Drive device

Abstract

A drive device (10) is provided with: a center pulley (12) (rotating body) capable of rotating about a center axis (X); a motor (14) that rotates the central pulley (12) in a first direction; a coil spring (16) (energy storage unit), one end (16A) of which is attached to the central pulley (12), the coil spring (16) extending along with the rotation of the central pulley (12) to store energy, and contracting when the energy is released, and the other end (16B) of which moves around the central axis (X) so as to approach the one end (16A); an output part (18) which rotates along with the movement of the coil spring (16); and a lock mechanism (20) capable of switching between a locked state in which the movement of the coil spring (16) is restricted and an unlocked state in which the restriction of the movement of the coil spring (16) is released.

Description

Technical Field

[0001] This disclosure relates to a drive device. Background Technology

[0002] Japanese Patent Application Publication No. 2013-255969 discloses an arm mechanism that, when the arm is fixed by a locking unit, stores energy by stretching a tension coil spring through an actuator, and releases the spring's energy as the rotational force of the arm by releasing the locking unit from the arm. Summary of the Invention

[0003] The technical problem that the invention aims to solve

[0004] In legged mobile robots, if they can not only walk on flat ground but also perform dynamic actions such as jumping or running, they can overcome obstacles and perform a wider range of tasks. For the drive mechanisms used to enable the joints of legged robots to perform high-frequency jumping, agile running, and dynamic movements, the performance of outputting high-speed and high-torque at short intervals is required. Furthermore, to achieve high acceleration, it is preferable to reduce the mass of the drive mechanism.

[0005] When using a small actuator with low output power to reduce mass while aiming for high output, the energy extracted from the actuator increases as energy is stored in the spring for a long time under high reduction ratio and high torque. However, because this structure requires a long time to store energy, it is suitable for movements such as a single vertical jump, but not for movements such as continuous jumping.

[0006] In the above-mentioned existing example, in order for the arm to rotate in the same way again, it is necessary to return the rotated arm to the initial position, which can be considered difficult to perform the action in a short interval.

[0007] The purpose of this disclosure is to enable intermittent and repeated output in a drive device at short intervals.

[0008] Solutions for solving technical problems

[0009] In this drive unit, a rotating body is constantly rotated by an actuator. At the end of this rotating body where an energy storage unit is mounted, if the rotating body is rotated in a locked state where the movement of the energy storage unit is restricted by a locking mechanism, the energy storage unit extends and stores energy. If, while energy is stored, the locking mechanism is released, and the restriction on the movement of the energy storage unit is lifted, the energy storage unit contracts and moves around its central axis so that the other end of the energy storage unit approaches the first end. At this time, the energy stored in the energy storage unit is released. This energy is output from the output unit, which rotates due to the movement of the energy storage unit. Furthermore, since the rotating body at the end with the energy storage unit is constantly rotating by the actuator, reverse rotation of the rotating body is suppressed during energy release, so that the first end of the energy storage unit approaches the second end.

[0010] The rotating body is constantly rotating, so after energy release, energy accumulation immediately begins by locking the energy storage section. That is, there is no need to return the rotating body to its initial position for the next energy accumulation. Therefore, it is possible to intermittently repeat the output with short intervals.

[0011] By utilizing the output of the output unit, such as moving the robot's legs, dynamic actions such as jumping or running can be performed at high frequency.

[0012] The driving device involved in the first method includes: a rotating body capable of rotating about a central axis; an actuator that causes the rotating body to rotate in a first direction; an energy storage unit, one end of which is mounted on the rotating body, extends as the rotating body rotates to store energy, and contracts when the energy is released, and the other end of which moves about the central axis in a manner close to the first end; an output unit that rotates as the energy storage unit moves; and a locking mechanism capable of switching between a locked state that restricts the movement of the energy storage unit and a locked-out state that releases the restriction on the movement of the energy storage unit.

