Carriage

Abstract

To provide a carriage that can freely run, while keeping an angle of a loading platform constant, without being influenced by a surrounding environment and a road surface condition.SOLUTION: A carriage is provided with a load platform, running units including at least four wheels, which are configured to be able to move in a first direction, support units and a control device that can control the support units and the running units. The support units are provided between the load platform and the running units and are configured to be able to move the wheels of the running units along a second direction crossing the first direction with respect to the load platform and to hold the wheels at predetermined positions in the second direction with respect to the load platform. The control device is configured to obtain an inclination of the load platform with respect to a horizontal direction and loads acting on each of the at least four wheels and to hold the load platform at a predetermined angle, while making the wheels ground, by controlling the support units on the basis of the obtained inclination of the load platform and the obtained loads.SELECTED DRAWING: Figure 9

Description

[Technical field]

[0001] The present disclosure relates to a dolly. [Background technology]

[0002] Patent Document 1 discloses a method for controlling the horizontality of a loading platform. The method of Patent Document 1 is configured to drive each cylinder to rise or fall according to the movement amount of the cylinder rod of each wheel, which is calculated from the horizontal correction value of the distance between the loading platform body and the axle for each wheel and the height of the uneven part of the floor surface in front of each wheel. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 9-315127 Summary of the Invention [Problem to be solved by the invention]

[0004] The method of Patent Document 1 has room for improvement in terms of being able to travel freely without being affected by the surrounding environment or road conditions while keeping the bed angle constant.

[0005] An object of the present disclosure is to provide a cart that can run freely without being affected by the surrounding environment or road conditions while keeping the loading platform angle constant. [Means for solving the problem]

[0006] According to one aspect of the present disclosure, there is provided a dolly comprising: The loading platform and A traveling unit including at least four wheels and configured to move the platform in a first direction; a support unit provided between the platform and the traveling unit, the support unit being configured to be able to move the wheels of the traveling unit along the first direction relative to the platform and to hold the wheels at a predetermined position in a second direction intersecting the first direction relative to the platform; a control device capable of controlling the support unit and the traveling unit; Equipped with The control device includes: The tilt of the platform with respect to the horizontal direction and the load acting on each of the at least four wheels are obtained, The support unit is controlled based on the acquired inclination of the loading platform and the load, and the loading platform can be held at a predetermined angle while the wheels are in contact with the ground. Effect of the Invention

[0007] According to the present disclosure, it is possible to realize a cart that can move freely without being affected by the surrounding environment or road conditions while keeping the loading platform angle constant. [Brief description of the drawings]

[0008] [Figure 1] FIG. 1 is a perspective view of a dolly according to one embodiment of the present disclosure. [Diagram 2] FIG. 2 is a front view of the trolley of FIG. 1; [Diagram 3] FIG. 2 is a partial rear view of the trolley of FIG. 1; [Figure 4] FIG. 2 is a front view of the carriage of FIG. 1 with some parts removed. [Diagram 5] FIG. 2 is a schematic diagram for explaining a support unit of the carriage in FIG. 1 . [Figure 6] Block diagram of the bogie in Figure 1. [Figure 7] FIG. 2 is a first diagram for explaining an example of control that can be performed by the bogie of FIG. 1; [Figure 8] FIG. 2 is a second diagram for explaining an example of control that can be performed by the bogie of FIG. 1; [Figure 9] 4 is a flowchart for explaining an example of a movement control process of the cart in FIG. 1; [Figure 10] FIG. 2 is a first diagram for explaining a modified example of the carriage of FIG. 1; [Figure 11] FIG. 2 is a second diagram for explaining a modified example of the carriage of FIG. 1. [Figure 12] FIG. 3 is a third diagram for explaining a modified example of the bogie in FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] An example of the present disclosure will be described below with reference to the accompanying drawings. The following description is merely illustrative in nature and is not intended to limit the present disclosure, the application of the present disclosure, or the use of the present disclosure. The accompanying drawings are schematic, and the ratio of each dimension does not necessarily correspond to the actual one.

[0010] As shown in Fig. 1, a dolly 1 according to an embodiment of the present disclosure includes a platform 10, a traveling unit 20, and a support unit 30. The traveling unit 20 is configured to be able to move the platform 10 in a first direction (e.g., the X direction). The first direction X is, for example, a horizontal direction. The support unit 30 is provided between the platform 10 and the traveling unit 20.

[0011] As an example, the loading platform 10 has a substantially rectangular plate shape with the first direction X as the longitudinal direction, and is configured to be able to place luggage on it. The luggage that can be placed on the loading platform 10 is not limited to objects, but also includes, for example, people. The loading platform 10 has a plate-shaped main body 11, rod-shaped protrusions 12 provided at both ends of the main body 11 in the first direction X, and rod-shaped protrusions 13 provided at both ends of the main body 11 in a direction intersecting the first direction X (for example, the short-side direction Y of the loading platform 10). Each protrusion 12 extends from one end to the other end of the main body 11 along the short-side direction Y of the loading platform 10. Each protrusion 13 is located between two protrusions 12 with a gap between them. By providing the protrusions 12 and 13, luggage can be prevented from sliding off the loading platform 10 even if the loading platform 10 is tilted.

[0012] The loading platform 10 may be configured so that one or both of the protrusions 12 are detachable, or the protrusions 12 are provided only at one end in the first direction X. The loading platform 10 may be configured so that one or both of the protrusions 13 are detachable, or the protrusions 13 are provided only at one end in the Y direction. The loading platform 10 may be configured so that only the protrusions 12 are provided, or so that only the protrusions 13 are provided, or so that neither the protrusions 12, 13 are provided. In this way, when some or all of the protrusions 12, 13 are not provided or are detachable, the loading platform 10 can be tilted by the user's selection / operation, as described below, to easily unload luggage from the loading platform 10.

[0013] As an example, the traveling unit 20 includes a plurality of wheel devices 21. In this embodiment, the traveling unit 20 includes six wheel devices 21. Specifically, the traveling unit 20 includes three pairs of wheel devices 21 spaced apart in the first direction X, and each pair of wheel devices 21 is composed of two wheel devices 21 facing each other in the short-side direction Y of the loading platform 10. The two wheel devices 21 constituting each pair are positioned point-symmetrically with respect to a center point CP (see FIG. 3). As an example, the center point CP is the intersection point between an imaginary line passing through the center of the short-side direction Y of the loading platform 10 and extending in the first direction X, and an axis on which the rotation axes of wheels 22 described later of the two wheel devices 21 constituting each pair are located.

