Unmanned transport vehicle

Abstract

The invention provides an unmanned transport vehicle capable of suppressing posture change of a vehicle body when switching between a normal travel mode and a transverse travel mode. An unmanned transport vehicle capable of switching between a normal travel mode in which straight travel can be performed in the front-rear direction and a horizontal travel mode in which straight travel can be performed in the left-right direction comprises: a plurality of wheels (a left front wheel, a right front wheel, a left rear wheel, and a right rear wheel); a drive unit that restricts rotation of the left front wheel and the left rear wheel; a steering device that changes the orientation of the plurality of wheels; and a control device. The control device controls the steering device so as to change the orientation of the left front wheel and the right rear wheel after changing the orientation of the left front wheel and the right rear wheel when switching between the normal travel mode and the transverse travel mode, and further controls the drive unit so as to restrict the rotation of the left rear wheel when changing the orientation of the left front wheel and the right rear wheel. The rotation of the left front wheel is restricted when the orientation of the right front wheel and the left rear wheel is changed.

Description

Technical Field

[0001] The present invention relates to an automated guided vehicle capable of switching between a normal traveling mode and a lateral traveling mode. Background Art

[0002] An automated guided vehicle is known that can switch between a normal traveling mode in which it can travel straight in the front-rear direction and a lateral traveling mode in which it can travel straight in the left-right direction (for example, refer to Patent Document 1). The switching between the normal traveling mode and the lateral traveling mode is performed by changing the orientation of the wheels.

[0003] Figure 8 of (A) to Figure 8 Examples (C) illustrate an existing automated guided vehicle including a vehicle body 102 and a plurality of wheels 103. As Figure 8 shown in (A), the wheels 103 of the automated guided vehicle in the normal traveling mode face the front-rear direction X. When switching from the normal traveling mode to the lateral traveling mode, as Figure 8 shown in (B), a steering device (not shown) changes the orientation of the wheels 103 so that the wheels 103 face the left-right direction Y. At this time, depending on the uneven state of the road surface or the grounding state of the wheels 103, as Figure 8 shown in (C), there is a problem that the posture of the vehicle body 102 changes. Therefore, as described in Patent Document 1, the posture change of the vehicle body is corrected during traveling.

[0004] However, when correcting the posture change of the vehicle body during traveling, there is a problem that the posture change of the vehicle body cannot be sufficiently corrected when the distance from the start of traveling to the stop is short when switching between the normal traveling mode and the lateral traveling mode.

[0005] [Prior Art Documents]

[0006] [Patent Documents]

[0007] [Patent Document 1] Japanese Patent Application Laid-Open No. 2007-328442 Summary of the Invention

[0008] [Problems to be Solved by the Invention]

[0009] In view of the above circumstances, the present invention aims to provide an automated guided vehicle that can suppress the posture change of the vehicle body when switching between the normal traveling mode and the lateral traveling mode.

[0010] [Means for Solving the Problems]

[0011] In order to solve the above problems, the automated guided vehicle of the present invention can switch between a normal driving mode in which it can drive straight in the front-rear direction and a lateral driving mode in which it can drive straight in the left-right direction. The automated guided vehicle includes: a plurality of wheels arranged at intervals in the front-rear direction and the left-right direction; a braking device that restricts the rotation of at least two of the wheels; a steering device that changes the orientation of the plurality of wheels; and a control device that controls the braking device and the steering device. The control device designates a set of the plurality of wheels as primary steering wheels and another set of the wheels as secondary steering wheels. When switching between the normal driving mode and the lateral driving mode, the control device controls the steering device to change the orientation of the secondary steering wheels after changing the orientation of the primary steering wheels, and then controls the braking device to restrict the rotation of at least one of the wheels included in the secondary steering wheels when changing the orientation of the primary steering wheels, and to restrict the rotation of at least one of the wheels included in the primary steering wheels when changing the orientation of the secondary steering wheels.

[0012] In addition, it is preferable that the wheels include a front wheel and a rear wheel arranged at intervals in the front-rear direction. The front wheel includes a left front wheel and a right front wheel arranged at intervals in the left-right direction, and the rear wheel includes a left rear wheel and a right rear wheel arranged at intervals in the left-right direction. Among a set of the left front wheel and the right rear wheel and a set of the right front wheel and the left rear wheel, one set is the primary steering wheels and the other set is the secondary steering wheels.

