described.  FIG. 7  is a flowchart illustrating a control operation of the manual operation instruction mode of exhaustive travel. 
     The control flowchart described below is an example, and each step can be omitted or replaced as necessary. A plurality of steps may be executed simultaneously, or some or all of the steps may be executed in an overlapping manner. 
     Furthermore, each block of the control flowchart is not limited to a single control operation, but can be replaced by a plurality of control operations represented by a plurality of blocks. 
     The operation of each device is a result of a command from the controller to each device, which is represented by each step of a software application. 
     In step S 1 , the ball collecting route travel schedule generator  57  acquires a point sequence (coordinate value) of position information representing the traveling region TA at the time of execution of the manual operation instruction mode. 
     In step S 2 , the ball collecting route travel schedule generator  57  determines the traveling region TA. 
     In step S 3 , the ball collecting route travel schedule generator  57  creates the ball collecting route travel schedule  101  including an exhaustive route in the traveling region TA, and stores the same in the storage  13 . 
     Step S 3  of  FIG. 4  will be described in detail with reference to  FIGS. 8 to 12 .  FIG. 8  is a flowchart illustrating details of steps of creating the ball collecting route travel schedule.  FIGS. 9 to 12  are schematic views illustrating in a stepwise manner a state in which the ball collecting route is created in the traveling region. 
     In step S 4 , as illustrated in  FIG. 9 , the ball collecting route travel schedule generator  57  divides the region into  2 N regions in a strip shape. At this time, the longitudinal direction of each region is the main direction, and a direction orthogonal thereto is the sub direction. At this time, the width of the divided region is set to be equal to or less than the width of the ball collector and discharger  23 . 
     In step S 5 , as illustrated in  FIG. 10 , the ball collecting route travel schedule generator  57  determines a travel order of the divided regions such as the first region, the N+1-th region, the second region, the N+2-th region, and so on. 
     In step S 6 , as illustrated in  FIG. 11 , the ball collecting route travel schedule generator  57  sets a traveling route in each of the  2 N regions. In this case, the travel direction of the first to N-th regions and the travel direction of the N+1 to  2 N-th regions are set inversely. 
     In step S 7 , as illustrated in  FIG. 12 , the routes are connected each other. Specifically, the end point of the m (1, 2, . . . N-1)-th traveling route and the start point of the m+N-th traveling route are connected together, and the end point of the m+N-th traveling route and the start point of the m+1 traveling route are connected together. This connection operation is repeated by incrementing m by one from 1 to N-1. 
     Furthermore, the end point of the N-th traveling route and the start point of the  2 N-th traveling route are connected together, after that the end point of the  2 N-th traveling route and the start point of the first traveling route are connected together, and generation of the partial traveling route is finished. 
     When the two traveling routes are connected as described above, as illustrated in  FIG. 12 , a 90° curve is provided on a connecting line of the two traveling routes. The radius of this curve is set to be equal to or greater than the minimum radius at the time of rotation of the ball collecting and discharging machine  1 . 
     The number of regions divided to provide a ball collecting route may be  2 N+1 (odd number). 
     In addition, in order to provide the ball collecting route, one lap route may be created first and reused. 
     The outline of the ball collecting route will be described with reference to  FIG. 13 .  FIG. 13  is a schematic plan view illustrating the ball collecting route in the traveling region. 
     The ball collecting route travel schedule generator  57  generates a ball collecting route  41  including a plurality of lap routes (specifically,  63 A to  63 F) coupled together while shifted in the sub direction intersecting the main direction in the traveling region TA in the ball scattered area  3 . 
     The positions (turn-around positions) of the main direction of turn-around portions (specifically,  64   b  to  69   b  and  64   d  to  69   d ) in the main direction of the respective lap routes include at least one set of turn-around positions shifted from each other (described in detail later). 
     The ball collecting and discharging machine  1  travels on the ball collecting route  41  including the plurality of lap routes coupled together while shifted in the sub direction intersecting the main direction in the traveling region TA in the ball scattered area  3 . Therefore, the untraveled area can be reduced even if the ball collecting and discharging machine has a large minimum turning radius. Furthermore, the turn-around positions in the main direction of the respective lap routes include at least one set of turn-around positions shifted from each other. Accordingly, overlapping travel areas at the turn-around positions are reduced. 
