Towing system

Abstract

To provide a towing system which can accomplish space-saving for a passage, and which can reduce a possibility such that a constraint occurs on a running route.SOLUTION: A towing system 1 includes: a towing vehicle 2; a towed vehicle 3 that is towed by the towing vehicle 2; and a control unit 6 that controls the operation of the towed vehicle 3. The control unit 6 obtains a towing steering angle that is the steering angle of the towing vehicle 2, and controls a towed steering angle that is the steering angle of the towed vehicle 3 based on the towing steering angle.SELECTED DRAWING: Figure 9

Description

Technical Field

[0001] The present disclosure relates to a towing system.

Background Art

[0002] As a technology related to a towing system for towing a towed vehicle using a towing vehicle, the system described in Patent Document 1 is known. This system searches for the traveling route of the towing vehicle according to whether the towing vehicle is traveling alone or in a towing operation towing a bogie. The traveling route includes a towing traveling route section where the bogie can travel without interfering with obstacles during towing operation, and an independent traveling route section during independent traveling.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In the system described above, when the towing vehicle performs towing operation, in order to prevent the towed vehicle (bogie) from interfering with obstacles, a more circuitous towing traveling route section is searched compared to the independent traveling route section. Therefore, when the towing vehicle towing the towed vehicle travels, a wider passage is required compared to when the towing vehicle travels alone. Thus, in addition to requiring a large space as a passage, there was a possibility that the traveling routes of the towing vehicle and the towed vehicle would be restricted regarding the width of the passage.

[0005] An object of the present disclosure is to provide a towing system that can achieve space saving of the passage and reduce the possibility of restrictions on the traveling route.

Means for Solving the Problems

[0006] A towing system according to one aspect of the present disclosure includes a towing vehicle, a towed vehicle towed by the towing vehicle, and a control unit that controls the operation of the towed vehicle. The control unit acquires a towing steering angle that is the steering angle of the towing vehicle. The control unit controls a towed steering angle that is the steering angle of the towed vehicle based on the towing steering angle.

[0007] In this towing system, the towed steering angle of the towed vehicle towed by the towing vehicle is controlled based on the towing steering angle of the towing vehicle. For example, by controlling the towed steering angle according to the towing steering angle when the towing vehicle travels on a curved passage, the deviation between the travel trajectory of the towed vehicle and the travel trajectory of the towing vehicle can be corrected. Since the towed vehicle can be made to travel along the travel trajectory of the towing vehicle, for example, when the towing vehicle travels on a curved passage, it is not necessary to travel on a wide passage to prevent the towed vehicle from interfering with the wall of the passage. Also, when exploring the travel routes of the towing vehicle and the towed vehicle, the constraints regarding the width of the passage are reduced. From the above, space saving of the passage can be realized, and the possibility of constraints occurring in the travel route can be reduced.

[0008] The control unit may calculate the relative position of the towed vehicle with respect to the towing vehicle. The control unit may control the towed steering angle based on the relative position. In this case, the towed steering angle is controlled in consideration of the relative position of the towed vehicle with respect to the towing vehicle in addition to the towing steering angle. Thereby, the deviation between the travel trajectory of the towed vehicle and the travel trajectory of the towing vehicle can be corrected more accurately. Therefore, space saving of the passage can be realized more reliably, and the possibility of constraints occurring in the travel route can be reduced further.

[0009] The control unit may calculate the relative position based on the preset lengths of the towing vehicle and the towed vehicle in the front-rear direction, and the preset arrangement order of the towed vehicles. In this case, since the relative position of the towed vehicle with respect to the towing vehicle is calculated using the preset values, the relative position can be calculated easily.

[0010] The control unit may calculate a towed direction in which the towed vehicle is towed by the towing vehicle and an orbital direction along the travel orbit of the towing vehicle based on the towing steering angle. The control unit may control the towed steering angle based on the towed direction and the orbital direction. In this case, for example, the towed steering angle of the towed vehicle can be controlled so that the traveling direction of the towed vehicle approaches the orbital direction. Thereby, the towed vehicle can be made to travel more accurately along the travel orbit of the towing vehicle. Therefore, space saving of the passage can be more surely realized, and the possibility that restrictions occur in the travel route can be further reduced.

[0011] The control unit may control the towed steering angle so that the traveling direction of the towed vehicle coincides with the orbital direction. In this case, the towed vehicle can be made to travel more accurately along the travel orbit of the towing vehicle. Therefore, space saving of the passage can be more surely realized, and the possibility that restrictions occur in the travel route can be further reduced.

[0012] The control unit may acquire the speed of the towing vehicle. The control unit may control the towed steering angle based on the speed of the towing vehicle. In this case, the towed steering angle is controlled in consideration of the speed of the towing vehicle in addition to the towing steering angle. Thereby, the deviation between the travel orbit of the towed vehicle and the travel orbit of the towing vehicle can be corrected more accurately. Therefore, space saving of the passage can be more surely realized, and the possibility that restrictions occur in the travel route can be further reduced.

