Articulated wheel mechanism

Abstract

An articulated wheel mechanism 20 is provided with a body (21), a wheel (22), joints (32, 33) for changing the support angle of the wheel with respect to the body, a first motor (MA) for generating power for driving the wheel, and a second motor (MB) for generating power for driving the joints. The articulated wheel mechanism comprises: a differential mechanism (30) that transmits power between the wheel and the joints; and a control unit (40) that controls the rotation state of the first motor and the second motor.

Description

Articulated Wheel Mechanism CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application is based on Japanese Application No. 2024-010911, filed on January 29, 2024, the contents of which are incorporated herein by reference.

[0002] The present disclosure relates to an articulated wheel mechanism that includes a wheel that propels a moving body and a joint that changes the support angle of the wheel relative to the body of the moving body.

[0003] For example, a mobile body includes a first rotating shaft rotatably connected to a main body and supporting the main body, a motor for rotating the first rotating shaft, a first pulley fixed to the first rotating shaft, a second rotating shaft for rotating a wheel, a second pulley fixed to the second rotating shaft, a belt connecting the first pulley and the second pulley, and an arm connecting the first pulley and the second pulley in parallel with the belt (see Patent Document 1). In the mobile body described in Patent Document 1, when the wheel contacts a step and stops rotating, the second pulley stops rotating, and the motor's rotation torque rotates the arm. As a result, the arm lifts the main body and moves the center of gravity beyond the step. After the weight of the main body stops the rotation of the arm around the second rotating shaft, the arm rotates around the first rotating shaft and pulls the wheel up the step. The mobile body described in Patent Document 1 does not require an actuator for driving the arm in addition to the motor for driving the wheel, thereby simplifying its structure.

[0004] JP 2012-240661 A

[0005] Although the moving body (joint wheel mechanism) described in Patent Document 1 can simplify its structure, it is not possible to simultaneously control the drive of the wheels and the drive of the arms (joints).Furthermore, the moving body described in Patent Document 1 cannot use either the power for driving the wheels or the power for driving the arms for the other, and there is still room for improvement.

[0006] The present disclosure has been made to solve the above-mentioned problems, and its main purpose is to enable one of the power driving the wheel and the power driving the joint to be used for the other in a joint wheel mechanism that includes a wheel that drives a moving body and a joint that changes the support angle of the wheel relative to the body of the moving body.

[0007] A first means for solving the above problem is a joint wheel mechanism comprising: a main body; a wheel; a joint that changes the support angle of the wheel relative to the main body; a first motor that generates power to drive the wheel; a second motor that generates power to drive the joint; a differential mechanism that transmits power between the wheel and the joint; and a control unit that controls the rotational states of the first motor and the second motor.

[0008] According to the above configuration, the control unit controls the first motor that generates power to drive the wheels, thereby controlling the driving of the wheels, and the control unit controls the second motor that generates power to drive the joints, thereby controlling the support angle of the wheels with respect to the main body.

[0009] Here, the differential mechanism transmits power between the wheels and the joints. Therefore, for example, while the wheels are being driven by the first motor, the power of the second motor can be transmitted to the wheels via the differential mechanism. Therefore, the power for driving the joints can be used to drive the wheels. As a result, the rated output of the first motor can be reduced, allowing the first motor to be made smaller. Alternatively, by driving the wheels with the power of the first motor and the second motor, the maximum force for driving the wheels can be increased.

[0010] The above and other objects, features, and advantages of the present disclosure will become more apparent from the following detailed description taken in conjunction with the accompanying drawings, in which Fig. 1 is a partially sectional perspective view of a first embodiment of an articulated wheel mechanism, Fig. 2 is a front view of the articulated wheel mechanism of Fig. 1, Fig. 3 is a partially sectional perspective view showing a driving mode of the wheels of the articulated wheel mechanism of Fig. 1, Fig. 4 is a partially sectional perspective view showing a driving mode of the joints of the articulated wheel mechanism of Fig. 1, Fig. 5 is a block diagram showing normal control of the articulated wheel mechanism of Fig. 1, Fig. 6 is a block diagram showing assist control of the articulated wheel mechanism of Fig. 1, and Fig. 7 is a block diagram showing a mode in which a moving object overcomes a step. 8 is a schematic diagram showing a partial cross-sectional perspective view of the joint wheel mechanism of the second embodiment, FIG. 9 is a front view of the joint wheel mechanism of FIG. 8, FIG. 10 is a partial cross-sectional perspective view showing a driving mode of the wheels of the joint wheel mechanism of FIG. 8, FIG. 11 is a partial cross-sectional perspective view showing a driving mode of the joints of the joint wheel mechanism of FIG. 8, FIG. 12 is a partial cross-sectional view of a modified example of the joint wheel mechanism, FIG. 13 is a perspective view of another modified example of the joint wheel mechanism, and FIG. 14 is a perspective view of another modified example of the joint wheel mechanism.