[0013] In addition, it is preferable that the rotation of any one of a set of the left front wheel and the left rear wheel, a set of the right front wheel and the right rear wheel, a set of the left front wheel and the right front wheel, and a set of the left rear wheel and the right rear wheel is restricted by the braking device.

[0014] In addition, it is preferable that the wheels include a front wheel and a rear wheel arranged at intervals in the front-rear direction. The front wheel includes a left front wheel and a right front wheel arranged at intervals in the left-right direction, and the rear wheel includes a left rear wheel and a right rear wheel arranged at intervals in the left-right direction. A set of the left front wheel and the left rear wheel, a set of the right front wheel and the right rear wheel, a set of the left front wheel and the right front wheel, or a set of the left rear wheel and the right rear wheel is the primary steering wheels.

[0015] In addition, it is preferable that the rotation of one of a set of the left front wheel and the right rear wheel and a set of the right front wheel and the left rear wheel is restricted by the braking device.

[0016] [Advantages of the Invention]

[0017] According to the present invention, an automated guided vehicle that can suppress changes in the posture of the vehicle body when switching between the normal driving mode and the lateral driving mode can be provided. Description of the Drawings

[0018] Figure 1 is a schematic structural diagram of an automated guided vehicle according to an embodiment of the present invention.

[0019] Figure 2 is a block diagram showing the schematic structure of the automated guided vehicle according to the embodiment.

[0020] Figure 3 is a flowchart showing the process of the driving mode switching process according to the embodiment.

[0021] Figure 4 of (A) to Figure 4 of (D) is a schematic diagram for explaining the operation of the automated guided vehicle according to the embodiment.

[0022] Figure 5 of (A) to Figure 5 of (D) is a schematic diagram for explaining the operation of the automated guided vehicle according to a modification example.

[0023] Figure 6 of (A) to Figure 6 of (D) is a schematic diagram for explaining the operation of the automated guided vehicle according to a modification example.

[0024] Figure 7 of (A) to Figure 7 of (D) is a schematic diagram for explaining the operation of the automated guided vehicle according to a modification example.

[0025] Figure 8 of (A) to Figure 8 of (C) is a schematic diagram for explaining the operation of the automated guided vehicle according to an existing example.

[0026] [Description of Reference Numerals]

[0027] 1: Automated guided vehicle

[0028] 2: Vehicle body

[0029] 3F: Front wheel (wheel)

[0030] 3R: Rear wheel (wheel)

[0031] 3FL: Left front wheel

[0032] 3FR: Right front wheel

[0033] 3RL: Left rear wheel

[0034] 3RR: Right rear wheel

[0035] 6: Drive unit (brake device)

[0036] 7: Steering device

[0037] 8: Control device

[0038] X: Front - rear direction

[0039] Y: Left - right direction Detailed implementation mode

[0040] Refer to Figures 1 to 4 (A) - Figure 4 of (D) to describe an embodiment of the present invention.

[0041] As Figure 1 shown, the automated guided vehicle 1 of this embodiment includes a vehicle body 2, front wheels 3F and rear wheels 3R as wheels, induction sensors 4F and 4R for normal driving mode, and induction sensors 5L and 5R for transverse driving mode. The automated guided vehicle 1 switches between a normal driving mode in which it can travel straight in the front - rear direction X and a transverse mode in which it can travel straight in the left - right direction Y.

[0042] A table (both not shown) including a transfer device is provided on the vehicle body 2. The transfer device includes, for example, a belt conveyor or a roller conveyor driven by a loading and unloading motor, and is controlled by a control device 8 described later (refer to Figure 2 ).

