Movable body

Abstract

To detect an abnormality in a transmission mechanism of a movable body.SOLUTION: A movable body 1 comprises a pair of left and right omnidirectional wheels 3 and a control device 7. Each omnidirectional wheel includes: a pair of drive disks 18; a main wheel 19; a pair of electric motors 20; a pair of transmission mechanisms 24; a pair of current sensors 33; and a pair of angular velocity sensors 34. The control device acquires a current actual value for each of the electric motors on the basis of signals from the respective current sensors, calculates the components of driving force of each omnidirectional wheel along a reference line L1 that connects the contact points of the pair of omnidirectional wheels on the basis of each current actual value, and determines that an abnormality has occurred when the absolute value of the difference between the components along the reference line of driving force of the respective omnidirectional wheels is equal to or greater than a predetermined determination value.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a vehicle having a pair of omni-directional wheels. [Background technology]

[0002] Patent Document 1 discloses a moving body having a pair of left and right omnidirectional wheels. Each of the omnidirectional wheels has a pair of drive discs, an annular main wheel arranged between the pair of drive discs, and a pair of electric motors that rotate the drive discs. Each of the electric motors is connected to the corresponding drive disc by a transmission mechanism. The main wheel has an annular core body and a plurality of driven rollers that are rotatably supported by the core body and are in contact with the pair of drive discs. When the pair of electric motors rotate the corresponding drive discs, the driven rollers rotate around their own axes or around the axes of the core body, and the omnidirectional wheels move in translation in any direction including forward / backward and left / right. In addition, the moving body turns due to a difference in the rotation speed between the left and right omnidirectional wheels. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent Publication No. 2023-19525 Summary of the Invention [Problem to be solved by the invention]

[0004] In such a moving body, if an abnormality such as a belt coming off or breaking occurs in any of the transmission mechanisms, the corresponding drive disk will not rotate in response to the rotation of the electric motor. However, the drive disk receives frictional force from the main wheels and rotates together with the main wheels. In this case, the change in the behavior of the moving body is small, and the occupant may not be able to recognize that an abnormality has occurred. However, if an abnormality such as a belt coming off or breaking occurs in the transmission mechanism, the braking torque generated by the electric motor or the braking device provided on the electric motor will not be transmitted to the drive disk. Therefore, it is preferable to detect the abnormality in the transmission mechanism early.

[0005] In view of the above background, an object of the present invention is to detect an abnormality in a transmission mechanism in a moving body. [Means for solving the problem]

[0006] In order to solve the above-mentioned problems, one aspect of the present invention is a moving body (1) comprising a vehicle body (2), a pair of left and right omnidirectional wheels (3) provided on the vehicle body, and a control device (7) for controlling the pair of omnidirectional wheels, each of which comprises a pair of drive discs (18), an annular main wheel (19) disposed between the pair of drive discs, a pair of electric motors (20) for rotating each of the drive discs, a pair of transmission mechanisms (24) for transmitting the rotational force of the electric motor to the corresponding drive disc, a pair of current sensors (33) for detecting the current flowing through each of the electric motors, and a pair of angular velocity sensors (34) for detecting the angular velocity of each of the electric motors, each of which comprises an annular core body (31) and a pair of annular core bodies (31) rotatably supported by the core body. and a plurality of driven rollers (32) in contact with the pair of drive disks, and the control device sets angular velocity target values ​​of each of the electric motors based on a longitudinal velocity target value, a lateral velocity target value, and a yaw angular velocity target value of the vehicle body, feedback controls each of the electric motors so that the angular velocity of each of the electric motors approaches the corresponding angular velocity target value, obtains a current realization value of each of the electric motors based on a signal from each of the current sensors, calculates a component of the driving force of each of the omnidirectional wheels along a reference line (L1) connecting each ground point of the pair of omnidirectional wheels based on each of the current realization values, and determines that an abnormality has occurred when an absolute value of a difference between the components of the driving force of each of the omnidirectional wheels along the reference line is equal to or greater than a predetermined determination value.

[0007] According to this aspect, the moving body can detect an abnormality in the transmission mechanism based on the realized current value of each electric motor. When an abnormality occurs in the transmission mechanism, the torque applied to the electric motor changes compared to normal, and the current flowing through the electric motor changes. As a result, the driving force of the pair of omnidirectional wheels calculated from the current flowing through the electric motor changes. Since the pair of omnidirectional wheels provided on the vehicle body cannot move relative to each other, the components of the driving force of each of the omnidirectional wheels along the reference line are set to be equal. Therefore, by comparing the difference between the components of the driving force of each of the omnidirectional wheels along the reference line with a judgment value, it can be determined whether or not an abnormality has occurred in the transmission mechanism.

[0008] In the above aspect, each of the transmission mechanisms may include a pulley and a belt.

[0009] According to this aspect, the moving body can detect the falling off or breakage of the belt.

[0010] In the above aspect, the control device may set a current target value for each of the electric motors based on a difference between the angular velocity target value and the angular velocity realized value, and set an applied voltage based on the difference between the current target value and the current realized value.

[0011] According to this aspect, the moving body can detect an abnormality in the transmission mechanism based on the realized current value of each electric motor.

