Drive unit

Abstract

A drive unit according to the present disclosure comprises: an elastic structure that includes at least one spiral-shaped spring; a motor that imparts a rotational drive force to the spiral-shaped spring; a first link that is fixed to a body part of the motor; and a second link that is removeable with respect to the spiral-shaped spring.

Description

[Technical field]

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

[0002] Patent Document 1 discloses a walking assistance device that can reduce the burden on the user's body. This walking assistance device assists walking by swinging a lower leg attachment relative to a thigh attachment by driving a motor. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2016-106955 A Summary of the Invention [Problem to be solved by the invention]

[0004] Most of the drive units in the prior art, like the motor in Patent Document 1, were used only for a specific purpose, such as walking assistance. After extensive research, the inventors of the present application have come up with the idea of ​​a drive unit that can be used for a wider variety of purposes.

[0005] That is, an object of the present disclosure is to provide a drive unit that can be used for a wider variety of purposes. [Means for solving the problem]

[0006] One aspect of a drive unit according to the present disclosure comprises an elastic structure including at least one spiral spring, a motor that provides a rotational driving force to the spiral spring, a first link fixed to a main body of the motor, and a second link that is detachable from the spiral spring. Effect of the Invention

[0007] According to the present disclosure, a drive unit that can be used for a wider variety of purposes can be provided. [Brief description of the drawings]

[0008] [Figure 1] FIG. 2 is a perspective view of the drive unit (joint mode) according to the present embodiment. [Diagram 2] FIG. 2 is a perspective view of the drive unit (wheel mode) according to the present embodiment. [Diagram 3] FIG. 2 is an exploded perspective view of the drive unit shown in FIG. [Figure 4] 4 is a view of the detachable part shown in FIG. 3 viewed from the axial direction. [Diagram 5] FIG. 5 is an enlarged perspective view of the periphery of a rib in FIG. 4. [Figure 6] 1. FIG. 4 is a diagram illustrating a procedure for converting the drive unit of FIG. 1 from a joint mode to a wheel mode. [Figure 7] FIG. 2 is a block diagram illustrating a control system of the drive unit according to the embodiment. [Figure 8] 1A to 1C are diagrams illustrating an example of a use of the drive unit according to the present embodiment. [Figure 9] 1A to 1C are diagrams illustrating an example of a use of the drive unit according to the present embodiment. [Figure 10] 1A to 1C are diagrams illustrating an example of a use of the drive unit according to the present embodiment. [Figure 11] 1A to 1C are diagrams illustrating an example of a use of the drive unit according to the present embodiment. [Figure 12] 1A to 1C are diagrams illustrating an example of a use of the drive unit according to the present embodiment. [Figure 13] 1A to 1C are diagrams illustrating an example of a use of the drive unit according to the present embodiment. [Figure 14] FIG. 13 is a perspective view of a drive unit (wheel mode) according to a modified example. [Figure 15] 15 is a perspective view of the drive unit shown in FIG. 14, seen from a different angle. [Figure 16] FIG. 15 is an exploded perspective view of the drive unit shown in FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] Hereinafter, embodiments of the present disclosure will be described with reference to the drawings. Note that the scope of the present disclosure is not limited to the following embodiments, and can be modified as desired within the scope of the technical concept of the present disclosure.

[0010] 1 and 2 are perspective views showing the drive unit 1 according to this embodiment. Fig. 1 shows the drive unit 1 in a "joint mode", and Fig. 2 shows the drive unit 1 in a "wheel mode". That is, the drive unit 1 of this embodiment is capable of switching between the joint mode and the wheel mode.

[0011] As shown in FIG. 1 and FIG. 2, the drive unit 1 includes an elastic structure 10, two motors (a first motor 31 and a second motor 32), a first link 60, a second link 50, and a detachable unit 40. As the motors 31 and 32, for example, DC motors may be adopted, or other types of motors may be adopted. In the joint mode shown in FIG. 1, the first link 60 and the second link 50 swing around a central axis O. In the wheel mode shown in FIG. 2, the elastic structure 10 rotates around a central axis O while maintaining the relative positions of the first link 60 and the second link 50. The central axis O coincides with the rotation centers of the motors 31 and 32.

