An Adaptive Variable Stiffness Driving Module and Its Application

Abstract

An adaptive variable stiffness drive module provided by the present disclosure includes a frame and a drive unit, a variable stiffness unit, and a control unit disposed therein; the drive unit includes a coaxial central shaft and a drive motor, and the output end of the drive motor is connected to an external connection end on the frame; the variable stiffness unit includes a non-linear coil spring and a stiffness adjustment assembly. The non-linear coil spring is formed by sequentially connecting multiple coil spring segments with different stiffnesses end to end and integrally. The stiffness adjustment assembly is connected to the non-linear coil spring and the central shaft, and applies the torque transmitted by the load of the carrier through the central shaft to the non-linear coil spring. The stiffness adjustment assembly performs one-way or two-way locking and pre-tightening or unloading on the end of the non-linear coil spring to balance the corresponding load torque and enable the carrier to reach a desired working angle; the control unit is used to control the stiffness adjustment assembly and the drive motor to balance the torques of the load, the non-linear coil spring, and the drive motor, and achieve adaptive adjustment for different loads while providing power for the carrier.

Description

Technical Field

[0001] The present disclosure relates to the technical field of actuators, and more particularly to an adaptive variable stiffness drive module and its applications. Background Art

[0002] The joint drive module of a robot is a core component of the robot's motion system, responsible for achieving precise joint motion and providing sufficient driving force to ensure that the robot can perform complex tasks. The joint drive module not only improves the flexibility and adaptability of the robot, enabling it to operate flexibly in various environments, but also enhances the load capacity and energy efficiency, thereby improving work efficiency and endurance. Through real-time monitoring and adjustment, the joint drive module also enhances the safety and reliability of the robot, which is particularly important in scenarios where human-robot collaboration is required. High-performance joint drive modules can support a wide range of application fields, including automated production lines in industrial manufacturing, surgical robots in the medical field, automatic delivery and cleaning robots in the service industry, automated planting and harvesting equipment in agriculture, legged robots, exoskeletons, and exploration and rescue robots, thus promoting the overall development of robotics and bringing more intelligent and efficient robot systems.

[0003] In most application scenarios, the joint drive module of a robot usually swings within a certain range and always needs to overcome the gravity of the robotic arm itself and the load it operates during the movement, which brings additional energy consumption (useless work), and further puts more stringent index requirements on the output torque of the joint drive module, becoming an important bottleneck restricting the current development of joint drive module technology. With the rapid development of artificial intelligence and robotics technology, joint drive modules with higher payload ratios (the ratio of load to self-weight) and longer endurance are an important direction and inevitable path for future technology development. Currently, large torque motors used for robot joints mainly adopt large reduction ratio reducers (such as harmonic and RV reducers) to achieve the drive of larger loads, but they cannot solve the problem of useless work caused by overcoming the gravity of the robotic arm and the load. In actual use, most of the power consumption is used to overcome the gravity work, greatly reducing the endurance of the robot.

[0004] In the prior art, the so-called gravity balance (compensation) technology can offset the gravity effect of the robotic arm and its load by using mechanical means such as springs, balance weights, or pneumatic devices. This not only reduces the load on the motor and control system, improves the control accuracy and response speed, but also improves energy efficiency and stability, extends the system life, and reduces the operating cost. The gravity balance technology enables the robotic arm to more flexibly handle different load conditions and working environments, thus effectively solving the key challenges of the robot joint module in the face of high self-weight, heavy load, and variable load scenarios. However, through research, it is found that although the existing related gravity balance technologies provide the supporting force (moment) for gravity balance by introducing elastic elements such as springs and coil springs in parallel or in series with the motor, they are only applicable to the case of constant load (moment) or small load (moment) changes. When facing most real working conditions, they still cannot solve the following important problems - how the joint drive module should adaptively adjust when the load changes greatly and the working angle has a limited range to achieve the optimal energy efficiency. For example, the mass of the load grasped by the robotic arm changes greatly or even rapidly over time, and there are large moment changes as the robotic arm changes its angle. The applicable working condition range of the elastic element with a single stiffness in the existing related technologies is relatively narrow and cannot meet the above requirements. Therefore, it is extremely necessary to carry out innovative design research on the variation range of the load and the working angle, and propose an innovative structure and its design method that can adapt to the changes of the load and the working angle and has variable stiffness. Summary of the Invention

[0005] This disclosure aims to solve at least one of the technical problems existing in the prior art.