[0014] As shown in FIG. 2, each wheel device 21 has a wheel 22, a driving unit 23, and a shock absorbing unit 24. For example, the wheel 22 can be a wheel of any diameter and width and made of any material. The wheels 22 of each pair of wheel devices 21 have coaxial rotation axes. The driving unit 23 is configured to be able to drive the wheels 22. The driving unit 23 includes, for example, but is not limited to, an in-wheel motor. The shock absorbing unit 24 is configured to be able to absorb shock from the wheels 22. In this embodiment, the shock absorbing unit 24 extends from an inner side of one wheel 22 of each pair of wheel devices 21 facing the other wheel 22 along a second direction intersecting the first direction X (for example, a Z direction intersecting the first direction X and the short-side direction Y of the loading platform 10, in other words, a direction intersecting the horizontal direction). The shock absorbing unit 24 includes, for example, but is not limited to, a damper.

[0015] Each wheel device 21 in this embodiment has a steering unit 25. The steering unit 25 is configured to be able to rotate the wheel 22 about a rotation axis CL1 extending along the second direction Z. In this embodiment, the steering unit 25 has a first member 251, a second member 252, and a steering device 253. The traveling unit 20 is configured, for example, to be able to cause the carriage 1 to perform turning traveling and / or sliding traveling as described below. Turning travel in which the steering unit 25 causes the direction of some of the wheels 22 (for example, the direction of the side of the wheels 22 relative to the first direction X) to differ from that of the remaining wheels 22, thereby turning the cart 1 to the right or left relative to the traveling direction. · Sliding travel in which the steering unit 25 aligns the directions of all the wheels 22 (for example, makes them parallel) and the cart 1 slides along a plane that intersects the vertical direction.

[0016] The first member 251 extends from the wheel 22 toward the loading platform 10 in the second direction Z. The second member 252 extends from one of the ends of the first member 251 in the second direction Z that is closer to the loading platform 10 along the rotation axis CL2 of the wheel 22 (for example, in a direction perpendicular to the rotation axis CL1). The steering device 253 is connected to the support unit 30 and is configured to rotate the second member 252 around the rotation axis CL1. The second member 252 is connected to the steering device 253 at a portion that is farther away from the first member 251 than the center of the direction in which the second member 252 extends. The traveling unit 20 is connected to the support unit 30 via the steering section 25.

[0017] The support unit 30 is configured to be able to move the traveling unit 20 along the second direction Z relative to the loading platform 10 and to hold the traveling unit 20 at a predetermined position in the second direction Z relative to the loading platform 10. In this embodiment, the support unit 30 includes a plurality of support devices 31.

[0018] As shown in FIG. 3, the multiple support devices 31 are arranged at intervals along the first direction X. Each support device 31 is configured to be able to move one corresponding wheel 22 along the second direction Z and to hold it at a predetermined position in the second direction Z. That is, in this embodiment, the support unit 30 includes six support devices 31 corresponding to each of the six wheel devices 21. When viewed along the second direction Z, each support device 31 extends in a direction (e.g., A direction) that intersects with a first virtual straight line L1 extending in the front-rear direction (e.g., first direction X) of the loading platform 10 and a second virtual straight line L2 extending in the left-right direction (e.g., Y direction) that intersects with the front-rear direction of the loading platform 10. Among the multiple support devices 31, the two support devices 31 corresponding to the two wheel devices 21 that constitute each pair are positioned point-symmetrically with respect to the center point CP.

[0019] As shown in FIG. 4, each of the support devices 31 includes a moving body 40, a first link member 50, and a second link member 60.

[0020] The movable body 40 is connected to the platform 10 so as to be movable along a third direction intersecting the first direction X and the second direction Z, and is configured to be able to be held at a predetermined position between a first end P1 (see FIG. 5) and a second end P2 (see FIG. 5) of the movable range. In this embodiment, the third direction is, for example, the A direction, and the movable body 40 is configured to be able to move in a direction intersecting the first virtual straight line L1 and the second virtual straight line L2 when viewed along the second direction Z. The first end P1 is located farther away from the wheel device 21 corresponding to each support device 31 than the second end P2. Each support device 31 includes a drive device 70 for moving and holding the movable body 40. The drive device 70 includes, but is not limited to, a motor 71 (see FIG. 3) and a ball screw 72 (see FIG. 4).

[0021] The first link member 50 has a first link end 501 rotatably connected to the moving body 40 and a second link end 502 connected to the traveling unit 20. In this embodiment, the first link member 50 is composed of two members 51 and 52. Each of the members 51 and 52 is made of, for example, metal and has a substantially rectangular column shape. One end of each of the members 51 and 52 in the direction in which the members 51 and 52 extend is rotatably connected to the moving body 40 around rotation axes CL3 and CL4 perpendicular to the third direction A, forming a part of the first link end 501. The other end of each of the members 51 and 52 in the direction in which the members 51 and 52 extend is rotatably connected to the connecting member 80 around rotation axes CL5 and CL6 perpendicular to the third direction A, forming a part of the second link end 502.

[0022] The connecting member 80 extends from the second link end 502 of the first link member 50 to the same side as the second link member 60 with respect to the first link member 50, and connects the second link end 502 and the traveling unit 20. In this embodiment, the connecting member 80 extends from the second link end 502 of the first link member 50 toward the steering device 253 of the wheel device 21. Of both ends of the connecting member 80 in the direction in which the connecting member 80 extends, one end is rotatably connected to the second link end 502 of the first link member 50, and the other end is non-rotatably connected to the steering device 253.

[0023] A holding member 90 is provided between the first link end 501 and the second link end 502 of the first link member 50. The holding member 90 rotatably holds a fourth link end 602 of the second link member 60 (described later) on the outside of the first link member 50 (in other words, between the first link member 50 and the loading platform 10). In this embodiment, the holding member 90 is composed of two plate-like members 91 and 92 located on both sides of the width direction of the first link member 50 (for example, the direction in which the rotation axes CL3 to CL6 extend). The two members 91 and 92 are connected by three members 93 having a substantially cylindrical shape that penetrate the two members 51 and 52 of the first link member 50 and the second link member 60, respectively. That is, the two members 51 and 52 of the first link member 50 and the second link member 60 each have a through hole in which the member 93 is rotatably accommodated. The member 93 penetrating the two members 51, 52 of the first link member 50 is located inside the first link member 50, and the member 93 penetrating the second link member 60 is located outside the first link member 50.