[0012] (direction definition) In this specification, the direction along the central axis O is referred to as the "axial direction." When viewed from the axial direction, a direction intersecting the central axis O is referred to as the radial direction, and a direction going around the central axis O is referred to as the circumferential direction.

[0013] Fig. 3 is an exploded perspective view of the drive unit 1. As shown in Fig. 3, the elastic structure 10 includes two spiral springs (a first spiral spring 11 and a second spiral spring 12). The two spiral springs 11, 12 are arranged side by side in the axial direction. The two spiral springs 11, 12 have different winding directions. That is, when viewed from the direction along the central axis O, one of the two spiral springs 11, 12 is wound in the CW direction, and the other is wound in the CCW direction.

[0014] The spiral springs 11, 12 are formed, for example, from a thin metal plate. However, the material of the spiral springs 11, 12 may be changed. The drive unit 1 has a first connecting member 13 (see FIG. 6(a)) and a second connecting member 14. The radially inner end of the spiral spring 11 (i.e., the center of the spiral) is fixed to the connecting member 13. The radially inner end of the spiral spring 12 is fixed to the connecting member 14. The connecting members 13, 14 are cylindrical and extend in the axial direction. The connecting members 13, 14 are arranged side by side in the axial direction.

[0015] The holes in the connecting members 13 and 14 are so-called D-cut shaped and engage with the rotating shafts 31b and 32b of the motors 31 and 32, respectively. The tips of the rotating shafts 31b and 32b also have a D-cut shape. Therefore, the rotational driving forces of the motors 31 and 32 are transmitted to the spiral springs 11 and 12, respectively, via the connecting members 13 and 14. That is, the connecting member 13 connects the spiral spring 11 to the motor 31, and the connecting member 14 connects the spiral spring 12 to the motor 32. The connected state between the motors 31 and 32 and the spiral springs 11 and 12 remains unchanged regardless of whether the drive unit 1 is in the joint mode or the wheel mode.

[0016] As shown in FIG. 3, the drive unit 1 includes two expandable tubes (a first tube 21 and a second tube 22). The tube 21 is disposed inside a spiral gap of the spiral spring 11. The tube 22 is disposed inside a spiral gap of the spiral spring 12. The tubes 21 and 22 are each tubular. Although not shown in FIG. 3 etc., the ends of the tubes 21 and 22 are connected to the pump 5 (see FIG. 7). It is more preferable that the tubes 21 and 22 have elasticity.

[0017] When the pump 5 supplies air to the tubes 21, 22, the tubes 21, 22 inflate. Note that the drive unit 1 may have two pumps 5, and each pump 5 may be connected to the tubes 21, 22 individually. Alternatively, the two tubes 21, 22 may be connected to one pump 5. Instead of the pump 5, another type of air supply device may be connected to the tubes 21, 22. The tubes 21, 22 in the inflated state function as dampers that attenuate and transmit force.

[0018] As shown in FIG. 3, the second link 50 is fixed to the detachable part 40. The second link 50 and the detachable part 40 may be formed as one unit. The first link 60 has a connecting member 61, a first support member 62, and a second support member 63. Although detailed description is omitted, the connecting member 61, the first support member 62, and the second support member 63 are fixed to each other by screws or the like. The first link 60 may be composed of two or less members or four or more members. Also, each member of the first link 60 may be fixed to each other by a fixing means other than a screw.

[0019] The first support member 62 has a first side wall portion 62a and a first support portion 62b. The second support member 63 has a second side wall portion 63a and a second support portion 63b. The first side wall portion 62a and the second side wall portion 63a are each plate-shaped. As shown in FIG. 1, the first side wall portion 62a and the second side wall portion 63a face each other in the axial direction. The elastic structure 10 and the detachable portion 40 are located between the first side wall portion 62a and the second side wall portion 63a.

