Trolley

Abstract

The present invention provides a trolley with wheels that are difficult to slip and capable of performing appropriate rotational movements. The trolley (1) includes: a vehicle body (2); a pair of left and right wheels (3) provided on the vehicle body; left and right drive units (4) for driving the wheels; a handle (5) provided on the vehicle body for accepting user operations; a sensor (6) for detecting the front and rear loads applied to the handles and the torque around the vertical axis; and a control device (7) for controlling the drive unit. The control device sets a target front and rear speed of the vehicle body based on the front and rear loads, and sets a target angular velocity of the vehicle body around the vertical axis based on the torque around the vertical axis. When the product of the target front and rear speed and the target angular velocity is greater than a predetermined threshold, the target front and rear speed is corrected so that the product of the target front and rear speed and the target angular velocity becomes less than the threshold, and the drive unit is controlled based on the corrected target front and rear speed and the target angular velocity.

Description

Technical Field

[0001] This invention relates to a trolley. Background Technology

[0002] Patent document 1 discloses a power-assisted trolley having: a handle for detecting the user's operating force; and a power-assisted control unit for driving and steering a drive wheel based on the operating force input to the handle.

[0003] [Existing Technical Documents]

[0004] [Patent Literature]

[0005] Patent Document 1: Japanese Patent Application Publication No. 2004-114800 Summary of the Invention

[0006] [The problem the invention aims to solve]

[0007] In a trolley like Patent Document 1, if the forward and backward speed or angular velocity becomes too high during rotation, the centrifugal force applied to the drive wheel will increase, and the drive wheel may slip.

[0008] The objective of this invention is, in view of the above background, to provide a trolley whose wheels are difficult to slip and which is capable of performing appropriate rotational movements.

[0009] [Technical means to solve the problem]

[0010] To address the aforementioned problem, one embodiment of the present invention provides a trolley 1, comprising: a body 2; a pair of left and right wheels 3 disposed on the body; left and right drive units 4 for driving each of the wheels; a handle 5 disposed on the body for receiving user operation; a sensor 6 for detecting the front and rear loads applied to the handle and the torque about a vertical axis; and a control device 7 for controlling the drive units. The control device sets a target front and rear speed of the body based on the front and rear loads, and sets a target angular velocity of the body about a vertical axis based on the torque about the vertical axis. When the product of the target front and rear speed and the target angular velocity is greater than a predetermined threshold, the target front and rear speed is corrected so that the product of the target front and rear speed and the target angular velocity is below the threshold. The drive units are then controlled based on the corrected target front and rear speed and the target angular velocity.

[0011] According to this embodiment, the forward and backward velocity of the target is corrected so that the product of the forward and backward velocity of the target and the target angular velocity is below a specified threshold, thus providing a trolley in which the wheels are difficult to slip and can perform appropriate rotational movements.

[0012] To address the aforementioned problem, one embodiment of the present invention provides a trolley 1, comprising: a body 2; a pair of left and right wheels 3 disposed on the body; left and right drive units 4 for driving each of the wheels; a handle 5 disposed on the body for receiving user operation; a sensor 6 for detecting the front and rear loads applied to the handle and the torque about a vertical axis; and a control device 7 for controlling the drive units. The control device sets a target front and rear speed of the body based on the front and rear loads, and sets a target angular velocity of the body about a vertical axis based on the torque about the vertical axis. When the product of the target front and rear speeds and the target angular velocity is greater than a predetermined threshold, the target angular velocity is corrected so that the product of the target front and rear speeds and the target angular velocity is below the threshold. The drive units are controlled based on the corrected target angular velocity and the target front and rear speeds.

[0013] According to this embodiment, the target angular velocity is corrected so that the product of the target forward and backward velocity and the target angular velocity is below a specified threshold, thus providing a trolley in which the wheels are difficult to slip and can perform appropriate rotational movements.

[0014] To address the aforementioned problem, one embodiment of the present invention provides a trolley 1, comprising: a body 2; a pair of left and right wheels 3 disposed on the body; left and right drive units 4 for driving each of the wheels; a handle 5 disposed on the body for receiving user operation; a sensor 6 for detecting the front and rear loads applied to the handle and the torque about a vertical axis; and a control device 7 for controlling the drive units. The control device sets a target front and rear speed of the body based on the front and rear loads, and sets a target angular velocity of the body about a vertical axis based on the torque about the vertical axis. When the product of the target front and rear speed and the target angular velocity is greater than a predetermined threshold, the control device corrects the target front and rear speed and the target angular velocity so that the product of the target front and rear speed and the target angular velocity is below the threshold. The control device then controls the drive units based on the corrected target angular velocity and the corrected target front and rear speed.

[0015] According to this embodiment, the target forward and backward velocity and the target angular velocity are corrected so that the product of the target forward and backward velocity and the target angular velocity is below a specified threshold, thus providing a trolley in which the wheels are difficult to slip and can perform appropriate rotational movements.