[0012] Another aspect of the present invention is a moving body (1) comprising a vehicle body (2), a pair of left and right omnidirectional wheels (3) provided on the vehicle body, and a control device (7) for controlling the pair of omnidirectional wheels, each of which comprises a pair of drive discs (18), an annular main wheel (19) disposed between the pair of drive discs, a pair of electric motors (20) for rotating the respective drive discs, a pair of transmission mechanisms (24) for transmitting the rotational force of the electric motor to the corresponding drive disc, a pair of current sensors (33) for detecting currents flowing through the respective electric motors, and a pair of angular velocity sensors (34) for detecting the angular velocity of the respective electric motors, each of which comprises an annular core body (31), a pair of front wheels (19) rotatably supported by the core body, and a pair of front wheels (19) rotatably supported by the core body. and a plurality of driven rollers (32) in contact with the drive disk, and the control device sets current target values ​​for each of the electric motors based on a longitudinal velocity target value, a lateral velocity target value, and a yaw angular velocity target value of the vehicle body, feedback controls each of the electric motors so that each realized current value of the electric motors approaches the corresponding current target value, obtains an angular velocity realized value of each of the electric motors based on a signal from each of the angular velocity sensors, calculates a velocity component of each of the omnidirectional wheels along a reference line (L1) connecting each ground contact point of a pair of the omnidirectional wheels based on each of the angular velocity realized values, and determines that an abnormality has occurred when an absolute value of a difference between the components of the velocity of each of the omnidirectional wheels along the reference line is equal to or greater than a predetermined determination value.

[0013] According to this aspect, the moving body can detect an abnormality in the transmission mechanism based on the realized angular velocity values ​​of each electric motor. Effect of the Invention

[0014] According to the above configuration, an abnormality in the transmission mechanism in a moving body can be detected. [Brief description of the drawings]

[0015] [Figure 1] FIG. 1 is a perspective view of a moving body according to an embodiment; [Diagram 2] Plan view of the moving object [Diagram 3] Cross-section of an omni-directional wheel [Figure 4] Side view of the main wheel [Diagram 5] Illustration of left and right omni-directional wheels [Figure 6] An explanatory diagram showing the relationship between the rotation and driving force of each drive disk. [Figure 7] FIG. 2 is an explanatory diagram showing a control block of each electric motor of the control device according to the first embodiment; [Figure 8] FIG. 11 is an explanatory diagram showing the relationship between the rotation of each drive disk and the driving force when the right belt of the left omni-directional wheel comes off or breaks. [Figure 9] FIG. 13 is an explanatory diagram showing the relationship between the rotation of each drive disk and the driving force when the left belt of the left omni-directional wheel comes off or breaks. [Figure 10] FIG. 4 is a flow diagram of a control flow for detecting an abnormality in a transmission mechanism, which is executed by the control device according to the first embodiment; [Figure 11] An explanatory diagram showing the relative positions of the left and right omnidirectional wheels [Figure 12] FIG. 1 is a time chart showing the results of abnormality determination control according to the first embodiment; [Figure 13] FIG. 11 is an explanatory diagram showing a control block of each electric motor of a control device according to a second embodiment; [Figure 14] FIG. 4 is a flow diagram of a control flow for detecting an abnormality in a transmission mechanism, which is executed by the control device according to the first embodiment; DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0016] Hereinafter, a moving body according to the present invention will be described with reference to the drawings. First, the configuration of the moving body will be described. In this embodiment, the moving body functions as a dolly. Hereinafter, each direction will be determined based on the moving body.

[0017] As shown in FIG. 1, the mobile body 1 has a vehicle body 2, a pair of left and right omnidirectional wheels 3 mounted on the vehicle body 2 for moving the vehicle body 2 in all directions along the floor surface, a handlebar 5 mounted on the vehicle body 2 for receiving operation from the user, a force sensor 6 for detecting the load applied to the handlebar 5, and a control device 7 for controlling each omnidirectional wheel 3 based on the loads detected by each of the force sensors 6.

[0018] The vehicle body 2 extends in the front-rear direction. A rear portion 2A of the vehicle body 2 extends upward more than a front portion 2B. A support base 11 for supporting other devices is provided on the front portion 2B of the vehicle body 2. The devices supported by the support base 11 include, for example, inspection equipment such as an X-ray scanner. The devices may be fastened to the support base 11. A control device 7, a battery, and various sensors may be provided inside the rear portion 2A of the vehicle body 2.

[0019] In this embodiment, a pair of omni-directional wheels 3 are provided at the bottom of the rear part 2A of the vehicle body 2. Left and right casters 13 are supported at the bottom of the front part 2B of the vehicle body 2 via a suspension. The suspension is disposed below the vehicle body 2 and has an arm 14 extending left and right, and a spring 15 and a shock absorber 16 disposed between the vehicle body 2 and the arm 14. Each caster 13 is disposed below the left and right ends of the arm 14. Each caster 13 has a fork 13A rotatably connected to the arm 14 about an axis extending vertically, and a wheel 13B rotatably supported by the fork 13A about an axis extending horizontally. The fork 13A rotates freely relative to the arm 14, and the wheel 13B rotates freely relative to the fork 13A.