[0011] First Embodiment A first embodiment embodied in a jointed wheel mechanism mounted on a moving body will be described below with reference to the drawings. The moving body includes, for example, four jointed wheel mechanisms and a host controller, and travels on four wheels.

[0012] 1 and 2, the articulated wheel mechanism 20 includes a main body 21, a wheel 22, a planetary gear mechanism 30, a first motor MA, a second motor MB, a cooperative controller 40, a first rotational speed sensor 51, a second rotational speed sensor 52, a wheel speed sensor 54, and a joint angle sensor 55. Note that the bottom 22a of the cylindrical wheel 22 with a bottom is not shown in FIG.

[0013] The main body 21 is formed as part of the main body of the moving body. The main body of the moving body is formed, for example, in the shape of a hollow rectangular parallelepiped. The main bodies 21 of the four joint wheel mechanisms 20 are respectively formed by the four corners of the lower part of the main body of the moving body.

[0014] The main body 21 houses the second motor MB and a cooperative controller 40. The second motor MB is fixed to the main body 21. The second motor MB is, for example, a brushless motor. Power to drive the second motor MB is supplied, for example, from a storage battery (not shown) housed in the main body of the mobile object. The second motor MB has a drive shaft 23. The drive shaft 23 is rotatably supported by the bottoms 22a and 22b of the wheels 22. The drive shafts 23 are rotatably supported on the bottoms 22a and 22b at positions radially spaced a predetermined distance from the center. The rotational state of the second motor MB is controlled by the cooperative controller 40.

[0015] The wheel 22 houses a first motor MA and a planetary gear mechanism 30 therein. The first motor MA is fixed to, for example, the bottom 22b of the wheel 22 on the main body 21 side. The first motor MA is, for example, a brushless motor. Power to drive the first motor MA is supplied from, for example, a storage battery (not shown) housed in the main body of the mobile object. The first motor MA has a drive shaft 25. The drive shaft 25 is fixed to, for example, the center of the bottom 22a of the wheel 22 on the side opposite the main body 21. The cylindrical portion 22c and the bottom 22a of the wheel 22 are fixed, and the cylindrical portion 22c and the bottom 22a rotate together. The cylindrical portion 22c and the bottom 22a are rotatably supported by the bottom 22b. The first motor MA generates power to drive the wheel 22. The rotational state of the first motor MA is controlled by a cooperative controller 40.

[0016] The planetary gear mechanism 30 (differential mechanism) includes a sun gear 31 , planetary gears 32 , and a carrier 33 .

[0017] The sun gear 31 is fixed to the drive shaft 25 of the first motor MA, and rotates integrally with the bottom portion 22a and cylindrical portion 22c (wheel 22) of the wheel 22. The first motor MA inputs power to the sun gear 31.

[0018] The planetary gears 32 are fixed to the drive shaft 23 of the second motor MB. The second motor MB inputs power to the planetary gears 32. The sun gear 31 and the planetary gears 32 are meshed with each other. That is, the sun gear 31 and the planetary gears 32 transmit power to each other. The diameter and number of teeth of the sun gear 31 and the diameter and number of teeth of the planetary gears 32 are set so that the reduction ratio between the sun gear 31 and the planetary gears 32 becomes a desired reduction ratio.