[0016] In the embodiments described above, preferably, when the threshold is Th, the forward and backward velocity of the target is vt1, and the angular velocity of the target is ωt, the control device can replace the forward and backward velocity of the target with a forward and backward velocity correction value vt1' that satisfies the following equation (1), and replace the angular velocity of the target with an angular velocity correction value ωt' that satisfies the following equation (2), thereby performing correction.

[0017]

[0018] According to this embodiment, the control device can easily correct the target's forward and backward speeds.

[0019] In the described embodiment, let the mass of the trolley be m, the distance from the center of gravity to the wheel in the front-to-back direction be L1, the distance from the center of gravity to the wheel in the width direction be L2, and the maximum static friction force of the wheel relative to the floor surface be F. max When the thrust of each wheel relative to the floor is F(i) (where i is the independent variable representing the wheel number), the threshold Th can be set below the minimum value of the upper limit τ(i) represented by equation (3).

[0020]

[0021] According to this embodiment, the threshold can be set appropriately and easily.

[0022] In the described embodiment, the control device may perform the correction process only when the trolley is reversing.

[0023] According to this embodiment, the processing performed by the control device for controlling the vehicle becomes simplified.

[0024] [The effects of the invention]

[0025] Based on the above structure, a trolley can be provided that makes it difficult for the wheels to slip and allows for appropriate rotational movements. Attached Figure Description

[0026] Figure 1 This is a perspective view of the trolley of the present invention.

[0027] Figure 2 This is a floor plan of the trolley.

[0028] Figure 3 This is a cross-sectional view of the omnidirectional wheel 3.

[0029] Figure 4 This is a side view of the main wheel.

[0030] Figure 5 This is a block diagram representing the control device of the trolley.

[0031] Figure 6 This is a flowchart illustrating the control flow executed by the control device in the first embodiment.

[0032] Figure 7 This is a schematic diagram showing the propulsive force of the omnidirectional wheel 3, the centrifugal force of the trolley, and the force couple when the trolley moves forward.

[0033] Figure 8 This is a flowchart illustrating the control flow executed by the control device in the second embodiment.

[0034] Figure 9 This is a flowchart illustrating the control flow executed by the control device in the third embodiment.

[0035] Figure 10 This is a flowchart illustrating a modified example of the control flow executed by the control device of the first embodiment.

[0036] Figure 11 This is a schematic diagram showing the propulsive force of the omnidirectional wheel 3, the centrifugal force of the trolley, and the force couple when the trolley is reversing.

[0037] [Explanation of Symbols]

[0038] 1: Cart

[0039] 2: Body

[0040] 3: Omnidirectional wheel (an example of a wheel)

[0041] 4: Drive Unit

[0042] 5: Handle

[0043] 6: Force sensor (an example of a sensor)

[0044] 7: Control device Detailed Implementation

[0045] <<First Implementation>>

[0046] Hereinafter, embodiments of the trolley of the present invention will be described with reference to the accompanying drawings. The trolley will be used as a reference for defining each aspect.

[0047] like Figure 1 As shown, the trolley 1 has: a body 2; at least one omnidirectional wheel 3 disposed on the body 2, allowing the body 2 to move in all directions along the floor surface; a drive unit 4, driving each omnidirectional wheel 3; a handle 5 disposed on the body 2, receiving operation from the user; a force sensor 6, detecting the load applied to the handle 5; and a control device 7, controlling the drive unit 4 based on the load detected by each force sensor 6.

[0048] The vehicle body 2 extends front to back. The rear part 2A of the vehicle body 2 extends higher than the front part 2B. A support platform 11 for supporting other devices is provided at the front part 2B of the vehicle body 2. Devices supported by the support platform 11 include, for example, inspection machines containing X-ray scanners. These devices can be secured to the support platform 11. Inside the rear part 2A of the vehicle body 2, control devices 7, batteries, and various sensors can be provided.

[0049] In this embodiment, a pair of omnidirectional wheels 3 are provided at the lower part of the rear portion 2A of the vehicle body 2. Furthermore, left and right casters 13 are supported by a suspension at the lower part of the front portion 2B of the vehicle body 2. The suspension has an arm 14 positioned below the vehicle body 2 and extending laterally, and a spring 15 and a shock absorber 16 positioned between the vehicle body 2 and the arm 14. Each caster 13 is positioned below the left and right ends of the arm 14. Each caster 13 has: a fork 13A, rotatably coupled to the arm 14 with its vertically extending axis as the center; and a wheel 13B, rotatably supported on the fork 13A with its horizontally extending axis as the center. The fork 13A rotates freely relative to the arm 14, and the wheel 13B rotates freely relative to the fork 13A.

[0050] like Figure 2 As shown, a pair of omnidirectional wheels 3 are arranged spaced apart on the left and right sides. In this embodiment, the pair of omnidirectional wheels 3 are arranged on the lower left and lower right sides of the rear part 2A of the vehicle body 2. Figure 3 As shown, each omnidirectional wheel 3 has a frame 17, a pair of drive discs 18 rotatably supported on the frame 17, and an annular main wheel 19 disposed between the pair of drive discs 18.