[0024] The second link member 60 has a third link end 601 rotatably connected to the loading platform 10, and a fourth link end 602 rotatably connected between the first link end 501 and the second link end 502 of the first link member 50. In this embodiment, the second link member 60 is made of metal, for example, and has a substantially rectangular column shape. The third link end 601 is located on an imaginary straight line L3 (see FIG. 5) connecting the first end P1 and the second end P2, and on the opposite side of the first end P1 with respect to the second end P2. The imaginary straight line L3 extends substantially parallel to the loading platform 10 along the third direction A.

[0025] As shown in Fig. 5, when the moving body 40 moves from the first end P1 toward the second end P2, the wheels 22 move in the second direction Z in a direction away from the bed 10. On the other hand, when the moving body 40 moves from the second end P2 toward the first end P1, the wheels 22 move in the second direction Z in a direction approaching the bed 10. The movement of the wheels 22 in the second direction Z is performed almost linearly by each support device 31. Therefore, the movement of the wheels 22 in the second direction Z causes almost no change in the tread and wheelbase.

[0026] 6, the bogie 1 of this embodiment includes a control device 100. The control device 100 includes a processor 101, a storage device 102, and a communication device 103, and is configured to be able to control the traveling unit 20 and the support unit 30. The processor 101, the storage device 102, and the communication device 103 constitute, for example, a part of a processing circuit.

[0027] The processor 101 includes, for example, a CPU, an MPU, a GPU, a DSP, an FPGA, an ASIC, or a combination thereof. The storage device 102 includes, for example, a non-transitory computer-readable storage medium configured as an internal storage medium or an external storage medium. The internal storage medium includes a non-volatile memory, etc. The external storage medium includes a hard disk (HDD), a solid state drive (SSD), an optical disk device, etc. The communication device 103 is configured, for example, as a communication circuit or a communication module for transmitting and receiving data to and from an external device such as a server, a mobile terminal device such as a smartphone or a tablet, or an external input device such as a remote controller (remote control device).

[0028] The control device 100 includes an acquisition unit 110 and a cart control unit 120. The acquisition unit 110 and the cart control unit 120 are realized by, for example, the processor 101 executing a predetermined program stored in the storage device 102.

[0029] The acquisition unit 110 is configured to be able to acquire the inclination of the loading platform 10 with respect to the horizontal direction (hereinafter also referred to as the angle of the loading platform 10) and the load acting on each wheel 22. In this embodiment, the dolly 1 is equipped with a tilt detection sensor 131 and a load detection sensor 132. The inclination of the loading platform 10 with respect to the horizontal direction is acquired from the tilt detection sensor 131, and the load acting on each wheel 22 is acquired from the load detection sensor 132. The tilt detection sensor 131 is, for example, an inertial measurement unit, and the load detection sensor 132 is, for example, a load cell. The tilt detection sensor 131 is provided at a location other than the loading surface of the loading platform 10 on which luggage is loaded (for example, a side surface of the loading platform 10). The inclination of the loading platform 10 is calculated (simulated), for example, from a virtual loading surface generated based on the distance (e.g., xyz direction distance) between a predetermined position of the loading platform 10 and the inclination detection sensor 131 and the acquired output value of the inclination detection sensor 131.

[0030] The dolly control unit 120 is configured to control the support unit 30 based on the acquired inclination of the platform 10 and the load applied to each wheel 22, and to hold the platform 10 at a predetermined angle while the wheels 22 are in contact with the ground. In this embodiment, the dolly control unit 120 determines that the wheels 22 are in contact with the ground when the acquired output value of the load detection sensor 132 is equal to or greater than a first predetermined value. When the acquired output value of the load detection sensor 132 is less than the first predetermined value, the dolly control unit 120 controls the support unit 30 to move the wheels 22 along the second direction Z until the acquired output value of the load detection sensor 132 becomes equal to or greater than the first predetermined value. The first predetermined value is set according to the specifications of the dolly 1, etc. The dolly control unit 120 may be configured to determine that the wheels 22 are not in contact with the ground when the acquired output value of the load detection sensor 132 is less than an intermediate predetermined value that is smaller than the first predetermined value. In this case, if the acquired output value of the load detection sensor 132 is within the range of "intermediate predetermined value≦output value<first predetermined value", the trolley control unit 120 controls the support unit 30 to lower the wheels 22 while continuing the travel of the trolley 1. If the acquired output value of the load detection sensor 132 is within the range of "output value<intermediate predetermined value", the trolley control unit 120 controls the support unit 30 to prevent the trolley 1 from tipping over, and stops the travel of the trolley 1 or changes the traveling direction of the trolley 1 to make a detour.

[0031] The carriage control unit 120 may be configured to selectively execute the following controls 1 to 8, for example.

[0032] (Control 1) When the acquired angle of the loading platform 10 is an angle shown below, the truck control unit 120 determines that the truck 1 is on a slope that exceeds its specifications, and executes a process for stopping the truck 1 or a process for notifying the user. When the notification process is executed, the occurrence of an error is notified to the user. The occurrence of an error is notified, for example, by emitting a sound such as a voice, by turning on a light such as an LED lamp, or by displaying an error code on a display device such as a 7-segment display. - When the calculated angle of the loading platform 10 is equal to or greater than the first angle. The angle of the loading platform 10 calculated after controlling the support unit 30 to hold the loading platform 10 at a predetermined angle is equal to or greater than a second angle smaller than the first angle. The second angle is, for example, an angle larger than zero degrees.