[0019] The carrier 33 connects the sun gear 31 and the planetary gear 32. The carrier 33 is rotatable around the drive shaft 23 of the second motor MB and the drive shaft 25 of the first motor MA. The rotation of the planetary gear 32 and the carrier 33 around the drive shaft 23 changes the support angle of the wheel 22 relative to the main body 21. In other words, the planetary gear 32 and the carrier 33 form the joint of the articulated wheel mechanism 20. The second motor MB generates power to drive the joint. As described above, the planetary gear mechanism 30 transmits power between the wheel 22 and the joint.

[0020] The cooperative controller 40 (controller) is configured by an electronic control unit (ECU) including, for example, a CPU, ROM, RAM, an input / output interface, and drive circuits for the motors MA and MB. The cooperative controller 40 controls the rotational states of the motors MA and MB. Details of the cooperative controller 40 will be described later.

[0021] The first rotational speed sensor 51 detects the rotational speed of the first motor MA and inputs the detection result to the cooperative controller 40. The second rotational speed sensor 52 detects the rotational speed of the second motor MB and inputs the detection result to the cooperative controller 40. The wheel speed sensor 54 detects the rotational speed of the wheels 22 and inputs the detection result to the cooperative controller 40. The joint angle sensor 55 detects the angle of the carrier 33 (joint) with respect to the main body 21 and inputs the detection result to the cooperative controller 40.

[0022] The host controller 90 is configured by, for example, an electronic control unit (ECU) including a CPU, ROM, RAM, an input / output interface, a communication module, etc. The host controller 90 wirelessly communicates with, for example, a management device that collectively controls multiple mobile bodies, and controls each of the joint wheel mechanisms 20 of the mobile bodies.

[0023] Fig. 3 is a partial cross-sectional perspective view showing the driving mode of the wheels 22 of the articulated wheel mechanism 20 of Fig. 1. Note that although the moving body is equipped with four articulated wheel mechanisms 20, the operation of one articulated wheel mechanism 20 will be described here as an example.

[0024] When the mobile object is moving, the first motor MA rotates the drive shaft 25, causing the bottom portion 22a and cylindrical portion 22c of the wheel 22 (hereinafter, sometimes simply referred to as "wheel 22") to rotate. At this time, the rotation of the bottom portion 22b is restricted by the drive shaft 23. This causes the wheel 22 to rotate and the mobile object to move. At this time, the rotation speeds of the motors MA and MB can be set so as to maintain the angle of the carrier 33 relative to the main body 21 (the support angle of the wheel 22 relative to the main body 21), i.e., the angle of the joint of the mobile object.

[0025] In addition to the drive by the first motor MA, the second motor MB rotates the drive shaft 23, thereby assisting the rotation of the wheel 22. Specifically, a force is applied from the planetary gear 32 to the sun gear 31 to rotate the sun gear 31 in the same direction as the drive by the first motor MA rotates the sun gear 31 and the wheel 22. That is, the joint is rotated (the joint rotation direction is set) so that the direction of the power transmitted from the planetary gear 32 to the sun gear 31 corresponds to the direction that rotates the wheel 22 in the target rotation direction, depending on the target rotation direction of the wheel 22. In this case, the rotational speeds of the motors MA and MB can be set so that the rotation of the wheel 22 is assisted and the angle of the joint of the mobile object is changed to the target angle.

[0026] Figure 4 is a partial cross-sectional perspective view showing the driving mode of the joints of the jointed wheel mechanism 20 of Figure 1. Note that although the moving body is equipped with four jointed wheel mechanisms 20, the operation of one jointed wheel mechanism 20 will be described here as an example.

[0027] When driving the joints of the mobile body, the relationship between the rotational direction of the first motor MA and the rotational direction of the second motor MB is set to be opposite to that during running, for example. That is, when driving the joints of the mobile body, the relationship between the rotational speed of the first motor MA and the rotational speed of the second motor MB is set to rotate the carrier 33. Specifically, for example, the drive shaft 25 of the first motor MA is rotated so as to rotate the sun gear 31 in a direction opposite to the direction of the force applied from the planetary gear 32 to the sun gear 31. This causes the sun gear 31 to revolve around the drive shaft 23, thereby rotating the carrier 33, i.e., the joint of the mobile body. Note that even if the direction of the force applied from the planetary gear 32 to the sun gear 31 and the direction in which the drive shaft 25 of the first motor MA rotates the sun gear 31 are the same, the angle of the carrier 33 (joint angle) relative to the main body 21 can be changed by setting the difference in rotational speed (rotational speed) between the motors MA and MB. It is also possible to change the angle of the carrier 33 relative to the main body 21 and simultaneously set the rotation speed of the motors MA and MB so that the wheels 22 rotate to move the mobile body.