[0051] like Figure 1 as well as Figure 3 As shown, the frame 17 has: an upper frame portion 17A attached to the lower part of the vehicle body 2, and a pair of frame side portions 17B extending downward from the left and right ends of the upper frame portion 17A. A left-right extending support shaft 21 is mounted at the lower end of the pair of frame side portions 17B. A pair of drive discs 18 are rotatably supported on the support shaft 21. The pair of drive discs 18 rotate about the axis Y1 of the support shaft 21. The position of each drive disc 18 relative to the support shaft 21 in the left-right direction is restricted. The drive discs 18 are spaced apart from each other in the left-right direction and face each other.

[0052] Drive discs 18 are respectively disposed on both sides of the annular main wheel 19, applying frictional force to the main wheel 19 to cause it to rotate around its central axis and around the axis of the annulus. Each drive disc 18 has: a disc-shaped base 18A rotatably supported on the frame 17; and a plurality of drive rollers 18B, inclined relative to each other and rotatably supported on the outer periphery of the base 18A, and in contact with the main wheel 19. The base 18A is coaxially arranged with the support shaft 21.

[0053] On opposite surfaces of each drive disc 18, driven pulleys 18C are provided. Driven pulleys 18C are coaxially arranged with the drive discs 18. A drive unit 4 is located at the lower part of the vehicle body 2 and has multiple electric motors 25 corresponding to each drive disc 18. In this embodiment, four electric motors 25 are provided corresponding to the four drive discs 18. A drive pulley 26 is provided on the output shaft of each electric motor 25. The corresponding drive pulley 26 is connected to the driven pulley 18C via a belt 27. Each electric motor 25 rotates independently, thereby causing each drive disc 18 to rotate independently.

[0054] like Figure 4 As shown, the main wheel 19 is annular and coaxially arranged between a pair of drive discs 18, and contacts a plurality of drive rollers 18B, thereby being rotatable about a central axis and about the axis of the annular shape. The main wheel 19 has an annular core 31 and a plurality of driven rollers 32 rotatably supported on the core 31. The plurality of driven rollers 32 are arranged at equal intervals along the circumference of the core 31. Each driven roller 32 is rotatably supported on the core 31 about the axis A1 (the axis of the annular shape) of the annular core 31. Each driven roller 32 can rotate about the tangent of the core 31 at various positions relative to the core 31. Each driven roller 32 rotates relative to the core 31 under the influence of an external force.

[0055] The main wheel 19 is arranged along the outer periphery of a pair of drive discs 18 and contacts a plurality of drive rollers 18B provided on each drive disc 18. The drive rollers 18B of each drive disc 18 contact the inner periphery of the main wheel 19, clamping the main wheel 19 from both sides. Furthermore, the drive rollers 18B of the left and right drive discs 18 contact the inner periphery of the main wheel 19, thereby limiting the radial displacement of the drive discs 18 towards the axis Y1. Thus, the main wheel 19 is supported by the left and right drive discs 18, and the central axis of the main wheel 19 (core 31) is coaxial with the axis Y1 of the left and right drive discs 18. The main wheel 19 contacts the plurality of drive rollers 18B of the left and right drive discs 18 in a plurality of driven rollers 32.

[0056] In each omnidirectional wheel 3, when a pair of drive discs 18 rotate in the same direction at the same speed, the main wheel 19 rotates together with the pair of drive discs 18. That is, the main wheel 19 rotates forward or backward around its own axis of rotation, which is aligned with axis Y1. At this time, the drive rollers 18B of the drive discs 18 and the driven rollers 32 of the main wheel 19 do not rotate relative to the core 31. In each omnidirectional wheel 3, when a speed difference is generated between the pair of drive discs 18, a component force orthogonal to the circumferential (tangential) force caused by the rotation of the pair of drive discs 18 acts from the left and right drive rollers 18B to the driven rollers 32 of the main wheel 19. Since the axis of the drive rollers 18B is inclined relative to the circumference of the drive rollers 18B, a component force is generated between the drive discs 18 due to the speed difference. With the aid of this component force, the drive rollers 18B rotate relative to the base 18A, and the driven rollers 32 rotate relative to the core 31. As a result, the main wheel 19 generates a driving force in the left and right directions.

[0057] The trolley 1 moves forward by rotating the left and right omnidirectional wheels 3 at the same speed in the forward direction. The trolley 1 moves backward by rotating the left and right omnidirectional wheels 3 at the same speed in the backward direction. The speed difference created by the rotation of the left and right omnidirectional wheels 3 in the forward and backward directions causes the trolley 1 to turn to the right or left. The rotation of the driven rollers 32 of each main wheel 19 of the left and right omnidirectional wheels 3 causes the trolley 1 to move parallel to the right or left.

[0058] like Figure 1 as well as Figure 2 As shown, a handlebar bracket 35 protruding upwards is provided at the upper part of the rear portion 2A of the vehicle body 2. The handlebar 5 is supported on the handlebar bracket 35 via a force sensor 6. The force sensor 6 can be a triaxial force sensor that detects loads along two axes orthogonal to each other on a horizontal plane and torques centered on the vertical axis (z-axis). In this embodiment, the force sensor 6 detects the loads applied to the handlebar 5 in the forward / backward direction (x-axis), i.e., the forward / backward load, the loads in the left / right direction (y-axis), i.e., the left / right load, and the torques about the vertical axis (z-axis). The force sensor 6 has a body portion and an input portion provided in the body portion. The body portion is attached to the handlebar bracket 35.