[0013] In the second method, the energy storage unit in the driving device involved in the first method is a constant force spring.

[0014] In this drive unit, the energy storage section is a constant force spring, so even a small, lightweight actuator with relatively low force can extend the energy storage section to store energy.

[0015] In the third method, in the drive device involved in the first method, in addition to the input from the actuator, the energy storage unit also stores the external force input in a manner that causes the energy storage unit to extend as energy.

[0016] In this drive unit, the energy storage unit stores external forces input by extending the energy storage unit, such as the reaction force when the robot's foot contacts the ground, as energy, thus enabling higher performance.

[0017] In the fourth embodiment of the driving device involved in the third embodiment, the driving device further includes a planetary gear mechanism, which comprises: a sun gear; planetary gears that mesh with the sun gear and rotate on their own axis while revolving around the sun gear; and an internal gear that meshes with the planetary gears. The actuator, in addition to rotating the rotating body, also rotates the sun gear. The other end of the energy storage unit is mounted on a bracket supporting the planetary gears, and the output unit outputs the rotational torque of the internal gear.

[0018] In this drive unit, the inputs to the planetary gear mechanism include an input from the actuator to the sun gear and an input from the energy storage unit to the support. The input from the energy storage unit to the support also includes energy stored by external forces. The output from the planetary gear mechanism is output from the internal gear to the output unit. The output is determined by the difference between the rotation of the sun gear and the rotation of the support.

[0019] According to this disclosure, it is possible to repeatedly output intermittently at short intervals. Attached Figure Description

[0020] Figure 1 This is a schematic diagram illustrating the drive device involved in this embodiment.

[0021] Figure 2 This diagram schematically illustrates the function of the energy storage unit in the drive device according to this embodiment, where the energy storage unit is in a locked state and energy is stored in the energy storage unit.

[0022] Figure 3 This diagram schematically illustrates the function of the energy storage unit in the drive device according to this embodiment when the energy storage unit is in a locked-out state and energy is released from the energy storage unit.

[0023] Figure 4 This is a diagram showing the appearance of the experimental setup.

[0024] Figure 5 It is a line graph showing the test results. Detailed Implementation

[0025] The embodiments for carrying out this disclosure will now be described based on the accompanying drawings. In the drawings, elements indicated by the same reference numerals refer to the same or identical elements. Furthermore, in the embodiments described below, repeated descriptions and reference numerals are sometimes omitted. Moreover, the drawings used in the following description are schematic, and the dimensional relationships and scales of the elements shown may not necessarily correspond to actual elements. Furthermore, the dimensional relationships and scales of the elements may not necessarily be consistent between the various drawings.

[0026] exist Figure 1 In this embodiment, the drive device 10 includes: a central pulley 12 as a rotating body, an electric motor 14 as an actuator, a coil spring 16 as an energy storage unit, an output unit 18, a locking mechanism 20, and a planetary gear mechanism 22.

[0027] The central pulley 12 is capable of rotating around the central axis X. A gear 24 is mounted on the same axis as the central pulley 12.

[0028] The electric motor 14 is used to move the central pulley 12 in the first direction, specifically in Figure 2 , Figure 3 The drive source, rotating to the left, rotates stably during operation. A pinion 26 and a gear 28 are coaxially mounted on the rotating shaft of the motor 14. The pinion 26 meshes with gear 24 of the central pulley 12. The gear 28 meshes with gear 30, which is capable of rotating about the central axis X. A sun gear 36 of a planetary gear mechanism 22 is mounted, for example, coaxially with gear 30. As gear 30 rotates, sun gear 36 also rotates. In this embodiment, the motor 14 rotates in the direction opposite to the first direction (rightward), while the central pulley 12 and sun gear 36 rotate in the first direction (leftward).

