Automatic traveling vehicle and control program for automatic traveling vehicle

Abstract

An automatic traveling vehicle (10) is provided with a plurality of magnetic sensors (S1 to S16) arranged in the left-right direction, and travels along a strip-shaped magnetic line provided on a travel path, on the basis of the results of detection of the magnetic line by the plurality of magnetic sensors. A range acquisition unit (31) acquires a detection range, which is a range including a series of magnetic sensors that have detected the magnetic line. If there are a plurality of detection ranges acquired by the range acquisition unit when the automatic traveling vehicle is instructed to travel straight, a range selection unit (32) selects one detection range that is predicted to correspond to a magnetic line that extends in the straight-ahead direction of the automatic traveling vehicle. A travel control unit (33) controls the traveling state of the automatic traveling vehicle so that the left-right center of the one detection range selected by the range selection unit is brought closer to the left-right center of the automatic traveling vehicle.

Description

Self-driving cars, control programs for self-driving cars CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application is based on Japanese Application No. 2023-213587, filed on December 19, 2023, the contents of which are incorporated herein by reference.

[0002] The present disclosure relates to an autonomous vehicle guided by a magnetic line.

[0003] For example, there is an autonomous vehicle that includes multiple magnetic sensors arranged in the left-right direction, and is configured so that only the magnetic sensor located directly above a magnetic tape is turned on, and detects the range of magnetic sensors that are turned on (hereinafter referred to as the "on range") and outputs a signal indicating the center of the on range (see Patent Document 1). The autonomous vehicle described in Patent Document 1 controls the rotational speeds of the left and right driving wheels so that the center of the on range coincides with the left-right center of the autonomous vehicle when traveling straight.

[0004] Japanese Patent Application Publication No. 8-44426

[0005] However, it has been discovered that when an autonomous vehicle is instructed to travel straight and enters a crossroads of magnetic tape (magnetic lines) at a slight angle, the following problem occurs: A magnetic sensor near the center detects the magnetic tape extending in the straight-line direction and turns on, while a magnetic sensor near the edge detects the magnetic tape extending in the left-right direction and turns on. In this case, if an attempt is made to align the center of the entire range, which combines the on-range near the center and the on-range near the edge and the range between them, with the left-right center of the autonomous vehicle, the direction of travel of the autonomous vehicle will change toward the magnetic sensor that turned on near the edge. As a result, the autonomous vehicle may not travel straight but may turn along the magnetic tape extending in the left-right direction.

[0006] This situation is not limited to magnetic tape crossings, but is generally common to any running path where a magnetic tape extending in a straight direction crosses another magnetic tape.

[0007] The present disclosure has been made to solve the above-mentioned problems, and its main purpose is to provide an autonomous vehicle that can travel straight as instructed even on a road where a magnetic line extending in a straight-line direction intersects with another magnetic line.

[0008] A first means for solving the above problem is an autonomous vehicle that has a plurality of magnetic sensors arranged in the left-right direction and travels along a strip-shaped magnetic line provided on a roadway based on the results of detection of the magnetic line by the plurality of magnetic sensors, the autonomous vehicle comprising: a range acquisition unit that acquires a detection range which is the range over which the magnetic sensors that detected the magnetic line are continuous; a range selection unit that, when there are a plurality of detection ranges acquired by the range acquisition unit when the autonomous vehicle is instructed to travel straight, selects one detection range that is predicted to correspond to the magnetic line extending in the straight-ahead direction of the autonomous vehicle; and a travel control unit that controls the travel state of the autonomous vehicle so as to bring the left-right center of the one detection range selected by the range selection unit closer to the left-right center of the autonomous vehicle.

[0009] According to the above configuration, the self-driving vehicle is equipped with a plurality of magnetic sensors arranged in the left-right direction, and drives along a strip-shaped magnetic line provided on the roadway based on the results of detection of the magnetic line by the plurality of magnetic sensors.

[0010] Here, the range acquisition unit acquires a detection range, which is the range in which the magnetic sensors that detected the magnetic line are continuous. Therefore, if there are multiple magnetic sensors that detected the magnetic line and these magnetic sensors are not continuous (separate from each other), these magnetic sensors are acquired as separate detection ranges. Note that only one magnetic sensor that detected the magnetic line is also acquired as a detection range. In other words, the detection range does not necessarily have to include multiple magnetic sensors.

[0011] When the range acquisition unit acquires a plurality of detection ranges when the autonomous vehicle is instructed to travel straight, the range selection unit selects one detection range that is predicted to correspond to the magnetic line extending in the straight-ahead direction of the autonomous vehicle. Therefore, when a magnetic line extending in the straight-ahead direction intersects with another magnetic line, the range selection unit can predict and select one detection range that corresponds to the magnetic line extending in the straight-ahead direction of the autonomous vehicle, rather than regarding the entire range that combines the plurality of detection ranges and the ranges between them as the detection range.