[0059] The handle 5 has a horizontal portion 5A extending to the left and right and a pair of vertical portions 5B extending forward from the left and right ends of the horizontal portion 5A. The central portion of the horizontal portion 5A in the left and right direction is connected to the input portion of the force sensor 6.

[0060] like Figure 2 As shown, when the user applies an external force fh and a torque mhz to the position rh of handle 5, the force sensor 6 detects the force fs and the torque msz at the sensor position rs. The detected force fs includes the front-rear load fs1 as the front-rear component and the left-right load fs2 as the left-right component.

[0061] The control device 7 is an electronic control unit (ECU) that includes a processor such as a central processing unit (CPU), non-volatile memory (read-only memory, ROM), and volatile memory (random access memory, RAM). The control device 7 controls the drive unit 4 by executing arithmetic operations in the processor based on a program stored in the non-volatile memory. The control device 7 can be configured as a single piece of hardware or as a unit containing multiple pieces of hardware. Furthermore, at least a portion of each functional unit of the control device 7 can be implemented in hardware such as large-scale integrated circuits (LSI), application-specific integrated circuits (ASIC), or field-programmable gate arrays (FPGA), or through a combination of software and hardware.

[0062] like Figure 5 As shown, the control device 7 is connected to the force sensor 6 and the drive unit 4. The force sensor 6 outputs a detection signal to the control device 7. The control device 7 outputs a control signal to the drive unit 4.

[0063] The control device 7 controls the drive unit 4 based on signals from the force sensor 6. The force sensor 6 is installed between the vehicle body 2 and the handle 5. The force sensor 6 detects the magnitude and direction of the operating force (load) applied by the user to the handle 5. The control device 7 can determine the target forward / backward speed vt1, the target left / right speed vt2, and the target angular velocity ωt of the trolley 1 based on the signals from the force sensor 6, and determine the control amount of each electric motor 25 of the drive unit 4 based on the target forward / backward speed vt1, the target left / right speed vt2, and the target angular velocity ωt.

[0064] Control device 7 is based on Figure 6 The flowchart shown illustrates the control of the drive unit 4. First, the control device 7 acquires the detected force fs and detected torque msz(S1) detected by the force sensor 6 based on the signal from the force sensor 6. The detected force fs includes the front and rear loads fs1 and the left and right loads fs2.

[0065] Next, the control device 7 sets the target front-rear velocity vt1 of the vehicle body 2 based on the front and rear load fs1, sets the target left and right velocity vt2 of the vehicle body 2 based on the left and right load fs2, and sets the target angular velocity ωt(S2) of the vehicle body 2 about the vertical axis based on the torque msz about the vertical axis.

[0066] When the current rear load fs1 is facing forward, the control device 7 sets the target forward-backward speed vt1 to face forward. In this embodiment, when the target forward-backward speed vt1 is facing forward, that is, when the trolley 1 moves forward, the target forward-backward speed vt1 is set to positive. That is, when the target forward-backward speed vt1 is facing backward, that is, when the trolley 1 moves backward, the target forward-backward speed vt1 is set to negative.

[0067] The target forward / backward velocity vt1 can be set, for example, by multiplying the forward / backward load fs1 by a predetermined coefficient k1. Similarly, the target left / right velocity vt2 can be set, for example, by multiplying the left / right load fs2 by a predetermined coefficient k2. Furthermore, the target angular velocity ωt can be set, for example, by multiplying the torque msz about the vertical axis by a predetermined coefficient k3. The target angular velocity ωt is set with reference point rc as the center. Reference point rc can be set to a position that coincides with the center of gravity G of the trolley 1 when viewed from above. In this embodiment, reference point rc is positioned at the midpoint of the line segment connecting a pair of omnidirectional wheels 3. However, the methods for setting the target forward / backward velocity vt1, the target left / right velocity vt2, and the target angular velocity ωt are not limited to these.

[0068] However, for the sake of simplicity, it is usually set here that the left and right loads fs2 applied by the operator that moves the trolley 1 are sufficiently smaller than the front and rear loads fs1, or the coefficient k2 is sufficiently smaller than the coefficients k1 and k3.

[0069] Next, the control device 7 calculates the thrust F(i) (S3) that the left and right omnidirectional wheels 3 should output in order to output the target forward and backward velocity vt1 and the target angular velocity ωt, respectively. Here, i in thrust F(i) refers to the independent variable (exponent) specified for each omnidirectional wheel 3. For example, i can also be specified as 1 for the left omnidirectional wheel 3 and 2 for the right omnidirectional wheel 3.

[0070] Next, the control device 7 uses the thrust F(i) to calculate the upper limit value τ(i) defined for each of the omnidirectional wheels 3. The upper limit value τ(i) is expressed by the following equation (4).