[0029] The coil spring 16 is a constant-force spring. One end 16A is mounted to the central pulley 12, extending as the central pulley 12 rotates to store energy, and contracting when the energy is released. The other end 16B moves about the central axis X in a manner close to one end 16A. A constant-force spring is a spring whose load is approximately constant regardless of its stroke. One end 16A of the coil spring 16 is mounted on, for example, the outer circumferential surface of the central pulley 12. The other end 16B of the coil spring 16 is mounted on an arm 42A extending from the bracket 42 of the planetary gear mechanism 22, which will be described later. Alternatively, other components may be clamped in the mounting of one end 16A and the other end 16B of the coil spring 16. As long as the structure is such that, with the rotation of the central pulley 12 during energy storage, one end 16A extends away from the other end 16B, and contracts when the energy is released, the other end 16B can move about the central axis X in a manner close to one end 16A.

[0030] The output section 18 is a part that rotates along with the movement of the coil spring 16. Figure 1 The shaft, which is equivalent to bevel gear 44, is in Figure 2 , Figure 3 The middle part is equivalent to the internal gear 40 of the planetary gear mechanism 22 described later.

[0031] Locking mechanism 20 is capable of switching the locking state that restricts the movement of disc spring 16. Figure 2 ) and the locked release state that releases the restriction on the movement of the coil spring 16 ( Figure 3The locking mechanism 20 has, for example, a motor 32 and a latch 34 as a locking component. The latch 34 is driven by the motor 32 and is configured to engage with the bracket 42 or a component that rotates with the bracket 42. By engaging the latch 34 with, for example, the bracket 42, the bracket 42 is in a locked state that restricts its rotation. By disengaging the latch, the bracket 42 is in a unlocked state that allows it to rotate.

[0032] In addition to the input from the electric motor 14, the coil spring 16 also stores energy from the external force input in a way that causes it to extend. To achieve this, a one-way clutch such as a ratchet can also be used in the locking mechanism 20. That is, in Figure 2 , Figure 3 In the middle, the bracket 42 in the locked state cannot rotate to the left where the coil spring 16 retracts, but the coil spring 16 can rotate to the right where it extends.

[0033] The planetary gear mechanism 22 includes: a sun gear 36; for example, three planetary gears 38 that mesh with the sun gear 36 and rotate on their own axis while revolving around the sun gear 36; and an internal gear 40 that meshes with the planetary gears 38.

[0034] In addition to rotating the central pulley 12, the electric motor 14 also rotates the sun gear 36 via the pinion 26, the large gear 28, and the gear 30, as described above. The other end 16B of the coil spring 16 is mounted on the bracket 42 that supports the planetary gear 38. The output section 18 outputs the rotational torque of the internal gear 40.

[0035] The planetary gear mechanism 22 is in Figure 1 The part described is a differential mechanism. A planetary gear mechanism is a type of differential mechanism; therefore, planetary gear mechanism 22 can also be a differential mechanism. Figure 1 In the differential mechanism, the rotation of the motor 32 is input to the side gear 46 via the large gear 28 and the gear 30. Furthermore, the rotation of a component corresponding to the bracket 42 mounted on the other end 16B of the disc spring 16 is transmitted to the side gear 50 opposite the side gear 46. The pinion 48 meshes with the side gears 46 and 50. A ring gear 52 is mounted in the housing 49 supporting the pinion 48. The ring gear 52 meshes with the bevel gear 44 of the output section 18. Figure 1 In the differential device, due to the different rotation of the side gears 46 and 50, the pinion 48 rotates along the side gears 46 and 50, thereby rotating the ring gear 52 and outputting the rotational torque of the bevel gear 44 from the output unit 18.