[0028] Fig. 5 is a block diagram showing normal control of the joint wheel mechanism 20 of Fig. 1. Note that although the moving body is equipped with four joint wheel mechanisms 20, the operation of one of the joint wheel mechanisms 20 will be described here as an example.

[0029] The host controller 90 communicates with, for example, each of the cooperative controllers 40, transmitting and receiving information to and from each of the cooperative controllers 40. The host controller 90 causes the moving body to follow a path and controls the attitude of the moving body. When performing path following and attitude control, the host controller 90 inputs the target rotational speed ω1ref of each wheel 22 and the target angle θref of the joint to each of the cooperative controllers 40 of each of the jointed wheel mechanisms 20.

[0030] The cooperative controller 40 includes a mechanism control unit 41 and a motor control unit 42 .

[0031] The mechanism control unit 41 calculates the target rotational speed ω1 of the sun gear 31 and the target rotational speed dθ / dt of the planetary gear 32 based on the target rotational speed ω1ref of the wheel 22 and the target angle θref of the joint. Specifically, the mechanism control unit 41 calculates the current (immediate) target rotational speed ω1 of the sun gear 31 based on the difference between the target rotational speed ω1ref of the wheel 22 and the actual rotational speed ω1 detected by the wheel speed sensor 54. The mechanism control unit 41 calculates the current (immediate) target rotational speed dθ / dt of the planetary gear 32 based on the difference between the target angle θref of the joint and the actual angle θ detected by the joint angle sensor 55.

[0032] The mechanism control unit 41 then calculates the target rotational speed ωAref of the first motor MA and the target rotational speed ωBref of the second motor MB based on the target rotational speed ω1 of the sun gear 31 and the target rotational speed dθ / dt of the planetary gears 32. For example, the rotational speeds of the first motor MA and the second motor MB that achieve the target rotational speed ω1 of the sun gear 31 and the target rotational speed dθ / dt of the planetary gears 32 can be obtained in advance based on experiments or the like and specified as a map. Then, the target rotational speed ωAref of the first motor MA and the target rotational speed ωBref of the second motor MB can be calculated by applying the current target rotational speed ω1 of the sun gear 31 and the current target rotational speed dθ / dt of the planetary gears 32 to the map.

[0033] The motor control unit 42 feedback-controls the control variable of the first motor MA so that the rotational speed of the first motor MA becomes the target rotational speed ωAref. For example, the motor control unit 42 feedback-controls the target torque of the first motor MA based on the difference between the target rotational speed ωAref of the first motor MA calculated by the mechanism control unit 41 and the actual rotational speed ωA detected by the first rotational speed sensor 51. The motor control unit 42 feedback-controls the control variable of the second motor MB so that the rotational speed of the second motor MB becomes the target rotational speed ωBref. For example, the motor control unit 42 feedback-controls the target torque of the second motor MB based on the difference between the target rotational speed ωBref of the second motor MB calculated by the mechanism control unit 41 and the actual rotational speed ωB detected by the second rotational speed sensor 52. Note that the feedback control may employ, for example, PI control, PID control, or the like.

[0034] As described above, the motors MA and MB are driven to drive the wheels 22 and the joints. The actual rotational speed ω1 of the wheels 22 is detected by the wheel speed sensor 54. The actual angle θ of the joint is detected by the joint angle sensor 55.

[0035] Fig. 6 is a block diagram showing the assist control of the articulated wheel mechanism 20 of Fig. 1. Note that although the moving body is equipped with four articulated wheel mechanisms 20, the operation of one articulated wheel mechanism 20 will be described here as an example.

[0036] In the planetary gear mechanism 30, the sun gear 31 and the planetary gears 32 transmit power to each other, and a joint is formed by the planetary gears 32 and the carrier 33. Therefore, depending on the direction of rotation of the joint, the direction of power transmitted from the planetary gears 32 to the sun gear 31 changes between a direction that assists or brakes the rotation of the sun gear 31 and, ultimately, the wheel 22. Note that the joint can be controlled to a target angle regardless of the rotation direction.