[0071]

[0072] In equation (4), L1 represents the distance in the longitudinal direction of the vehicle from the center of gravity G to the left and right omnidirectional wheels 3, and L2 represents the distance in the width direction (left and right direction of the vehicle) from the center of gravity G to the left and right omnidirectional wheels 3. maxThis represents the maximum static friction force of the left and right omnidirectional wheels 3 relative to the floor surface.

[0073] Next, the control device 7 extracts the minimum value of the upper limit value τ(i) with respect to i, and sets a predetermined value below this minimum value as the threshold Th. In this embodiment, since there are two omnidirectional wheels 3, the control device 7 sets the threshold Th (S4) in a manner that satisfies the following equation (5).

[0074] Th≤min(τ(1),τ(2))(5)

[0075] In equation (5), min(τ(1), τ(2)) represents the minimum values ​​of τ(1) and τ(2). The control device 7 can set the threshold Th as the minimum value of the upper limit τ(i) as in equation (5), and it can also set the threshold Th as a value obtained by accumulating the minimum value of the upper limit τ(i) to a specified positive constant that is less than 1.

[0076] When the threshold Th is calculated, the control device 7 calculates the product of the target's forward and backward velocity vt1 and the target's angular velocity ωt, and determines whether it is below the threshold Th, that is, whether it satisfies equation (6)(S5).

[0077] vt×ωt≤Th(6)

[0078] When the product of the target forward and backward velocity vt1 and the target angular velocity ωt is less than Th (yes in S5), the control device 7 sets the target rotation speed rt of each electric motor 25 based on the target forward and backward velocity vt1, the target left and right velocity vt2, and the target angular velocity ωt (S6).

[0079] When the target rotational speed rt of each electric motor 25 is set, the control device 7 controls the current supplied to each electric motor 25 to control each electric motor 25 so that the rotational speed of each electric motor 25 becomes the target rotational speed (S7).

[0080] When the product of the target's forward and backward velocity vt1 and the target's angular velocity ωt is not below the threshold Th, that is, when the calculated product of the target's forward and backward velocity vt1 and the target's angular velocity ωt is greater than the threshold Th (not in S5), the control device 7 performs a correction process to make the product of the target's forward and backward velocity vt1 and the target's angular velocity ωt below the threshold Th (S8).

[0081] In this embodiment, during the correction process, the control device 7 obtains a correction value vt1' that satisfies the following equation (7), sets this correction value vt1' as the target forward and backward velocity vt1, and thereby corrects the target forward and backward velocity vt1.

[0082] vt'≤Th / ωt(7)

[0083] The control device 7 can set the correction value vt1' to the value obtained by dividing the threshold Th by the target angular velocity ωt (i.e., the value on the right side of equation (7)), and it can also set the correction value vt1' to a specified positive number obtained by accumulating the value on the right side of equation (7) to be less than 1.

[0084] When the correction process is completed (S8), the control device 7 uses the corrected target forward / backward speed vt1 and target angular velocity ωt to calculate the thrust F(i) for each omnidirectional wheel 3 (S3). Subsequently, the control device 7 uses equations (4) and (5) to calculate the threshold Th (S4) and determines whether the product of the corrected target forward / backward speed vt1 and the target angular velocity ωt is below the threshold Th (S5). When the product of the corrected target forward / backward speed vt1 and the target angular velocity ωt is below the threshold Th, the target rotational speed rt of each electric motor 25 is set (S6), and the electric motor 25 is controlled (S7). When the product of the corrected target forward / backward speed vt1 and the target angular velocity ωt is greater than the threshold Th, the correction process is executed again (S8).

[0085] Next, the effects of the trolley 1 constructed in this way will be explained.

[0086] When the lateral load fs2 applied by the operator moving the trolley 1 is sufficiently smaller than the front-to-back load fs1 (or, when the coefficient k2 is sufficiently smaller than the coefficients k1 and k3), the trolley 1 rotates while performing circular motion at an angular velocity of the target angular velocity ωt. At this time, the centrifugal force F applied to the trolley 1 is expressed as F = m × vt1 × ωt.

[0087] like Figure 7 As shown, the centrifugal force F applied to the trolley 1 is distributed to each omnidirectional wheel 3, and a load of F / 2 is applied to each omnidirectional wheel 3 in the direction of rotation outward. Furthermore, to prevent the trolley 1 from rotating about its center of gravity G due to the load, a couple f is generated in each of the omnidirectional wheels 3. This couple f acts such that the sum of its resultant force and F / 2 is directed towards the center of gravity G of the trolley 1.

[0088] Based on the condition that the couple acts so that the sum of the resultant forces with F / 2 is directed toward the center of gravity G of the trolley 1, the couple f satisfies the following equation (8).

[0089] (F / 2)×L1=f×L2(8)

[0090] In the omnidirectional wheel 3 located near the center of rotation, the force couple f acts forward whether the trolley 1 is moving forward or backward (see reference). Figure 7On the other hand, in the omnidirectional wheel 3 located on the side furthest from the center of rotation, the couple f acts backwards whether the carriage 1 is moving forward or backward (see also...). Figure 11 ).