[0012] The driving control unit controls the driving state of the autonomous vehicle so as to bring the left-right center of the one detection range selected by the range selection unit closer to the left-right center of the autonomous vehicle. Therefore, even on a road where a magnetic line extending in a straight-ahead direction intersects with another magnetic line, the autonomous vehicle can bring the left-right rear center of the magnetic line extending in the straight-ahead direction closer to the left-right center of the autonomous vehicle, allowing it to travel straight as instructed.

[0013] The second means is a control program applied to an autonomous vehicle that has a plurality of magnetic sensors arranged in the left-right direction and travels along a strip-shaped magnetic line provided on a roadway based on the results of detection of the magnetic line by the plurality of magnetic sensors, and causes a computer to perform the following processes: acquiring a detection range that is the range over which the magnetic sensors that detected the magnetic line are continuous; when there are multiple acquired detection ranges when the autonomous vehicle is instructed to travel straight, selecting one detection range that is predicted to correspond to the magnetic line extending in the straight-ahead direction of the autonomous vehicle; and controlling the traveling state of the autonomous vehicle so that the left-right center of the selected one detection range approaches the left-right center of the autonomous vehicle.

[0014] According to the above configuration, by causing a computer to execute a control program applied to an autonomous vehicle, it is possible to achieve the same effects as those of the first means.

[0015] The above and other objects, features, and advantages of the present disclosure will become more apparent from the following detailed description taken in conjunction with the accompanying drawings, in which Fig. 1 is a schematic diagram showing a side view of an automated driving vehicle, Fig. 2 is a schematic diagram showing a front view of the automated driving vehicle, Fig. 3 is a schematic diagram showing the driving state of an automated driving vehicle that has entered a crossroads of magnetic lines straight when instructed to go straight, Fig. 4 is a schematic diagram showing the on state of the magnetic sensors at times ta and tc in Fig. 3, Fig. 5 is a schematic diagram showing the on state of the magnetic sensors at time tb in Fig. 3, and Fig. 6 is a schematic diagram showing the driving state of an automated driving vehicle of a comparative example that has entered a crossroads of magnetic lines diagonally when instructed to go straight. 7 is a schematic diagram showing the ON state of the magnetic sensor at tb in FIG. 6 , FIG. 8 is a block diagram showing the configuration of an autonomous vehicle, FIG. 9 is a flowchart showing control when a straight ahead instruction is given, FIG. 10 is a schematic diagram showing the positional relationship between the sensor unit of an autonomous vehicle that has entered the intersection of magnetic lines at an angle when a straight ahead instruction is given, and the intersection, FIG. 11 is a schematic diagram showing the ON state of the magnetic sensor at ta in FIG. 10 , and FIG. 12 is a schematic diagram showing the ON state of the magnetic sensor at tb in FIG. 13 is a schematic diagram showing the ON state of the magnetic sensor in a modified example of the autonomous vehicle; FIG. 14 is a schematic diagram showing the ON state of the magnetic sensor in another modified example of the autonomous vehicle; FIG. 15 is a schematic diagram showing the positional relationship between the sensor unit of an autonomous vehicle that has entered a T-junction of magnetic lines at an angle when instructed to go straight and the T-junction; FIG. 16 is a schematic diagram showing the positional relationship between the sensor unit of an autonomous vehicle that has entered a diagonal four-way intersection of magnetic lines at an angle when instructed to go straight and the diagonal four-way intersection; and FIG. 18 is a schematic diagram showing the positional relationship between the sensor unit of an autonomous vehicle that has entered a diagonal three-way intersection of a magnetic line diagonally when instructed to go straight and the diagonal three-way intersection; FIG. 19 is a schematic diagram showing the on state of the magnetic sensor at tb in FIG. 18; FIG. 20 is a schematic diagram showing the side of a modified example of an autonomous vehicle; and FIG. 21 is a flowchart showing a modified example of control when instructed to go straight.

[0016] Hereinafter, an embodiment will be described with reference to the drawings, in which the present invention is embodied in an automatic guided vehicle (AGV) that is guided by a magnetic tape (magnetic line) in a factory, a warehouse, etc. The automatic guided vehicle is, for example, an automatic guided vehicle or an automatic guided robot.

[0017] As shown in the side view of FIG. 1, an autonomous vehicle 10 includes a main body 11, a pair of left and right drive wheels 12, a pair of left and right driven wheels 13, a sensor unit 20, and the like.

[0018] The main body 11 is formed, for example, in the shape of a hollow rectangular parallelepiped. Motors (not shown) that rotate the drive wheels 12 are provided inside the main body 11. The direction of travel (driving state) of the autonomous vehicle 10 is controlled by providing a difference between the rotational speed at which each motor rotates the left drive wheel 12 and the rotational speed at which each motor rotates the right drive wheel 12. The autonomous vehicle 10 is, for example, a front-wheel drive vehicle in which a pair of drive wheels 12 are front wheels and a pair of driven wheels 13 are rear wheels. The pair of left and right driven wheels 13 rotate as the autonomous vehicle 10 travels.