[0037] Therefore, the cooperative controller 40 is provided with a direction calculation unit 43. Other configurations of the articulated wheel mechanism 20 are the same as those in Fig. 5. In the assist control, only the control related to the direction calculation unit 43 differs from the normal control in Fig. 5.

[0038] The direction calculation unit 43 calculates a sign (dθref / dt) that commands the rotation direction (target angular direction) of the joint based on the target rotational speed ω1ref (including the target rotation direction) of the wheel 22. Specifically, the direction calculation unit 43 calculates the sign (dθref / dt) in accordance with the target rotational direction of the wheel 22 so that the direction of the power transmitted from the planetary gear 32 to the sun gear 31 is a direction that rotates the wheel 22 in the target rotational direction.

[0039] The mechanism control unit 41 sets the rotation direction of the planetary gear 32 to the direction commanded by the sign (dθref / dt), and calculates the current (immediate) target rotation speed dθ / dt of the planetary gear 32. The subsequent control is the same as the normal control in Fig. 5. Note that the joint can be controlled to the target angle regardless of the rotation direction, but here the rotation direction of the joint is set to the direction commanded by the sign (dθref / dt).

[0040] 7 is a schematic diagram showing the manner in which the moving body 10 climbs over a step S. Hereinafter, the front wheels 22 will be referred to as "front wheels 22A" and the rear wheels 22 will be referred to as "rear wheels 22B."

[0041] At time t1, the mobile body 10 is traveling on flat ground. When traveling on flat ground, the mobile body 10 maintains, for example, the front wheels 22A and the rear wheels 22B at the center in the longitudinal direction and at the top in the vertical direction with respect to the main body 21 (a state in which the main body 21 is closest to the ground).

[0042] At time t2, when the front wheel 22A contacts (reaches) the step S, the movable body 10 rotates the joint so as to move the main body 21 forward relative to the front wheel 22A (moving the front wheel 22A rearward relative to the main body 21). This allows the center of gravity of the movable body 10 to move forward relative to the step S together with the driving of the front wheel 22A and the rear wheel 22B. At this time, the joint may be rotated in a direction that assists the rotation of the front wheel 22A (assist control). For example, if the diameter of the wheel 22 is 10 inches and the length of the carrier 33 (joint, leg) is 8 cm, the movable body 10 can overcome a 10 cm step S. Furthermore, by controlling the wheel 22 and the joint, the impact when contacting the step S can be mitigated, making it possible to transport fragile items.

[0043] At time t3, when the front wheels 22A go over the step S, the joints are rotated so that the main body 21 moves upward relative to the rear wheels 22B (the rear wheels 22B move downward relative to the main body 21). This prevents the main body 21 from tilting relative to the horizontal, allowing medicines and drinks to be transported without spilling.

[0044] At time t4, when the rear wheel 22B comes into contact with (reaches) the step S, the movable body 10 rotates the joint so as to move the main body 21 forward relative to the rear wheel 22B (moving the rear wheel 22B rearward relative to the main body 21). As a result, the center of gravity of the movable body 10 can be moved forward relative to the step S together with the driving of the front wheel 22A and the rear wheel 22B. At this time, the joint may be rotated in a direction that assists the rotation of the rear wheel 22B (assist control).

[0045] At time t5, when the rear wheel 22B passes over the step S, the front wheel 22A and the rear wheel 22B are moved to the center in the longitudinal direction and to the top end in the vertical direction relative to the main body 21 (the state where the main body 21 is closest to the ground).

[0046] At time t6, when the mobile object 10 reaches an uphill road, the joint is rotated so that the main body 21 moves upward relative to the rear wheels 22B (moving the rear wheels 22B downward relative to the main body 21). This prevents the main body 21 from tilting relative to the horizontal, allowing medicines or beverages to be transported without spilling. When the mobile object 10 reaches a downhill road, the joint is rotated so that the main body 21 moves upward relative to the front wheels 22A (moving the front wheels 22A downward relative to the main body 21). This prevents the main body 21 from tilting relative to the horizontal.

[0047] The present embodiment described above in detail has the following advantages.