[0091] The couple f and the propulsive force F(i) act in the direction of rotation on the omnidirectional wheel 3. Therefore, the sum of the couple f and the propulsive force F(i) equals the maximum static friction force F. max When equation (9) is satisfied, the slippage of each of the omnidirectional wheels 3 in their respective rotation directions can be reduced.

[0092] F(i)+f≤F max (i=1,2)(9)

[0093] By combining the equations F = m × vt1 × ωt, (8), and (9) related to centrifugal force F, we obtain the following equation (10) related to vt1 × ωt.

[0094]

[0095] That is, when the omnidirectional wheels 3 satisfy equation (10) respectively, the omnidirectional wheels 3 are unlikely to slip in the direction of rotation. Therefore, a trolley 1 capable of performing appropriate rotational movements can be provided.

[0096] Moreover, the threshold Th in equation (5) is equivalent to the minimum value on the right side of equation (10). Therefore, by using equations (4) and (5), it is possible to appropriately and easily set the threshold Th, which represents the upper limit of the product of the target's forward and backward velocity and the target's angular velocity, to prevent the omnidirectional wheel 3 from slipping in the direction of rotation.

[0097] In this embodiment, when the product of the target forward / backward velocity vt1 and the target angular velocity ωt is below a threshold Th (Yes in S5), the control device 7 controls the omnidirectional wheel 3 so that the forward / backward velocity becomes the target forward / backward velocity vt1 and the angular velocity becomes the target angular velocity ωt. The threshold Th, as shown in equation (5), is set to be below the minimum value of equation (10), so the product of the target forward / backward velocity vt1 and the target angular velocity ωt is set to satisfy equation (10). As a result, the omnidirectional wheel 3 becomes less prone to slippage.

[0098] Furthermore, when the product of the target forward / backward velocity vt1 and the target angular velocity ωt is greater than the threshold Th (not in S5), the control device 7 corrects the target forward / backward velocity vt1 until its product with the target angular velocity ωt becomes less than or equal to the threshold Th (S8). Therefore, the product of the output forward / backward velocity and angular velocity satisfies equation (7), thus making it difficult for the omnidirectional wheel 3 to slip.

[0099] Furthermore, during the correction process, the control device 7 can easily obtain the correction value vt1' by calculating the right side of equation (7). Therefore, the control device 7 can easily correct the forward and backward velocity vt1 of the target.

[0100] <<Second Implementation>>

[0101] In the second embodiment, when the product of the target forward and backward velocity vt1 and the target angular velocity ωt is greater than the threshold Th (not in S5), the correction process performed by the control device 7 is different from that in the first embodiment. The other structures are the same as in the first embodiment, so the description of the other structures is omitted.

[0102] like Figure 8 As shown, in the second embodiment, when the product of the target's forward and backward velocity vt1 and the target's angular velocity ωt is greater than the threshold Th (not in S5), the control device 7 performs a correction process to make the product of the target's angular velocity ωt and the target's forward and backward velocity vt1 less than the threshold Th (S18).

[0103] In this embodiment, during the correction process, the control device 7 obtains a correction value ωt' that satisfies the following equation (11), sets this correction value ωt' as the target angular velocity ωt, and thereby corrects the target angular velocity ωt.

[0104] ωt'≤Th / vt(11)

[0105] The control device 7 can set the correction value ωt' to the value obtained by dividing the threshold Th by the target forward and backward velocity vt1 (i.e., the value on the right side of equation (11)), and can also set the correction value ωt' to a specified positive number obtained by accumulating the value on the right side of equation (11) to be less than 1.

[0106] When the correction process is completed (S18), the control device 7 uses the target forward / backward speed vt1 and the corrected target angular velocity ωt to calculate the thrust F(i) for each omnidirectional wheel 3 (S3). Subsequently, the control device 7 uses equations (4) and (5) to calculate the threshold Th (S4) and determines whether the product of the target forward / backward speed vt1 and the corrected target angular velocity ωt is below the threshold Th (S5). When the product of the target forward / backward speed vt1 and the corrected target angular velocity ωt is below the threshold Th, the target rotational speed rt of each electric motor 25 is set (S6), and the electric motor 25 is controlled (S7). When the product of the target forward / backward speed vt1 and the corrected target angular velocity ωt is greater than the threshold Th, the correction process is executed again (S18).

[0107] Next, the effect of the trolley 1 constructed in this manner will be explained. When the product of the target forward / backward velocity vt1 and the target angular velocity ωt is greater than the threshold Th (not in S5), the control device 7 corrects the target angular velocity ωt until its product with the target forward / backward velocity vt1 becomes less than or equal to the threshold Th (S18). Therefore, the product of the output forward / backward velocity and angular velocity satisfies equation (10), thus making it difficult for the omnidirectional wheels 3 of the trolley 1 to slip. Therefore, a trolley capable of performing appropriate rotational movements can be provided.

[0108] Furthermore, during the correction process, the control device 7 can easily obtain the correction value ωt' by calculating the right side of equation (11). Therefore, the control device 7 can easily correct the target angular velocity ωt.