[0013] The towing vehicle may travel by the operation of the driver. In this case, for example, the necessity for the driver to travel the towing vehicle in consideration of the deviation between the travel orbit of the towed vehicle and the travel orbit of the towing vehicle can be reduced. Also, for example, the necessity for the driver to travel the towing vehicle while checking whether the towed vehicle interferes with a wall or the like or the rear can be reduced, so that the driver can travel the towing vehicle and the towed vehicle more safely.

[0014] The towing system may further include a detection unit that detects objects around the towing vehicle. The control unit may calculate the driving trajectory of the towing vehicle based on the detection result of the detection unit. In this case, when there is an obstacle as an object around the towing vehicle, the control unit can calculate a driving trajectory that avoids the obstacle. At this time, the control unit can calculate a driving trajectory on the premise of reducing the deviation between the driving trajectory of the towed vehicle and the driving trajectory of the towing vehicle. Therefore, the control unit can calculate the driving trajectory in a state where the constraints regarding the width of the passage are reduced.

Advantages of the Invention

[0015] According to the present disclosure, space saving of the passage can be realized, and the possibility of restrictions occurring in the driving route can be reduced.

Brief Description of the Drawings

[0016]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Modes for Carrying Out the Invention

[0017] Hereinafter, embodiments of the present disclosure will be described in detail with reference to the drawings. In this specification, based on the perspective of the drawings to be referred to, the clockwise direction may be referred to as the "rotation direction", and the counterclockwise direction may be referred to as the "reverse rotation direction". Also, "match" in this specification does not necessarily mean exact match, and includes being different from each other within a certain range.

[0018] FIG. 1 is a schematic diagram showing a towing system 1 according to this embodiment. The towing system 1 is used, for example, inside a factory. The towing system 1 travels on a passage P provided, for example, inside a factory. The passage P includes a passage that bends in plan view. The passage P may include a straight passage extending in one direction. The towing system 1 transports, for example, luggage. The type of luggage is not particularly limited. The towing system 1 includes a towing vehicle 2, a towed vehicle 3, a coupler 4, a detection unit 5, and a control unit 6.

[0019] The towing vehicle 2 is a vehicle that tows the towed vehicle 3. The towing vehicle 2 is, for example, a towing tractor. The type of the towing vehicle 2 is not particularly limited. In this embodiment, the towing vehicle 2 travels by the operation of a driver. The towing vehicle 2 receives, for example, a steering operation by the driver. The towing vehicle 2 travels in the steering direction at a turning radius corresponding to the steering angle of the received steering operation. The towing vehicle 2 receives, for example, a steering operation by the driver via a steering wheel mounted on the vehicle 2 itself.

[0020] The towing vehicle 2 includes a steering angle sensor (not shown) that detects the rotation amount of a steering shaft connected to the steering wheel. The steering angle sensor transmits the detected rotation amount of the steering shaft to the control unit 6. The towing vehicle 2 includes a speed sensor (not shown) that detects the speed of the vehicle 2 itself. The speed sensor transmits the detected speed of the towing vehicle 2 to the control unit 6. In the following description, each of the towing vehicle 2 and the towed vehicle 3 may be simply referred to as a "vehicle".

[0021] In this embodiment, the towing vehicle 2 has an input unit (not shown) that receives input of information by a user including a driver, and an output unit (not shown) that outputs information to the driver. The towing vehicle 2 has, for example, a display unit such as a touch panel as the input unit and the output unit. The display unit is input with vehicle information to be described later, for example. The display unit displays, for example, the travel route of the towing vehicle 2. The travel route of the towing vehicle 2 is, for example, the order of the passage P that the towing vehicle 2 travels until it reaches the destination. The types of the input unit and the output unit are not particularly limited.

[0022] The towed vehicle 3 is a vehicle towed by the towing vehicle 2. The towed vehicle 3 is, for example, a trolley. The towed vehicle 3 is loaded with, for example, the cargo transported by the towing system 1. In this embodiment, the towing system 1 includes a plurality of towed vehicles 3. The towing system 1 includes two towed vehicles 3. However, the number of towed vehicles 3 is not particularly limited. The two towed vehicles 3 are arranged side by side in the front-rear direction D1 of the towed vehicle 3. The two towed vehicles 3 are connected to each other. The front towed vehicle 3 of the two towed vehicles 3 is connected to the towing vehicle 2. The rear towed vehicle 3 of the two towed vehicles 3 is connected to the front towed vehicle 3.