[0020] As shown in Fig. 2, a pair of left and right omnidirectional wheels 3 are arranged at a distance from each other on the left and right. The position and orientation of each omnidirectional wheel 3 are fixed with respect to the vehicle body 2. In this embodiment, the pair of omnidirectional wheels 3 are arranged at the lower left and lower right of the rear part 2A of the vehicle body 2. As shown in Fig. 3, each omnidirectional wheel 3 has a frame 17, a pair of drive discs 18 rotatably supported by the frame 17, an annular main wheel 19 arranged between the pair of drive discs 18, and a pair of electric motors 20 that rotate the drive discs 18, respectively.

[0021] As shown in Figs. 1 and 3, the frame 17 has a frame upper portion 17A connected to the lower portion of the vehicle body 2, and a pair of frame side portions 17B extending downward from both the left and right ends of the frame upper portion 17A. A support shaft 21 extending left and right is hung between the lower ends 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 and the support shaft 21 are arranged coaxially. The axis of the pair of drive discs 18 forms the rotation axis A of the omni-directional wheel 3. The position of each drive disc 18 in the left-right direction is restricted with respect to the support shaft 21. The drive discs 18 face each other at a distance from each other in the left-right direction.

[0022] The drive discs 18 are disposed on both sides of the annular main wheel 19, and apply frictional force to the main wheel 19 to rotate the main wheel 19 about the central axis and about the annular axis. The drive disc 18 has a disk-shaped base 18A rotatably supported by the frame 17, and a plurality of drive rollers 18B that are rotatably supported on the outer periphery of the base 18A at an angle to each other and come into contact with the main wheel 19. The base 18A is disposed coaxially with the support shaft 21.

[0023] The pair of opposing drive discs 18 are formed symmetrically. That is, the positions and orientations of the drive rollers 18B of the left drive disc 18 and the positions and orientations of the drive rollers 18B of the right drive disc 18 are symmetrical to each other.

[0024] As shown in FIG. 5, each drive disk 18 is connected to a corresponding electric motor 20 via an electromagnetic brake 22, a reducer 23, and a transmission mechanism 24. The transmission mechanism 24 transmits the rotational force of the electric motor 20 to the corresponding drive disk 18. Each transmission mechanism 24 has a drive pulley 26 coupled to the output shaft of the corresponding reducer 23, a driven pulley 27 coupled to the corresponding drive disk 18, and a belt 28 stretched between the corresponding drive pulley 26 and the driven pulley 27. The driven pulley 27 is provided coaxially with the drive disk 18. The pair of electric motors 20 are provided at the bottom of the vehicle body 2. The electric motors 20 rotate independently of each other, and thus the drive disks 18 rotate independently of each other.

[0025] As shown in FIG. 4, the main wheel 19 is annular, and is disposed coaxially with the drive disk 18 between the pair of drive disks 18. The main wheel 19 is in contact with the drive rollers 18B and is rotatable around the central axis and the annular axis. The main wheel 19 has an annular core body 31 and a plurality of driven rollers 32 rotatably supported by the core body 31. The driven rollers 32 are arranged at equal intervals in the circumferential direction of the core body 31. Each driven roller 32 is supported by the core body 31 so as to be rotatable around the axis of the annular core body 31 (annular axis). Each driven roller 32 can rotate around a tangent to the core body 31 at its respective position relative to the core body 31. Each driven roller 32 rotates relative to the core body 31 when subjected to an external force.

[0026] The main wheels 19 are arranged along the outer periphery of the pair of drive discs 18, and are in contact with a plurality of drive rollers 18B provided on each drive disc 18. The drive rollers 18B of each drive disc 18 are in contact with the inner periphery of the main wheels 19, and sandwich the main wheels 19 from both the left and right sides. The drive rollers 18B of the left and right drive discs 18 are in contact with the inner periphery of the main wheels 19, thereby restricting radial displacement about the rotation axis A. As a result, the main wheels 19 are supported by the left and right drive discs 18, and the central axis of the main wheels 19 (core body 31) is arranged coaxially with the rotation axis A. The main wheels 19 are in contact with the plurality of drive rollers 18B of the left and right drive discs 18 at the plurality of driven rollers 32.

[0027] The main wheels 19 contact the ground below the rotation axis A. That is, in a plan view, the ground contact point of the omni-directional wheel 3 is located on the rotation axis A. The main wheels 19 are disposed on a plane perpendicular to the rotation axis A.

[0028] As shown in FIG. 5, the left and right omnidirectional wheels 3 have the same configuration. The left omnidirectional wheel 3 is designated 3L with a suffix L. The right omnidirectional wheel 3 is designated 3R with a suffix R. In the left omnidirectional wheel 3L, the left element of the pair of left and right components is designated LL and the right element is designated LR. Similarly, in the right omnidirectional wheel 3R, the left element of the pair of left and right components is designated RL and the right element is designated RR. For example, as shown in FIG. 5, the left omnidirectional wheel 3L has a left electric motor 20LL, a right electric motor 20LR, a left transmission mechanism 24LL, a right transmission mechanism 24LR, a left drive disk 18LL, a right drive disk 18LR, and a main wheel 19L. Similarly, the right omnidirectional wheel 3R has a left electric motor 20RL, a right electric motor 20RR, a left transmission mechanism 24RL, a right transmission mechanism 24RR, a left drive disc 18RL, a right drive disc 18RR, and a main wheel 19R.