[0020] The first support portion 62b is located at the radially inner end of the first side wall portion 62a, and the second support portion 63b is located at the radially inner end of the second side wall portion 63a. The first support portion 62b and the second support portion 63b are cylindrical and extend in the axial direction. The main body portion 31a of the motor 31 is fixed to the inside of the first support portion 62b. The main body portion 32a of the motor 32 is fixed to the inside of the second support portion 63b. Therefore, the motors 31 and 32 can rotate the respective rotating shafts 31b and 32b with the respective main bodies 31a and 32a supported by the first support portion 62b and the second support portion 63b.

[0021] The connecting member 61 connects a radially outer end of the first side wall portion 62a and a radially outer end of the second side wall portion 63a. The connecting member 61, the first support member 62, and the second support member 63 form the first link 60 into a C-shape as a whole.

[0022] As shown in FIG. 4, the detachable portion 40 has an annular portion 41, a plurality of ribs 42, a plurality of holding portions 43, and a protruding portion 44. The annular portion 41 is annular when viewed in the axial direction. When the drive unit 1 is in the joint mode, the elastic structure 10, the tubes 21, 22, etc. are disposed inside the annular portion 41. The plurality of ribs 42 and the plurality of holding portions 43 are formed on the inner peripheral surface of the annular portion 41 at intervals in the circumferential direction. The protruding portion 44 protrudes radially outward from the annular portion 41. A second link 50 is fixed to the protruding portion 44.

[0023] As shown in Fig. 5, the rib 42 extends in the axial direction. The holding portion 43 has a flange portion 43a and a facing portion 43b. The flange portion 43a extends radially inward from the rib 42. The facing portion 43b extends axially from a radially inner end of the flange portion 43a. The facing portion 43b and the annular portion 41 face each other in the radial direction. The rib 42 is disposed in a portion of the annular portion 41 facing the facing portion 43b.

[0024] A gap is provided between the facing portion 43b and the annular portion 41, and the outermost peripheral portions of the spiral springs 11 and 12 are accommodated in this gap. A plurality of grooves 11a are formed in the outermost peripheral portion of the spiral spring 11, each of which fits into a plurality of ribs 42 (see FIG. 3). Similarly, a plurality of grooves 12a are formed in the outermost peripheral portion of the spiral spring 12, each of which fits into a plurality of ribs 42. The grooves 11a and 12a are recessed radially inward from the outer peripheral surfaces of the spiral springs 11 and 12, and extend in the axial direction. The grooves 11a of the spiral spring 11 and the grooves 12a of the spiral spring 12 may fit into a common rib 42. Alternatively, the grooves 11a and 12a may fit into different ribs 42.

[0025] When the drive unit 1 is in the joint mode (FIG. 1), the rib 42 fits into the grooves 11a and 12a. On the other hand, when the drive unit 1 is in the wheel mode (FIG. 2), the rib 42 is disengaged from the grooves 11a and 12a.

[0026] In this specification, the spiral springs 11, 12, the connecting members 13, 14, the tubes 21, 22, the first link 60, the second link 50, and the detachable part 40 may be collectively referred to as the "conversion mechanism M." The conversion mechanism M enables the drive unit 1 to be converted between the wheel mode and the joint mode. The procedure for converting the drive unit 1 from the joint mode (FIG. 1) to the wheel mode (FIG. 2) will be described with reference to FIG.

[0027] First, as shown in FIG. 6(a), the detachable part 40 and the second link 50 are slid in the axial direction (the direction of the arrow in FIG. 6(a)). This causes the rib 42 of the detachable part 40 to be released from the grooves 11a, 12a of the spiral springs 11, 12. Next, as shown in FIG. 6(b), the detachable part 40 and the second link 50 are rotated around the central axis O. This causes the drive unit 1 to enter the wheel mode shown in FIG. 2. The second link 50 and the first link 60 may be fixed with a fastener or the like so that the relative positions (relative angle around the central axis O) between the second link 50 and the first link 60 are stabilized. In particular, when the elastic structure 10 is used as a wheel of a wheelchair or the like, it is preferable to fix the relative positions between the second link 50 and the first link 60. After the drive unit 1 is switched to the wheel mode, an elastic annular member may be fitted around the outer periphery of the spiral springs 11, 12 (i.e., the outer periphery of the elastic structure 10). The annular member may be given functions such as absorbing shocks like a tire, and preventing slippage between the drive surface and the annular member. Examples of materials for the annular member include rubber and silicon. When switching from the wheel mode to the joint mode, the above-described steps are carried out in reverse.