[0033] (Control 2) The dolly control unit 120 controls the inclination of the loading platform 10 via the support unit 30 to unload the cargo loaded on the loading platform 10. The dolly control unit 120 can control the amount of cargo unloaded by adjusting the angle of the loading platform 10 based on the load distribution of the loading platform 10 calculated based on the output of the load detection sensor 132 acquired. The dolly control unit 120 can also run the dolly 1 with the loading platform 10 inclined. This allows, for example, fertilizer or lime loaded on the loading platform 10 to be spread on a field, or calcium carbonate to be spread in a line on a schoolyard to draw a white line. For example, the inclination control of the loading platform 10 operates the support unit 30 so that one side of the loading platform 10 in the longitudinal direction X is high and the other side is low, or so that one side of the loading platform 10 in the lateral direction Y is high and the other side is low. Tilting the loading platform 10 along the short-side direction Y of the loading platform 10 results in a greater inclination of the loading platform 10 than tilting the loading platform 10 along the long-side direction X of the loading platform 10, allowing the cargo to be unloaded with force. When the truck 1 is configured so that the dimensional difference between the wheelbase and the tread of the loading platform 10 is small, the difference in the inclination of the loading platform 10 between the long-side direction X and the short-side direction Y of the loading platform 10 is small. Therefore, regardless of which direction the loading platform 10 is tilted along, the cargo can be unloaded in approximately the same manner. In addition, the loading platform 10 may be configured so that the user can select the direction in which to tilt the loading platform 10 depending on various conditions such as the surrounding environment or the load of the cargo.

[0034] (Control 3) The dolly control unit 120 is configured to control the steering unit 25 of the wheel device 21 when the dolly 1 is stopped, and rotate the wheels 22 so that the side of at least one wheel 22 intersects (for example, perpendicular to) the acquired tilt direction of the loading platform 10. As shown in FIG. 7 and FIG. 8, the angle of each wheel 22 may be the same as or different from the angle of the other wheels 22. This can prevent the wheels 22 from rolling on their own and the dolly 1 from moving unintentionally when the dolly 1 is stopped on a slope or when the loading platform 10 is tilted to unload luggage. Since it is not necessary to maintain the supply of electricity to the traveling unit 20 to prevent the wheels 22 from rolling, power can be saved, and when the traveling unit 20 is driven by a battery, the usable time of the battery can be extended. Since it is not necessary to provide a separate brake means to the dolly 1, the configuration of the dolly 1 is simplified and the parts cost can be reduced. 7 shows a diagram of the carriage 1 parked on a slope as viewed along the Y direction, and FIG. 8 shows a diagram of the carriage 1 shown in FIG.

[0035] (Control 4) The dolly control unit 120 judges the total load or load distribution of the luggage loaded on the loading platform 10 based on the acquired output value of the load detection sensor 132. If the judged total load of the luggage is equal to or greater than the second predetermined value and / or if it is judged that the load distribution is an excessively unbalanced load, the dolly control unit 120 issues an alarm to the user. The alarm is issued, for example, in the same manner as (control 1). This can prevent the dolly 1 from being damaged and / or tipping over. If it is judged that the load distribution is an excessively unbalanced load, the dolly control unit 120 controls the support unit 30 to bring the center of gravity of the luggage closer to the center of the loading platform 10. This can prevent the dolly 1 from tipping over. The center of gravity of the luggage is calculated, for example, based on the acquired load value of each wheel 22. Below are control examples (1) and (2) of the support unit 30 when bringing the center of gravity of the luggage closer to the center of the loading platform 10. (1) The wheels 22 carrying a heavy load are moved in a direction away from the loading platform 10. In this case, the cart 1 can be easily prevented from tipping over. (2) The wheels 22 carrying a light load are moved in a direction toward the loading platform 10. In this case, the center of gravity of the cart 1 can be kept low, so tipping over of the cart 1 can be easily and efficiently prevented. The cart control unit 120 determines that there is an unbalanced load, for example, when the calculated center of gravity position of the luggage is outside the allowable range, or when the difference between the maximum and minimum values ​​of the acquired load values ​​of each wheel 22 is equal to or greater than a third predetermined value. The second predetermined value, the third predetermined value, and the allowable range of the center of gravity position of the luggage are set according to the specifications of the cart 1, etc.

[0036] (Control 5) When the acquired output value of the load detection sensor 132 is a first load less than a first predetermined value and a second load acquired after the first load is acquired is smaller than the first load, the carriage control unit 120 controls the traveling unit 20 to stop or slow down the movement of the platform 10, or to move the platform 10 in a direction different from the current moving direction. The second load may be an output value of the load detection sensor 132 acquired immediately after the first load is acquired, or may be an output value of the load detection sensor 132 acquired a predetermined number of times after the acquisition of the first load. Even if the carriage control unit 120 controls the support unit 30, if the acquired output value of the load detection sensor 132 decreases or becomes zero, the carriage control unit 120 determines that the wheels 22 are not on the ground. As a result, even if some of the wheels 22 fall into a recess (hole or groove) in the road surface during traveling, the carriage 1 can be stopped from traveling before the carriage 1 (and thus the platform 10) tilts, thereby preventing the carriage 1 from falling over.

[0037] (Control 6) When performing a spin turn, the carriage control unit 120 calculates the optimal rotation speed of each wheel 22 based on the tilt angle of the platform 10 and the position of each wheel 22 in the second direction Z relative to the platform 10. For example, the carriage control unit 120 rotates the wheel 22 that moves a long distance faster because the movement distance of each wheel 22 differs due to the unevenness or inclination of the road surface. The position of each wheel 22 in the second direction Z relative to the platform 10 is determined by the drive amount of the support unit 30 (for example, the drive amount of the drive device 70) that is set based on the output of the acquired tilt detection sensor 131. For example, the carriage control unit 120 controls the support unit 30 so that the wheels 22 other than the wheels 22 that are steered and driven to run in order to perform a spin turn are moved away from the road surface. This allows the vehicle to perform a smooth spin turn.

[0038] (Control 7) The dolly control unit 120 judges whether or not the wheel 22 has come into contact with an obstacle that cannot be overcome while the dolly 1 is traveling, from the acquired output value of the load detection sensor 132. In a normal traveling state, the amplitude of the output value of the load detection sensor 132 acquired according to the unevenness of the road surface falls within a predetermined range, but when the wheel 22 comes into contact with an obstacle that cannot be overcome, the acquired output value of the load detection sensor 132 momentarily exceeds the predetermined range and becomes large. When the acquired output value of the load detection sensor 132 exceeds the predetermined range, the dolly control unit 120 judges that the wheel 22 has come into contact with an obstacle that cannot be overcome, stops the traveling of the dolly 1, and stops the dolly 1. In this case, the dolly control unit 120 may be configured to notify the user of an alarm. This can prevent the dolly 1 from falling over. The predetermined range of the amplitude of the output value of the load detection sensor 132 is set according to the specifications of the dolly 1, etc.