     The ball collecting route  41  will be described in detail with reference to  FIGS. 13, 14, and 15 .  FIGS. 14 and 15  are schematic plan views illustrating the lap route of the ball collecting route. Note that in this preferred embodiment, the main direction of the ball collecting route  41  is the orientation of an arrow Y and the sub direction is the orientation of an arrow X. The orientations of the arrows X and Y are orthogonal. 
     As illustrated in  FIG. 13 , the ball collecting route  41  is an exhaustive traveling route along which the vehicle travels over the entire area inside the traveling region TA, and the ball collecting route  41  has a first lap route  63 A, a second lap route  63 B, a third lap route  63 C, a fourth lap route  63 D, a fifth lap route  63 E, and a sixth lap route  63 F. 
     In  FIG. 13 , the travel order in the main direction route of the respective lap routes is indicated by encircled numbers in the entire ball collecting route  41 . 
     Hereinafter, the first lap route  63 A and the second lap route  63 B will be described in detail. However, the third lap route  63 C, the fourth lap route  63 D, the fifth lap route  63 E, and the sixth lap route  63 F are similar, and thus the description thereof will be omitted. 
     As illustrated in  FIG. 14 , the first lap route  63 A includes a first main direction route  64   a,  a first turn-around route  64   b,  a second main direction route  64   c,  and a second turn-around route  64   d  in a continuous manner. The first main direction route  64   a  and the second main direction route  64   c  extend in the main direction. The first turn-around route  64   b  and the second turn-around route  64   d  extend in the sub direction. The first turn-around route  64   b  and the second turn-around route  64   d  are positioned on the outermost side where traveling is possible in the main direction. 
     As illustrated in  FIG. 15 , the second lap route  63 B includes a first main direction route  65   a,  a first turn-around route  65   b,  a second main direction route  65   c,  and a second turn-around route  65   d  in a continuous manner. The first main direction route  65   a  and the second main direction route  65   c  extend in the main direction. The first turn-around route  65   b  and the second turn-around route  65   d  extend in the sub direction. 
     With reference to  FIG. 16 , the position relationship between the turn-around routes on the upper side of the lap route on the drawing will be described.  FIG. 16  is a schematic plan view illustrating the position relationship between the turn-around routes of the lap route. The same is true for the lower side in  FIG. 16 , and hence the description thereof will be omitted. 
     The first turn-around route  64   b  of the first lap route  63 A is at the farthest first position A. That is, the first turn-around route  64   b  is on the outermost side in the main direction. 
     The first turn-around route  65   b  of the second lap route  63 B is shifted in the main direction with respect to the first turn-around route  64   b,  and specifically, it is at a second position B shifted inwards in the main direction. 
     A first turn-around route  66   b  of the third lap route  63 C is shifted in the main direction with respect to the first turn-around route  65   b,  and specifically, it is at a third position C shifted inwards in the main direction. 
     A first turn-around route  67   b  of the fourth lap route  63 D is shifted in the main direction with respect to the first turn-around route  66   b,  and specifically, it is at the first position A shifted outwards in the main direction. The first turn-around route  67   b  is arranged on the outermost side in the main direction. 
     A first turn-around route  68   b  of the fifth lap route  63 E is shifted in the main direction with respect to the first turn-around route  67   b,  and specifically, it is at the second position B shifted inwards in the main direction. 
     A first turn-around route  69   b  of the sixth lap route  63 F is shifted in the main direction with respect to the first turn-around route  68   b,  and specifically, it is at the first position A shifted outwards in the main direction. That is, the first turn-around route  69   b  is on the outermost side in the main direction. 
     With reference to  FIGS. 17 and 18 , a difference in effect between when the turn-around position is shifted and when the turn-around position is not shifted will be described in detail.  FIG. 17  is a schematic plan view of the present preferred embodiment in which the turn-around position is shifted.  FIG. 18  is a schematic plan view of a conventional example in which the turn-around position is not shifted. 
     As illustrated in  FIG. 17 , the first turn-around route  65   b  of the second lap route  63 B is shifted in the main direction with respect to the first turn-around route  64   b  of the first lap route  63 A, and specifically, it is shifted inwards in the main direction. Accordingly, overlapping travel areas at the turn-around positions of the lap routes are reduced. 
     As described above, by changing the turn-around position of the lap route of the ball collecting route  41  generated based on the outer circumferential data, the position at which the wheels move can be shifted, and as a result, damage to the lawn can be reduced, for example. 