[0036] In this mechanism, the planetary gear mechanism 22 can also be configured such that, during energy accumulation, each central pulley 12 (denoted as "A") and the support 42 (denoted as "B") rotates in opposite directions by an angle θ. o1and the angle θ of the support 42 rotation during energy release. o2 They are facing opposite directions and are equal in size (θ) o1 =-θ o2 The sequence of designing such a planetary gear mechanism 22 will be explained. First, let the rotation angle of A be θ. a Let the rotation angle of B be θ. b The output angle via planetary gear mechanism 22 is set as θ. o =k a θ a +k b θ b At this time, k a k b This is the transfer ratio from each input to the output. Then, during energy accumulation, from when B is fixed until its release, A rotates by an angle θ. a =θ. Since B is fixed, θ b =0. Therefore, the rotation angle θ during energy accumulation is... o1 =k a θ. On the other hand, during energy release, because B shifts the amount of elastic energy stored in the coil spring 16, it shifts θ. b =θ. If motor 14 continues to rotate during energy release, but θ during energy release... a So small as to be negligible (θ) a If ≈0), then the output angle θ during energy release is... o2 =k b θ. Because of θ o1 =-θ o2 Therefore, k a =-k b Therefore, the output of the planetary gear mechanism 22 is represented as follows.

[0037] [Mathematical Expression 1]

[0038] According to this formula, the actuation mechanism can be said to be a mechanism that outputs the angle difference between A and B, i.e. the elongation of the coil spring 16, regardless of the position of the central pulley 12 (A) and the bracket 42 (B).

[0039] Furthermore, the contributions from the two inputs to the output in the planetary gear mechanism 22 are expressed as follows. First, the relationship between the input sun gear 36 and the output internal gear 40: If the rotation angle of the motor 14 during energy accumulation is set as θi, then the contribution to the output θi is... o1 It is represented as follows.

[0040] [Mathematical Expression 2]

[0041] Here, Z a Z c These are the number of teeth on the sun gear (36) and the internal gear (40), respectively, N. i1 This is the reduction ratio between the electric motor 14 and the sun gear 36. Next, if the spring system is considered as the input to the support 42, it becomes a configuration of a sun-type planetary gear unit. Furthermore, the rotation angle of the support 42 is equal to the rotation angle of the central pulley 12 during energy accumulation. If the reduction ratio between the electric motor 14 and the central pulley 12 is set to N... i2 The contribution θ to the final output is then... o2 It is represented as follows.

[0042] [Mathematical Expression 3]

[0043] Therefore, the final output θ of the planetary gear mechanism 22 is used. o It is represented as follows.

[0044] [Mathematical Expression 4]

[0045] To make it equivalent to equation (1), we only need θ o1 / θ o2 =-1 is sufficient. Therefore, the following relationship must be satisfied.

[0046] [Mathematical Expression 5]

[0047] Since the number of teeth that can be selected based on the planetary gear mechanism 22 is limited, in actual design, Z is selected first. a Z c Then set N i1 N i2 The order. As a design example, Z a =19, Z c =57, N i1 =1 / 2, N i2 =2.

[0048] (effect)

[0049] This embodiment is configured as described above, and its function will be explained below. Figure 2 , Figure 3 In the diagram, thin arrows indicate rotation from motor 14, thick arrows indicate rotation from coil spring 16, and dashed lines indicate direct rotational transmission. That is, components connected by dashed lines rotate as a single unit. Arrows labeled "OUTPUT" indicate rotation of output unit 18. Figure 2 The double-dotted arrow in the image indicates the rotation of the support 42 caused by external force.

[0050] exist Figure 2 , Figure 3 In the drive device 10 according to this embodiment, the central pulley 12 is constantly rotated by the electric motor 14. One end 16A of the central pulley 12 is mounted with a coil spring 16. If the locking mechanism 20 is in the unlocked state, the coil spring 16 and the central pulley 12 (rotating body) rotate as one. If the central pulley 12 is rotated in the locked state, in which the movement of the coil spring 16 is restricted by the locking mechanism 20, the coil spring 16 extends and stores energy.