[0039] (Control 8) The carriage control unit 120 has a first mode in which the height of the platform 10 is maintained when the carriage is stopped, and a second mode in which the platform 10 is lowered when the carriage is stopped. By selecting the first mode, the height of the platform 10 can be maintained at a height suitable for work. By selecting the second mode, tipping over when starting to travel can be prevented. The carriage control unit 120 may be configured to selectively execute the following controls. When the first mode is selected and the height of the platform 10 is equal to or greater than a predetermined value, the center of gravity of the dolly 1 is high, and there is a risk of the dolly 1 tipping over when it starts to travel. Therefore, when the dolly control unit 120 starts to travel with the platform 10's height being equal to or greater than a fourth predetermined value, it starts to control the traveling unit 20 after lowering the platform 10 so that the platform 10's height becomes lower than the fourth predetermined value. The fourth predetermined value is set according to the specifications of the dolly 1, etc. When the second mode is selected, the dolly control unit 120 determines whether or not to lower the platform 10 at the start of traveling, based on the height of the platform 10 and the total load or load distribution of the loaded luggage. When lowering the platform 10 at the start of traveling, the height of the platform 10 to be lowered is set according to the total load or load distribution of the loaded luggage. This makes it possible to lower the platform 10 to an appropriate height and reliably prevent the platform 10 from tipping over at the start of traveling, even if the center of gravity of the dolly 1 becomes high due to the loading of luggage. The dolly control unit 120 may be configured to raise the platform 10 to the height before the lowering at a predetermined timing after the start of traveling, when the platform 10 is lowered at the start of traveling. This makes it possible to easily return the height of the platform 10 to a height suitable for work.

[0040] An example of the movement control process of the dolly 1 will be described with reference to Fig. 9. The movement control process of the dolly 1 is implemented by the processor 101 executing a predetermined program stored in the storage device 102, for example.

[0041] When the movement control of the dolly 1 is started, the acquisition unit 110 acquires the inclination of the platform 10 and the load of the wheels 22 (step S1). In this embodiment, the load of each of the six wheels 22 is acquired.

[0042] When the inclination of the loading platform 10 and the load of the wheels 22 are acquired, the trolley control unit 120 judges whether the acquired inclination of the loading platform 10 is a predetermined angle or not (step S2). If it is not judged that the acquired inclination of the loading platform 10 is a predetermined angle, the trolley control unit 120 controls the support device 31 so that the inclination of the loading platform 10 becomes the predetermined angle (step S3), and returns to step S2. An example of the control of the support device 31 in step S3 is shown below. The trolley control unit 120 can be configured to execute either one or both of the following controls. The height of the loading platform 10 is judged, for example, from the height difference of a virtual loading surface (for example, four corners of the virtual loading surface) based on a virtual horizontal plane passing through the center point of the loading platform 10 (the center of the loading platform 10 in the longitudinal direction X and the center of the loading platform 10 in the lateral direction Y) based on the distance between a predetermined position of the loading platform 10 and the inclination detection sensor 131 and the output value of the inclination detection sensor 131. The wheels 22 located on the higher side of the loading platform 10 are moved in the second direction Z and in a direction approaching the loading platform 10. The wheel 22 corresponding to the lower position of the loading platform 10 is moved in the second direction and away from the loading platform 10.

[0043] When it is determined that the acquired inclination of the loading platform 10 is a predetermined angle, the truck control unit 120 determines whether or not the acquired load of the wheel 22 is equal to or greater than a predetermined value (step S4). When it is not determined that the acquired load of the wheel 22 is equal to or greater than the predetermined value, the truck control unit 120 controls the support device 31 corresponding to the wheel 22 whose load is not determined to be equal to or greater than the predetermined value to move the wheel 22 in the second direction Z (e.g., vertical direction) in a direction away from the loading platform 10 (step S5), and returns to step S4.

[0044] When it is determined that the inclination of the platform is at a predetermined angle, the trolley control unit 120 determines whether or not to stop the trolley 1 (step S6). For example, when the trolley control unit 120 does not receive a control signal from the controller for a certain period of time, or when it receives a command to stop the trolley 1 via the communication device 103, it determines that the trolley 1 is to be stopped, and the movement control process of the trolley 1 ends. When it is not determined that the trolley 1 is to be stopped, the process returns to step S1, and the inclination of the platform 10 and the load of the wheels 22 are acquired.

[0045] Cart 1 can provide the following effects:

[0046] The dolly 1 includes a platform 10, a traveling unit 20 configured to move the platform 10 in a first direction, and a plurality of support devices 31. The plurality of support devices 31 are provided between the platform 10 and the traveling unit 20, and are configured to move the traveling unit 20 relative to the platform 10 along a second direction intersecting the first direction and to be able to hold the traveling unit 20 at a predetermined position in the second direction relative to the platform 10. Each of the plurality of support devices 31 includes a moving body 40, a first link member 50, and a second link member 60. The moving body 40 is connected to the platform 10 so as to be able to move along a third direction intersecting the first direction and the second direction, and is configured to be able to be held at a predetermined position between a first end P1 and a second end P2 of the moving range. The first link member 50 has a first link end 501 rotatably connected to the moving body 40 and a second link end 502 connected to the traveling unit 20. The second link member 60 is located on the virtual straight line L3 connecting the first end P1 and the second end P2 and on the opposite side of the first end P1 with respect to the second end P2, and has a third link end 601 rotatably connected to the platform 10, and a fourth link end 602 rotatably connected between the first link end 501 and the second link end 502 of the first link member 50. With this configuration, it is possible to realize a dolly 1 that can freely run while keeping the angle of the platform 10 constant, without being affected by the surrounding environment and road surface conditions.

[0047] The dolly 1 is equipped with a control device 100 capable of acquiring the inclination of the loading platform 10 relative to the horizontal direction and controlling the moving body 40 and the traveling unit 20. The control device 100 is configured to control the support device 31 based on the acquired inclination of the loading platform 10 and to maintain the inclination of the loading platform 10 at a predetermined angle. With this configuration, the horizontality of the loading platform 10 can be more reliably maintained according to the road surface condition.

[0048] The traveling unit 20 includes a plurality of wheel devices 21 each connected to a second link end 502 of the first link member 50. Each of the plurality of wheel devices 21 has a wheel 22, a drive unit 23 capable of driving the wheel 22, and a shock absorbing unit 24 capable of absorbing shock from the wheel 22. With this configuration, vibrations or shocks caused by small unevenness in the road surface can be quickly absorbed without controlling the support device 31.