[0006] To this end, a drive module with adaptive variable stiffness provided by this disclosure has a compact structure, can be applicable to a large load (moment) variation range, can automatically adjust the stiffness of the module according to the load size to automatically adapt to various working conditions, and can simultaneously meet the rotation angle requirement and the output moment requirement of the driven load.

[0007] To achieve the above object, this disclosure adopts the following technical solutions:

[0008] A drive module with adaptive variable stiffness provided in the first aspect of this disclosure includes a frame, and a drive unit, a variable stiffness unit, and a control unit disposed within the frame;

[0009] The frame includes a frame body and an external connection end provided on the frame body, and accesses the load of the carrier through the external connection end and provides power to the carrier;

[0010] The drive unit includes a central shaft and a drive motor coaxially arranged, and the power output by the drive motor is transmitted to the external connection end through the central shaft;

[0011] The variable stiffness unit includes a non-linear coil spring and a stiffness adjustment component. The non-linear coil spring is formed by sequentially connecting multiple coil spring segments end to end and integrally molding, and the stiffness of adjacent two coil spring segments is different. The stiffness adjustment component is connected between the non-linear coil spring and the central axis. The load torque is transmitted to the stiffness adjustment component through the central axis, and then the torque acts on one end of the non-linear coil spring. The stiffness adjustment component locks one end of the non-linear coil spring unidirectionally or bidirectionally to change the number of working turns and output torque of the non-linear coil spring, so as to balance the corresponding load torque. The stiffness adjustment component pre-tightens or unloads the other end of the non-linear coil spring and makes the carrier reach the desired working angle. The non-linear coil spring is designed according to the following steps: divide the working curve of the given driving module into S segments. The working curve of the driving module is the functional relationship between the rotation angle of the central axis and the torque output through the external connection end. Take the number of segments of the non-linear coil spring as S. Take the i-th segment of the working curve and its slope as the working curve and stiffness of the i-th coil spring segment respectively, where i = 1, 2,..., S, and design the i-th coil spring segment according to the industry standard JB / T7366-1994 to obtain the parameters of the i-th coil spring segment, including elastic modulus E, cross-sectional thickness h, cross-sectional width b, and unfolded length l.

[0012] The control unit is used to control the stiffness adjustment component and the driving motor according to the current signal of the driving motor and the rotation angle signal of the central axis, so that the load torque, the torque of the non-linear coil spring, and the output torque of the driving motor are balanced, and the adaptive adjustment of different loads is realized while providing power for the carrier.

[0013] In some embodiments, the stiffness adjustment component includes an inner end adjustment part of the coil spring, a coil spring locking part, and a coil spring driving frame fixedly connected to the central axis. The inner end adjustment part of the coil spring is arranged at the center of the top cover of the frame body and is used to adjust the inner end rotation angle of the non-linear coil spring to realize pre-tightening or unloading of the inner end of the non-linear coil spring. The coil spring driving frame can rotate relative to the frame body and is fixedly connected to the outer end of the non-linear coil spring. The coil spring locking part includes a ratchet and pawl mechanism, a matching stop switch, and a return spring. The ratchet and pawl mechanism is connected between the inner end of the non-linear coil spring and the lower end surface of the top cover of the frame body. Each return spring always maintains a compressed state and is used to provide a force for the stop pawl to approach the ratchet. During the stiffness adjustment process of the non-linear coil spring, the stop switch makes the ratchet only move in the set direction according to the instruction of the control unit, so that the number of working turns of the non-linear coil spring increases or decreases until the load torque, the torque of the non-linear coil spring, and the output torque of the driving motor are balanced. The control unit controls the stop switch to lock the inner end of the non-linear coil spring.