[0019] A sensor unit 20 is attached (provided) to the bottom of the front of the main body 11. As shown in the front view of FIG. 2, the sensor unit 20 includes, for example, 16 magnetic sensors S1 to S16. The magnetic sensors S1 to S16 are arranged horizontally in a direction perpendicular to the straight-ahead direction of the autonomous vehicle 10. That is, the magnetic sensors S1 to S16 are arranged in the left-right direction of the autonomous vehicle 10. The magnetic sensors S1 to S16 are arranged at equal intervals from the right end to the left end of the autonomous vehicle 10. The magnetic sensors S1 to S16 turn on when magnetic tapes M1, M2 (see FIGS. 3 and 4) are present directly below them, and turn off when magnetic tapes M1, M2 are not present directly below them. That is, the magnetic sensors S1 to S16 detect only the magnetic tapes M1, M2 directly below them (the magnetic tapes M1, M2 directly below them).

[0020] 3 is a schematic diagram showing the traveling state of an autonomous vehicle 10 that has entered a crossroads of magnetic tapes M1 and M2 in a straight-ahead direction when instructed to proceed straight. For example, a strip-shaped magnetic tape M1 extending linearly in the straight-ahead direction and a magnetic tape M2 extending linearly in the left-right direction, perpendicular to magnetic tape M1, are attached (provided) on the traveling path of the autonomous vehicle 10. Here, an example will be described in which the autonomous vehicle 10 travels straight along magnetic tape M1 as instructed.

[0021] 4, the left-right positions of magnetic sensors S1 to S16 are referred to as positions 1 to 16, respectively. The left-right center position of magnetic sensors S1 to S16 is midway between position 8 of magnetic sensor S8 and position 9 of magnetic sensor S9, and is position 8.5 (hereinafter also referred to as "center position 8.5"). The left-right center position of autonomous vehicle 10 and the left-right center position 8.5 of sensor unit 20 coincide with each other.

[0022] When the sensor unit 20 is located at position ta in FIG. 3 or position tc in FIG. 3, the magnetic sensors S7 to S10 are turned on, as shown in FIG. 4, for example. Note that ta to tc represent the respective times. In this case, the detection range, which is the range in which the magnetic sensors that detected the magnetic tape M1 are continuous, is the detection range S7 to S10. The center of the detection range S7 to S10 is position 8.5. When the autonomous vehicle 10 is instructed to travel straight, the autonomous vehicle 10 controls each of the drive wheels 12 of the autonomous vehicle 10 so that the center in the lateral direction of the detection ranges S7 to S10 (position 8.5 in FIG. 4) coincides with (approaches) the center in the lateral direction of the autonomous vehicle 10 (center position 8.5). Therefore, when the sensor unit 20 is located at position ta in FIG. 3 or position tc in FIG. 3, the autonomous vehicle 10 travels straight along the magnetic tape M1.

[0023] When the sensor unit 20 is at position tb in FIG. 3 , the magnetic sensors S1 to S16 are turned on, as shown in FIG. 5 . In this case, the detection range, which is the range in which the magnetic sensors that detected the magnetic tapes M1 and M2 are continuous, is the detection range S1 to S16. The center of the detection range S1 to S16 is position 8.5. When the autonomous vehicle 10 is instructed to travel straight, the autonomous vehicle 10 controls each of the drive wheels 12 of the autonomous vehicle 10 so that the center in the left-right direction of the detection ranges S1 to S16 (position 8.5 in FIG. 5 ) coincides with the center in the left-right direction of the autonomous vehicle 10 (center position 8.5). Therefore, even when the sensor unit 20 is at position tb in FIG. 3 , the autonomous vehicle 10 travels straight along the magnetic tape M1.

[0024] 6 is a schematic diagram showing the traveling state of an autonomous vehicle of a comparative example that enters the intersection of magnetic tapes M1 and M2 at an angle when instructed to go straight. Here, an example will be described in which the autonomous vehicle turns right or left along magnetic tape M2.

[0025] When the sensor unit 20 is at position tb in FIG. 6 , for example, as shown in FIG. 7 , the magnetic sensors S7 to S10 and S16 are turned on. In this case, the detection range, which is the range where the magnetic sensors that detected the magnetic tape M1 are continuous, is detection range S7 to S10. Furthermore, the detection range, which is the range where the magnetic sensors that detected the magnetic tape M2 are continuous, is detection range S16. The center of detection range S7 to S10 is position 8.5. The center of detection range S16 is position 16. When the autonomous vehicle of the comparative example is instructed to go straight, the autonomous vehicle controls each drive wheel 12 of the autonomous vehicle 10 so that the center of the entire range S7 to S16, which is the combination of detection ranges S7 to S10, detection range S16, and the ranges S11 to S15 between those detection ranges (position 11.5 in FIG. 7 ), coincides with the center in the left-right direction of the autonomous vehicle 10 (center position 8.5). Therefore, when the sensor unit 20 is at the position tb in Fig. 6, the autonomous vehicle 10 turns left and moves along the magnetic tape M2. When the sensor unit 20 is at the position ta in Fig. 6, the autonomous vehicle 10 turns right and moves along the magnetic tape M2.