[0048] The planetary gear mechanism 30 transmits power between the wheels 22 and the joints. Therefore, for example, while the wheels 22 are being driven by the first motor MA, the power of the second motor MB can be transmitted to the wheels 22 via the planetary gear mechanism 30. This allows the power that drives the joints to be used to drive the wheels 22. As a result, the rated output of the first motor MA can be reduced, allowing the first motor MA to be made smaller. Alternatively, by driving the wheels 22 with the power of the first motor MA and the second motor MB, the maximum force that drives the wheels 22 can be increased.

[0049] Among the differential mechanisms that combine power, the planetary gear mechanism 30 is small in size, so the articulated wheel mechanism 20 can be made even more compact.

[0050] By setting the number of teeth of the sun gear 31 and the number of teeth of the planetary gears 32, it is possible to flexibly respond to the torque and rotational speed required for the wheels 22 and joints. Furthermore, the planetary gears 32 and the carrier 33 allow the joints to be configured simply. This makes it possible to prevent an increase in the number of parts, such as gears, required to respond to the torque and rotational speed required for the wheels 22 and joints, and allows the joint wheel mechanism 20 to be made more compact.

[0051] The first motor MA and the planetary gear mechanism 30 are housed inside the wheel 22. With this configuration, no space is required in the main body 21 to accommodate the first motor MA and the planetary gear mechanism 30, and the available space in the main body 21 can be increased. As a result, the degree of freedom in vehicle body design can be improved.

[0052] The target rotational speed ω1 of the sun gear 31 and the target rotational speed dθ / dt of the planetary gears 32, and therefore the target rotational speed ωAref of the first motor MA and the target rotational speed ωBref of the second motor MB, can be calculated based on the target rotational speed ω1ref of the wheels 22 and the target angle θref of the joints. Then, by feedback-controlling the rotational speeds of the first motor MA and the second motor MB to the target rotational speed ωAref of the first motor MA and the target rotational speed ωBref of the second motor MB, respectively, the rotational speeds of the wheels 22 and the angles of the joints can be accurately controlled to the respective target rotational speeds ω1ref and target angles θref.

[0053] The direction calculation unit 43 (cooperative controller 40) calculates the target angular direction of the joint according to the target rotation direction of the wheel 22 so that the direction of the power transmitted from the planetary gear 32 to the sun gear 31 is the direction that rotates the wheel 22 in the target rotation direction. Therefore, the power transmitted from the planetary gear 32 to the sun gear 31 can assist the rotation of the sun gear 31 and therefore the wheel 22, and the output required of the first motor MA can be reduced. As a result, the rated output of the first motor MA can be reduced, and the first motor MA can be made smaller.

[0054] The above-described embodiments can be modified as follows: The same parts as those in the above-described embodiments are denoted by the same reference numerals and the description thereof will be incorporated herein.

[0055] 8 and 9 , the planetary gear mechanism 30 may include a planetary gear 34 in addition to the planetary gear 32. Hereinafter, the planetary gear 32 will be referred to as the "first planetary gear 32," and the planetary gear 34 will be referred to as the "second planetary gear 34." The sun gear 31 meshes with the second planetary gear 34. The second planetary gear 34 meshes with the first planetary gear 32. The sun gear 31, the second planetary gear 34, and the first planetary gear 32 are connected by a carrier 33. The sun gear 31 and the first planetary gear 32 transmit power to each other via the second planetary gear 34.

[0056] In this case, too, the diameter and number of teeth of the sun gear 31, the diameter and number of teeth of the first planetary gear 32, and the diameter and number of teeth of the second planetary gear 34 can be set so that the reduction ratio between the sun gear 31 and the first planetary gear 32 becomes a desired reduction ratio. When the reduction ratio between the sun gear 31 and the first planetary gear 32 in FIG. 8 is equal to the reduction ratio between the sun gear 31 and the planetary gears 32 in FIG. 1, the planetary gear mechanism 30 in FIG. 8 has the following advantage. The diameter of the sun gear 31 in FIG. 8 can be smaller than the diameter of the sun gear 31 in FIG. 1, and the diameter of the first planetary gear 32 in FIG. 8 can be smaller than the diameter of the planetary gear 32 in FIG. 1. Therefore, the size of the planetary gear mechanism 30 in FIG. 8 can be smaller than the size of the planetary gear mechanism 30 in FIG. 1. 8, when the reduction ratio between the sun gear 31 and the planetary gears 32 is set to a desired value, the diameters of the sun gear 31 and the first planetary gears 32 can be made smaller than when the sun gear 31 and the planetary gears 32 are directly meshed with each other. Therefore, the planetary gear mechanism 30 can be made smaller.