[0109] <<Third Implementation Method>>

[0110] In the third embodiment, when the product of the target's forward and backward velocity vt1 and the target's angular velocity ωt is greater than the threshold Th (not in S5), the correction process performed by the control device 7 is different. The other structures are the same as in the first embodiment, so the description of other structures is omitted.

[0111] like Figure 9 As shown, in the third embodiment, when the product of the target forward and backward velocity vt1 and the target angular velocity ωt is greater than the threshold Th (not in S5), the control device 7 performs correction processing on the target angular velocity ωt and the target forward and backward velocity vt1 respectively so that the product of the target angular velocity ωt and the target forward and backward velocity vt1 becomes less than the threshold Th (S28).

[0112] In this embodiment, during the correction process, the control device 7 obtains the forward and backward velocity correction value vt1' and the angular velocity correction value ωt' that satisfy the following equations (12) and (13). Subsequently, the control device 7 replaces the target forward and backward velocity vt1 with the forward and backward velocity correction value vt1' to correct the target forward and backward velocity vt1, and replaces the target angular velocity ωt with the angular velocity correction value ωt' to correct the target angular velocity ωt.

[0113]

[0114] The control device 7 can set the forward and backward velocity correction value vt1' to the value on the right side of equation (12), and it can also set it to a value obtained by accumulating a certain positive number of the values ​​on the right side of equation (12) to be less than 1. The control device 7 can set the angular velocity correction value ωt' to the value on the right side of equation (13), and it can also set it to a value obtained by accumulating a certain positive number of the values ​​on the right side of equation (13) to be less than 1.

[0115] When the correction process is completed (S28), the control device 7 uses the corrected target forward / backward velocity vt1 and the corrected target angular velocity ωt to calculate the thrust F(i) for each omnidirectional wheel 3 (S3). Subsequently, the control device 7 uses equations (4) and (5) to calculate the threshold Th (S4) and determines whether the product of the corrected target forward / backward velocity vt1 and the corrected target angular velocity ωt is below the threshold Th (S5). When the product of the corrected target forward / backward velocity vt1 and the corrected target angular velocity ωt is below the threshold Th, the target rotational speed rt of each electric motor 25 is set (S6), and the electric motor 25 is controlled (S7). When the product of the corrected target forward / backward velocity vt1 and the corrected target angular velocity ωt is greater than the threshold Th, the correction process is executed again (S28).

[0116] Next, the effect of the trolley 1 constructed in this manner will be explained. When the product of the target forward / backward velocity vt1 and the target angular velocity ωt is greater than the threshold Th (not in S5), the control device 7 corrects the target forward / backward velocity vt1 and the target angular velocity ωt until the product of the target forward / backward velocity vt1 and the target angular velocity ωt becomes less than or equal to the threshold Th (S28). Therefore, the product of the output forward / backward velocity and angular velocity satisfies equation (10), thus making it difficult for the omnidirectional wheels 3 of the trolley 1 to slip. Therefore, a trolley capable of performing appropriate rotational movements can be provided.

[0117] Furthermore, during the correction process, the control device 7 can easily obtain the forward and backward velocity correction value vt1' and the angular velocity correction value ωt' by calculating the right side of equations (12) and (13). Therefore, the control device 7 can easily correct the target's forward and backward velocity vt1 and the target's angular velocity ωt.

[0118] <<Variations>>

[0119] As a variation of the first to third embodiments, the control device 7 may also be configured to perform correction processing only when the trolley 1 is reversing, that is, only when the forward and backward speed of the target is negative.

[0120] Figure 10 The flowchart in the modified example of the first embodiment is illustrated below. The control device 7 corrects the forward and backward velocity vt1 of the target only when the forward and backward velocity of the target is negative (S38).

[0121] Next, the effects of the modified examples constructed in this way will be explained.

[0122] For an omnidirectional wheel 3 located on the side furthest from the center of rotation, it is generally required to output a greater thrust F(i) than the side closer to the center of rotation.

[0123] On the other hand, in the omnidirectional wheel 3 located on the side closer to the center of rotation, the couple f always acts forward, while in the omnidirectional wheel 3 located on the side farther from the center of rotation, the couple f always acts backward.

[0124] When trolley 1 moves forward, as Figure 7 As shown, the omnidirectional wheels 3 output propulsive force F(i) in the forward direction. Therefore, when the trolley 1 moves forward, the propulsive force F(i) in the omnidirectional wheel 3 located on the side away from the center of rotation is in the opposite direction to the couple f.

[0125] When trolley 1 moves backward, as Figure 11 As shown, the omnidirectional wheels 3 output thrust F(i) in the rearward direction. Therefore, when the trolley 1 moves backward, the thrust F(i) in the omnidirectional wheel 3 located on the side away from the center of rotation becomes the same direction as the couple f (rearward), which makes it easy for slippage to occur in the omnidirectional wheel 3 located on the side away from the center of rotation.

[0126] By performing correction processing only when the target forward and backward speeds are negative, that is, only when the trolley 1 is reversing, the slippage of the omnidirectional wheel 3 can be reduced, especially when the omnidirectional wheel 3 is prone to slippage during reversal, and the processing that the control device 7 should perform is reduced, thus simplifying the processing performed by the control device 7 for controlling the trolley 1.