[0014] In some embodiments, the ratchet and pawl mechanism includes a ratchet shaft coaxial with the central shaft, a ratchet fixedly sleeved on the ratchet shaft, a positive stop pawl and a negative stop pawl that cooperate with the ratchet through tooth portions. The inner end of the non-linear coil spring is fixedly connected to the ratchet shaft. One end of the positive stop pawl and the negative stop pawl, which is far from their respective tooth portions, is rotatably connected to the lower end surface of the top cover of the frame body. A positive return spring and a positive stop switch are provided between one end of the positive stop pawl close to its tooth portion and the lower end surface of the top cover of the frame body. A negative return spring and a negative stop switch are provided between one end of the negative stop pawl close to its tooth portion and the lower end surface of the top cover of the frame body;

[0015] During the stiffness adjustment process of the non-linear coil spring, at most only one of the two stop pawls cooperating with the ratchet contacts the tooth portion of the ratchet; when the load torque, the torque of the non-linear coil spring, and the output torque of the drive motor reach balance, both of the two stop pawls cooperating with the ratchet contact the tooth portion of the ratchet.

[0016] In some embodiments, the stiffness adjustment assembly includes a coil spring locking member, a coil spring drive frame rotatably connected to the central shaft, an adjustment frame connected between the coil spring locking member and the coil spring drive frame, and an inner end fixing frame connected between the inner end of the non-linear coil spring and the central shaft; the coil spring locking member is used to maintain a self-locking state at any time when driving the inner end of the non-linear coil spring to rotate clockwise or counterclockwise. The worm and worm gear mechanism includes a worm adjustment member, a worm, and a worm gear connected in sequence. The worm adjustment member is arranged on the top cover of the frame body and is used to adjust the rotation angle of the outer end of the non-linear coil spring to achieve pre-tightening or unloading of the outer end of the non-linear coil spring, so as to meet the desired working angle requirements of the carrier after torque balance. The worm gear is fixedly connected to the coil spring drive frame through the adjustment frame. The outer end and the inner end of the non-linear coil spring are respectively fixedly connected to the coil spring drive frame and the inner end fixing frame, and the inner end fixing frame is fixedly connected to the central shaft.

[0017] In some embodiments, the control unit includes a circuit board and a main controller, a rotation angle sensor, and a current sensor arranged on the circuit board. The circuit board is fixedly connected to the frame body. The rotation angle sensor is used to measure the rotation angle of the central shaft in real time, the current sensor is used to measure the current of the drive motor in real time, and the main controller is used to control the drive motor and the stiffness adjustment assembly according to the rotation angle signal of the central shaft and the current signal of the drive motor.

[0018] In some embodiments, the control unit further includes an inertial measurement unit disposed on the circuit board, configured to collect the attitude angle and displacement of the carrier in real time and transmit them to the main controller. The main controller performs four-loop control on the drive motor according to the signals collected by the inertial measurement unit to achieve tracking of the target pose of the carrier. The four-loop control adds a pose loop on the basis of the FOC method. The pose loop is configured to obtain the desired rotation angle of the drive motor according to the deviation between the current pose and the target pose of the carrier, use this desired rotation angle as the input of the FOC method, and obtain the desired current value for the drive motor to maintain or reach the desired rotation angle after calculation by the FOC method.

[0019] In some embodiments, the control unit further includes a dust cover fixedly connected to the frame body, and the circuit board is located below the dust cover.

[0020] In some embodiments, the drive module further includes a handle adapted to the external connection end, enabling the drive module to have a manual power generation function. When manual power generation is required, the stiffness adjustment component is controlled by the control unit. At this time, one end of the non-linear coil spring is in a free state, and then the handle is connected to the external connection end. By rotating the handle, power is transmitted through the external connection end and the central shaft to the mover of the drive motor to generate current.

[0021] In some embodiments, the drive unit, the control unit, and the variable stiffness unit are coaxially and hierarchically arranged in the frame body, and the carrier and the variable stiffness unit are respectively arranged on both sides of the drive unit; a part of the central shaft is located inside the drive motor, and the remaining part of the central shaft protrudes from the drive motor.

[0022] In some embodiments, the frame body includes an upper shell and a lower shell that are fixedly connected and coaxially arranged with the central shaft. The drive motor and the central shaft are both located inside the lower shell, and the upper end of the central shaft protrudes from the upper end surface of the lower shell. The external connection end is rotatably arranged at the center of the lower end surface of the lower shell through a bearing; the variable stiffness unit and the control unit are both located inside the upper shell.