[0043] The front wheels 3F and the rear wheels 3R are arranged at intervals in the front - rear direction X. The front wheels 3F include a left front wheel 3FL and a right front wheel 3FR arranged at intervals in the left - right direction Y. The rear wheels 3R include a left rear wheel 3RL and a right rear wheel 3RR arranged at intervals in the left - right direction Y. In this embodiment, the left front wheel 3FL and the left rear wheel 3RL are driving wheels that rotate by being transmitted the driving force for the travel of the automated guided vehicle 1, and the right front wheel 3FR and the right rear wheel 3RR are driven wheels that rotate as the left front wheel 3FL and the left rear wheel 3RL rotate. When the left front wheel 3FL, the right front wheel 3FR, the left rear wheel 3RL, and the right rear wheel 3RR (hereinafter collectively referred to as "four wheels") face the front - rear direction X, the automated guided vehicle 1 is in the normal driving mode, and when the four wheels face the left - right direction Y, the automated guided vehicle 1 is in the transverse driving mode. Each of the four wheels is configured to be rotatable about an axis A orthogonal to the front - rear direction X and the left - right direction Y.

[0044] The induction sensors 4F and 4R are arranged at intervals in the front - rear direction X. When the automated guided vehicle 1 travels in the normal driving mode, the induction sensors 4F and 4R detect an induction line LX provided on the road surface extending in the front - rear direction X, and output the detection result to a control device 8 described later (refer to Figure 2 ).

[0045] The induction sensors 5L and 5R are arranged at intervals in the left-right direction Y. When the automated guided vehicle 1 travels in the lateral mode, the induction sensors 5L and 5R detect the induction line LY provided on the road surface extending in the left-right direction Y, and output the detection result to the control device 8 described later (refer to Figure 2 ).

[0046] In addition, as Figure 2 shown, the automated guided vehicle 1 includes a drive unit 6FL, a drive unit 6RL (hereinafter collectively referred to as "drive unit 6"), a steering device 7FL, a steering device 7FR, a steering device 7RL, and a steering device 7RR (hereinafter collectively referred to as "steering device 7"), and a control device 8.

[0047] The drive unit 6 includes a traveling motor with a brake. The drive unit 6 functions as a driving device for driving the drive wheels by operating the traveling motor, and also functions as a braking device for restricting the rotation of the drive wheels by operating the brake of the traveling motor. The drive unit 6FL is the driving device and braking device for the left front wheel 3FL, and the drive unit 6RL is the driving device and braking device for the left rear wheel 3RL.

[0048] The steering device 7 includes a steering motor with a potentiometer. The steering device 7 changes the orientation (steering angle) of the wheel by rotating the wheel around the axis A (refer to Figure 1 ). The steering device 7FL changes the orientation of the left front wheel 3FL, the steering device 7FR changes the orientation of the right front wheel 3FR, the steering device 7RL changes the orientation of the left rear wheel 3RL, and the steering device 7RR changes the orientation of the right rear wheel 3RR.

[0049] The control device 8 includes a programmable logic controller and a motor driver. The control device 8 controls the drive unit 6 and the steering device 7 so that the automated guided vehicle 1 travels along the induction line LX detected by the induction sensors 4F and 4R in the normal traveling mode, and controls the drive unit 6 and the steering device 7 so that the automated guided vehicle 1 travels along the induction line LY detected by the induction sensors 5L and 5R in the lateral mode.

[0050] In addition, the control device 8 controls the drive unit 6 and the steering device 7 to perform a driving mode switching process when switching from the normal driving mode to the crab mode and when switching from the crab mode to the normal driving mode. Regarding the control device 8, in the driving mode switching process, the control device 8 sets a set of wheels among the four wheels, which are a plurality of wheels, as the primary steering wheels, and sets the other set of wheels as the secondary steering wheels, and controls the steering device 7 to change the orientation of the secondary steering wheels after changing the orientation of the primary steering wheels. In the present embodiment, the control device 8 sets the left front wheel 3FL and the right rear wheel 3RR as the primary steering wheels, sets the right front wheel 3FR and the left rear wheel 3RL as the secondary steering wheels, and controls the steering devices 7FR and 7RL after controlling the steering devices 7FL and 7RR.