[0026] Therefore, in this embodiment, as shown in Figure 8, the autonomous vehicle 10 is equipped with a range acquisition unit 31, a range selection unit 32, a driving control unit 33, an antenna 41, a receiving unit 42, a motor drive unit 50, etc.

[0027] The receiving unit 42 is configured by, for example, a communication module. The receiving unit 42 receives a straight-ahead instruction, a right-turn instruction, a left-turn instruction, etc. from a management device (not shown) or the like via the antenna 41. The receiving unit 42 inputs the received straight-ahead instruction, right-turn instruction, left-turn instruction, etc. to the range selecting unit 32.

[0028] The range acquisition unit 31, range selection unit 32, and driving control unit 33 are configured by a microcomputer 30 including, for example, a CPU, ROM, RAM, an input / output interface, etc. The microcomputer 30 (computer) realizes the functions of the range acquisition unit 31, range selection unit 32, and driving control unit 33, etc., by executing an installed control program. The microcomputer 30 can transmit and receive data and update software (programs) by wireless communication via an antenna 41 and a receiver 42, for example, using OTA (Over The Air) technology.

[0029] The range acquisition unit 31 receives a signal from the sensor unit 20 indicating which magnetic sensors are turned on. Based on the signal received from the sensor unit 20, the range acquisition unit 31 acquires a detection range, which is a range in which the magnetic sensors that detected the magnetic tapes M1 and M2 are continuous. When only one detection range is acquired by the range acquisition unit 31 when the autonomous vehicle 10 is instructed to go straight, the range selection unit 32 selects the only detection range. When multiple detection ranges are acquired by the range acquisition unit 31 when the autonomous vehicle 10 is instructed to go straight, the range selection unit 32 selects the detection range closest to the center in the left-right direction of the autonomous vehicle 10. Furthermore, when the autonomous vehicle 10 is instructed to turn right, the range selection unit 32 selects, as the detection range, one magnetic sensor closest to the right edge of the autonomous vehicle 10 from among the magnetic sensors that are turned on. When the autonomous vehicle 10 is instructed to turn left, the range selection unit 32 selects, as the detection range, one magnetic sensor closest to the left edge of the autonomous vehicle 10 from among the magnetic sensors that are turned on. Thereafter, the instruction to the autonomous vehicle 10 is switched to an instruction to go straight.

[0030] The driving control unit 33 sets the drive amount of each motor so that the center in the left-right direction of one detection range selected by the range selection unit 32 coincides with (approaches) the center in the left-right direction of the autonomous vehicle 10 (center position 8.5). In other words, the driving control unit 33 controls the traveling direction (driving state) of the autonomous vehicle 10.

[0031] The motor drive unit 50 includes, for example, a power supply and a drive circuit (not shown). The motor drive unit 50 drives each motor that rotates each drive wheel 12 based on the drive amount set by the travel control unit 33. This causes the autonomous vehicle 10 to travel along the magnetic tape M1 or M2 in accordance with instructions from a management device or the like.

[0032] 9 is a flowchart showing the control when the autonomous vehicle 10 is instructed to go straight. This series of processes is repeatedly executed by the microcomputer 30 at a predetermined interval when the autonomous vehicle 10 is instructed to go straight by a management device or the like.

[0033] First, it is determined whether two or more detection ranges have been acquired (S10). If it is determined that two or more detection ranges have been acquired (S10: YES), the detection range closest to the center of the autonomous vehicle 10 is selected (S11). On the other hand, if it is determined that two or more detection ranges have not been acquired (S10: NO), the only existing detection range is selected (S12).

[0034] Next, the motor drive unit 50 is controlled based on the selected detection range (S13). Specifically, the drive amount of each motor is set so that the center of the selected detection range in the left-right direction coincides with the center of the autonomous vehicle 10 in the left-right direction (center position 8.5). After that, this series of processes is temporarily ended (END). The motor drive unit 50 then drives each motor based on the set drive amount.

[0035] The process of S10 corresponds to the process performed by the range acquisition unit 31, the processes of S11 and S12 correspond to the process performed by the range selection unit, and the process of S13 corresponds to the process performed by the driving control unit 33.

[0036] FIG. 10 is a schematic diagram showing the positional relationship between the sensor unit 20 of the autonomous vehicle 10 that has entered the intersection of the magnetic tapes M1 and M2 at an angle when instructed to go straight and the intersection.

[0037] When the autonomous vehicle 10 is traveling straight along the magnetic tape M1 and enters the intersection of the magnetic tapes M1 and M2 at a slight angle (time ta), the range acquisition unit 31 may acquire multiple detection ranges (see FIG. 11 ). In this case, of the detection range S1 and the detection ranges S8 to S11 acquired by the range acquisition unit 31, the detection range S8 to S11 closest to the center position 8.5 in the left-right direction of the autonomous vehicle 10 is likely to be the detection range acquired by the range acquisition unit 31 before the autonomous vehicle 10 entered the intersection. Note that the dashed line C indicates the center position 8.5 of the autonomous vehicle 10 and the sensor unit 20.