[0023] In some embodiments, the drive unit further includes a speed reducer disposed between the output end of the drive motor and the external connection end and the central shaft. The output end of the drive motor is connected to the central shaft through the high-speed end of the speed reducer, and the output end of the drive motor is connected to the external connection end through the low-speed end of the speed reducer.

[0024] Compared with the prior art, an adaptive variable stiffness drive module provided in the first aspect of the present disclosure has the following characteristics and beneficial effects:

[0025] An adaptive variable stiffness drive module provided by the first aspect of the present disclosure has a large stiffness adjustment range, a relatively small built-in non-linear coil spring, a simple stiffness adjustment component, a relatively small occupied volume, and a weight comparable to that of a common drive. The coaxial arrangement among the non-linear coil spring, the stiffness adjustment component, and the control unit makes the structure of the drive module compact, with low power consumption and simple control. The introduction of the non-linear coil spring enables the drive module to meet the corner requirements of the carrier and the torque requirements of the coil spring simultaneously under compact space constraints. It can be adaptively adjusted according to the size of different carrier loads. Specifically:

[0026] 1. Due to the optimization of the power transmission chain, the non-linear coil spring has a large stiffness adjustment range, a relatively small occupied volume, and a weight comparable to that of a common drive.

[0027] 2. The stiffness adjustment component, the non-linear coil spring, and the drive unit are coaxially matched, and the carrier and the non-linear coil spring are located on both sides of the drive unit instead of the same side. Such a position configuration makes the connection between the carrier and the drive unit more convenient, the axial position more reasonable, and the structure compact.

[0028] 3. Compared with a linear coil spring with a smaller stiffness, the non-linear coil spring can withstand a greater load torque under the same outer diameter of the coil spring and the number of turns of rotation. Compared with a linear coil spring with a larger stiffness, the non-linear coil spring can make the central axis rotate more turns under the same outer diameter of the coil spring and the load torque. Therefore, the introduction of the non-linear coil spring enables the drive module to provide a larger range of rotation angles of the central axis and a larger range of torques of the coil spring under the same space constraints.

[0029] 4. The stiffness adjustment component adjusts the stiffness of the non-linear coil spring by controlling the engagement of the pawl or the contact of the friction wheel in the stiffness adjustment component according to the instruction issued by the control unit to automatically adapt to various working conditions; in addition, the control unit can also control the drive motor according to the real-time motion state of the carrier to achieve precise tracking of the target pose of the carrier by the drive module.

[0030] Some advantages of this application will be given in the following description, some will become obvious from the following description, or will be learned through the practice of this application.

[0031] A robotic dog provided by the second aspect of the present disclosure includes a fuselage, legs, a first connecting member, a second connecting member, and a plurality of drive modules according to any one of the embodiments of the first aspect of the present disclosure disposed between the fuselage and the legs, and a transmission member disposed inside the legs. The legs include a thigh and a calf;

[0032] A first drive module for providing a driving force for the leg to move within the cross-section of the fuselage. The frame body of the first drive module is fixedly connected to the fuselage, and the external connection end of the first drive module is fixedly connected to the first connecting member;

[0033] The first connecting member, the second driving module, the second connecting member, and the third driving module are connected in sequence and coaxially arranged. The second driving module is used to provide a driving force for the thigh to move in the sagittal plane of the fuselage, and the third driving module is used to provide a driving force for the calf to move in the sagittal plane of the fuselage. The frame body of the second driving module is fixedly connected to the first connecting member, the external connection end of the second driving module is fixedly connected to one end of the second connecting member, the frame body of the third driving module is fixedly connected to one end of the thigh close to the fuselage, and the external connection end of the third driving module is connected to the calf through the transmission member arranged in the thigh.

[0034] In some embodiments, the transmission member adopts a belt drive mode and includes a first pulley, a second pulley, a tension pulley, and a synchronous belt. Both the first pulley and the second pulley are in contact and cooperation with the synchronous belt. The first pulley is fixedly connected to the external connection end of the third driving module. The tension pulley is rotatably arranged in the middle of the thigh and is used to tension the synchronous belt. The second pulley is rotatably sleeved on the pulley shaft and is fixedly connected to one end of the calf close to the thigh. The pulley shaft is fixedly connected to one end of the thigh close to the calf.