[0028] The operation of each part in the joint mode and the wheel mode will be described below.

[0029] <In joint mode> In the joint mode, the rib 42 of the detachable part 40 and the grooves 11a, 12a of the spiral springs 11, 12 are fitted together. In this state, the spiral springs 11, 12 and the detachable part 40 are fixed together at least at the fitted portions. The outermost peripheries of the spiral springs 11, 12 are sandwiched between the annular part 41 and the retaining part 43, so that the fitted state of the rib 42 and the grooves 11a, 12a is maintained. In other words, the retaining part 43 has a role of maintaining the fitted state of the rib 42 and the grooves 11a, 12a.

[0030] When the motors 31, 32 rotate, the rotation is transmitted to the center of the spiral springs 11, 12 via the connecting members 13, 14. Since the spiral springs 11, 12 have elasticity, the spiral springs 11, 12 can move relative to the detachable part 40 at a location away from the part where they are fitted with the rib 42. For example, when the motor 31 rotates in a direction opposite to the winding direction of the spiral spring 11, the center of the spiral spring 11 is wound around the outer periphery of the connecting member 13. At this time, at least a part of the rotational force of the motor 31 is also transmitted to the detachable part 40 via the spiral spring 11. Note that the "winding direction" refers to the rotation direction of the spiral from the center of the spiral shape toward the outside.

[0031] Like the motor 31, at least a part of the rotational force of the motor 32 is also transmitted to the detachable part 40. The detachable part 40 is fixed to the second link 50. In other words, when the drive unit 1 is in the joint mode, the rotation of the motors 31, 32 causes the second link 50 and the first link 60 to swing about the central axis O. The responsiveness (transmission rate of the rotational force, response speed, etc.) when the input of the rotation of the motors 31, 32 appears as an output of the swing of the second link 50 and the first link 60 can be controlled by the pressure of the air supplied to the tubes 21, 22.

[0032] For example, when air is supplied to the tubes 21, 22, the tubes 21, 22 expand inside the gaps between the spiral springs 11, 12. When the tubes 21, 22 expand and come into close contact with the spiral springs 11, 12, the apparent rigidity of the elastic structure 10 increases. This increases the transmission rate and response speed of the rotational force from the input (rotation of the motors 31, 32) to the output (oscillation of the second link 50 and the first link 60). The apparent rigidity of the elastic structure 10 is correlated with the air pressure in the tubes 21, 22. In other words, increasing the air pressure in the tubes 21, 22 increases the transmission rate and response speed of the rotational force, and decreasing the air pressure decreases the transmission rate and response speed of the rotational force.

[0033] <In wheel mode> In the wheel mode, as shown in FIG. 2, the spiral springs 11, 12 are not housed inside the annular portion 41 of the detachable portion 40. In other words, the elastic structure 10 is exposed. When the motors 31, 32 are rotated in this state, the spiral springs 11, 12 rotate around the central axis O. Therefore, the elastic structure 10 can be regarded as a single wheel. In addition, it is also possible to change the outer diameter of the elastic structure 10 by controlling the pressure of the air supplied to the tubes 21, 22 and the rotation direction of the motors 31, 32.

[0034] For example, when the pressure of the air supplied to the tubes 21 and 22 is increased, the tubes 21 and 22 expand, and the outer diameter of the elastic structure 10 increases. Conversely, when the pressure of the air supplied to the tubes 21 and 22 is decreased, the tubes 21 and 22 contract, and the outer diameter of the elastic structure 10 decreases. Also, for example, when the motor 31 is rotated in a direction opposite to the winding direction of the spiral spring 11, the outer diameter of the spiral spring 11 increases. Conversely, when the motor 31 is rotated in the same direction as the winding direction of the spiral spring 11, the outer diameter of the spiral spring 11 decreases. FIG. 2 shows a state in which the outer diameter of the elastic structure 10 is made larger than the outer diameter of the annular portion 41 in the detachable portion 40.