[0023] The coupler 4 connects vehicles to each other. In this embodiment, the towing system 1 includes the same number of couplers 4 as the towed vehicles 3. One coupler 4 connects the towing vehicle 2 and the above-described front towed vehicle 3. Another coupler 4 different from the one coupler 4 connects the two towed vehicles 3 arranged side by side in the front-rear direction D1. In this embodiment, the coupler 4 is non-expandable and non-contractable in the front-rear direction D1. When the towing vehicle 2 and the towed vehicle 3 are traveling or stopped, the distance between the vehicles is kept substantially constant.

[0024] The detection unit 5 detects objects around the towing vehicle 2. The object is, for example, an obstacle that hinders the travel of the towing vehicle 2 and the towed vehicle 3. The obstacle is, for example, a shelf arranged beside the passage P or a wall of the passage P. In the present embodiment, the detection unit 5 is mounted on the towing vehicle 2. The detection unit 5 is provided at the front part of the towing vehicle 2. However, the position where the detection unit 5 is provided is not particularly limited. The detection unit 5 may be constituted by various sensors such as a laser range finder (LRF), a stereo camera, a time-of-flight (ToF) camera, a radar sensor, an ultrasonic sensor, or a combination of these sensors. Further, the detection unit 5 may be an imaging device such as a camera provided near the ceiling of the passage P on which the towing vehicle 2 and the towed vehicle 3 travel.

[0025] The detection unit 5 generates detection information. In the present embodiment, the detection information indicates the position of the object detected by the detection unit 5. The position of the object includes, for example, the distance from the towing vehicle 2 to the object and the direction in which the object is located as seen from the towing vehicle 2.

[0026] The control unit 6 controls the operation of the towed vehicle 3. The control unit 6 includes an ECU (Electronic Control Unit) that comprehensively manages the towing system 1. The ECU is an electronic control unit having a communication circuit such as a CAN (Controller Area Network) in addition to a CPU (Central Processing Unit), a ROM (Read Only Memory), and a RAM (Random Access Memory). In the ECU, for example, a program stored in the ROM is loaded into the RAM, and various functions are realized by executing the program loaded into the RAM with the CPU. The control unit 6 is, for example, a controller that controls the operation of each part of the towing system 1.

[0027] In this embodiment, the control unit 6 is mounted on the towing vehicle 2. The control unit 6 acquires the steering angle of the towing vehicle 2 (hereinafter sometimes referred to as the "towing steering angle"). Based on the acquired towing steering angle, the control unit 6 controls the steering angle of the towed vehicle 3 (hereinafter sometimes referred to as the "towed steering angle"). The operation of the control unit 6 will be described later.

[0028] Subsequently, the towed vehicle 3 will be described in detail. FIG. 2 is a side view showing the towed vehicle 3 shown in FIG. 1. FIG. 3 is a bottom view showing the towed vehicle 3 shown in FIG. 2. The towed vehicle 3 includes a loading platform 31. On the loading platform 31, the goods transported by the towing system 1 are arranged. The loading platform 31 is supported, for example, on a frame (not shown) provided at the lower part of the towed vehicle 3. The loading platform 31 includes, for example, a flat plate-shaped member extending in both the front-rear direction D1 and the vehicle width direction D2 of the towed vehicle 3.

[0029] As shown in FIG. 3, the towed vehicle 3 includes front wheels 32 and the same number of rotating shafts 32a as the front wheels 32. In this embodiment, the towed vehicle 3 includes a pair of front wheels 32 and a pair of rotating shafts 32a. The pair of front wheels 32 are arranged at the front and below the loading platform 31. The pair of front wheels 32 are spaced apart from each other in the vehicle width direction D2. In this embodiment, the separation width of the pair of front wheels 32 is shorter than the length of the loading platform 31 in the vehicle width direction D2.

[0030] The rotating shaft 32a rotatably supports the front wheel 32 around the rotating shaft 32a. In this embodiment, the rotating shaft 32a extends in the height direction D3 of the towed vehicle 3. The rotating shaft 32a may be attached, for example, to a front wheel support portion (not shown) extending downward from the frame supporting the loading platform 31. The front wheel 32 is attached to the lower end portion of the rotating shaft 32a.

[0031] When the front wheel 32 rotates around the rotation axis 32a, the towed steering angle of the towed vehicle 3 changes. In the present embodiment, the towed steering angle is the angle of the steering direction of the towed vehicle 3 with respect to the front-rear direction D1. For example, with the front-rear direction D1 as the reference (0°), the towed steering angle when the steering direction of the towed vehicle 3 is inclined in the rotational direction may be set as a positive value, and the towed steering angle when the steering direction of the towed vehicle 3 is inclined in the reverse rotational direction may be set as a negative value.

[0032] The towed vehicle 3 includes a drive unit 32b that rotates the front wheel 32 around the rotation axis 32a. In the present embodiment, the towed vehicle 3 includes the same number of drive units 32b as the front wheels 32. The drive unit 32b is attached to the rotation axis 32a, for example. The drive unit 32b is a steering motor, for example.