     As illustrated in  FIG. 18 , as an example different from the present preferred embodiment, the first turn-around route  65   b  of the second lap route  63 B is not shifted in the main direction with respect to the first turn-around route  64   b  of the first lap route  63 A. Accordingly, in this ball collecting and discharging machine, an overlapping travel area R at the turn-around position becomes long. The above is a conventional example assumed as an example in which the problem to be solved by the present preferred embodiment arises. 
     The turn-around position of the sixth lap route  63 F, which is the last lap route in the traveling region TA, is the first turn-around position A. The first turn-around position A is on the travel direction innermost side in the main direction among the plurality of turn-around positions A to C. Due to this, the ball collecting and discharging machine  1  reduces the untraveled area in the sixth lap route  63 F. 
     This characteristic is not essential and can be omitted. 
     The turn-around position of the first lap route  63 A, which is the first lap route in the traveling region TA, is the first turn-around position A. The first turn-around position A is on the travel direction innermost side in the main direction among the plurality of turn-around positions A to C. Due to this, the ball collecting and discharging machine  1  reduces the untraveled area in the first lap route  63 A. 
     This characteristic is not essential and can be omitted. 
     The shift of the turn-around position may be equal to or greater than the width of the wheels  33  of the conveyor  21 . Due to this, in the ball collecting and discharging machine  1 , since the shift of the turn-around position is sufficiently large, overlap of the lap routes at the turn-around positions hardly occurs. 
     In this preferred embodiment, the shift of the turn-around position is set so as to always occur between continuous lap routes. It is seen in, as illustrated in  FIG. 17 , for example, a case of the turn-around route  64   b  of the first lap route  63 A and the turn-around route  65   b  of the second lap route  63 B. It is because a long overlapping travel region is provided when the turn-around routes of the continuous lap routes overlap each other, and it is preferable to avoid formation of a long overlapping travel region. 
     A shift amount at the turn-around position of a certain ball collecting route may be made different from the shift amount of the turn-around position of the previous ball collecting route. 
     2. Second Preferred Embodiment 
     In the first preferred embodiment, the route generation of a single exhaustive travel is described. In reality, exhaustive travel is performed for a plurality of times. Then, the route generation after the first time that is a route generation in which an overlapping travel area is reduced by making a change to the last or past exhaustive travel will be described in the following second to fifth preferred embodiments. 
     In the second preferred embodiment, the ball collecting and discharging machine may travel after creating the exhaustive route each time the traveling route is set, or may travel after appropriately selecting one or more among a plurality of patterns of exhaustive routes formed in advance (the same is true for the following other preferred embodiments). 
     The second preferred embodiment will be described with reference to  FIG. 19 .  FIG. 19  is a schematic plan view illustrating the ball collecting route in the traveling region according to the second preferred embodiment. 
     In route generation after the first time, the ball collecting route travel schedule generator  57  sets the main direction of the lap route with respect to the traveling region TA at an angle different from the main direction of the lap route created last time. Due to this, since the angles of the main direction of the lap routes are different in the respective route generations, overlapping travel areas are reduced. 
     In  FIG. 19 , a first ball collecting route  41 A created in the first time for example is indicated by a solid line, and a second ball collecting route  41 B created in the second time for example is indicated by a broken line. The main direction of the lap route of the second ball collecting route  41 B is set at an angle different from the main direction of the lap route of the first ball collecting route  41 A. In this preferred embodiment, the angle is 90 degrees. Specifically, the main direction of the first ball collecting route  41 A is the orientation of the arrow Y and the sub direction is the orientation of the arrow X, meanwhile the main direction of the second ball collecting route  41 B is the orientation of the arrow X and the sub direction is the orientation of the arrow Y. 
     As described above, the main direction of an exhaustive travel (the direction in which the length of the straight line becomes longest) is changed with respect to the last or past exhaustive traveling route. Accordingly, overlapping travel areas in the ball collecting routes are reduced. 
     The above angle is any angle appropriately selectable from a range of about  45  degrees to about  135  degrees, for example. 
     The angle change may be made for each ball collecting route creation, or ball collecting route creation without changing the angle may be carried out continuously. 
     Furthermore, although not illustrated in  FIG. 19 , in each ball collecting route, the turn-around position of the lap route may be shifted as in the first preferred embodiment. For example, the turn-around positions of the lap route may be shifted in the entire respective ball collecting routes, or the turn-around positions of the lap route may be shifted only in some ball collecting routes. 
     3. Third Preferred Embodiment 
     The third preferred embodiment will be described with reference to  FIG. 20 .  FIG. 20  is a schematic plan view illustrating the ball collecting route in the traveling region according to the third preferred embodiment. 