[0049] The control device 100 is configured to be able to acquire the load acting on the wheels 22, and when the acquired load is less than a predetermined value, controls the moving body 40 to move the wheels 22 in the second direction until the acquired load becomes equal to or greater than the predetermined value. With this configuration, each wheel 22 can be reliably grounded, and the load on the loading platform 10 can be stably supported.

[0050] Each of the plurality of support devices 31 includes a holding member 90 that is provided between the first link end 501 and the second link end 502 of the first link member 50 and rotatably holds the fourth link end 602 of the second link member 60 outside the first link member 50. With this configuration, the link members 50, 60 can be connected to each other with a simple configuration without interfering with each other, and the support device 31 can be configured compactly.

[0051] Each of the multiple support devices 31 includes a connection member 80 that extends from the second link end 502 of the first link member 50 to the same side as the second link member 60 with respect to the first link member 50, and connects the second link end 502 and the traveling unit 20. With this configuration, even when each link member 50, 60 is rotated with respect to the loading platform 10, the angle of the traveling unit 20 with respect to the loading platform 10 does not change, and the loading platform 10 can be stably moved along the second direction Z.

[0052] When viewed along the second direction, the movable body 40 is configured to be movable in a direction intersecting a first imaginary straight line L1 extending in the front-rear direction of the platform 10 and a second imaginary straight line L2 extending in a left-right direction intersecting the front-rear direction. This configuration allows the dolly 1 to be made compact. Also, when the dolly 1 is viewed along the second direction Z, the rotation axes CL2 of the paired wheels 22 can be made to substantially coincide in the left-right direction (e.g., Y direction) intersecting the first direction X, allowing the dolly 1 to travel stably.

[0053] The dolly 1 includes a loading platform 10, a traveling unit 20 including six wheels 22 and configured to be able to move the loading platform 10 in a first direction, a support unit 30, and a control device 100 capable of controlling the support unit 30 and the traveling unit 20. The support unit 30 is provided between the loading platform 10 and the traveling unit 20, and configured to be able to move the wheels 22 of the traveling unit 20 relative to the loading platform 10 along a second direction intersecting the first direction and to be able to hold the wheels 22 of the traveling unit 20 at a predetermined position in the second direction relative to the loading platform 10. The control device 100 is configured to be able to acquire the inclination of the loading platform 10 with respect to the horizontal direction and the load acting on each of the six wheels 22, and is configured to control the support unit 30 based on the acquired inclination of the loading platform 10 and the load of the wheels 22 to hold the loading platform 10 at a predetermined angle while the wheels 22 are in contact with the ground. With this configuration, the loading platform 10 can be stably maintained in a state inclined at a predetermined inclination angle according to the road surface condition. As a result, a trolley 1 can be realized that is capable of freely traveling while keeping the angle of the platform 10 constant, without being affected by the surrounding environment or road surface conditions.

[0054] The traveling unit 20 includes a shock absorbing section 24 capable of absorbing shock from the wheels 22. If vibrations caused by small irregularities in the road surface were to be absorbed by the lifting and lowering action of a link mechanism or a cylinder mechanism, the support unit 30 would need to be operated at extremely high speed, making control of the support unit 30 complicated. In the bogie 1, since the traveling unit 20 includes the shock absorbing section 24, vibrations caused by small irregularities are absorbed by the shock absorbing section 24, and complicated control of the support unit 30 can be avoided.

[0055] The traveling unit 20 includes a steering unit 25 capable of rotating the wheels 22 around a rotation axis CL1 extending along the second direction. The control device 100 is configured to control the steering unit 25 to rotate the wheels 22 so that the side of the wheels 22 intersects with the acquired tilt direction of the loading platform 10. With this configuration, unintended movement of the dolly 1 along the tilt direction can be prevented.

[0056] The control device 100 is configured to calculate the load distribution of the luggage on the loading platform 10 based on the acquired load of the wheels 22, judge whether the luggage is unbalanced based on the calculated load distribution, and, if it is judged that the luggage is unbalanced, control the support unit 30 to move the center of gravity of the luggage closer to the center of the loading platform 10. With this configuration, it is possible to prevent the cart 1 from tipping over due to the unbalanced load.

[0057] When the acquired load of the wheels 22 is a first load less than a predetermined value, and a second load, which is a load of the wheels 22 acquired after the first load is acquired, is smaller than the first load, the control device 100 controls the traveling unit 20 to stop or slow down the movement of the platform 10, or to move the platform 10 in a direction different from the current moving direction. With this configuration, when the wheels 22 are not in contact with the road surface, the traveling of the platform 1 can be stopped before the platform 1 tilts.

[0058] The cart 1 can also be configured as follows.

[0059] As shown in FIG. 10, the moving body 40 may be configured to move in the second direction Z from the platform 10 and in a direction away from the platform 10 (for example, vertically downward) as it moves from the second end P2 to the first end P1. FIG. 11 shows a dolly 1 configured so that the moving body 40 moves substantially parallel to the platform 10 along the third direction A. Comparing the dolly 1 in FIG. 10 and the dolly 1 in FIG. 11, when the stroke amount of the wheel 22 is set to the same degree (S1=S2), the moving distance M1 of the moving body 40 of the dolly 1 in FIG. 10 is shorter than the moving distance M2 of the moving body 40 of the dolly 1 in FIG. 11. Therefore, the time required for the wheel 22 to move in the second direction Z can be shortened. In FIG. 10 and FIG. 11, the moving body 40 and the like are omitted, and the dolly 1 is illustrated in a simplified manner in which each link member 50, 60 and each link end portion 501, 502, 601, 602 are the main parts.

[0060] In the dolly 1 of Figs. 10 and 11, the first link member 50 and the second link member 60 have the following relationship. In the dolly 1 of Figs. 10 and 11, by configuring as described below, the wheels 22 can be moved substantially linearly along the second direction Z. Therefore, even if the loading platform 10 is moved in the second direction Z, the tread and the wheel base do not change substantially. As a result, the area occupied by the dolly 1 when the loading platform 10 is moved in the second direction Z is reduced, and the loading platform 10 can be moved in the second direction Z even in a narrow place where there are obstacles around. In addition, luggage can be stably placed on the loading platform 10 even when the loading platform 10 is moved in the second direction Z. (Figure 10) The length W1 from the first link end 501 of the first link member 50 to the portion to which the second link member 60 is connected is approximately the same as the length W3 of the second link member 60. The length W2 from the portion of the first link member 50 where the second link member 60 is connected to the second link end 502 is longer than the length W1 from the first link end 501 of the first link member 50 to the portion where the second link member 60 is connected, and the length W3 of the second link member 60 (for example, W1:W2:W3 = 1:1.25:1). (Fig. 11) The length W4 from the first link end 501 of the first link member 50 to the portion where the second link member 60 is connected, the length W5 from the portion where the second link member 60 of the first link member 50 is connected to the second link end 502, and the length W6 of the second link member 60 are approximately the same length.