[0029] The left drive disc 18LL of the left omnidirectional wheel 3L and the left drive disc 18RL of the right omnidirectional wheel 3R have the same shape. The right drive disc 18LR of the left omnidirectional wheel 3L and the right drive disc 18RR of the right omnidirectional wheel 3R have the same shape.

[0030] Each electric motor 20 is provided with a current sensor 33 (33LL, 33LR, 33RL, 33RR) that detects a current flowing through the electric motor 20. Each electric motor 20 is provided with an angular velocity sensor 34 (34LL, 34LR, 34RL, 34RR) that detects the angular velocity of the electric motor 20.

[0031] As shown in FIG. 11, a straight line connecting the ground contact points of a pair of omnidirectional wheels 3L, 3R is defined as a reference line L1. In a plan view, the left and right main wheels 19L, 19 may be inclined with respect to the reference line L1. In a plan view, the rotation axes A, A of the left and right omnidirectional wheels 3L, 3R may be inclined with respect to the reference line L1. In this embodiment, in a plan view, the reference line L1 extends in the left-right direction. In addition, the left and right main wheels 19L, 19R form an angle of 90 degrees with respect to the reference line L1. In a plan view, the rotation axes A of the left and right omnidirectional wheels 3L, 3R coincide with the reference line L1.

[0032] In each omni-directional wheel 3, when the pair of drive discs 18 rotate in the same direction at the same rotational 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, which coincides with the rotation axis A. At this time, the drive roller 18B of the drive disc 18 and the driven roller 32 of the main wheel 19 do not rotate relative to the core body 31. In each omni-directional wheel 3, when a rotational speed difference occurs between the pair of drive discs 18, a component force in a direction perpendicular to the circumferential (tangential) force caused by the rotation of the pair of drive discs 18 acts on the driven roller 32 of the main wheel 19 from the left and right drive rollers 18B. Since the axis of the drive roller 18B is inclined with respect to the circumferential direction of the drive roller 18B, a component force occurs between the drive discs 18 due to the rotational speed difference. This component force causes the drive roller 18B to rotate relative to the base 18A and the driven roller 32 to rotate relative to the core body 31. As a result, the main wheels 19 generate driving forces in the left and right directions.

[0033] As shown in FIG. 6, when the right drive disk 18 rotates forward and the left drive disk 18 rotates backward (reverse) in each omni-directional wheel 3, the grounded driven roller 32 rotates rightward, generating a rightward driving force component. The black arrow indicates the rotation direction and magnitude of the angular velocity of the drive disk 18. The white arrow indicates the direction and magnitude of the driving force generated by the omni-directional wheel 3. Here, forward rotation is clockwise rotation when the drive disk 18 is viewed from the right, and negative rotation is counterclockwise rotation. At this time, if the angular velocity (number of rotations) of the right drive disk 18 is smaller than the angular velocity of the left drive disk 18, the main wheel 19 rotates backward, generating a backward driving force component. On the other hand, if the angular velocity of the right drive disk 18 is larger than the angular velocity of the left drive disk 18, the main wheel 19 rotates forward, generating a forward driving force component.

[0034] In each omni-directional wheel 3, when the right drive disc 18 rotates in the negative direction and the left drive disc 18 rotates in the positive direction, the grounded driven roller 32 rotates leftward, generating a leftward driving force component. At this time, if the angular velocity (number of rotations) of the right drive disc 18 is smaller than the angular velocity of the left drive disc 18, the main wheel 19 rotates forward, generating a forward driving force component. On the other hand, if the angular velocity of the right drive disc 18 is larger than the angular velocity of the left drive disc 18, the main wheel 19 rotates backward, generating a backward driving force component.

[0035] As shown in FIG. 6, when the right drive disc 18LR of the left omnidirectional wheel 3L rotates forward and the left drive disc 18LL rotates backward at a greater angular velocity than the drive disc 18LR, and at the same time the right drive disc 18RR of the right omnidirectional wheel 3R rotates forward and the left drive disc 18RL rotates backward at a smaller angular velocity than the drive disc 18RR, the moving object 1 turns left while drifting rightward.

[0036] The left and right omnidirectional wheels 3 rotate forward at the same speed, causing the moving body 1 to move forward. The left and right omnidirectional wheels 3 rotate backward at the same speed, causing the moving body 1 to move backward. The left and right omnidirectional wheels 3 generate speed in the forward and backward rotations, causing the moving body 1 to turn to the right or left. The left and right omnidirectional wheels 3 rotate as driven rollers 32 of each main wheel 19, causing the moving body 1 to move in parallel to the right or left.