     The ball collecting route travel schedule generator  57  generates a fourth ball collecting route  41 D so as to shift the lap route of the fourth ball collecting route  41 D to the sub direction (e.g., the orientation of the arrow X) and/or the main direction (e.g., the orientation of the arrow Y) with respect to the lap route of a third ball collecting route  41 C created last time. Due to this, since the lap routes of the ball collecting route are shifted in the respective route generations, overlapping travel areas are reduced. 
     As illustrated in  FIG. 20 , the third ball collecting route  41 C includes the first lap route  63 A, the second lap route  63 B, the third lap route  63 C, the fourth lap route  63 D, the fifth lap route  63 E, and the sixth lap route  63 F. 
     As illustrated in  FIG. 20 , the fourth ball collecting route  41 D includes a first lap route  70  A, a second lap route  70 B, a third lap route  70 C, a fourth lap route  70 D, a fifth lap route  70 E, and a sixth lap route  70 F. 
     The fourth ball collecting route  41 D preferably includes the lap routes in the same number, the same shape, the same orientation, and the same dimensions as those of the third ball collecting route  41 C. In the fourth ball collecting route  41 D, the lap routes are shifted in the sub direction and the main direction, and specifically, they are shifted to diagonally right in the drawing. 
     As described above, since the exhaustive route is shifted with respect to the last or past exhaustive traveling route, overlapping travel areas in the ball collecting routes are reduced. 
     The fourth ball collecting route  41 D may be shifted only in the main direction or only in the sub direction with respect to the third ball collecting route  41 C. 
     The above shift may be performed for each ball collecting route creation, or ball collecting route formation without forming the shift may be carried out continuously. 
     Furthermore, although not illustrated in  FIG. 20 , in each ball collecting route, the turn-around position of the lap route may be shifted as in the first preferred embodiment. For example, the turn-around positions of the lap route may be shifted in the entire respective ball collecting routes, or the turn-around positions of the lap route may be shifted only in some ball collecting routes. 
     4. Fourth Preferred Embodiment 
     In route generation of a sixth ball collecting route  41 F, the ball collecting route travel schedule generator  57  sets the width in the sub direction of the sixth ball collecting route  41 F (e.g., the orientation of the arrow X) to a length different from the width in the sub direction of a fifth ball collecting route  41 E created previously. Due to this, since the widths in the sub direction of the lap routes are different in the respective route generations, overlapping travel areas are reduced. 
     The fourth preferred embodiment will be described with reference to  FIG. 21 .  FIG. 21  is a schematic plan view illustrating the ball collecting route in the traveling region according to the fourth preferred embodiment. 
     In  FIG. 21 , the travel order in the main direction route of the respective lap routes is indicated by encircled numbers in the entire fifth ball collecting route  41 E. In addition, the travel order in the main direction route of the respective lap routes is indicated by triangle-enclosed numbers in the entire sixth ball collecting route  41 F. 
     As illustrated in  FIG. 21 , the fifth ball collecting route  41 E has the first lap route  63 A, the second lap route  63 B, the third lap route  63 C, the fourth lap route  63 D, the fifth lap route  63 E, and the sixth lap route  63 F. 
     As illustrated in  FIG. 21 , the sixth ball collecting route  41 F has a first lap route  71 A, a second lap route  71 B, a third lap route  71 C, and a fourth lap route  71 D. 
     In the fifth ball collecting route  41 E and the sixth ball collecting route  41 F, the main direction routes of the first lap route overlap (circle  1  and triangle  1 ), and the main direction routes of the last lap route of the fifth ball collecting route  41 E and the sixth ball collecting route  41 F overlap (circle  12  and triangle  8 ). 
     On the other hand, while the number of the lap routes is  6  in the fifth ball collecting route  41 E, the number of the lap routes is 4 in the sixth ball collecting route  41 F. Accordingly, the sub direction width is different between the both main direction routes. In this preferred embodiment, the sub direction width between the main direction routes of the lap route of the fifth ball collecting route  41 E is W 1 , and the sub direction width between the main direction routes of the lap route of the sixth ball collecting route  41 F is W 2 . W 2  is longer than W 1 . As a result, the main direction routes (circle  2  to circle  11 , and triangles  2  to  7 ) on the sub direction inside of the fifth ball collecting route  41 E and the sixth ball collecting route  41 F do not overlap one another. 