[0035] A robotic arm provided in the third aspect of the present disclosure includes a base, a fixing frame, a first arm, a second arm, a robotic claw, and two driving modules according to any one of the embodiments of the first aspect of the present disclosure;

[0036] The fixing frame is installed on the base, and a motor for driving the fixing frame to rotate around the axis of the base is provided in the base;

[0037] The first driving module is arranged between the fixing frame and the first arm and is used to provide a driving force for the first arm. The frame body of the first driving module is fixedly connected to the fixing frame, and the external connection end of the first driving module is fixedly connected to one end of the first arm;

[0038] The second driving module is arranged between the first arm and the second arm and is used to provide a driving force for the second arm. The frame body of the second driving module is fixedly connected to the other end of the first arm, the external connection end of the second driving module is fixedly connected to one end of the second arm, and the other end of the second arm is connected to the robotic claw.

[0039] An exoskeleton provided in the fourth aspect of the present disclosure includes a waistband, a driving module, a driving module fixing frame, and a leg fixing frame;

[0040] The waistband is fixed to the waist of the wearer and is fixedly connected to the driving module fixing frame;

[0041] The leg fixing bracket is fixed to the leg of the wearer;

[0042] The driving module adopts the driving module according to any one of the embodiments of the first aspect of the present disclosure, and is used to provide driving force for the leg fixing bracket. The frame body of the driving module is fixedly connected to the driving module fixing bracket, and the external connection end of the driving module is fixedly connected to the leg fixing bracket. Description of the Drawings

[0043] Figure 1 It is a schematic diagram of the overall structure of an adaptive variable stiffness driving module provided in Embodiment 1 of the present disclosure, wherein the non-linear scroll spring is a planar scroll spring with a variable cross-sectional thickness.

[0044] Figure 2 It is a schematic longitudinal sectional view of an adaptive variable stiffness driving module provided in Embodiment 1 of the present disclosure.

[0045] Figure 3 is Figure 1 An exploded view of the driving unit in the shown driving module.

[0046] Figure 4 is Figure 1 An exploded view of the variable stiffness unit in the shown driving module from the first perspective.

[0047] Figure 5 is Figure 1 An exploded view of the variable stiffness unit in the shown driving module from the second perspective.

[0048] Figure 6 It is a schematic diagram of the overall structure of another adaptive variable stiffness driving module provided in Embodiment 1 of the present disclosure, wherein the non-linear scroll spring is a planar scroll spring with a variable cross-sectional width.

[0049] Figure 7 In (a), (b), (c) are Figure 1 Schematic diagrams of the working process of the stiffness adjustment component of the variable stiffness unit in the shown driving module.

[0050] Figure 8 In (a), (b) are respectively Figure 1 Schematic diagrams of the structure of the shown driving module in the manual power generation mode and the state of its internal stiffness adjustment component.

[0051] Figure 9 It is a schematic diagram of the overall structure of an adaptive variable stiffness driving module provided in Embodiment 2 of the present disclosure.

[0052] Figure 10a is Figure 9 The A-A sectional view in.

[0053] Figure 10b Yes Figure 9 Partial enlarged schematic view of the driving module

[0054] Figure 11 In (a) and (b), they are respectively the overall structural schematic diagram and cross-sectional view of applying the driving module provided in Embodiment 1 of the present disclosure to a robotic dog

[0055] Figure 12 Structural schematic diagram of applying the driving module provided in Embodiment 1 of the present disclosure to a robotic arm

[0056] Figure 13 Structural schematic diagram of applying the driving module provided in Embodiment 1 of the present disclosure to an exoskeleton

[0057] In the figure:

[0058] 100 is a frame, 110 is a frame body, 111 is an upper housing, 1111 is a boss, 112 is a lower housing, 1121 is a second journal, 120 is an external connection end, 121 is a pin shaft, 130 is a handle;