[0038] When the sensor unit 20 is at position ta in FIG. 10 , for example, as shown in FIG. 11 , the magnetic sensors S1 and S8 to S11 are turned on. In this case, the detection range, which is the range where the magnetic sensors that detected the magnetic tape M2 are continuous, is the detection range S1. The center of the detection range S1 is position 1. The detection range, which is the range where the magnetic sensors that detected the magnetic tape M1 are continuous, is the detection range S8 to S11. The center of the detection ranges S8 to S11 is position 9.5. Therefore, the range selection unit 32 selects the detection range S8 to S11 that is closest to the center position 8.5 in the left-right direction of the autonomous vehicle 10. In other words, when there are multiple detection ranges acquired by the range acquisition unit 31 when the autonomous vehicle 10 is instructed to travel straight, the range selection unit 32 selects one detection range that is predicted to correspond to the magnetic tape M1 extending in the straight-ahead direction of the autonomous vehicle 10.

[0039] Then, the driving control unit 33 controls each drive wheel 12 of the autonomous vehicle 10 so that the center in the left-right direction of the detection ranges S8 to S11 (position 9.5 in FIG. 11 ) coincides with the center position 8.5 in the left-right direction of the autonomous vehicle 10. As a result, the traveling direction of the autonomous vehicle 10 is corrected to the left. As a result, the autonomous vehicle 10 moves straight along the magnetic tape M1.

[0040] Furthermore, when the sensor unit 20 is at position tb in FIG. 10 , for example, as shown in FIG. 12 , magnetic sensors S6 to S9 and S16 are turned on. In this case, the detection range, which is the range where the magnetic sensors that detected the magnetic tape M2 are continuous, is detection range S16. The center of detection range S16 is position 16. The detection range, which is the range where the magnetic sensors that detected the magnetic tape M1 are continuous, is detection ranges S6 to S9. The center of detection ranges S6 to S9 is position 7.5. Therefore, the range selection unit 32 selects detection ranges S6 to S9, which are closest to the lateral center position 8.5 of the autonomous vehicle 10. Then, the driving control unit 33 controls each drive wheel 12 of the autonomous vehicle 10 so that the lateral center of detection ranges S6 to S9 (position 7.5 in FIG. 12 ) coincides with the lateral center position 8.5 of the autonomous vehicle 10. As a result, the traveling direction of the autonomous vehicle 10 is corrected to the right. As a result, the automatic vehicle 10 moves straight along the magnetic tape M1.

[0041] The present embodiment described above in detail has the following advantages.

[0042] The range acquisition unit 31 acquires a detection range, which is the range in which the magnetic sensors that detected the magnetic tapes M1 and M2 are continuous. Therefore, as shown in Fig. 11, when magnetic sensors S1 and S8 to S11 that detected the magnetic tapes M1 and M2 exist and the magnetic sensor S1 and the magnetic sensors S8 to S11 are not continuous (are separated from each other), the magnetic sensor S1 and the magnetic sensors S8 to S11 are acquired as separate detection ranges S1 and S8 to S11.

[0043] 11 , for example, when there are multiple detection ranges acquired by the range acquisition unit 31 when the autonomous vehicle 10 is instructed to travel straight, the range selection unit 32 selects one detection range S8 to S11 that is predicted to correspond to the magnetic tape M1 extending in the straight-ahead direction of the autonomous vehicle 10. Therefore, when another magnetic tape M2 intersects with the magnetic tape M1 extending in the straight-ahead direction, rather than regarding the entire range combining the multiple detection ranges and the ranges between them as the detection range, it is possible to predict and select one detection range S8 to S11 that corresponds to the magnetic tape M1 extending in the straight-ahead direction of the autonomous vehicle 10.

[0044] The driving control unit 33 controls the driving state of the autonomous vehicle 10 so that the left-right center of one detection range selected by the range selection unit 32 approaches the left-right center position 8.5 of the autonomous vehicle 10. Therefore, even on a driving path where another magnetic tape M2 intersects with the magnetic tape M1 extending in the straight-ahead direction, the autonomous vehicle 10 can bring the left-right center of the magnetic tape M1 extending in the straight-ahead direction closer to the left-right center position 8.5 of the autonomous vehicle 10, and can drive straight as instructed.

[0045] Of the multiple detection ranges acquired by the range acquisition unit 31 when the autonomous vehicle 10 has been instructed to travel straight, the range selection unit 32 selects the one detection range that is closest to the center position 8.5 in the left-right direction of the autonomous vehicle 10 as the one detection range predicted to correspond to the magnetic tape M1 extending in the straight-ahead direction. With this configuration, if there are multiple detection ranges acquired by the range acquisition unit 31 when the autonomous vehicle 10 has been instructed to travel straight, it is possible to select with a high probability the one detection range that corresponds to the magnetic tape M1 extending in the straight-ahead direction of the autonomous vehicle 10.