[0127] The above describes the specific implementation method, but the present invention is not limited to the described implementation method and can be widely modified and implemented.

[0128] In other embodiments, a sensor capable of detecting the front-to-back load, left-to-right load, and torque about the vertical axis applied to the handle 5 may be used instead of the force sensor 6. For example, the sensor may also be configured by combining multiple independent load sensors.

[0129] In the described embodiment, the trolley 1 is provided with omnidirectional wheels 3, but it is not limited to this embodiment. The trolley 1 can be any form as long as it is provided with a pair of left and right wheels that can be driven based on the target's forward and backward speed and the target's angular velocity instead of the omnidirectional wheels 3.

Claims

1. A trolley, comprising: Body; A pair of wheels, one on the left and one on the right, are mounted on the vehicle body; The left and right drive units drive each of the wheels; A handle is located on the vehicle body to receive user input. Sensors detect the front and rear loads applied to the handle and the torque about the vertical axis; as well as The control device controls the drive unit. The control device is The target front-rear speed of the vehicle body is set based on the front and rear loads. The target angular velocity of the vehicle body about the vertical axis is set based on the torque about the vertical axis. When the product of the target forward / backward velocity and the target angular velocity is greater than a predetermined threshold, the target forward / backward velocity is corrected so that the product of the target forward / backward velocity and the target angular velocity is below the threshold, and the drive unit is controlled based on the corrected target forward / backward velocity and the target angular velocity.

2. The trolley according to claim 1, wherein the mass of the trolley is m, the distance in the front-to-back direction from the center of gravity to the wheel is L1, the distance in the width direction from the center of gravity to the wheel is L2, and the maximum static friction force of the wheel relative to the floor surface is F. max When the propulsive force of each wheel relative to the floor is F(i), the threshold is set to be below the minimum value of the upper limit τ(i) expressed by Equation 3, wherein, i is the independent variable representing the wheel number.

3. The trolley according to claim 1, wherein the control device performs the correction process only when the trolley is reversing.

4. A trolley, comprising: Body; A pair of wheels, one on the left and one on the right, are mounted on the vehicle body; The left and right drive units drive each of the wheels; A handle is located on the vehicle body to receive user input. Sensors detect the front and rear loads applied to the handle and the torque about the vertical axis; as well as The control device controls the drive unit. The control device is The target front-rear speed of the vehicle body is set based on the front and rear loads. The target angular velocity of the vehicle body about the vertical axis is set based on the torque about the vertical axis. When the product of the target forward / backward velocity and the target angular velocity is greater than a predetermined threshold, the target angular velocity is corrected so that the product of the target forward / backward velocity and the target angular velocity is below the threshold, and the drive unit is controlled based on the corrected target angular velocity and the target forward / backward velocity.

5. The trolley according to claim 4, wherein the mass of the trolley is m, the distance in the front-to-back direction from the center of gravity to the wheel is L1, the distance in the width direction from the center of gravity to the wheel is L2, and the maximum static friction force of the wheel relative to the floor surface is F. max When the propulsive force of each wheel relative to the floor is F(i), the threshold is set to be below the minimum value of the upper limit τ(i) expressed by Equation 3, wherein, i is the independent variable representing the wheel number.

6. The trolley according to claim 4, wherein the control device performs the correction process only when the trolley is reversing.

7. A trolley, comprising: Body; A pair of wheels, one on the left and one on the right, are mounted on the vehicle body; The left and right drive units drive each of the wheels; A handle is located on the vehicle body to receive user input. Sensors detect the front and rear loads applied to the handle and the torque about the vertical axis; as well as The control device controls the drive unit. The control device is The target front-rear speed of the vehicle body is set based on the front and rear loads. The target angular velocity of the vehicle body about the vertical axis is set based on the torque about the vertical axis. When the product of the target forward / backward velocity and the target angular velocity is greater than a predetermined threshold, the target forward / backward velocity and the target angular velocity are corrected so that the product of the target forward / backward velocity and the target angular velocity is below the threshold, and the drive unit is controlled based on the corrected target angular velocity and the corrected target forward / backward velocity.

8. The trolley according to claim 7, wherein when the threshold is Th, the target forward / backward speed is vt1, and the target angular velocity is ωt, the control device replaces the target forward / backward speed with a forward / backward speed correction value vt1' satisfying Equation 1, and replaces the target angular velocity with an angular velocity correction value ωt' satisfying Equation 2, thereby performing correction.

9. The trolley according to claim 7, wherein the mass of the trolley is m, the distance in the front-to-back direction from the center of gravity to the wheel is L1, the distance in the width direction from the center of gravity to the wheel is L2, and the maximum static friction force of the wheel relative to the floor surface is F. max When the propulsive force of each wheel relative to the floor is F(i), the threshold is set to be below the minimum value of the upper limit τ(i) expressed by Equation 3, wherein, i is the independent variable representing the wheel number.

10. The trolley according to claim 7, wherein the control device performs the correction process only when the trolley is reversing.

Images