[0035] The drive unit 1 has at least six control parameters (the rotation direction of the motor 31, the rotation speed of the motor 31, the rotation direction of the motor 32, the rotation speed of the motor 32, the pressure of the tube 21, and the pressure of the tube 22). Using these six control parameters, it is possible to control the outer diameter, the rotation direction, and the rotation speed of the elastic structure 10 as a wheel.

[0036] Next, the control system of the drive unit 1 will be described with reference to Fig. 7. As shown in Fig. 7, the drive unit 1 is controlled by a control unit C. In this specification, the drive unit 1 and the control unit C may be collectively referred to as the "drive system S." As shown in FIG. 7, the drive unit 1 includes an IMU (Inertial Measurement Unit) sensor 4. The IMU sensor 4 is capable of measuring physical quantities such as the attitude or rotational speed of the conversion mechanism M. The "attitude of the conversion mechanism M" includes, for example, the angle between the first link 60 and the second link 50 when the drive unit 1 is in joint mode. The "rotational speed" includes, for example, the rotational speed of the elastic structure 10 when the drive unit 1 is in wheel mode. Physical quantities other than those mentioned above may be measured by the IMU sensor 4. The measurement results by the IMU sensor 4 are input to the control unit C. The control unit C may execute feedback control of the drive unit 1 based on the measurement results by the IMU sensor 4.

[0037] The control unit C includes a controller 2, an embedded system 3, a pressure sensor 6, a motor sensor 7, a driver 8, etc. When the pump 5 supplies air to the tubes 21, 22, the pressure inside the tubes 21, 22 increases. This pressure is measured by the pressure sensor 6. The motor sensor 7 includes a current sensor that measures the current flowing through the motors 31, 32, an encoder that measures the rotation angles of the motors 31, 32, etc. Measurement data by the pressure sensor 6 and the motor sensor 7 is input to the embedded system 3.

[0038] The controller 2 receives information from the embedded system 3 and generates a control signal for controlling the drive unit 1. The control signal may reflect the calculation result in the feedback control. The control signal is input to the driver 8 via the embedded system 3. The driver 8 supplies current and voltage to the motors 31, 32 and the pump 5 based on the control signal. As a result, the motors 31, 32 rotate the elastic structure 10, and the pump 5 supplies air to the tubes 21, 22.

[0039] Each function of the controller 2, the embedded system 3, etc. is realized by, for example, a hardware processor such as a CPU (Central Processing Unit) executing a program (software). Some or all of these components may be realized by hardware (including circuitry) such as an LSI (Large Scale Integration), an ASIC (Application Specific Integrated Circuit), an FPGA (Field-Programmable Gate Array), or a GPU (Graphics Processing Unit), or may be realized by a combination of software and hardware. The program may be stored in a storage device (not shown) in advance, or may be stored in a removable storage medium (non-transient storage medium) such as a DVD or CD-ROM, and installed in the storage device by mounting the storage medium in a drive device.

[0040] Next, a description will be given of examples of applications of the drive unit 1. Note that each member of the drive unit 1 is shown diagrammatically in Figs. As shown in Fig. 8, the drive unit 1 can be used as a part of a walking assist device. Specifically, the drive unit 1 is in a joint mode, and the second link 50 and the first link 60 are each part of the exoskeleton of the walking assist device. The swinging of the second link 50 and the first link 60 can assist the user in walking.

[0041] As shown in Fig. 9, the drive unit 1 can be used as a part of a wheelchair. Specifically, the drive unit 1 is in a wheel mode, the elastic structure 10 is used as a wheel, and the second link 50 and the first link 60 are used as a supporting frame of the chair. By changing the outer diameter of the elastic structure 10, the size of the wheel can be adjusted to suit the body type of the user. In addition, the walking assistance device shown in Fig. 8 and the wheelchair shown in Fig. 9 can be realized by using the same drive unit 1.