[0051] If the locking mechanism 20 is released while the energy is stored, thus removing the restriction on the movement of the coil spring 16, the coil spring 16 contracts, and the other end 16B of the coil spring 16 moves about the central axis X in a manner close to one end 16A. At this time, the energy stored in the coil spring 16 is released. This energy is output from the output section 18, which rotates due to the movement of the coil spring 16.

[0052] Furthermore, the central pulley 12, which has one end 16A of the coil spring 16 mounted on it, is always rotating via the motor 14. Therefore, when energy is released, the reverse rotation of the central pulley 12 is suppressed, so that one end 16A of the coil spring 16 is brought closer to the other end 16B. Due to the accumulation of greater elastic energy, the maximum efficient torque of the motor 14 can be applied regardless of the spring's displacement.

[0053] The central pulley 12 is always directed in the first direction by the rotation of the electric motor 14. Figure 2 , Figure 3 The coil spring 16 rotates to the left, thus immediately initiating energy accumulation after energy release by locking the coil spring 16. That is, there is no need to return the central pulley 12 to its initial position for the next energy accumulation. Therefore, the output can be repeated intermittently at short intervals.

[0054] By utilizing the output of output unit 18, for example, the robot's legs can be moved, thereby enabling dynamic actions such as jumping or running at high frequency. Furthermore, by utilizing the output of output unit 18, the robot's hands can be moved, thereby enabling high-frequency vibration of flasks and other implements, or rhythmic movement of tools such as cutting tools. Moreover, high-frequency processing can be achieved using processing machinery that requires large instantaneous forces, such as stamping presses used in metal processing.

[0055] In this drive unit, a disc spring 16, which is a constant-force spring, is used as an energy storage unit. Therefore, even a small, lightweight, and relatively low-force electric motor 14 can extend the disc spring 16 to store energy. Furthermore, by using a constant-force spring, the maximum efficiency torque of the electric motor 14 can be applied regardless of the spring's displacement, and a greater amount of elastic energy can be stored.

[0056] By using, for example, a one-way clutch in the locking mechanism 20, the coil spring 16 can store external forces input in a way that causes the coil spring 16 to extend, such as the reaction force when the robot's foot contacts the ground, as energy, thus enabling it to achieve higher performance.

[0057] When using the planetary gear mechanism 22, the inputs to the planetary gear mechanism 22 include an input from the motor 14 to the sun gear 36 and an input from the coil spring 16 to the support 42. The input from the coil spring 16 to the support 42 also includes energy stored by external forces, such as the reaction force from the robot's feet contacting the ground. The output from the planetary gear mechanism 22 is output from the internal gear 40 to the output section 18. The output is determined by the difference between the rotation of the sun gear 36 and the rotation of the support 42.

[0058] Thus, according to this embodiment, it is possible to continuously output power intermittently at short intervals while making the motor 14 rotate stably with maximum efficiency.

[0059] [Other Implementation Methods]

[0060] The above describes one example of an embodiment of the present disclosure. However, the embodiments of the present disclosure are not limited to the above-described embodiments. In addition to the above, various modifications can be made without departing from its spirit.

[0061] (Experimental example)

[0062] To evaluate the characteristics of the proposed mechanism, a motion was performed involving lifting a heavy object using a spring-based high-output mechanism. In the experiment, as shown... Figure 4As shown, the drive device according to this embodiment is fixed to a frame, and a weight is lifted by winding a metal wire around a pulley connected to the output unit. The weights used in the tests were 500g, 1000g, and 1500g. To stretch the spring with each weight, the rotation angle of the central pulley was increased by five stages in 45-degree increments. During this process, from the activation of the locking mechanism to the complete stop of the spring system, the position of the spring system moves; therefore, the input angle and the spring elongation are not proportional but linear. In this test, since locking begins when the central pulley rotates to a minimum of 67.5 degrees, 67.5 + 45 degrees was set as the minimum input angle. A torque meter (UNIPULSE UTMII-10Nm) was used to measure the maximum torque and maximum speed of the output unit during energy release in each test. Measurements were performed 10 times under each condition, and the average value was obtained.