[0057] Figure 10 is a partial cross-sectional perspective view showing the driving mode of the wheel 22 of the articulated wheel mechanism 20 of Figure 8. The driving mode of the wheel 22 of the articulated wheel mechanism 20 is the same as that of Figure 3, except that the relationship between the rotational direction of the drive shaft 25 and sun gear 31 and the rotational direction of the drive shaft 23 and first planetary gear 32 is opposite to that of Figure 3. Also, Figure 11 is a partial cross-sectional perspective view showing the driving mode of the joint of the articulated wheel mechanism 20 of Figure 8. The driving mode of the joint of the articulated wheel mechanism 20 is the same as that of Figure 4, except that the relationship between the rotational direction of the drive shaft 25 and sun gear 31 and the rotational direction of the drive shaft 23 and first planetary gear 32 is opposite to that of Figure 4.

[0058] As shown in FIG. 12 , the articulated wheel mechanism 20 may include a planetary gear mechanism 130 and a speed-up gear 36. The planetary gear mechanism 130 (differential mechanism) includes a sun gear 31, a first planetary gear 32, a second planetary gear 34, a carrier 33, and an internal gear 35. The first planetary gear 32 meshes with the internal gear 35. The first planetary gear 32 and the carrier 33 form a joint. The articulated wheel mechanism 20 includes a speed-up gear 36. The power of the first motor MA is transmitted to the bottom portion 22 a and the cylindrical portion 22 c of the wheel 22 via the sun gear 31, the second planetary gear 34, the first planetary gear 32, the internal gear 35, and the speed-up gear 36. Even with this configuration, the power that drives the joint can be used to drive the wheel 22.

[0059] 13, the articulated wheel mechanism 20 may include a differential gear 230. The differential gear 230 (differential mechanism) includes a ring gear, a pinion gear, a side gear, etc. With this configuration, the power that drives the joints can also be used to drive the wheels 22. Furthermore, a belt transmission mechanism (differential mechanism) using a timing belt can combine the force that drives the wheels 22 and the force that drives the joints.

[0060] 14 , the articulated wheel mechanism 20 may include a belt 38, a first planetary gear mechanism 330A (differential mechanism), and a second planetary gear mechanism 330B (differential mechanism). With such a configuration, the power for driving the joints can also be used to drive the wheels 22. Furthermore, because both the first motor MA and the second motor MB can be fixed to the main body 21, wiring is easier than with a configuration in which the first motor MA moves relative to the main body 21.

[0061] By lengthening the carrier 33 of the joint wheel mechanism 20 to give it leg functionality, the joint wheel mechanism 20 can also be used as a walking leg wheel mechanism.

[0062] The cooperative controller 40 can also control the rotational speed of the wheels 22 and the angles of the joints by feedforward control instead of feedback control.

[0063] The moving body may be an autonomous vehicle such as an AGV (Automatic Guided Vehicle), an unmanned transport vehicle, or an unmanned transport robot, as well as an outdoor delivery robot, an agricultural robot, a construction site robot, a factory robot, a food distribution robot, a cleaning robot, an inspection robot, etc.

[0064] The number of joint wheel mechanisms 20 provided in the moving body can be set arbitrarily depending on the purpose of each moving body.

[0065] The above-described embodiment and modifications may be combined within the scope of possible combinations.