[0042] As shown in Fig. 10, the drive unit 1 can be used in a device that assists a user in standing up. Specifically, as shown in Fig. 10(a), in the drive unit 1 (wheel mode) used as part of a wheelchair, the outer diameter of the elastic structure 10 is deformed to be smaller as shown in Fig. 10(b). At this time, elastic energy is stored in the spiral springs 11 and 12. By releasing this elastic energy and deforming the outer diameter of the elastic structure 10 to be larger, it is possible to assist the user in standing up as shown in Fig. 10(c).

[0043] As shown in Fig. 11, the drive unit 1 can be used as part of a wheelchair whose wheel outer diameter changes. Specifically, the elastic structures 10 of the two drive units 1 are used as both wheels of the wheelchair. As shown in Figs. 11(a) to (c), when one wheel goes over a step, the outer diameter of that wheel (elastic structure 10) is made smaller, and the outer diameter of the other wheel is kept constant. In this case, it is possible to prevent the user from losing their posture when the wheelchair goes over a step.

[0044] As shown in FIG. 12, the drive unit 1 can be used as a part of a wheelchair equipped with an automatic brake function. Specifically, four drive units 1 are provided in the wheelchair. The elastic structures 10 of the two drive units 1 located at the front are the front wheels Wf. The elastic structures 10 of the two drive units 1 located at the rear are the rear wheels Wr. As shown in FIG. 12(a) and (b), when the wheelchair approaches an obstacle while traveling, the outer diameter of the rear wheels Wr is reduced and the outer diameter of the front wheels Wf is increased. As a result, the center of gravity G of the wheelchair moves toward the rear wheels Wr, and the distance between the center of gravity G and the ground is reduced. In this state, the magnitude of the force felt by the user when the wheelchair suddenly stops is reduced. The automatic brake function may be realized by mounting an obstacle sensor that detects an obstacle in front of the wheelchair and incorporating the obstacle sensor into the drive system S (see FIG. 7). Inertial force sensors may be provided at different points on the wheelchair to grasp the position, state, etc. of the wheelchair system.

[0045] As shown in Fig. 13, the drive unit 1 can be used as a wheel for a vehicle. By changing the outer diameter of the elastic structures 10 used as the front and rear wheels of the vehicle, it becomes possible to control the attitude of the vehicle with a high degree of freedom.

[0046] In this embodiment, the elastic structure 10 includes two spiral springs 11 and 12. However, the number of spiral springs may be one. Also, the tubes 21 and 22 may be omitted. Even in these cases, the drive unit 1 can be switched between the joint mode and the wheel mode, and can be used for various purposes. The number of tubes and motors provided in the drive unit 1 may be one, according to the number of spiral springs.

[0047] As described above, the drive unit 1 according to the present disclosure includes an elastic structure 10 including at least one spiral spring (first spiral spring 11 or second spiral spring 12), a motor (first motor 31 or second motor 32) that provides a rotational driving force to the spiral spring, a first link 60 fixed to a main body of the motor, and a second link 50 that is detachable from the spiral spring. According to the present disclosure, a drive unit 1 that can be used for a variety of purposes can be provided.

[0048] The drive unit 1 may further include an expandable tube (first tube 21 or second tube 22) disposed in the spiral gap of the spiral spring. In this case, by controlling the pressure of the air supplied to the tube, it is possible to change the damping performance of the tube or the apparent rigidity of the elastic structure 10.

[0049] Moreover, the elastic structure 10 may include two spiral springs 11, 12, the two spiral springs 11, 12 having different winding directions, and the second link 50 may be detachable from the two spiral springs 11, 12. By using two spiral springs 11, 12 in this manner, the freedom of control of the drive unit 1 is increased, making it possible to use the drive unit for a wider variety of applications.