[0059] 200 is a driving unit, 210 is a central shaft, 220 is a driving motor, 221 is a rotor frame, 2211 is a first journal, 222 is a permanent magnet, 223 is a winding frame, 224 is a coil, 230 is a speed reducer, 231 is a planet carrier, 231a is a bolt hole, 2311 is a planet carrier body, 2311a is a planet shaft, 2312 is a planet carrier top cover, 232 is a sun gear, 233 is a planet gear, 234 is an internal gear ring;

[0060] 300 is a variable stiffness unit, 310 is a non-linear coil spring, 320 is a stiffness adjustment component, 321 is a coil spring locking part, 3210 is a ratchet wheel, 3211 is a first pin, 3212 is a first set screw, 3213 is a positive stop pawl, 3214 is a negative stop pawl, 3215 is a positive return spring, 3216 is a positive stop switch, 3217 is a negative return spring, 3218 is a negative stop switch, 322 is a coil spring driving frame, 3221 is a third journal, 3222 is a second set screw, 3223 is a second pin, 323 is a coil spring adjustment motor, 341 is a worm, 3411 is a third set screw, 342 is a worm gear, 343 is a worm adjustment motor, 344 is an adjustment frame, 3441 is a first bolt, 3442 is a second bolt, 345 is an inner end fixing frame;

[0061] 400 is a control unit, 410 is a circuit board, 420 is a dust cover;

[0062] a is a first bearing, b is a second bearing, c is a third bearing, d is a fourth bearing, e is a fifth bearing;

[0063] 11 is the first drive module in the robotic dog, 12 is the second drive module in the robotic dog, 13 is the third drive module in the robotic dog, 2 is the fuselage, 3 is the thigh, 4 is the calf, 5 is the first connecting member, 6 is the second connecting member, 7 is the transmission member, 71 is the first pulley, 72 is the second pulley, 73 is the tension pulley, 74 is the timing belt, 75 is the pulley shaft;

[0064] 11’ is the first drive module in the robotic arm, 12’ is the second drive module in the robotic arm, 2’ is the base, 3’ is the fixing bracket, 41’ is the first arm, 42’ is the second arm, 5’ is the robotic claw;

[0065] 01 is the belt, 02 is the drive module in the exoskeleton, 03 is the drive module fixing bracket, 04 is the leg fixing bracket. Detailed implementation mode

[0066] Next, the technical solutions in the embodiments of the present application will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present application.

[0067] For a better description and illustration of the embodiments of the present application, one or more accompanying drawings can be referred to, but the additional details or examples used to describe the accompanying drawings should not be considered as limiting the scope of any one of the inventive concepts of the present application, the currently described embodiments, or the preferred modes.

[0068] It should be noted that when a component is referred to as being "connected" to another component, it can be directly connected to the other component or there may also be an intermediate component. When a component is considered to be "disposed on" another component, it can be directly disposed on the other component or there may be an intermediate component at the same time.

[0069] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those of ordinary skill in the technical field to which this application belongs. The terms used in the specification of this application herein are only for the purpose of describing specific embodiments and are not intended to limit this application.

[0070] Embodiment 1

[0071] See Figure 1 、 Figure 2 , an adaptive variable stiffness drive module provided in this embodiment includes a frame 100, and a drive unit 200, a variable stiffness unit 300, and a control unit 400 disposed in the frame 100; wherein,

[0072] The frame 100 includes a frame body 110 and an external connection end 120 disposed on the frame body 110. The load of the carrier is connected through the external connection end 120, and power is provided to the carrier.

[0073] The driving unit 200 includes a central shaft 210 and a driving motor 220 arranged coaxially. The driving motor 220 drives the central shaft 210 to rotate, and then is connected to the external connection end 120 through a speed reducer 230.

[0074] The variable stiffness unit 300 includes a non-linear coil spring 310 and a stiffness adjustment component 320. The non-linear coil spring 310 is a flat spiral spring formed by sequentially connecting multiple coil springs end to end and integrally molding. The stiffness of adjacent two coil spring segments is different. The stiffness adjustment component 320 is connected between the central shaft 210 and the non-linear coil spring 310. The load torque is transmitted to the stiffness adjustment component 320 through the speed reducer 230 and the central shaft 210, and then the torque acts on one end (such as the outer end) of the non-linear coil spring 310. The stiffness adjustment component 320 locks one end of the non-linear coil spring 310 unidirectionally or bidirectionally to change the number of working turns and output torque of the non-linear coil spring 310, so as to balance the corresponding load torque. The stiffness adjustment component 320 pre-tightens or unloads the other end (such as the inner end) of the non-linear coil spring 310 to make the carrier reach the desired working angle.