[0063] Figure 5 The results of the measurement are shown. Figure 5 In the diagram, the horizontal axis represents the input angle, and the vertical axis represents the rotational speed. By increasing the input angle under all conditions, we can observe a tendency for the output speed to increase, but this increase is not linear and continuous; rather, it shows a tendency for the rate of speed increase to decrease as the input angle increases. This can be attributed to factors such as friction in the rotating components of the device, which limit the speed increase.

[0064] [Postscript]

[0065] The following notes describe the possible methods that may be used in this disclosure.

[0066] (Note 1)

[0067] A driving device, comprising: A rotating body capable of rotating about a central axis; An actuator causes the rotating body to rotate in a first direction; An energy storage unit is installed at one end on the rotating body, which extends as the rotating body rotates to store energy and contracts when the energy is released. The other end moves around the central axis in a manner close to the first end. The output section rotates as the energy storage section moves; and The locking mechanism is capable of switching between a locked state that restricts the movement of the energy storage unit and a unlocked state that releases the restriction on the movement of the energy storage unit.

[0068] (Note 2)

[0069] According to the drive device described in Appendix 1, wherein... The energy storage unit is a constant force spring.

[0070] (Note 3)

[0071] According to the driving device described in Appendix 1 or Appendix 2, wherein, In addition to the input from the actuator, the energy storage unit also stores external forces input in a manner that causes the energy storage unit to extend as energy.

[0072] (Note 4)

[0073] The drive device according to any one of Appendices 1 to 3, wherein... The drive unit also includes a planetary gear mechanism, which comprises: a sun gear; planetary gears that mesh with the sun gear and rotate on their own axis while revolving around the sun gear; and internal gears that mesh with the planetary gears. The actuator, in addition to rotating the rotating body, also rotates the sun gear. The other end of the energy storage unit is mounted on a bracket that supports the planetary gear. The output unit outputs the rotational torque of the internal gear.

[0074] The entire disclosure of Japanese Patent Application No. 2023-144866, filed on September 6, 2023, is incorporated herein by reference.

[0075] All documents, patent applications and technical specifications described in this specification are identical to those specifically described and incorporated herein by reference.

[0076] Explanation of reference numerals in the attached figures

[0077] 10: Drive unit; 12: Central pulley (rotating body); 14: Electric motor; 16: Disc spring (energy storage part); 16A: One end; 16B: The other end; 18: Output part; 20: Locking mechanism; 22: Planetary gear mechanism; 36: Sun gear; 38: Planetary gear; 40: Internal gear; 42: Support.

Claims

1. A driving device comprising: A rotating body capable of rotating about a central axis; An actuator causes the rotating body to rotate in a first direction; An energy storage unit is installed at one end on the rotating body, which extends as the rotating body rotates to store energy and contracts when the energy is released. The other end moves around the central axis in a manner close to the first end. The output section rotates as the energy storage section moves; as well as The locking mechanism is capable of switching between a locked state that restricts the movement of the energy storage unit and a unlocked state that releases the restriction on the movement of the energy storage unit.

2. The driving device according to claim 1, wherein, The energy storage unit is a constant force spring.

3. The driving device according to claim 1, wherein, In addition to the input from the actuator, the energy storage unit also stores external forces input in a manner that causes the energy storage unit to extend as energy.

4. The driving device according to claim 3, wherein, The drive unit also has a planetary gear mechanism. The planetary gear mechanism has the following features: Sun gear; The planetary gear meshes with the sun gear, rotating on its own axis while revolving around the sun gear. as well as The internal gear meshes with the planetary gear. The actuator, in addition to rotating the rotating body, also rotates the sun gear. The other end of the energy storage unit is mounted on a bracket that supports the planetary gear. The output unit outputs the rotational torque of the internal gear.

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