[0046] When the autonomous vehicle 10 is instructed to go straight and there is only one detection range acquired by the range acquisition unit 31, the range selection unit 32 selects the only detection range that exists. With this configuration, it is possible to select a detection range even when there is only one detection range acquired by the range acquisition unit 31 when the autonomous vehicle 10 is instructed to go straight. Therefore, the control by the driving control unit 33 can be performed in the same way whether there are multiple acquired detection ranges or only one acquired detection range.

[0047] The above-mentioned effects can be achieved by having the microcomputer 30 execute the control program applied to the autonomous vehicle 10.

[0048] The above embodiment can be modified as follows: The same parts as those in the above embodiment are denoted by the same reference numerals and the description thereof will be incorporated herein.

[0049] When the autonomous vehicle 10 is traveling straight and enters the intersection of the magnetic tapes M1 and M2 at a slight angle, for example, as shown in FIG. 11 , the range acquisition unit 31 may acquire a new detection range S1 in addition to the detection ranges S8 to S11 acquired by the range acquisition unit 31 before entering the intersection. In this case, the new detection range S1 acquired by the range acquisition unit 31 is likely to be initially narrower than the detection ranges S8 to S11 acquired by the range acquisition unit 31 before entering the intersection. Therefore, of the detection range S1 and the detection ranges S8 to S11 acquired by the range acquisition unit 31, it is relatively likely that the widest detection range S8 to S11 is the detection range acquired by the range acquisition unit 31 before entering the intersection.

[0050] 11 , for example, range selection unit 32 may select, from among multiple detection ranges acquired by range acquisition unit 31 when autonomous vehicle 10 is instructed to travel straight, one detection range S8-S11 that is closest to the center position 8.5 in the left-right direction of autonomous vehicle 10 and has the widest range, as the single detection range predicted to correspond to magnetic tape M1 extending in the straight-ahead direction. With this configuration, when multiple detection ranges are acquired by range acquisition unit 31 when autonomous vehicle 10 is instructed to travel straight, it is possible to select detection range S8-S11 that satisfies two requirements that make it highly likely to be the detection range acquired by range acquisition unit 31 before entering the intersection. Therefore, it is possible to select one detection range that corresponds to magnetic tape M1 extending in the straight-ahead direction of autonomous vehicle 10 with even higher probability.

[0051] 13 , among the multiple detection ranges acquired by range acquisition unit 31 when autonomous vehicle 10 is instructed to travel straight, there may be multiple detection ranges that are the widest. Here, the width of detection ranges S1 to S4 is equal to the width of detection ranges S8 to S11. In this case, range selection unit 32 may select, from the multiple detection ranges acquired by range acquisition unit 31 when autonomous vehicle 10 is instructed to travel straight, one detection range S8 to S11 that is closest to the center position 8.5 in the left-right direction of autonomous vehicle 10, as the one detection range predicted to correspond to magnetic tape M1 extending in the straight-ahead direction.

[0052] 14 , for example, among the multiple detection ranges acquired by range acquisition unit 31 when autonomous vehicle 10 is instructed to travel straight, one detection range S8-S11 closest to central position 8.5 in the left-right direction of autonomous vehicle 10 may differ from one detection range S1-S5 with the widest range. Therefore, if one detection range S8-S11 closest to central position 8.5 in the left-right direction of autonomous vehicle 10 differs from one detection range S1-S5 with the widest range among the multiple detection ranges acquired by range acquisition unit 31 when autonomous vehicle 10 is instructed to travel straight, range selection unit 32 may select one detection range S8-S11 closest to central position 8.5 in the left-right direction of autonomous vehicle 10 as the one detection range predicted to correspond to magnetic tape M1 extending in the straight-line direction. With this configuration, even if the one detection range S8 to S11 closest to the center position 8.5 in the left-right direction of the autonomous vehicle 10 is different from the one detection range S1 to S5 with the widest range, it is possible to select the one detection range S8 to S11 that is more likely to be the detection range acquired by the range acquisition unit 31 before entering the intersection.

[0053] 11 , among the multiple detection ranges acquired by the range acquisition unit 31 when the autonomous vehicle 10 is instructed to travel straight, the detection range S8-S11 closest to the center position 8.5 in the left-right direction of the autonomous vehicle 10 often coincides with the single detection range S8-S11 with the widest range. Furthermore, there is a relatively high possibility that the single detection range S8-S11 with the widest range was acquired by the range acquisition unit 31 before the autonomous vehicle 10 entered the intersection. Therefore, the range selection unit 32 may select the single detection range S8-S11 with the widest range from the detection range S1 and the detection ranges S8-S11 acquired by the range acquisition unit 31 when the autonomous vehicle 10 is instructed to travel straight as the single detection range predicted to correspond to the magnetic tape M1 extending in the straight-ahead direction. Even with this configuration, when the autonomous vehicle 10 is instructed to go straight and there are multiple detection ranges acquired by the range acquisition unit 31, it is possible to select one detection range S8 to S11 corresponding to the magnetic tape M1 extending in the straight-ahead direction of the autonomous vehicle 10 with a relatively high probability.