[0051] Furthermore, the control device 8 controls the drive unit 6 to restrict the rotation of at least one wheel included in the secondary steering wheels when changing the orientation of the primary steering wheels, and restricts the rotation of at least one wheel included in the primary steering wheels when changing the orientation of the secondary steering wheels. In the present embodiment, the control device 8 controls the drive unit 6RL to restrict the rotation of the left rear wheel 3RL when changing the orientation of the left front wheel 3FL and the right rear wheel 3RR, and controls the drive unit 6FL to restrict the rotation of the left front wheel 3FL when changing the orientation of the right front wheel 3FR and the left rear wheel 3RL.

[0052] Refer to Figure 3 , and the process of the driving mode switching process for switching between the normal driving mode and the crab mode will be described in detail. In addition, the driving mode switching process starts in a state where the automated guided vehicle 1 has stopped running.

[0053] First, the control device 8 releases the brake of the drive wheel included in the primary steering wheels (step S1). In the present embodiment, the control device 8 releases the brake of the left front wheel 3FL by releasing the brake of the drive unit 6FL.

[0054] Next, the control device 8 changes the orientation of the primary steering wheels such that the steering angle of the primary steering wheels changes by 90 degrees (step S2). In the present embodiment, the control device 8 changes the orientation of the left front wheel 3FL and the right rear wheel 3RR by operating the steering devices 7FL and 7RR so that the steering angles of the left front wheel 3FL and the right rear wheel 3RR change by 90 degrees.

[0055] Next, the control device 8 restricts the rotation of the drive wheels included in the primary steering wheels (step S3), and releases the braking of the drive wheels included in the secondary steering wheels (step S4). In the present embodiment, the control device 8 restricts the rotation of the left front wheel 3FL by operating the brake of the drive unit 6FL, and releases the braking of the left rear wheel 3RL by releasing the brake of the drive unit 6RL.

[0056] Next, the control device 8 changes the orientation of the secondary steering wheels in such a manner that the steering angle of the secondary steering wheels changes by 90 degrees (step S5). In the present embodiment, the control device 8 changes the orientation of the right front wheel 3FR and the left rear wheel 3RL by operating the steering devices 7FR and 7RL so that the steering angles of the right front wheel 3FR and the left rear wheel 3RL change by 90 degrees.

[0057] Then, the control device 8 restricts the rotation of the drive wheels included in the secondary steering wheels (step S6). In the present embodiment, the control device 8 restricts the rotation of the left rear wheel 3RL by operating the brake of the drive unit 6RL.

[0058] Refer to Figure 4 of (A) to Figure 4 of (D) to describe the change in the orientation of the front wheels 3F and the rear wheels 3R when switching from the normal driving mode to the lateral movement mode. In addition, in Figure 4 of (A) to Figure 4 of (D), the wheels in the state where the rotation is restricted are illustrated with thick lines as compared with the wheels in the state where the rotation is not restricted.

[0059] As shown in Figure 4 of (A), before switching from the normal driving mode to the lateral movement mode, the drive units 6FL and 6RL restrict the rotation of the left front wheel 3FL and the left rear wheel 3RL by operating the brakes to stop the unmanned transport vehicle 1. In addition, if the unmanned transport vehicle 1 stops, the driving mode switching process can be started without restricting the rotation of the left front wheel 3FL and the left rear wheel 3RL.

[0060] Next, as shown in Figure 4 of (B), the orientation of the left front wheel 3FL and the right rear wheel 3RR is changed by the steering devices 7FL and 7RR, and the left front wheel 3FL and the right rear wheel 3RR face the left and right direction Y. At this time, the drive unit 6FL releases the restriction on the rotation of the left front wheel 3FL by releasing the brake, and the drive unit 6RL restricts the rotation of the left rear wheel 3RL by operating the brake. Therefore, the displacement of the vehicle body 2 in the front-rear direction X is suppressed by the left rear wheel 3RL, and the displacement of the vehicle body 2 in the left-right direction Y is suppressed by the right front wheel 3FR and the left rear wheel 3RL.

[0061] Next, as shown in Figure 4As shown in (C), the orientations of the right front wheel 3FR and the left rear wheel 3RL are changed by the steering devices 7FR and 7RL, and the right front wheel 3FR and the left rear wheel 3RL also face the left and right direction Y. At this time, the drive unit 6RL releases the restriction on the rotation of the left rear wheel 3RL by releasing the brake, and the drive unit 6FL restricts the rotation of the left front wheel 3FL by operating the brake. Therefore, the displacement of the vehicle body 2 in the front-rear direction X is suppressed by the left front wheel 3FL and the right rear wheel 3RR, and the displacement of the vehicle body 2 in the left and right direction Y is suppressed by the left front wheel 3FL.