[0033] The towed vehicle 3 includes a pair of rear wheels 33. The pair of rear wheels 33 are arranged at the rear and below the loading platform 31. The pair of rear wheels 33 are spaced apart from each other in the vehicle width direction D2. In the present embodiment, the separation width of the pair of rear wheels 33 is shorter than the length of the loading platform 31 in the vehicle width direction D2. The rear wheels 33 are provided behind the front wheels 32. The rear wheels 33 may be non-rotatably supported by a rear wheel support portion (not shown) that extends downward from the loading platform 31.

[0034] Subsequently, the operation of the towing system 1 will be described. FIG. 4 is a flowchart showing the operation of the towing system 1 according to the present embodiment. Before starting to travel, the towing system 1 executes step S1. In step S1, the towing system 1 is input with vehicle information. In step S1, the user inputs vehicle information via the input unit of the towing vehicle 2. The control unit 6 acquires the vehicle information input via the input unit. The vehicle information is information related to the vehicle constituting the towing system 1. The vehicle information is used to calculate the relative position of each towed vehicle 3 with respect to the towing vehicle 2.

[0035] The vehicle information includes the lengths of the towing vehicle 2 and the towed vehicle 3 in the longitudinal direction D1, and the arrangement order of the towed vehicles 3. In this embodiment, the vehicle information includes the length of the towing vehicle 2 in the longitudinal direction D1, the lengths of the towed vehicles 3 in the longitudinal direction D1, the length of the coupler 4 in the longitudinal direction D1, and the arrangement order of the towed vehicles 3. The arrangement order of the towed vehicles 3 includes, for example, the number of towed vehicles 3 towed by the towing vehicle 2 and the order in which each towed vehicle 3 is connected starting from the towing vehicle 2. For example, the connection order of the towed vehicle 3 connected to the towing vehicle 2 is the first. The connection order of the towed vehicle 3 connected to the first towed vehicle 3 is the second.

[0036] Instead of the length of the towing vehicle 2 in the longitudinal direction D1, the vehicle information may include the information necessary to specify the length of the towing vehicle 2 in the longitudinal direction D1. The vehicle information may include, for example, an ID that uniquely identifies the towing vehicle 2. In this case, it is sufficient if the control unit 6 has a preset length of the towing vehicle 2 in the longitudinal direction D1 associated with the ID of the towing vehicle 2. The control unit 6 identifies the towing vehicle 2 that constitutes the towing system 1 from the ID of the towing vehicle 2 input via the input unit of the towing vehicle 2. The control unit 6 may obtain the length of the identified towing vehicle 2 in the longitudinal direction D1 based on the preset length of the towing vehicle 2 in the longitudinal direction D1.

[0037] Instead of the lengths of the towed vehicles 3 in the longitudinal direction D1, the vehicle information may include the information necessary to specify the lengths of the towed vehicles 3 in the longitudinal direction D1. The vehicle information may include, for example, an ID that uniquely identifies the towed vehicle 3. In this case, it is sufficient if the control unit 6 has a preset length of the towed vehicle 3 in the longitudinal direction D1 associated with the ID of the towed vehicle 3. The control unit 6 identifies the towed vehicles 3 that constitute the towing system 1 from the IDs of the towed vehicles 3 input via the input unit of the towing vehicle 2. The control unit 6 may obtain the lengths of the identified towed vehicles 3 in the longitudinal direction D1 based on the preset lengths of the towed vehicles 3 in the longitudinal direction D1.

[0038] Furthermore, when the control unit 6 has a preset length of the coupler 4 in the longitudinal direction D1, the vehicle information may not include the length of the coupler 4 in the longitudinal direction D1.

[0039] Subsequently, the towing system 1 starts running (step S2). In step S2, the towing vehicle 2 runs by the operation of the driver. In step S2, the driver performs a steering operation via the steering wheel of the towing vehicle 2, and runs the towing vehicle 2 in the steering direction at a turning radius corresponding to the steering angle of the steering operation.

[0040] Subsequently, the control unit 6 acquires the towing steering angle (step S3). In step S3, the control unit 6 receives the rotation amount of the steering shaft from the steering angle sensor of the towing vehicle 2. The control unit 6 calculates the towing steering angle from the received rotation amount. The control unit 6 acquires the calculated towing steering angle.

[0041] Subsequently, the control unit 6 calculates the relative position of each towed vehicle 3 with respect to the towing vehicle 2 (step S4). In step S4, the control unit 6 calculates the relative position based on the vehicle information acquired in step S1. In the present embodiment, the control unit 6 calculates the distance along the front-rear direction D1 from the towing vehicle 2 to the towed vehicle 3 as the relative position. The control unit 6 calculates the distance along the front-rear direction D1 from the rear end of the towing vehicle 2 to the rear end of the towed vehicle 3 as the relative position. The control unit 6 calculates the relative position for each of the plurality of towed vehicles 3.