[0075] The control unit 400 is used to control the stiffness adjustment component 320 and the driving motor 220 according to the current signal of the driving motor 220 and the rotation angle signal of the central shaft 210, so that the load torque, the torque of the non-linear coil spring 310 and the output torque of the driving motor 220 (hereinafter, the output torque of the driving motor is simply referred to as "driving torque") reach balance, and realize the adaptive adjustment of different loads while providing power to the carrier.

[0076] Further, the frame body 110 serves as a base for providing support and positioning for other components in the driving module of this embodiment. Optionally, the frame body 110 includes an upper shell 111 and a lower shell 112 that are fixedly connected by bolts and arranged coaxially with the central shaft 210. The driving motor 220 and the central shaft 210 are both located inside the lower shell 112, and the upper end of the central shaft 210 protrudes from the upper end surface of the lower shell 112. The external connection end 120 is rotatably arranged at the center of the lower end surface of the lower shell 112 through a third bearing c. The variable stiffness unit 300 and the control unit 400 are both located inside the upper shell 111.

[0077] Further, refer to Figure 3, the drive motor 220 serves as the power source of the drive module in this embodiment, providing power for the carrier. In this embodiment, the drive motor 220 is a brushless DC motor. The difference from currently commercially available motors lies in its rotating central axis. Generally, the central axis of currently commercially available motors is built inside the motor housing, while in the embodiment of the present disclosure, the central axis 210 replaces the high-speed shaft of the commercially available motor, facilitating connection with the variable stiffness unit 300. Most of the central axis 210 is located inside the drive motor 220, and the top end of the central axis 210 protrudes from the top end of the drive motor 220. The drive motor 220 of this embodiment includes a rotor frame 221, and a permanent magnet 222, a winding frame 223, and a coil 224 located inside the rotor frame 221. The permanent magnet 222 is fixed on the inner side wall of the rotor frame 221, and the coil 224 is wound around the winding frame 223. A first journal 2211 with a through hole is formed at the center of the upper end face of the rotor frame 221. Part of the first journal 2211 protrudes from the upper end face of the rotor frame 221 and part is located inside the rotor frame 221. The outer side wall of the first journal 2211 protruding from the upper end face of the rotor frame 221 is rotatably connected to the inner side wall of the second journal 1121 at the center of the upper end face of the lower housing 112 through a first bearing a. The outer side wall of the first journal 2211 located inside the rotor frame 221 is rotatably connected to the planetary carrier top cover 2312 through a second bearing b. At the same time, the external connection end 120 is also rotatably connected to the lower end of the lower housing 112 through a third bearing c. When the coil 224 is energized to generate a magnetic field, the permanent magnet 222 drives the rotor frame 221 to rotate under the action of the magnetic field. Then, the rotation of the rotor frame 221 drives the central axis 210 circumferentially fixed thereto to rotate synchronously. One end of the central axis 210 is a gear (this gear is the sun gear 232 in the speed reducer 230), and then drives the external connection end 120 to rotate through the speed reducer 230, realizing the external output of power.