[0050] The drive unit 1 may also include two expandable tubes 21, 22 arranged in the spiral gaps of the two spiral springs 11, 12. In this case, the degree of freedom in controlling the drive unit 1 can be further increased by using the pressure of the air supplied to each of the two tubes 21, 22 as a control parameter.

[0051] Furthermore, the drive unit 1 may include two motors 31, 32, which provide rotational drive forces to the two spiral springs 11, 12, respectively. In this case, the degree of freedom in controlling the drive unit 1 can be further increased by using the rotation directions and rotation speeds of the two motors 31, 32 as control parameters.

[0052] The drive unit 1 further includes a detachable part 40 fixed to the second link 50, and the detachable part 40 has an annular part 41 capable of accommodating the elastic structure 10 and a rib 42 formed on the inner peripheral surface of the annular part 41 and extending in the axial direction (direction along the central axis O) of the motors 31 and 32, and the spiral springs 11 and 12 may have grooves 11a and 12a that engage with the rib 42. In this case, in the joint mode, the rib 42 and the grooves 11a and 12a are engaged with each other to transmit the driving force of the motors 31 and 32 to the second link 50 via the spiral springs 11 and 12 and the detachable part 40. Therefore, the first link 60 and the second link 50 can be swung. In the wheel mode, the rib 42 is released from the grooves 11a and 12a to allow the elastic structure 10 to rotate relative to the first link 60 and the second link 50, and the elastic structure 10 can be used as a wheel. By sliding the detachable portion 40 in the axial direction relative to the elastic structure 10, the drive unit 1 can be converted between the joint mode and the wheel mode.

[0053] (Modification) Next, a modified example of the embodiment will be described. A drive unit 1A according to the modified example is shown in Fig. 14. In the drive unit 1A, the same parts as those in the drive unit 1 are given the same reference numerals and the description thereof will be omitted.

[0054] As shown in FIG. 14, the drive unit 1A has a detachable part 40A, a second link 50A, a pair of detachable motors 33, a pair of swing arms 70, and a pair of bearings 80. One end of the swing arm 70 is connected to the first link 60 via the bearing 80. The bearing 80 is arranged coaxially with the central axis O. Therefore, the swing arm 70 can swing around the central axis O. However, the bearing 80 has an electromagnetic lock function, and can switch between a swingable state and a non-swingable state of the swing arm 70. Each of the detachable motors 33 is fixed to the other end of each of the swing arms 70. The second link 50A is fixed to the detachable part 40A. The second link 50A has a pair of motor connection parts 51. Each of the motor connection parts 51 extends from the second link 50A toward each of the detachable motors 33. The motor connection part 51 is directly or indirectly connected to the attachment / detachment motor 33. The motor connection part 51 is a part for transmitting the rotational driving force of the attachment / detachment motor 33 to the second link 50A and the attachment / detachment part 40A.

[0055] The detachable portion 40A has an arc-shaped portion 41A. The arc-shaped portion 41A is semicircular. When the drive unit 1A is in joint mode (not shown), the arc-shaped portion 41A abuts against or approaches the elastic structure 10 from the radially outer side. When the drive unit 1A is in wheel mode (FIG. 14), the arc-shaped portion 41A is separated from the elastic structure 10.

[0056] 15, a plurality of electromagnetic locks 42A are provided on the inner peripheral surface of the arc-shaped portion 41A. A plurality of permanent magnets 15 are fixed to the outer peripheral surface of the elastic structure 10 (i.e., the outer peripheral surfaces of the spiral springs 11 and 12) so as to correspond to these electromagnetic locks 42A.

[0057] When the drive unit 1A is in the joint mode, the electromagnetic lock 42A is supplied with power and functions as an electromagnet, generating an attractive force (magnetic force) between the permanent magnet 15. This attractive force fixes the detachable part 40A to the outer circumferential surface of the elastic structure 10. Therefore, when the motors 31 and 32 are driven, the rotational driving force is transmitted to the detachable part 40A via the elastic structure 10. In addition, the detachable part 40A is connected to the swing arm 70 via the second link 50A. As a result, when the motors 31 and 32 are driven, the second link 50A and the first link 60 swing relatively around the central axis O. Note that when the second link 50A and the first link 60 swing relatively, the electromagnetic lock of the bearing 80 is turned off. When it is desired to fix the relative angle between the second link 50A and the first link 60, the electromagnetic lock of the bearing 80 should be turned on.