[0042] Subsequently, the control unit 6 acquires the speed of the towing vehicle 2 (step S5). In step S5, the control unit 6 receives and acquires the speed of the towing vehicle 2 from the speed sensor of the towing vehicle 2.

[0043] Subsequently, the control unit 6 calculates the towed direction A1 and the track direction A2 (see FIG. 5) (step S6). FIG. 5 is a diagram for explaining an example of the process of determining the steering direction A3. The towed direction A1 is the direction in which the towed vehicle 3 is towed by the towing vehicle 2. The track direction A2 is the direction along the traveling track R1 of the towing vehicle 2. The "traveling track" is, for example, a track through which the center portion in the vehicle width direction D2 at the front end of the vehicle passes when the vehicle travels. In FIG. 5, the traveling track R1 of the towing vehicle 2 is shown by a thin solid line. Also, the towed direction A1 is shown by a thick solid line arrow, the track direction A2 is shown by a broken line arrow, and the steering direction A3 of the towed vehicle 3 is shown by a thin solid line arrow.

[0044] In step S6, the control unit 6 calculates the towed direction A1 based on the tow steering angle acquired in step S3. In the present embodiment, the control unit 6 calculates the towed direction A1 based on the tow steering angle acquired in step S3 and the relative position calculated in step S4. Further, the control unit 6 calculates the track direction A2 based on the tow steering angle acquired in step S3. More specifically, the control unit 6 calculates the travel track R1 traveled by the towing vehicle 2 based on the acquired tow steering angle. The control unit 6 calculates the direction along the calculated travel track R1 as the track direction A2.

[0045] Subsequently, the control unit 6 controls the towed steering angle based on the tow steering angle acquired in step S3 (step S7). In the present embodiment, the control unit 6 controls the towed steering angle based on the speed of the towing vehicle 2 acquired in step S5 and the towed direction A1 and the track direction A2 calculated in step S6. The control unit 6 controls the towed steering angle for each of the plurality of towed vehicles 3.

[0046] In step S7, the control unit 6 controls the towed steering angle so that the traveling direction of the towed vehicle 3 coincides with the track direction A2 calculated in step S6. First, the control unit 6 calculates the traveling direction of the towed vehicle 3 for each steering direction A3 while changing the steering direction A3 based on the towed direction A1 calculated in step S6 and the speed of the towing vehicle 2 acquired in step S5. The control unit 6 specifies the steering direction A3 in which the calculated traveling direction coincides with the track direction A2 calculated in step S6. The control unit 6 sets the steering angle corresponding to the specified steering direction A3 as the towed steering angle.

[0047] The processing of the control unit 6 in steps S6 and S7 is not limited to the processing described above. The control unit 6 may control the towed steering angle using known means so that the traveling direction of the towed vehicle 3 coincides with the track direction A2.

[0048] The control unit 6 rotates the front wheels 32 of the towed vehicle 3 around the rotation axis 32a by driving the drive unit 32b of the towed vehicle 3. The control unit 6 controls the amount of drive of the drive unit 32b to control the towed steering angle of the towed vehicle 3.

[0049] Subsequently, an example of the operation of outputting the travel trajectory R1 of the towing vehicle 2 will be described. FIG. 6 is a flowchart showing an example of the operation for outputting the travel trajectory R1 of the towing vehicle 2. In the present embodiment, the towing system 1 performs the operation shown in FIG. 6 during travel. However, the timing at which the towing system 1 performs the operation shown in FIG. 6 can be changed as appropriate.

[0050] First, the detection unit 5 detects an object around the towing vehicle 2 (step S11). In step S11, the detection unit 5 detects, as the object, an obstacle that obstructs the travel of the towing vehicle 2 and the towed vehicle 3. The detection unit 5 generates detection information indicating the position of the detected object.

[0051] Subsequently, the control unit 6 calculates the travel trajectory R1 of the towing vehicle 2 based on the detection result in step S11 (step S12). In the present embodiment, in step S12, the control unit 6 calculates the travel trajectory R1 of the towing vehicle 2 so that the object does not interfere with the towing vehicle 2 and the towed vehicle 3 based on the position of the object detected in step S11. The control unit 6 may calculate the travel trajectory R1 of the towing vehicle 2 using known means.

[0052] Subsequently, the control unit 6 outputs the travel trajectory R1 calculated in step S12 (step S13). In step S13, the control unit 6 outputs the travel trajectory R1 to, for example, the driver. The control unit 6, for example, displays the travel trajectory R1 on the display unit of the towing vehicle 2 as an output of the travel trajectory R1. The control unit 6 may, for example, display the travel trajectory R1 calculated in step S12 as a line on a map including a preset passage P in the factory. The driver drives the towing vehicle 2 along the travel trajectory R1 output in step S13.