[0037] As shown in Figs. 1 and 2, a handle holder 35 protruding upward is provided on the upper part of the rear part 2A of the vehicle body 2. The handle 5 is supported by the handle holder 35 via a force sensor 6. The force sensor 6 is preferably a three-axis force sensor that detects loads along two axes perpendicular to each other on a horizontal plane and a moment about a vertical axis (z-axis). In this embodiment, the force sensor 6 detects a front-rear load that is a load in the front-rear direction (x-axis) applied to the handle 5, a left-right load that is a load in the left-right direction (y-axis), and a moment about the vertical axis (z-axis). The force sensor 6 has a main body and an input unit provided in the main body. The main body is connected to the handle holder 35.

[0038] The handle 5 has a horizontal portion 5A extending left and right, and a pair of vertical portions 5B extending forward from the left and right ends of the horizontal portion 5A. A central portion in the left and right direction of the horizontal portion 5A is connected to an input portion of the force sensor 6.

[0039] 2, when a user applies an external force fh and a moment mhz to the position rh of the handle 5, the force sensor 6 detects a detection force fs and a detection moment msz at the sensor position rs. The detection force fs includes a front-rear load, which is a front-rear component, and a left-right load, which is a left-right component.

[0040] The control device 7 is an electronic control unit (ECU) including a processor such as a CPU, a non-volatile memory (ROM), and a volatile memory (RAM). The control device 7 controls each of the omni-directional wheels 3 by executing arithmetic processing in the processor according to a program stored in the non-volatile memory. The control device 7 may be configured as a single piece of hardware, or may be configured as a unit consisting of multiple pieces of hardware. Furthermore, at least a part of each functional unit of the control device 7 may be realized by hardware such as an LSI, an ASIC, or an FPGA, or may be realized by a combination of software and hardware.

[0041] The control device 7 is connected to the force sensor 6, each electric motor 20, each current sensor 33, and each angular velocity sensor 34. The force sensor 6, each current sensor 33, and each angular velocity sensor 34 output detection signals to the control device 7. The control device 7 outputs control signals to each electric motor 20.

[0042] The control device 7 controls each electric motor 20 of each omnidirectional wheel 3 based on signals from the force sensor 6, each current sensor 33, and each angular velocity sensor 34. The force sensor 6 detects the magnitude and direction of the operating force (load) applied to the handle 5 by the user. The control device 7 determines the target longitudinal velocity value, the target lateral velocity value, and the target yaw angular velocity value of the moving body 1 based on the signal from the force sensor 6, and sets the target angular velocity value (target number of rotations) of each electric motor 20 of each omnidirectional wheel 3 based on the target longitudinal velocity value, the target lateral velocity value, and the target yaw angular velocity value. The control device 7 may set the target angular velocity value of each electric motor 20 based on the target longitudinal velocity value, the target lateral velocity value, and the target yaw angular velocity value using a map that specifies the relationship between the target longitudinal velocity value, the target lateral velocity value, and the target yaw angular velocity value and the target angular velocity value of each electric motor 20.

[0043] When the control device 7 sets the angular velocity target value of each electric motor 20 of each omnidirectional wheel 3 based on the longitudinal velocity target value, the lateral velocity target value, and the yaw angular velocity target value, the control device 7 sets the angular velocity target value of each electric motor 20 so that the driving forces in the lateral direction generated by the left and right omnidirectional wheels 3L, 3R are equal. This is because the left and right omnidirectional wheels 3L, 3R cannot move relative to each other in the lateral direction. Note that, when the orientation of the left and right omnidirectional wheels 3L, 3R is inclined with respect to the reference line L1, the control device 7 sets the angular velocity target value of each electric motor 20 so that the driving forces along the reference line L1 generated by the left and right omnidirectional wheels 3L, 3R are equal.

[0044] FIG. 7 shows an example of a control block of the control device 7 corresponding to each electric motor 20. For each electric motor 20, the control device 7 sets a current target value by multiplying the difference between the angular velocity target value and the angular velocity realized value detected by the angular velocity sensor 34 by a gain Kvp. Then, the control device 7 may set an applied voltage to the electric motor 20 by PI control based on the difference between the current target value and the current realized value detected by the current sensor 33. The control device 7 sets an applied voltage independently for each electric motor 20, and applies the set applied voltage to the corresponding electric motor 20. As a result, each electric motor 20 rotates at the angular velocity target value.

[0045] The vehicle body 2 is provided with an alarm device 38. The alarm device 38 includes at least one of an indicator, a display, a warning light, and a speaker.

[0046] (Behavior of transmission mechanism when abnormal) FIG. 8 is an explanatory diagram showing the relationship between the rotation and the driving force of each drive disk 18 when the right belt 28LR of the left omnidirectional wheel 3L is detached or broken. In FIG. 8, the rotation of the drive disks 18LL, 18RL, and 18RR is the same as in FIG. 6, but the rotation of the drive disk 18LR differs from that in FIG. 6 due to the detachment or breakage of the belt 28LR. The black arrow indicates the rotation direction and magnitude of the angular velocity of the drive disk 18. The white arrow indicates the direction and magnitude of the driving force generated by the omnidirectional wheel 3. When the right belt 28LR of the left omnidirectional wheel 3L is detached or broken, the rotation force of the electric motor 20LR is not transmitted to the drive disk 18LR. In this case, the drive disk 18LR rotates together with the main wheel 19 due to frictional force. Therefore, the drive disk 18LR rotates in the same direction and at the same angular velocity as the drive disk 18LL. As a result, the direction of the driving force generated by the left omnidirectional wheel 3L differs from that in FIG. 6. However, since the moving body 1 turns left as in FIG. 6, it is difficult for the user to recognize the abnormality in the belt 28LR.