[0054] 15 is a schematic diagram showing the positional relationship between the sensor unit 20 of the autonomous vehicle 10 that has entered the T-junction marked by magnetic tapes M1 and M2 at an angle when instructed to go straight and the T-junction. In this case, too, when the sensor unit 20 is at position ta in FIG. 15, the magnetic sensors S1, S8 to S11 turn on, as shown in FIG. 11, for example. Therefore, by applying the above-described embodiment and each of the above-described modifications, the autonomous vehicle 10 can go straight as instructed.

[0055] 16 is a schematic diagram showing the positional relationship between the sensor unit 20 of the autonomous vehicle 10 that has entered the diagonal four-way intersection marked by magnetic tapes M1 and M2 at an angle when instructed to go straight and the diagonal four-way intersection. In this case, when the sensor unit 20 is at position ta in FIG. 16, the magnetic sensors S1 to S4 and S8 to S11 turn on, as shown in FIG. 13, for example. Also, when the sensor unit 20 is at position tb in FIG. 16, the magnetic sensors S6 to S9 and S16 turn on, as shown in FIG. 12, for example. Therefore, by applying the above-described embodiment and each of the above-described modifications, the autonomous vehicle 10 can go straight as instructed.

[0056] 17 is a schematic diagram showing the positional relationship between the sensor unit 20 of the autonomous vehicle 10 that has entered the diagonal three-way intersection marked by magnetic tapes M1 and M2 at an angle when instructed to go straight and the diagonal three-way intersection. In this case, too, when the sensor unit 20 is at position ta in FIG. 17, the magnetic sensors S1, S8 to S11 turn on, as shown in FIG. 11, for example. Therefore, by applying the above-described embodiment and each of the above-described modifications, the autonomous vehicle 10 can go straight as instructed.

[0057] 18 is a schematic diagram showing the positional relationship between the sensor unit 20 of the autonomous vehicle 10 that has entered the four-way intersection marked by magnetic tapes M1, M2, and M3 at an angle when instructed to go straight and the intersection. In this case, when the sensor unit 20 is at position ta in FIG. 18, the range selection unit 32 selects the only detection range that exists. The driving control unit 33 then controls each drive wheel 12 of the autonomous vehicle 10 so that the lateral center of the selected detection range coincides with the lateral center position 8.5 of the autonomous vehicle 10. This allows the autonomous vehicle 10 to travel straight along the magnetic tape M1.

[0058] 18, magnetic sensors S1, S6 to S9, and S13 to S16 are turned on, for example, as shown in FIG. 19. In this case, detection ranges S6 to S9 corresponding to magnetic tape M1 extending in the straight-ahead direction of autonomous vehicle 10 are the widest and closest to center position 8.5 in the left-right direction of autonomous vehicle 10 among the multiple detection ranges acquired by range acquisition unit 31. Therefore, by applying the above embodiment and each of the above modifications, autonomous vehicle 10 can travel straight as instructed.

[0059] 20 is a schematic diagram showing the side of a modified example of the autonomous vehicle 10. In this modified example, the autonomous vehicle 10 is equipped with two sensor units 20. One sensor unit 20 is attached to the bottom of the front (one end in the front-to-rear direction) of the main body 11, and the other sensor unit 20 is attached to the bottom of the rear (the other end in the front-to-rear direction) of the main body 11. In this case, the autonomous vehicle 10 detects the magnetic tapes M1 to M3 using the front sensor unit 20 when moving forward, and detects the magnetic tapes M1 to M3 using the rear sensor unit 20 when moving backward. Even with this configuration, it is possible to achieve the same effects as the above embodiment and each of the above modified examples.

[0060] FIG. 21 is a flowchart showing a modified example of control when a straight-ahead instruction is issued. Note that the same processes as those in FIG. 12 are designated with the same step number S, and the description thereof is incorporated herein. In FIG. 21 , if it is determined in S10 that two or more detection ranges have not been acquired (S10: NO), the motor drive unit 50 is controlled based on the only existing detection range (S12A). Specifically, the motor drive unit 50 is controlled so that the center of the only existing detection range coincides with the center of the autonomous vehicle 10. This configuration can also achieve the same effects as those of the above embodiment.

[0061] The driving control unit 33 may set the drive amount of each motor so that the deviation between the left-right center of one detection range selected by the range selection unit 32 and the left-right center of the autonomous vehicle 10 (center position 8.5) is smaller than a predetermined deviation. In other words, the driving control unit 33 may set the drive amount of each motor so that the left-right center of one detection range selected by the range selection unit 32 and the left-right center of the autonomous vehicle 10 approach each other.