[0053] Through the above steps, the towing system 1 completes a series of operations. However, the order and content of each step of the operation of the towing system 1 are not limited to the order and content described above.

[0054] Subsequently, while explaining the towing system 100 according to the comparative example with reference to FIGS. 7 and 8, the problems of the present disclosure will be explained. FIG. 7 is a top view showing the towing system 100 according to the comparative example. FIG. 8 is a diagram for explaining the problems of the present disclosure. The towing system 100 is different from the towing system 1 in that it includes a towed vehicle 300 instead of the towed vehicle 3. The towed vehicle 300 is different from the towed vehicle 3 in that it does not include a drive unit 32b.

[0055] Since the towed vehicle 300 does not include a drive unit 32b, it travels in a straight line. In other words, the towed vehicle 300 travels while being towed by the towing vehicle 2 without receiving control of the towed steering angle by the control unit 6. In this case, the front wheels 32 rotate around the rotation axis 32a so that the steering direction A3 of the towed vehicle 300 approaches the towed direction A1. Therefore, as shown in FIG. 7, when the towing vehicle 2 travels along the curved travel track R1, the travel track R200 of the towed vehicle 300 cuts inside the travel track R1.

[0056] As shown in FIG. 8, when the towing vehicle 2 travels on the bent passage P, in order to prevent the towed vehicle 300 from interfering with an obstacle P1 (for example, a shelf), the towing vehicle 2 needs to travel along a larger turning travel track R3 compared to the travel track R1 when traveling alone. Note that "traveling alone" means that the towing vehicle 2 travels without towing the towed vehicle 300. Therefore, when the towing vehicle 2 travels in a state of towing the towed vehicle 300, a wider passage P is required compared to the case where the towing vehicle 2 travels alone. Therefore, in addition to requiring a large space as the passage P, there may be restrictions on the width of the passage P in the travel routes of the towing vehicle 2 and the towed vehicle 300.

[0057] In addition, when the towing vehicle 2 travels by the operation of the driver, there is a need for the driver to drive the towing vehicle 2 in consideration of the deviation between the traveling trajectory R200 of the towed vehicle 300 and the traveling trajectory R1 of the towing vehicle 2. As a result, the working efficiency may decrease. Further, for example, there is a need to drive the towing vehicle 2 while checking whether the towed vehicle 300 interferes with the wall of the passage P or the like at the rear, and there is room for improvement in safety.

[0058] Based on the above-described comparative examples and problems, the operation and effect of the towing system 1 will be described. In the towing system 1, based on the towing steering angle of the towing vehicle 2, the towed steering angle of the towed vehicle 3 towed by the towing vehicle 2 is controlled. For example, when the towing vehicle 2 travels on a bent passage P, by controlling the towed steering angle according to the towing steering angle, as shown in FIG. 9, the deviation between the traveling trajectory R2 of the towed vehicle 3 and the traveling trajectory R1 of the towing vehicle 2 can be corrected. Since the towed vehicle 3 can be made to travel along the traveling trajectory R1 of the towing vehicle 2, for example, even when the towing vehicle 2 travels on a bent passage P, it is not necessary to travel on a wide passage P in order to prevent the towed vehicle 3 from interfering with the wall of the passage P or the like. Since it is not necessary to travel on a wide passage P, when the towing system 1 travels in the factory, space saving in the factory can be realized. In addition, when searching for the traveling routes of the towing vehicle 2 and the towed vehicle 3, the constraints regarding the width of the passage P are reduced. From the above, space saving of the passage P can be realized, and the possibility of constraints occurring in the traveling route can be reduced.

[0059] The control unit 6 calculates the relative position of the towed vehicle 3 with respect to the towing vehicle 2. The control unit 6 controls the towed steering angle based on the relative position. Thereby, the towed steering angle is controlled in consideration of the relative position of the towed vehicle 3 with respect to the towing vehicle 2 in addition to the towing steering angle. Thereby, the deviation between the traveling trajectory R2 of the towed vehicle 3 and the traveling trajectory R1 of the towing vehicle 2 can be corrected more accurately. Therefore, space saving of the passage P can be realized more reliably, and the possibility of constraints occurring in the traveling route can be reduced more.

[0060] The control unit 6 calculates the relative position based on the preset lengths of the towing vehicle 2 and the towed vehicle 3 in the front-rear direction D1 and the preset arrangement order of the towed vehicles 3. Thereby, since the relative position of the towed vehicle 3 with respect to the towing vehicle 2 is calculated using the preset values, the relative position can be easily calculated.