[0047] FIG. 9 is an explanatory diagram showing the relationship between the rotation and the driving force of each drive disk 18 when the left belt 28LL of the left omnidirectional wheel 3L is detached or broken. In FIG. 9, the rotation of the drive disks 18LR, RL, and RR is the same as in FIG. 6, but the rotation of the drive disk 18LL differs from that in FIG. 6 due to the detachment or breakage of the belt 28LL. The black arrow indicates the rotation direction and magnitude of the angular velocity of the drive disk 18. The white arrow indicates the direction and magnitude of the driving force generated by the omnidirectional wheel 3. When the left belt 28LL of the left omnidirectional wheel 3L is detached or broken, the rotation force of the electric motor 20LL is not transmitted to the drive disk 18LL. In this case, the drive disk 18LL rotates together with the main wheel 19 due to frictional force. Therefore, the drive disk 18LL rotates in the same direction and at the same angular velocity as the drive disk 18LR. As a result, the direction of the driving force generated by the left omnidirectional wheel 3L differs from that in FIG. 6. In this case, the left omnidirectional wheel 3L generates a forward driving force, causing the moving body 1 to turn to the right. Therefore, the behavior of the moving body 1 changes significantly compared to the state shown in FIG.

[0048] (Method of detecting abnormality in transmission mechanism 24) Fig. 10 is a flow diagram of abnormality detection control of the transmission mechanism 24 executed by the control device 7. The control device 7 executes the abnormality detection control shown in Fig. 10 at a predetermined time interval. The control device 7 first acquires the realized current value of each electric motor 20 based on the signal from each current sensor 33 (S1).

[0049] Next, the control device 7 calculates the component F of the driving force of the right omnidirectional wheel 3R along the reference line L1 based on each of the current realization values ​​of the pair of electric motors 20RL, 20RR of the right omnidirectional wheel 3R. 1R Next, the control device 7 calculates the component F of the driving force of the left omnidirectional wheel 3L along the reference line L1 based on the current realization values ​​of the pair of electric motors 20LL, 20LR of the left omnidirectional wheel 3L (S2). 1L Calculate (S3).

[0050] An example of a method for calculating the components of the driving force of the omni-directional wheels 3 from the realized current values ​​of the pair of electric motors 20 of the omni-directional wheels 3 will be described below. In a plan view, the direction perpendicular to the rotation axis A of each omni-directional wheel 3 is defined as the x direction, and the direction along the rotation axis A is defined as the y direction. The driving force F of each omni-directional wheel 3 is D The x-component of F D,x can be calculated based on the sum of the current realization values ​​of the pair of electric motors 20 and the speed ratio from the electric motors 20 to the main wheels 19. D The y-component of F D,y The driving force F of each omni-directional wheel 3 can be calculated based on the difference between the current realization values ​​of the pair of electric motors 20 and the speed ratio from the electric motors 20 to the main wheels 19. D The x-component of F D,x and the y-component F D,y can be calculated from the realized current values ​​of the pair of electric motors 20 based on the following formulas (1) to (3), for example.

number

number

number

[0051] As shown in Fig. 11, in a plan view, the angle between the x direction of the right omnidirectional wheel 3R and the reference line L1 is φ1 [rad], and the angle between the x direction of the left omnidirectional wheel 3L and the reference line L1 is φ2 [rad]. As a result, the component F of the driving force of the right omnidirectional wheel 3R along the reference line L1 is 1R is expressed by the following equation (4).

number

number

[0052] Next, the control device 7 calculates the component F of the driving force of the right omnidirectional wheel 3 along the reference line L1. 1R and the component F of the driving force of the left omnidirectional wheel 3 along the reference line L1. 1L It is determined whether the absolute value of the difference between the measured value and the actual value is equal to or greater than a predetermined determination value (S4). The determination value may be set to, for example, 500 to 1200 N.

[0053] The control device 7 detects the component F of the driving force of the right omnidirectional wheel 3 along the reference line L1. 1R and the component F of the driving force of the left omnidirectional wheel 3 along the reference line L1. 1L If the absolute value of the difference between the values ​​is equal to or greater than the judgment value (the judgment result in S4 is Yes), it is judged that there is an abnormality in the transmission mechanism 24 (S5). When it is judged that there is an abnormality in the transmission mechanism 24, the control device 7 may, for example, control the notification device 38 to notify the user. Furthermore, the control device 7 may prohibit the driving of each electric motor 20, or may suppress the driving amount of each electric motor 20.

[0054] The control device 7 detects the component F of the driving force of the right omnidirectional wheel 3 along the reference line L1. 1R and the component F of the driving force of the left omnidirectional wheel 3 along the reference line L1. 1L If the absolute value of the difference between the above is less than the judgment value (the judgment result of S4 is No), it is judged that there is no abnormality in the transmission mechanism 24 (S6).