[0066] The following describes characteristic configurations extracted from the above-described embodiments and modified examples. [Configuration 1] An articulated wheel mechanism (20) comprising: a main body (21); wheels (22); joints (32, 33) for changing the support angle of the wheels relative to the main body; a first motor (MA) for generating power to drive the wheels; a second motor (MB) for generating power to drive the joints; a differential mechanism (30, 130, 230, 330A, 330B) for transmitting power between the wheels and the joints; and a control unit (40) for controlling the rotational states of the first motor and the second motor. [Configuration 2] The articulated wheel mechanism according to Configuration 1, wherein the differential mechanism is a planetary gear mechanism (30, 130, 330A, 330B). [Configuration 3] The planetary gear mechanism (30) comprises a sun gear (31) fixed to the wheel, planetary gears (32) that transmit power to and from the sun gear, and a carrier (33) that connects the sun gear and the planetary gears, the first motor inputs power to the sun gear, and the second motor inputs power to the planetary gears, and the planetary gears and the carrier form the joint. [Configuration 4] The articulated wheel mechanism of Configuration 3, wherein the first motor and the planetary gear mechanism are housed inside the wheel. [Configuration 5] The articulated wheel mechanism according to Configuration 3 or 4, wherein the control unit calculates a target rotational speed of the sun gear and a target rotational speed of the planetary gears based on the target rotational speed of the wheel and the target angle of the joint, calculates a target rotational speed of the first motor and a target rotational speed of the second motor based on the target rotational speed of the sun gear and the target rotational speed of the planetary gears, and feedback-controls the rotational speed of the first motor and the rotational speed of the second motor to the target rotational speed of the first motor and the target rotational speed of the second motor, respectively. [Configuration 6] The articulated wheel mechanism according to Configuration 5, wherein the control unit calculates a target angular direction of the joint in accordance with the target rotational direction of the wheel so that the direction of power transmitted from the planetary gear to the sun gear is a direction that rotates the wheel in the target rotational direction.[Configuration 7] The articulated wheel mechanism according to any one of Configurations 3 to 6, wherein the planetary gears include a first planetary gear (32) and a second planetary gear (34), the second motor inputs power to the first planetary gears, and the sun gear and the first planetary gear transmit power to each other via the second planetary gears.

[0067] Although the present disclosure has been described with reference to the embodiments, it is understood that the present disclosure is not limited to the embodiments or structures. The present disclosure also encompasses various modifications and equivalent modifications. In addition, various combinations and forms, including only one element, more than one element, or less than one element, are also within the scope and spirit of the present disclosure.

Claims

1. An articulated wheel mechanism (20) comprising: a body (21); wheels (22); joints (32, 33) for changing the support angle of the wheels relative to the body; a first motor (MA) for generating power to drive the wheels; a second motor (MB) for generating power to drive the joints; a differential mechanism (30, 130, 230, 330A, 330B) for transmitting power between the wheels and the joints; and a control unit (40) for controlling the rotational states of the first motor and the second motor.

2. The articulated wheel mechanism of claim 1, wherein the differential mechanism is a planetary gear mechanism (30, 130, 330A, 330B).

3. The articulated wheel mechanism according to claim 2, wherein the planetary gear mechanism (30) comprises a sun gear (31) fixed to the wheel, planetary gears (32) which transmit power to and from the sun gear, and a carrier (33) which connects the sun gear and the planetary gears, the first motor inputs power to the sun gear, the second motor inputs power to the planetary gears, and the joint is constituted by the planetary gears and the carrier.

4. The articulated wheel mechanism according to claim 3, wherein said first motor and said planetary gear mechanism are housed inside said wheel.

5. The articulated wheel mechanism of claim 3 or 4, wherein the control unit calculates the target rotational speed of the sun gear and the target rotational speed of the planetary gears based on the target rotational speed of the wheel and the target angle of the joint, calculates the target rotational speed of the first motor and the target rotational speed of the second motor based on the target rotational speed of the sun gear and the target rotational speed of the planetary gears, and feedback-controls the rotational speed of the first motor and the rotational speed of the second motor to the target rotational speed of the first motor and the target rotational speed of the second motor, respectively.

6. The articulated wheel mechanism of claim 5, wherein the control unit calculates a target angular direction of the joint in accordance with the target rotation direction of the wheel so that the direction of power transmitted from the planetary gear to the sun gear is a direction that rotates the wheel in the target rotation direction.

7. An articulated wheel mechanism according to claim 3 or 4, wherein the planetary gears include a first planetary gear (32) and a second planetary gear (34), the second motor inputs power to the first planetary gears, and the sun gear and the first planetary gear transmit power to each other via the second planetary gear.

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