[0061] The control unit 6 calculates a towed direction A1 in which the towed vehicle 3 is towed by the towing vehicle 2 and a track direction A2 along the travel track R1 of the towing vehicle 2 based on the towing steering angle. The control unit 6 controls the towed steering angle based on the towed direction A1 and the track direction A2. Thereby, for example, since the towed steering angle of the towed vehicle 3 can be controlled so that the traveling direction of the towed vehicle 3 approaches the track direction A2, the towed vehicle 3 can be made to travel more accurately along the travel track R1 of the towing vehicle 2. Therefore, space saving of the passage P can be more reliably realized, and the possibility of restrictions occurring in the travel route can be further reduced.

[0062] The control unit 6 controls the towed steering angle so that the traveling direction of the towed vehicle 3 coincides with the track direction A2. Thereby, the towed vehicle 3 can be made to travel more accurately along the travel track R1 of the towing vehicle 2. Therefore, space saving of the passage P can be more reliably realized, and the possibility of restrictions occurring in the travel route can be further reduced.

[0063] The control unit 6 acquires the speed of the towing vehicle 2. The control unit 6 controls the towed steering angle based on the speed of the towing vehicle 2. Thereby, the towed steering angle is controlled in consideration of the speed of the towing vehicle 2 in addition to the towing steering angle. Thereby, the deviation between the travel track R2 of the towed vehicle 3 and the travel track R1 of the towing vehicle 2 can be corrected more accurately. Therefore, space saving of the passage P can be more reliably realized, and the possibility of restrictions occurring in the travel route can be further reduced.

[0064] The towing vehicle 2 travels by the operation of the driver. For example, the driver can reduce the need to drive the towing vehicle 2 considering the deviation between the travel track R2 of the towed vehicle 3 and the travel track R1 of the towing vehicle 2. Also, for example, since the need to drive the towing vehicle 2 while checking whether the towed vehicle 3 interferes with a wall or the like can be reduced, the driver can drive the towing vehicle 2 and the towed vehicle 3 more safely.

[0065] The towing system 1 further includes a detection unit 5 that detects objects around the towing vehicle 2. The control unit 6 calculates the travel track R1 of the towing vehicle 2 based on the detection result of the detection unit 5. Thereby, when an obstacle P1 exists as an object around the towing vehicle 2, the control unit 6 can calculate a travel track R1 that avoids the obstacle P1. At this time, the control unit 6 can calculate a travel track R1 on the premise of reducing the deviation between the travel track R2 of the towed vehicle 3 and the travel track R1 of the towing vehicle 2. Therefore, the control unit 6 can calculate the travel track R1 in a state where the constraints regarding the width of the passage P are reduced.

[0066] The present disclosure is not limited to the above-described embodiment. In the above-described embodiment, an example in which the towing vehicle 2 travels by the operation of the driver has been described. However, the towing vehicle 2 may travel under the control of the control unit 6. In this case, the control unit 6 may drive the towing vehicle 2 along a preset travel track R1. The control unit 6 may calculate the travel track R1 of the towing vehicle 2 by executing a predetermined process and drive the towing vehicle 2 along the calculated travel track R1. Even in this case, it is not necessary for the towing vehicle 2 and the towed vehicle 3 to travel on a wide passage P, and the constraints regarding the width of the passage P are reduced in searching for the travel route. As a result, the need to search for a travel route including a wide passage P and the need to search for the travel track R1 of the towing vehicle 2 so that the towed vehicle 3 does not interfere with the obstacle P1 can be reduced. Therefore, the search for the travel route of the towing vehicle 2 can be simplified.

[0067] In the above-described embodiment, an example in which the control unit 6 is mounted on the towing vehicle 2 has been described. However, the control unit 6 may be mounted on the towed vehicle 3. The control unit 6 may be provided outside the towing vehicle 2 and the towed vehicle 3.

[0068] In the above embodiment, an example has been described in which the control unit 6 calculates the relative position of the towed vehicle 3 with respect to the towing vehicle 2 based on the preset lengths of the towing vehicle 2 and the towed vehicle 3 in the front-rear direction D1, and the preset arrangement order of the towed vehicles 3. However, the method by which the control unit 6 calculates the relative position of the towed vehicle 3 is not limited to the method described above. For example, the towing vehicle 2 may include a distance measuring sensor that detects the distance from the own vehicle 2 to the towed vehicle 3. The control unit 6 may calculate the distance detected by the distance measuring sensor of the towing vehicle 2 as the relative position. In this case, the control unit 6 may not preset the vehicle information. The towing system 1 may omit the execution of step S1.

[0069] In the above embodiment, an example has been described in which the control unit 6 calculates the distance along the front-rear direction D1 from the towing vehicle 2 to the towed vehicle 3 as the relative position. However, the control unit 6 may calculate the distance from the towing vehicle 2 to the towed vehicle 3 and the direction of the towed vehicle 3 as seen from the towing vehicle 2 as the relative position.

[0070] In the above embodiment, an example has been described in which the control unit 6 acquires the speed of the towing vehicle 2 and controls the towed steering angle based on the acquired speed. However, the control unit 6 may not acquire the speed of the towing vehicle 2.