[0055] The moving body 1 can detect an abnormality in the transmission mechanism 24 based on the realized current value of each electric motor 20. As described above, the control device 7 calculates the components F of the driving forces of the left and right omnidirectional wheels 3 along the reference line L1. 1R , F 1L In order to set the angular velocity target values ​​of the electric motors 20 so that the components F of the driving forces of the left and right omnidirectional wheels 3 along the reference line L1 are equal to each other, if there is no abnormality in the transmission mechanism 24, 1R , F 1LHowever, if the belt 28 has fallen off or broken, the load on the corresponding electric motor 20 decreases, and the realized current value when the angular velocity target value and the realized angular velocity value match is lower than normal. As a result, the component of the driving force of the right omnidirectional wheel 3 along the reference line L1, which is calculated from the realized current value, changes. Therefore, the control device 7 calculates the component F of the driving force of the right omnidirectional wheel 3 along the reference line L1. 1R and the component F of the driving force of the left omnidirectional wheel 3 along the reference line L1. 1L By measuring whether the absolute value of the difference between the detected value and the reference value is equal to or greater than the judgment value, an abnormality in the transmission mechanism 24 can be detected.

[0056] FIG. 12 is a time chart showing the results of the abnormality determination control when all the transmission mechanisms 24 are normal and when the left belt 28LL of the left omnidirectional wheel 3L is removed. For this measurement, a moving body 1 was used in which the reference line L1 extends in the left-right direction and the angle between the x direction of the left and right omnidirectional wheels 3 and the reference line L1 is 90 degrees. In this moving body 1, the component of each omnidirectional wheel 3L along the reference line L1 coincides with the lateral component (y direction component) of each omnidirectional wheel 3L. In the normal case and when the belt 28LL is removed, the electric motors 20 were driven by giving the longitudinal velocity target value, the lateral velocity target value, and the yaw angular velocity target value. The current realization value of each electric motor 20 at that time was measured, and the absolute value of the difference of the lateral component of each omnidirectional wheel 3L was calculated from the current realization value. The judgment value for determining an abnormality of the belt 28 was set to 800N.

[0057] When all the transmission mechanisms 24 are normal, even if various longitudinal velocity target values, lateral velocity target values, and yaw angular velocity target values ​​are given, the absolute value of the difference in the lateral components of each omnidirectional wheel 3L does not exceed the judgment value, and no abnormality is determined. On the other hand, when the belt 28LL is removed, when the longitudinal velocity target value, lateral velocity target value, and yaw angular velocity target value reach certain values, the absolute value of the difference in the lateral components of each omnidirectional wheel 3L exceeds the judgment value, and an abnormality of the belt 28 is detected. For example, when the longitudinal velocity target value, lateral velocity target value, and yaw angular velocity target value corresponding to the drift turning or lateral translation movement of the moving body 1 are given, the absolute value of the difference in the lateral components of each omnidirectional wheel 3L exceeds the judgment value.

[0058] Second embodiment In the second embodiment, the control device 7 determines the longitudinal velocity target value, the lateral velocity target value, and the yaw angular velocity target value of the moving body 1 based on the signal from the force sensor 6, and determines the current target value of each electric motor 20 of each omni-directional wheel 3 based on the longitudinal velocity target value, the lateral velocity target value, and the yaw angular velocity target value. Then, as shown in FIG. 13, the control device 7 performs feedback control so that the current realization value of each electric motor 20 coincides with the current target value. In this case, the control device 7 can determine an abnormality based on the angular velocity realization value of each electric motor 20 instead of the current realization value of each electric motor 20. The control device 7 executes the abnormality detection control shown in FIG. 14 at a predetermined time interval. The control device 7 first acquires the angular velocity realization value of each electric motor 20 based on the signal from each angular velocity sensor 34 (S11).

[0059] Next, the control device 7 calculates the component v of the velocity of the right omnidirectional wheel 3R along the reference line L1 based on each of the realized angular velocities of the pair of electric motors 20RL, 20RR of the right omnidirectional wheel 3R. 1R Next, the control device 7 calculates the component v of the velocity of the left omnidirectional wheel 3L along the reference line L1 based on each of the realized angular velocities of the pair of electric motors 20LL, 20LR of the left omnidirectional wheel 3L (S12). 1L is calculated (S13).

[0060] An example of a method for calculating the component of the driving force of the omni-directional wheels 3 along the reference line L1 from the realized angular velocity values ​​of the pair of electric motors 20 of the omni-directional wheels 3 will be described below. In a plan view, the direction perpendicular to the rotation axis A of each omni-directional wheel 3 is defined as the x direction, and the direction along the rotation axis A is defined as the y direction. The speed v of each omni-directional wheel 3 is defined as D The x-component of v D,x can be calculated based on the sum of the angular velocity realization values ​​of the pair of electric motors 20 and the speed ratio from the electric motors 20 to the main wheels 19. D The y-component of v D,y can be calculated based on the difference between the angular velocities of the pair of electric motors 20 and the speed ratio from the electric motors 20 to the main wheels 19. D The x-component of v D,x and the y-component v D,y can be calculated from the realized angular velocities of the pair of electric motors 20 based on the following formulas (6) to (8), for example.