[0062] Then, as Figure 4 shown in (D), after switching from the normal running mode to the transverse running mode, the drive units 6FL and 6RL operate the brakes until the driverless transport vehicle 1 starts running to restrict the rotation of the left front wheel 3FL and the left rear wheel 3RL. In addition, after switching from the normal running mode to the transverse running mode, the driverless transport vehicle 1 may start running without restricting the rotation of the left front wheel 3FL and the left rear wheel 3RL.

[0063] The following effects can be obtained in this embodiment.

[0064] (1) The control device 8 sets the left front wheel 3FL and the right rear wheel 3RR as the primary steering wheels, and the right front wheel 3FR and the left rear wheel 3RL as the secondary steering wheels, and controls the steering devices 7 when switching between the normal running mode and the transverse running mode to change the orientation of the secondary steering wheels after changing the orientation of the primary steering wheels. Further, the control device 8 controls the drive unit 6 (brake device) to restrict the rotation of the left rear wheel 3RL included in the secondary steering wheels when changing the orientation of the primary steering wheels, and to restrict the rotation of the left front wheel 3FL included in the primary steering wheels when changing the orientation of the secondary steering wheels. With this structure, when the orientation of the primary steering wheels is changed, the posture change of the vehicle body 2 is suppressed by the non-movement of the secondary steering wheels including the left rear wheel 3RL whose rotation is restricted, and when the orientation of the secondary steering wheels is changed, the posture change of the vehicle body 2 is suppressed by the non-movement of the primary steering wheels including the left front wheel 3FL whose rotation is restricted. Therefore, the posture change of the vehicle body 2 can be suppressed when switching between the normal running mode and the transverse running mode.

[0065] (2) A set of the left front wheel 3FL and the right rear wheel 3RR is the primary steering wheels, and a set of the right front wheel 3FR and the left front wheel 3RL is the secondary steering wheels. Therefore, by changing the orientations of a pair of the front wheels 3F and the rear wheels 3R arranged at a distance from each other at the same time, the posture change of the vehicle body 2 can be further suppressed.

[0066] The present invention is not limited to the above-described embodiment, and the above-described structure may also be changed. For example, it may be implemented by changing as follows, or may be implemented by combining the following changes.

[0067] It is also possible to set the right front wheel 3FR and the left rear wheel 3RL as the primary steering wheels, and set the left front wheel 3FL and the right rear wheel 3RR as the secondary steering wheels. In this case, the control device 8 controls the drive unit 6 to limit the rotation of the left front wheel 3FL included in the secondary steering wheels when changing the orientation of the primary steering wheels, and limit the rotation of the left rear wheel 3RL included in the primary steering wheels when changing the orientation of the secondary steering wheels.

[0068] It is also possible to set the right front wheel 3FR and the right rear wheel 3RR as the drive wheels and the left front wheel 3FL and the left rear wheel 3RL as the driven wheels by changing the structure of the drive unit 6. That is, it is also possible to configure that the rotation of the right front wheel 3FR and the right rear wheel 3RR is restricted by the braking device.

[0069] It is also possible to set one of the front wheels 3F and the rear wheels 3R as the drive wheel and the other as the driven wheel by changing the structure of the drive unit 6. That is, it is also possible to configure that the rotation of the left front wheel 3FL and the right front wheel 3FR, or the rotation of the left rear wheel 3RL and the right rear wheel 3RR is restricted by the braking device.

[0070] Refer to Figure 5 of (A) to Figure 5 of (D) to describe the changes in the orientations of the front wheels 3F and the rear wheels 3R when switching from the normal driving mode to the lateral movement mode in the structure where the rotations of the left front wheel 3FL and the right front wheel 3FR are restricted.

[0071] As Figure 5 shown in (A) of, before switching from the normal driving mode to the lateral movement mode, the rotations of the left front wheel 3FL and the right front wheel 3FR are restricted to stop the unmanned transport vehicle 1 from traveling.