[0062] The driven wheels 13 of the autonomous vehicle 10 can also be changed to steered wheels. In this case, the driving control unit 33 may set the amount of steering wheel operation so that the lateral center of one detection range selected by the range selection unit 32 coincides with (approaches) the lateral center of the autonomous vehicle 10 (center position 8.5). The steering wheel may then be operated by an actuator based on the set amount of operation. With this configuration, the driving control unit 33 can also control the traveling direction (driving state) of the autonomous vehicle 10. Note that the driving control unit 33 may set the amount of steering wheel operation so that the deviation between the lateral center of one detection range selected by the range selection unit 32 and the lateral center of the autonomous vehicle 10 is smaller than a predetermined deviation. In other words, the driving control unit 33 may set the amount of steering wheel operation so that the lateral center of one detection range selected by the range selection unit 32 approaches the lateral center of the autonomous vehicle 10.

[0063] The number of magnetic sensors included in the sensor unit 20 may be less than sixteen or more than sixteen.

[0064] The microcomputer 30 (range acquisition unit 31, range selection unit 32, and driving control unit 33) and the method thereof described in the present disclosure may be realized by a special-purpose computer provided by configuring a processor and memory programmed to execute one or more functions (instructions) embodied in a computer program. Alternatively, the microcomputer 30 and the method thereof described in the present disclosure may be realized by a special-purpose computer provided by configuring a processor with one or more dedicated hardware logic circuits. Alternatively, the microcomputer 30 and the method thereof described in the present disclosure may be realized by one or more special-purpose computers configured by combining a processor and memory programmed to execute one or more functions with a processor configured with one or more hardware logic circuits. Furthermore, the computer program may be stored in a computer-readable non-transitory tangible recording medium as instructions executed by a computer.

[0065] The above-described embodiment and each modified example may be combined within a range where they can be combined.

[0066] Although the present disclosure has been described with reference to the embodiments, it is understood that the present disclosure is not limited to the embodiments or structures. The present disclosure also encompasses various modifications and equivalent modifications. In addition, various combinations and forms, including only one element, more than one element, or less than one element, are also within the scope and spirit of the present disclosure.

Claims

1. An autonomous vehicle (10) having a plurality of magnetic sensors (S1 to S16) arranged in the left-right direction, and traveling along a strip-shaped magnetic line provided on a roadway based on the results of detection of the magnetic line by the plurality of magnetic sensors, the autonomous vehicle comprising: a range acquisition unit (31) that acquires a detection range which is a range in which the magnetic sensors that detected the magnetic line are continuous; a range selection unit (32) that selects one of the detection ranges predicted to correspond to the magnetic line extending in the straight-line direction of the autonomous vehicle when there are multiple detection ranges acquired by the range acquisition unit when the autonomous vehicle is instructed to travel straight; and a driving control unit (33) that controls the traveling state of the autonomous vehicle so as to bring the left-right center of the one detection range selected by the range selection unit closer to the left-right center of the autonomous vehicle.

2. The autonomous vehicle described in claim 1, wherein the range selection unit selects, from among the multiple detection ranges acquired by the range acquisition unit when the autonomous vehicle is instructed to go straight, the one detection range that is closest to the center in the left-right direction of the autonomous vehicle as the predicted one detection range.

3. The autonomous vehicle described in claim 2, wherein the range selection unit selects, from among the multiple detection ranges acquired by the range acquisition unit when the autonomous vehicle is instructed to go straight, the one detection range that is closest to the center in the left-right direction of the autonomous vehicle and has the widest range as the predicted one detection range.

4. The autonomous vehicle described in claim 3, wherein, when one of the multiple detection ranges acquired by the range acquisition unit when the autonomous vehicle is instructed to go straight is closest to the center in the horizontal direction of the autonomous vehicle and the one detection range with the widest range is different, the range selection unit selects the one detection range closest to the center in the horizontal direction of the autonomous vehicle as the predicted one detection range.

5. The autonomous vehicle of claim 1, wherein the range selection unit selects the single detection range with the widest range from among the multiple detection ranges acquired by the range acquisition unit when the autonomous vehicle is instructed to go straight as the single predicted detection range.

6. An autonomous vehicle as described in any one of claims 1 to 5, wherein, when there is only one detection range acquired by the range acquisition unit when the autonomous vehicle is instructed to go straight, the range selection unit selects the only existing detection range.

7. A control program applied to an autonomous vehicle (10) that has a plurality of magnetic sensors (S1 to S16) arranged in the left-right direction and travels along a strip-shaped magnetic line provided on a roadway based on the results of detection of the magnetic line by the plurality of magnetic sensors, the control program causing a computer (30) to execute the following processes: acquiring a detection range that is the range in which the magnetic sensors that detected the magnetic line are continuous; when the autonomous vehicle is instructed to travel straight and there are multiple acquired detection ranges, selecting one of the detection ranges that is predicted to correspond to the magnetic line extending in the straight-line direction of the autonomous vehicle; and controlling the traveling state of the autonomous vehicle so as to bring the left-right center of the selected one detection range closer to the left-right center of the autonomous vehicle.

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