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[0061] As shown in FIG. 11, in a plan view, when the angle between the x direction of the right omnidirectional wheel 3R and the reference line L1 is φ1 [rad], and the angle between the x direction of the left omnidirectional wheel 3L and the reference line L1 is φ2 [rad], the component v of the velocity of the right omnidirectional wheel 3R along the reference line L1 is 1R is expressed by the following equation (9).

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[0062] Next, the control device 7 calculates the component v of the speed of the right omnidirectional wheel 3 along the reference line L1. 1R and the component v of the velocity of the left omnidirectional wheel 3 along the reference line L1. 1L It is determined whether the absolute value of the difference between the two is equal to or greater than a predetermined determination value (S14).

[0063] The control device 7 calculates the component v of the speed of the right omnidirectional wheel 3 along the reference line L1. 1R and the component v of the velocity of the left omnidirectional wheel 3 along the reference line L1. 1L If the absolute value of the difference between the speed of the right omnidirectional wheel 3 and the reference line L1 is equal to or greater than the judgment value (YES in S14), it is judged that there is an abnormality in the transmission mechanism 24 (S15). 1R and the component v of the velocity of the left omnidirectional wheel 3 along the reference line L1. 1LIf the absolute value of the difference between the values ​​is less than the determination value (the determination result in S14 is No), it is determined that there is no abnormality in the transmission mechanism 24 (S16).

[0064] Although the specific embodiment has been described above, the present invention is not limited to the above embodiment and can be modified in a wide range of ways. [Explanation of symbols]

[0065] 1: Cart 2: Body 3: Omnidirectional wheels 5: Handle 6: Force sensor 7: Control device 17: Frame 18: Drive disk 18A: Bass 18B: Drive roller 19: Main wheel 25: Electric motor 27: Belt 31: Core body 32: Driven roller

Claims

1. A mobile object, The car body and A pair of left and right omnidirectional wheels provided on the vehicle body; a control device for controlling the pair of omni-directional wheels, Each of the omni-directional wheels includes a pair of drive discs, an annular main wheel disposed between the pair of drive discs, a pair of electric motors for rotating the respective drive discs, a pair of transmission mechanisms for transmitting the rotational force of the electric motors to the corresponding drive discs, a pair of current sensors for detecting currents flowing through the respective electric motors, and a pair of angular velocity sensors for detecting the angular velocity of the respective electric motors; Each of the main wheels has an annular core body and a plurality of driven rollers rotatably supported by the core body and in contact with the pair of drive disks, The control device includes: setting angular velocity target values ​​of the electric motors based on a longitudinal velocity target value, a lateral velocity target value, and a yaw angular velocity target value of the vehicle body, and feedback-controlling each of the electric motors so that the angular velocities of the electric motors approach the corresponding angular velocity target values; obtaining a current realization value of each of the electric motors based on a signal from each of the current sensors; calculating a component of a driving force of each of the omnidirectional wheels along a reference line connecting the grounding points of each of the pair of omnidirectional wheels based on each of the current realizations; The moving body determines that an abnormality has occurred when the absolute value of the difference between the components of the driving forces of the omnidirectional wheels along the reference line is equal to or greater than a predetermined determination value.

2. The moving body according to claim 1 , wherein each of the transmission mechanisms includes a pulley and a belt.

3. 2. The movable body according to claim 1, wherein the control device sets a current target value for each of the electric motors based on a difference between the angular velocity target value and the angular velocity realized value, and sets an applied voltage for each of the electric motors based on the difference between the current target value and the current realized value.

4. A mobile object, The car body and A pair of left and right omnidirectional wheels provided on the vehicle body; a control device for controlling the pair of omni-directional wheels, Each of the omni-directional wheels includes a pair of drive discs, an annular main wheel disposed between the pair of drive discs, a pair of electric motors for rotating the respective drive discs, a pair of transmission mechanisms for transmitting the rotational force of the electric motors to the corresponding drive discs, a pair of current sensors for detecting currents flowing through the respective electric motors, and a pair of angular velocity sensors for detecting the angular velocity of the respective electric motors; Each of the main wheels has an annular core body and a plurality of driven rollers rotatably supported by the core body and in contact with the pair of drive disks, The control device includes: setting current target values ​​for the electric motors based on a longitudinal velocity target value, a lateral velocity target value, and a yaw angular velocity target value of the vehicle body, and feedback-controlling each of the electric motors so that a current realization value of each of the electric motors approaches the corresponding current target value; obtaining an actual angular velocity value of each of the electric motors based on a signal from each of the angular velocity sensors; calculating a component of a velocity of each of the omnidirectional wheels along a reference line connecting each ground contact point of the pair of omnidirectional wheels based on each of the angular velocity realizations; The moving body determines that an abnormality has occurred when the absolute value of the difference between the components of the speeds of the omnidirectional wheels along the reference line is equal to or greater than a predetermined determination value.

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