[0072] Next, as Figure 5 shown in (B) of, the orientations of the left front wheel 3FL and the right rear wheel 3RR are changed by the steering devices 7FL and 7RR, and the left front wheel 3FL and the right rear wheel 3RR face the left - right direction Y. At this time, the restriction on the rotation of the left front wheel 3FL is released, and the rotation of the right front wheel 3FR is restricted. Therefore, the displacement of the vehicle body 2 in the front - rear direction X is suppressed by the right front wheel 3FR, and the displacement of the vehicle body 2 in the left - right direction Y is suppressed by the right front wheel 3FR and the left rear wheel 3RL.

[0073] Next, as Figure 5 shown in (C) of, the orientations of the right front wheel 3FR and the left rear wheel 3RL are changed by the steering devices 7FR and 7RL, and the right front wheel 3FR and the left rear wheel 3RL also face the left - right direction Y. At this time, the restriction on the rotation of the right front wheel 3FR is released, and the rotation of the left front wheel 3FL is restricted. Therefore, the displacement of the vehicle body 2 in the front - rear direction X is suppressed by the left front wheel 3FL and the right rear wheel 3RR, and the displacement of the vehicle body 2 in the left - right direction Y is suppressed by the left front wheel 3FL.

[0074] Then, as shown in (D) of Figure 5 after switching from the normal driving mode to the lateral movement mode, the rotation of the left front wheel 3FL and the right front wheel 3FR is restricted until the automated guided vehicle 1 starts to move.

[0075] · Also, by changing the structure of the drive unit 6, in one set of the left front wheel 3FL and the right rear wheel 3RR, and one set of the right front wheel 3FR and the left rear wheel 3RL, one set can be set as the drive wheels and the other set can be set as the driven wheels. That is, it can also be configured such that the rotation of the left front wheel 3FL and the right rear wheel 3RR, or the rotation of the right front wheel 3FR and the left rear wheel 3RL is restricted by the braking device.

[0076] Referring to Figure 6 (A) to Figure 6 (D) of

[0077] As Figure 6 (A) of

[0078] shown, before switching from the normal driving mode to the lateral movement mode, the rotation of the left front wheel 3FL and the right rear wheel 3RR is restricted to stop the automated guided vehicle 1 from moving. Figure 6 Next, as shown in (B) of

[0079] shown, by the steering devices 7FL and 7RL, the orientations of the left front wheel 3FL and the left rear wheel 3RL are changed, and the left front wheel 3FL and the left rear wheel 3RL are oriented in the left - right direction Y. At this time, the restriction on the rotation of the left front wheel 3FL is released, and the rotation of the right rear wheel 3RR is restricted. Therefore, the displacement of the vehicle body 2 in the front - rear direction X is suppressed by the right rear wheel 3RR, and the displacement of the vehicle body 2 in the left - right direction Y is suppressed by the right front wheel 3FR and the right rear wheel 3RR. Figure 6

[0080] Figure 6 Then, as shown in (D) of after switching from the normal driving mode to the lateral movement mode, the rotation of the left front wheel 3FL and the right rear wheel 3RR is restricted until the automated guided vehicle 1 starts to move.

[0081] Furthermore, referring to Figure 7 (A) to Figure 7 (D) of FIG. 2, the change in the orientation of the front wheels 3F and the rear wheels 3R when switching from the normal driving mode to the crab mode in a structure where the left front wheel 3FL and the right rear wheel 3RR are set as drive wheels and the front wheels 3F are set as primary steering wheels will be described.

[0082] As Figure 7 shown in (A) of FIG. 2, before switching from the normal driving mode to the crab mode, the rotation of the left front wheel 3FL and the right rear wheel 3RR is restricted to stop the unmanned transport vehicle 1 from traveling.

[0083] Next, as Figure 7 shown in (B) of FIG. 2, the orientations of the left front wheel 3FL and the right front wheel 3FR are changed by the steering devices 7FL and 7FR, and the left front wheel 3FL and the right front wheel 3FR are oriented in the left - right direction Y. At this time, the restriction on the rotation of the left front wheel 3FL is released, and the rotation of the right rear wheel 3RR is restricted. Therefore, the displacement of the vehicle body 2 in the front - rear direction X is suppressed by the right rear wheel 3RR, and the displacement of the vehicle body 2 in the left - right direction Y is suppressed by the left rear wheel 3RL and the right rear wheel 3RR.