[0061] The support device 31 may include a one-way clutch. The one-way clutch is configured to be able to restrict the movement of the moving body 40 from the second end P2 to the first end P1 when the moving body 40 is stopped. By including the one-way clutch in the support device 31, when the support device 31 is not operated, the movement of the moving body 40 in the direction in which the first link end 501 of the first link member 50 moves away from the third link end 601 of the second link member 60 is restricted, so that the loading platform 10 does not unexpectedly lower. On the other hand, when the support device 31 is not operated, the loading platform 10 does not unexpectedly rise against gravity. In other words, it is not necessary to restrict the movement of the moving body 40 in the direction in which the first link end 501 of the first link member 50 approaches the third link end 601 of the second link member 60. For this reason, the unexpected movement of the moving body 40 when the support device 31 is not operated can be easily restricted by the one-way clutch.

[0062] The dolly 1 may include an operation unit for a user to input operation instructions to the dolly 1. The operation unit is configured, for example, with a mobile terminal such as a smartphone or a tablet, or a remote controller (remote control device), and is connected to the control device 100 via the communication device 103 by wire or wirelessly.

[0063] The control device 100 can be omitted. In this case, the dolly 1 may be configured to include, for example, a platform 10, a traveling unit 20, and a plurality of support devices 31, and each support device 31 may be configured to include a moving body 40, a first link member 50, and a second link member 60. When the control device 100 is omitted, the moving body 40 is moved, for example, electrically or manually by a user's operation. The traveling unit 20 may be configured to include, for example, at least three wheels 22, or may be configured to include a caterpillar.

[0064] The support unit 30 is not limited to including the movable body 40, the first link member 50, and the second link member 60, and may include, for example, a cylinder mechanism instead of these configurations. When the support unit 30 includes the movable body 40, the first link member 50, and the second link member 60, the lower limit position of the platform 10 can be lowered compared to when the support unit 30 includes the cylinder mechanism. When the support unit 30 does not include the movable body 40, the first link member 50, and the second link member 60, the dolly 1 may be configured to include, for example, the platform 10, a traveling unit 20 including at least four wheels 22, and a control device 100.

[0065] The support unit 30 includes a first link member 50 and a second link member 60, or a cylinder mechanism, and the control device 100 is capable of controlling the support unit 30 based on the acquired inclination of the loading platform 10 and the load acting on the wheels 22. In this case, the dolly 1 may include, in addition to the support unit 30 and the control device 100, for example, the loading platform 10, a traveling unit 20 including at least four wheels 22, an inclination detection sensor 131, and a load detection sensor 132.

[0066] The wheel device 21 is not limited to having the wheels 22, the driving unit 23, the shock absorbing unit 24, and the steering unit 25. For example, the shock absorbing unit 24 and the steering unit 25 can be omitted.

[0067] In the above embodiment, the longitudinal direction X of the loading platform 10 is defined as the "front-rear direction of the loading platform 10" and the lateral direction Y of the loading platform 10 is defined as the "left-right direction of the loading platform 10", but this is not limited thereto. As shown in Fig. 12, the lateral direction Y of the loading platform 10 may be defined as the "front-rear direction of the loading platform 10" and the longitudinal direction X of the loading platform 10 may be defined as the "left-right direction of the loading platform 10". Fig. 12 shows the dolly 1 as viewed along the second direction Z.

[0068] Various embodiments of the present disclosure have been described in detail above with reference to the drawings. Finally, various aspects of the present disclosure will be described.

[0069] The cart according to the first-1 aspect of the present disclosure includes: The loading platform and A traveling unit configured to move the platform in a first direction; a plurality of support devices respectively provided between the loading platform and the traveling unit, the support devices being configured to be capable of moving the traveling unit relative to the loading platform along a second direction intersecting the first direction and to be capable of holding the traveling unit at a predetermined position in the second direction relative to the loading platform; Equipped with Each of the plurality of support devices is a movable body connected to the platform so as to be movable along a third direction intersecting the first direction and the second direction, and configured to be retained at a predetermined position between a first end and a second end of a moving range; A first link member having a first link end rotatably connected to the moving body and a second link end connected to the traveling unit; a second link member having a third link end rotatably connected to the platform, the third link end being located on a virtual line connecting the first end and the second end and on an opposite side of the second end to the first end, and a fourth link end rotatably connected between the first link end and the second link end of the first link member; Includes.

[0070] A cart according to a first-2 aspect of the present disclosure is the cart according to the first-1 aspect, a control device capable of acquiring an inclination of the platform with respect to a horizontal direction and controlling the moving body and the traveling unit; The control device is configured to control the support device based on the acquired inclination of the loading platform, thereby being able to maintain the inclination of the loading platform at a predetermined angle.

[0071] A dolly according to a first to third aspect of the present disclosure is the dolly according to the first to second aspect, The traveling unit is a plurality of wheel devices respectively connected to the second link ends of the first link members; Each of the plurality of wheel devices is Wheels and A drive unit capable of driving the wheels; a shock absorbing portion capable of absorbing shock from the wheel; has.

[0072] A trolley according to a first to fourth aspect of the present disclosure is the trolley according to the first to third aspect, The control device includes: A load acting on the wheel can be acquired, When the acquired load is less than a predetermined value, the moving body is controlled to move the wheels in the second direction until the acquired load becomes equal to or greater than a predetermined value.

[0073] A cart according to a 1-5 aspect of the present disclosure is a cart according to any one of the 1-1 to 1-4 aspects, Each of the plurality of support devices is The movable body includes a one-way clutch capable of restricting movement of the movable body from the second end to the first end when the movable body is stopped.

[0074] A dolly according to a 1-6 aspect of the present disclosure is a dolly according to any one of the 1-1 to 1-5 aspects, The movable body is configured to move in the second direction from the platform and in a direction away from the platform as it moves from the second end to the first end.