[0058] When the drive unit 1A is switched from the joint mode to the wheel mode, the electromagnetic lock 42A of the detachment part 40A is turned off. Also, the detachment motor 33 is driven to rotate the second link 50A around the central axis O1 of the detachment motor 33. This causes the detachment part 40A to move away from the elastic structure 10, and the mode becomes the wheel mode.

[0059] When the drive unit 1A is switched from the wheel mode to the joint mode, the detachment motor 33 is driven to rotate the second link 50A around the central axis O1 of the detachment motor 33. This brings the detachment part 40A closer to the elastic structure 10. Furthermore, the electromagnetic lock 42A of the detachment part 40A is turned on. This causes an attractive force to act between the electromagnetic lock 42A and the permanent magnet 15, fixing the detachment part 40A and the elastic structure 10, and the drive unit 1A enters the wheel mode.

[0060] As described above, the drive unit 1A according to the modified example includes the detachable part 40A fixed to the second link 50A and the detachable motor 33 capable of moving the detachable part 40A toward and away from the elastic structure 10. A permanent magnet 15 is disposed on the outer peripheral surface of the elastic structure 10, and the detachable part 40A has an electromagnetic lock 42A capable of generating an attractive force between the permanent magnet 15. With this configuration, it is possible to switch between the joint mode and the wheel mode by controlling the electromagnetic lock 42A and the detachable motor 33. Therefore, it is possible to provide a drive unit 1A in which the mode can be switched more easily.

[0061] The technical scope of the present disclosure is not limited to the above-described embodiment, and various modifications can be made without departing from the spirit of the present disclosure.

[0062] For example, in the above embodiment, the second link 50 is detachable from the spiral springs 11, 12 together with the detachable portion 40. However, a configuration may be adopted in which the detachable portion 40 and the second link 50 are integrally formed, and the second link 50 itself has the annular portion 41, etc.

[0063] In addition, the above-described embodiments and modifications may be combined as appropriate. [Explanation of symbols]

[0064] 1, 1A... Drive unit 10... Elastic structure 11, 12... Spiral spring 11a, 12a... Groove 15... Permanent magnet 21, 22... Tube 31, 32... Motor 33... Detachable motor 40, 40A... Detachable portion 41... Annular portion 42... Rib 42A... Electromagnetic lock 50, 50A... Second link 60... First link

Claims

1. an elastic structure including at least one spiral spring; a motor for applying a rotational driving force to the spiral spring; A first link fixed to a main body of the motor; a second link that is detachable from the spiral spring.

2. The drive unit of claim 1 , further comprising an expandable tube disposed in a spiral gap of the spiral spring.

3. the elastic structure includes two spiral springs including the spiral spring, The two spiral springs have different winding directions, The drive unit according to claim 1 , wherein the second link is detachable from the two spiral springs.

4. The drive unit according to claim 3 , further comprising two expandable tubes disposed in the spiral gaps of the two spiral springs, respectively.

5. Two motors including the motor are provided, The drive unit according to claim 3 , wherein the two motors provide rotational drive forces to the two spiral springs, respectively.

6. A detachable part is further provided, the detachable part being fixed to the second link. the detachable portion has an annular portion capable of accommodating the elastic structure, and a rib formed on an inner circumferential surface of the annular portion and extending in an axial direction of the motor, The drive unit according to claim 1 , wherein the spiral spring has a groove that mates with the rib.

7. A detachable portion fixed to the second link; a motor for attaching and detaching the attachment part to and from the elastic structure, A permanent magnet is disposed on the outer circumferential surface of the elastic structure, The drive unit according to claim 1 , wherein the attachment / detachment section has an electromagnetic lock capable of generating an attractive force between the attachment / detachment section and the permanent magnet.

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