[0084] Next, as Figure 7 shown in (C) of FIG. 2, the orientations of the left rear wheel 3RL and the right rear wheel 3RR are changed by the steering devices 7RL and 7RR, and the left rear wheel 3RL and the right rear wheel 3RR are also oriented in the left - right direction Y. At this time, the restriction on the rotation of the right rear wheel 3RR is released, and the rotation of the left front wheel 3FL is restricted. Therefore, the displacement of the vehicle body 2 in the front - rear direction X is suppressed by the left front wheel 3FL and the right front wheel 3FR, and the displacement of the vehicle body 2 in the left - right direction Y is suppressed by the left front wheel 3FL.

[0085] Then, as Figure 7 shown in (D) of FIG. 2, after switching from the normal driving mode to the crab mode, the rotation of the left front wheel 3FL and the right rear wheel 3RR is restricted until the unmanned transport vehicle 1 starts to travel.

[0086] The unmanned transport vehicle 1 may also include five or more wheels. In addition, the braking device may restrict the rotation of three or more wheels, and the control device may control the steering device to restrict the rotation of two or more wheels included in the secondary steering wheels when changing the orientation of the primary steering wheels, or restrict the rotation of two or more wheels included in the primary steering wheels when changing the orientation of the secondary steering wheels.

Claims

1. An unmanned transport vehicle capable of switching between a normal driving mode in which the vehicle can travel straight forward in the front-rear direction and a lateral driving mode in which the vehicle can travel straight forward in the left-right direction. The unmanned transport vehicle is characterized by comprising: A plurality of wheels are arranged at intervals in the front-rear direction and the left-right direction; a brake device for limiting the rotation of at least two of the wheels; A steering device for changing the orientation of the plurality of wheels; as well as a control device for controlling the braking device and the steering device, The control device One set of the wheels among the plurality of wheels is set as the primary steering wheels, and another set of the wheels is set as the secondary steering wheels. When switching between the normal driving mode and the lateral driving mode, the steering device is controlled so that the direction of the secondary steering wheels is changed after the direction of the primary steering wheels is changed. The braking device is then controlled to restrict the rotation of at least one of the wheels included in the secondary steering wheels when the direction of the primary steering wheel is changed, and to restrict the rotation of at least one of the wheels included in the primary steering wheels when the direction of the secondary steering wheel is changed.

2. The unmanned guided vehicle according to claim 1, characterized in that: The wheels include a front wheel and a rear wheel that are spaced apart in the front-rear direction. The front wheels include a left front wheel and a right front wheel which are spaced apart in the left-right direction, and the rear wheels include a left rear wheel and a right rear wheel which are spaced apart in the left-right direction. Among the set of the left front wheel and the right rear wheel, and the set of the right front wheel and the left rear wheel, one set is a primary steering wheel, and the other set is a secondary steering wheel.

3. The unmanned guided vehicle according to claim 2, characterized in that: The rotation of any one of the group of the left front wheel and the left rear wheel, the group of the right front wheel and the right rear wheel, the group of the left front wheel and the right front wheel, and the group of the left rear wheel and the right rear wheel is restricted by the braking device.

4. The unmanned guided vehicle according to claim 1, characterized in that: The wheels include a front wheel and a rear wheel that are spaced apart in the front-rear direction. The front wheels include a left front wheel and a right front wheel which are spaced apart in the left-right direction, and the rear wheels include a left rear wheel and a right rear wheel which are spaced apart in the left-right direction. A set of the left front wheel and the left rear wheel, a set of the right front wheel and the right rear wheel, a set of the left front wheel and the right front wheel, or a set of the left rear wheel and the right rear wheel are primary steered wheels.

5. The unmanned guided vehicle according to claim 4, characterized in that: The rotation of one of the set of the left front wheel and the right rear wheel and the set of the right front wheel and the left rear wheel is restricted by the braking device.

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