[0071] The towing system 1 may include towed vehicles other than the towed vehicle 3. The towed vehicle may be a vehicle that does not include the drive unit 32b. Even in this case, by controlling the towed steering angle of the towed vehicle 3 based on the towing steering angle of the towing vehicle 2, it is possible to bring the traveling trajectory of the towed vehicle other than the towed vehicle 3 closer to the traveling trajectory R1 of the towing vehicle 2.

[0072] In the above-described embodiment, an example in which the front wheels 32 of the towed vehicle 3 are rotatable around the rotation axis 32a and the rear wheels 33 of the towed vehicle 3 are non-rotatable around the height direction D3 has been described. However, the rear wheels 33 of the towed vehicle 3 may be rotatable around the height direction D3. In the above-described embodiment, an example in which the towed vehicle 3 includes a pair of front wheels 32 and a pair of rear wheels 33 has been described. However, the towed vehicle 3 may include one or three or more front wheels 32 and one or three or more rear wheels 33. The control unit 6 may be input with the position and number of wheels rotatable around the height direction D3 as vehicle information. The control unit 6 may control the towed steering angle based on the position and number of wheels rotatable around the height direction D3 in addition to the towing steering angle.

[0073] [Embodiment 1] A towing vehicle, A towed vehicle towed by the towing vehicle, And a control unit that controls the operation of the towed vehicle. The control unit Obtains a towing steering angle that is the steering angle of the towing vehicle, And controls a towed steering angle that is the steering angle of the towed vehicle based on the towing steering angle. A towing system. [Embodiment 2] The control unit Calculates the relative position of the towed vehicle with respect to the towing vehicle, And controls the towed steering angle based on the relative position. The towing system according to Embodiment 1. [Embodiment 3] The control unit calculates the relative position based on the preset lengths of the towing vehicle and the towed vehicle in the front-rear direction and the preset arrangement order of the towed vehicles. The towing system according to Embodiment 2. [Embodiment 4] The control unit Based on the towing steering angle, calculates a towed direction in which the towed vehicle is towed by the towing vehicle and an orbit direction along the traveling orbit of the towing vehicle, And controls the towed steering angle based on the towed direction and the orbit direction. The towing system according to any one of Forms 1 to 3. [Form 5] The control unit controls the steered angle of the towed vehicle so as to align the steering direction of the towed vehicle with the track direction. The towing system according to Form 4. [Form 6] The control unit acquires the speed of the towing vehicle, and controls the steered angle of the towed vehicle based on the speed of the towing vehicle. The towing system according to any one of Forms 1 to 5. [Form 7] The towing vehicle travels by the operation of a driver. The towing system according to any one of Forms 1 to 6. [Form 8] The towing system further includes a detection unit that detects an object around the towing vehicle. The control unit calculates the travel track of the towing vehicle based on the detection result of the detection unit. The towing system according to any one of Forms 1 to 7.

Explanation of Signs

[0074] 1, 100... Towing system, 2... Towing vehicle, 3, 300... Towed vehicle, 5... Detection unit, 6... Control unit, A1... Towed direction, A2... Track direction, A3... Steering direction, D1... Front-rear direction, R1... Travel track.

Claims

1. A towing vehicle, a towed vehicle towed by the towing vehicle, and a control unit for controlling the operation of the towed vehicle, comprising: The control unit, acquires a towing steering angle which is a steering angle of the towing vehicle, and controls a towed steering angle which is a steering angle of the towed vehicle based on the towing steering angle. A towing system.

2. The control unit, calculates a relative position of the towed vehicle with respect to the towing vehicle, and controls the towed steering angle based on the relative position. The towing system according to Claim 1.

3. The control unit calculates the relative position based on a preset length in the front-rear direction of the towing vehicle and the towed vehicle, and a preset arrangement order of the towed vehicles. The towing system according to Claim 2.

4. The control unit, calculates a towed direction in which the towed vehicle is towed by the towing vehicle and an orbital direction along a travel orbit of the towing vehicle based on the towing steering angle, and controls the towed steering angle based on the towed direction and the orbital direction. The towing system according to any one of Claims 1 to 3.

5. The control unit controls the towed steering angle so that a steering direction of the towed vehicle coincides with the orbital direction. The towing system according to Claim 4.

6. The control unit, acquires a speed of the towing vehicle, and controls the towed steering angle based on the speed of the towing vehicle. The towing system according to any one of Claims 1 to 3.

7. The towing vehicle travels by an operation of a driver. The towing system according to any one of Claims 1 to 3.

8. The towing system further includes a detection unit for detecting an object around the towing vehicle, and the control unit calculates a travel orbit of the towing vehicle based on a detection result of the detection unit. The towing system according to any one of Claims 1 to 3.

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