     As described above, in the route generation after the first time, the ball collecting route travel schedule generator  57  forms the lap route such that the sub direction width between the lap routes becomes a length different from the sub direction width between the lap routes  3  creased last time. As a result, since the sub direction width between the lap routes is different in each route generation, overlapping travel areas in the ball collecting routes are reduced. 
     The sub direction width of the main direction routes of the fourth ball collecting route  41 D may be shorter than the sub direction width of the main direction routes of the third ball collecting route  41 C. 
     The above change may be formed for each ball collecting route creation, or lap route creation without making the change may be carried out continuously. 
     Furthermore, although not illustrated in  FIG. 21 , in each ball collecting route, the turn-around position of the lap route may be shifted as in the first preferred embodiment. For example, the turn-around positions of the lap route may be shifted in the entire respective ball collecting routes, or the turn-around positions of the lap route may be shifted only in some ball collecting routes. 
     5. Fifth Preferred Embodiment 
     In the first to fourth preferred embodiments, the traveling region TA is a square, but the traveling region TA may have any shape. For example, the traveling region TA may have another shape such as a rectangle and a trapezoid. 
     Such a preferred embodiment will be described as the fifth preferred embodiment with reference to  FIG. 22 .  FIG. 22  is a schematic plan view illustrating the ball collecting route in the traveling region according to the fifth preferred embodiment. 
     In this preferred embodiment, the traveling region TA is a trapezoid, and a ball collecting route  41 G for the vehicle to travel over the entire area inside the traveling region TA. 
     In this preferred embodiment, the direction in which the parallel top side and bottom side of the trapezoid extend is the main direction of the lap routes  63 A to  63 D. The turn-around routes of the lap routes  63 A to  63 D extend along the both sides of the trapezoid. 
     6. Common Matters of Preferred Embodiments 
     The first to fifth preferred embodiments have the following configurations and functions in common. 
     The autonomous travel vehicle (e.g., the ball collecting and discharging machine  1 ) plans and travels an autonomous traveling route in a designated region (e.g., the traveling region TA), and includes the main body, the route generator, and the travel controller. 
     The main body (e.g., the main body  11 ) includes the conveyor (e.g., the travel motor  31 ). 
     The route generator (e.g., the ball collecting route travel schedule generator  57 ) generates an autonomous traveling route (e.g., the ball collecting route  41  or  41 A to  41 F) along which the autonomous travel vehicle reciprocates the plurality of times in the main direction in the designated region. 
     The travel controller (e.g., the travel controller  51 ) moves the main body along the autonomous traveling route by controlling the conveyor. 
     The route generator generates an autonomous traveling route including the plurality of lap routes (e.g., the lap routes  63 A to  63 F) coupled together while being shifted in the sub direction intersecting the main direction in the region. 
     The turn-around positions (e.g., A to C) in the main direction of the respective lap routes include at least one set of turn-around positions shifted from each other. 
     The autonomous travel vehicle travels on the autonomous traveling route including the plurality of lap routes coupled together while being shifted in the sub direction intersecting the main direction in the region. Therefore, the untraveled area is able to be reduced or prevented even if the autonomous travel vehicle has a large minimum turning radius. Furthermore, since the turn-around positions in the main direction of the respective lap routes include at least one set of turn-around positions shifted from each other, overlapping travel areas at the turn-around positions are reduced. 
     7. Other Preferred Embodiments 
     While the plurality of preferred embodiments of the present invention have been described above, the present invention is not limited to the above-described preferred embodiments, and various modifications can be made without departing from the scope of the present invention. In particular, the plurality of preferred embodiments and alternative preferred embodiments described in the present description can be combined in any manner as necessary. 
     Preferred embodiments of the present invention are not limited to a ball collecting and discharging machines, as long as it is an autonomous travel vehicle that performs exhaustive travel in a predetermined region. Preferred embodiments of the present invention can also be applied to, for example, a cleaning machine and a traveling device for amusement rides. 
     In the first to fifth preferred embodiments, there are three types of turn-around positions, but there is no particular limitation as long as there are two or more types of them. 
     In the first to fourth preferred embodiments, the width between the pair of main direction routes of each ball collecting route is the same, but different combinations may be provided. 
     Preferred embodiments of the present invention can be widely applied to an autonomous travel vehicle that performs exhaustive travel. 
     While preferred embodiments of the present invention have been described above, it is to be understood that variations and modifications will be apparent to those skilled in the art without departing from the scope and spirit of the present invention. The scope of the present invention, therefore, is to be determined solely by the following claims.