[0075] A cart according to a 1-7th aspect of the present disclosure is a cart according to any one of the 1-1 to 1-6 aspects, Each of the plurality of support devices is The first link member includes a holding member provided between the first link end and the second link end, the holding member rotatably holding the fourth link end of the second link member outside the first link member.

[0076] A dolly according to a 1-8th aspect of the present disclosure is a dolly according to any one of the 1-1 to 1-7 aspects, Each of the plurality of support devices is A connecting member extends from the second link end of the first link member on the same side of the first link member as the second link member, and connects the second link end and the traveling unit.

[0077] A dolly according to a 1-9th aspect of the present disclosure is a dolly according to any one of the 1-1 to 1-8 aspects, The movable body is configured to be movable in a direction intersecting a first virtual line extending in the fore-and-aft direction of the loading platform and a second virtual line extending in the left-right direction intersecting the fore-and-aft direction when viewed along the second direction.

[0078] The cart according to the second-first aspect of the present disclosure includes: The loading platform and A traveling unit including at least four wheels and configured to move the platform in a first direction; a support unit provided between the platform and the traveling unit, the support unit being configured to be able to move the wheels of the traveling unit relative to the platform along a second direction intersecting the first direction and to be able to hold the wheels at a predetermined position in the second direction relative to the platform; a control device capable of controlling the support unit and the traveling unit; Equipped with The control device includes: The tilt of the platform with respect to the horizontal direction and the load acting on each of the at least four wheels are obtained, The support unit is controlled based on the acquired inclination of the loading platform and the load, and the loading platform can be held at a predetermined angle while the wheels are in contact with the ground.

[0079] A cart according to a 2-2 aspect of the present disclosure is the cart according to the 2-1 aspect, The traveling unit includes a shock absorbing portion capable of absorbing shock from the wheel.

[0080] A cart according to a second aspect of the present disclosure is a cart according to a second aspect of the present disclosure, The traveling unit includes a steering unit capable of rotating the wheels around a rotation axis extending along the second direction, The control device is configured to control the steering unit to rotate the wheels so that the side of the wheels intersects with the obtained tilt direction of the loading platform.

[0081] A cart according to a 2-4 aspect of the present disclosure is a cart according to any one of the 2-1 to 2-3 aspects, The control device includes: Calculating a load distribution of the luggage on the platform based on the acquired load, and determining whether the luggage is an unbalanced load based on the calculated load distribution; When it is determined that the load is unevenly distributed, the support unit is controlled to move the center of gravity of the load closer to the center of the platform.

[0082] A cart according to a 2-5 aspect of the present disclosure is a cart according to any one of the 2-1 to 2-4 aspects, The control device includes: When the acquired load is a first load that is less than a predetermined value, and a second load that is the load acquired after the first load is acquired is less than the first load, the driving unit is controlled to stop or slow down the movement of the loading platform, or to move the loading platform in a direction different from the current moving direction.

[0083] A cart according to a 2-6 aspect of the present disclosure is a cart according to any one of the 2-1 to 2-5 aspects, The control device includes: When the acquired load is less than a predetermined value, the support unit is controlled to move the wheel along the second direction until the acquired load becomes equal to or greater than the predetermined value.

[0084] In the present disclosure, any of the above-described various embodiments and modifications may be appropriately combined. Combinations of the embodiments and / or modifications include combinations of configurations included in the embodiments and / or configurations included in the examples.

[0085] The present disclosure has been fully described through the above-mentioned embodiments and / or modifications with reference to the accompanying drawings, but the above-mentioned embodiments and / or modifications do not cover all of the present disclosure. Many modifications and variations are possible for those skilled in the art in the technical field of the present disclosure. Such modifications and variations should be understood to be included in the present disclosure as long as they do not deviate from the scope of the present disclosure. [Explanation of symbols]

[0086] 1 Cart 10 Cargo Bed 11 Main body 12 Protrusion 20 Traveling Unit 21 Wheel device 22 wheels 23 Drive unit 24 Shock absorbing part 25 Steering section 251 First Component 252 Second member 253 Steering Gear 30 Support Unit 31 Support device 40 Mobile 50 First link member 501 First link end 502 End of second link 51, 52 Parts 60 Second link member 601 Third link end 602 End of 4th link 70 Drive unit 71 Motor 80 Connection parts 90 Retaining member 91, 92, 93 Parts 100 Control device 101 Processor 102 Storage device 103 Communication equipment 110 Acquisition Department 120 Truck control unit 131 Tilt detection sensor 132 Load detection sensor

Claims

1. The loading platform and A traveling unit including at least four wheels and configured to move the platform in a first direction; a support unit provided between the platform and the traveling unit, the support unit being configured to be able to move the wheels of the traveling unit relative to the platform along a second direction intersecting the first direction and to be able to hold the wheels at a predetermined position in the second direction relative to the platform; a control device capable of controlling the support unit and the traveling unit; Equipped with The control device includes: A tilt of the loading platform with respect to a horizontal direction and a load acting on each of the at least four wheels are obtained; The cart is configured to control the support unit based on the acquired inclination of the loading platform and the load, and to hold the loading platform at a predetermined angle while keeping the wheels in contact with the ground.

2. The bogie according to claim 1 , wherein the traveling unit includes a shock absorbing portion capable of absorbing a shock from the wheels.

3. The traveling unit includes a steering unit capable of rotating the wheels around a rotation axis extending along the second direction, The trolley according to claim 1 , wherein the control device is configured to control the steering unit to rotate the wheels so that the side surfaces of the wheels intersect with the acquired tilt direction of the loading platform.

4. The control device includes: Calculating a load distribution of the luggage on the platform based on the acquired load, and determining whether the luggage is an unbalanced load based on the calculated load distribution; The dolly according to claim 1 , further comprising: a support unit configured to control the support unit when the load is determined to be an unbalanced load, so as to move the center of gravity of the load closer to the center of the platform.

5. The control device includes: The trolley described in claim 1, wherein when the acquired load is a first load that is less than a predetermined value, and a second load that is the load acquired after the first load is acquired is less than the first load, the running unit is controlled to stop or slow down the movement of the loading platform, or to move the loading platform in a direction different from the current moving direction.

6. The control device includes: A trolley as described in any one of claims 1 to 5, wherein, when the acquired load is less than a predetermined value, the support unit is controlled to move the wheels along the second direction until the acquired load becomes equal to or greater than the predetermined value.

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