[0078] See Figure 3, a speed reducer 230 disposed between the output end of the driving motor 220 and the external connection end 120 is used to reduce the rotational speed of the output end of the driving motor 220 to amplify the output torque. The output end of the driving motor 220 is the central shaft 210, and one end gear 232 thereof is the high-speed input end of the speed reducer 230, and the low-speed output end of the speed reducer 230 is the external connection end 120. When the load torque changes little with time during use, the torque generated by the driving motor 220 is sufficient to overcome the change in the load torque. At this time, it is not necessary to reduce the motor speed to amplify the output torque, so the speed reducer 230 can be omitted. The speed reducer 230 in this embodiment is a planetary gear speed reducer, including an internal gear ring 234, a planetary carrier 231, a sun gear 232, and several planetary gears 233; the internal gear ring 234 is fixedly connected to the lower layer housing 112 and is internally meshed with each planetary gear 233; the planetary carrier 231 includes a fixedly connected planetary carrier body 2311 and a planetary carrier top cover 2312. The planetary carrier body 2311 is the external connection end 120. A plurality of planetary shafts 2311a are circumferentially arranged on the planetary carrier body 2311 around the sun gear 232. Each planetary gear 233 is respectively sleeved on a corresponding planetary shaft 2311a through a fourth bearing d, and each planetary gear 233 is meshed with the sun gear 232 fixed to one end of the central shaft 210. The central shaft 210 serves as the axle of the sun gear 232 and is integrally formed with the sun gear 232; a plurality of bolt holes 231a are provided on the planetary carrier body 2311 and the planetary carrier top cover 2312, and the two are fixedly connected by bolts to form the planetary carrier 231. In addition to the planetary gear speed reducer, the speed reducer 230 includes, but is not limited to, other types of speed reducers such as RV speed reducers, harmonic gear speed reducers, or cycloidal pinwheel speed reducers, etc., which will not be exemplified here.

[0079] Further, referring to Figure 4 , Figure 5 , in the variable stiffness unit 300 of this embodiment, the non-linear coil spring 310 is disposed in the upper layer housing 111 of the frame body 110 and is a single planar scroll spring formed by sequentially connecting the ends of multiple rectangular steel strips (each steel strip serves as a corresponding coil spring segment) end to end and integrally forming. The non-linear coil spring 310 is designed according to the following steps:

[0080] The working curve of the given driving module is divided into S segments. The number of segments S is determined according to the control accuracy of the carrier pose and the stiffness adjustment accuracy requirements. The higher the accuracy requirements, the larger the number of segments S, and S is a positive integer greater than or equal to 2. The working curve of the driving module is the functional relationship between the rotation angle (independent variable) of the central shaft and the torque (dependent variable) output through the external connection end. The number of segments of the non-linear coil spring 310 is taken as S, and the first coil spring segment is located at the outermost end of the non-linear coil spring 310;

[0081] The working curve of the i-th (i = 1, 2,..., S) coil spring segment and its slope are respectively taken as the working curve and stiffness of the i-th coil spring segment, and the i-th coil spring segment is designed according to the industry standard JB / T7366-1994 to obtain the parameters of the i-th coil spring segment, including the elastic modulus E, the cross-sectional thickness h, the cross-sectional width b, and the unfolded length l. In this embodiment, it is assumed that the elastic modulus E, the cross-sectional width b, and the unfolded length l of each coil spring segment are equal, and the non-linear coil spring 310 is made to meet the working curve requirements of the drive module by changing the cross-sectional thickness h of each coil spring segment. That is, in this embodiment, the non-linear coil spring used is a flat spiral spring with a variable cross-sectional thickness. See Figure 1 and Figure 2 . Similarly, it is also possible to make the elastic modulus E, the cross-sectional thickness h, and the unfolded length l of each coil spring segment equal, and use a flat spiral spring with a variable cross-sectional width, as shown in Figure 6 .

[0082] It should be noted that the overall dimensions of the non-linear coil spring 310 obtained according to the above design steps in the free state should meet the set space requirements. If not, re-design is required.

[0083] It can be understood that since there is a proportional relationship (reduction gear transmission ratio) between the rotation angle of the external connection end 120 connecting the load and the rotation angle of the central axis 210, and the initial rotation angle of the inner circle of the coil spring can be adjusted by the coil spring adjustment motor 323 in the stiffness adjustment component 320, in most application cases, when the relationship between the load rotation angle range and the working torque needs to meet the set function curve, even in a limited installation space, it is still possible to design a non-linear coil spring 310 approximately meeting the set function curve according to the above steps.

[0084] In the variable stiffness unit 300 of this embodiment, the stiffness adjustment component 320 includes a coil spring locking member 321, a coil spring driving frame 322, and a coil spring adjustment motor 323. The coil spring adjustment motor 323 is arranged at the center of the top cover of the upper shell 111 of the frame body 110, and the output end of the coil spring adjustment motor 323 is connected to the inner end of the non-linear coil spring 310. The coil spring adjustment motor 323 is controlled by the control unit 400 to realize the adjustment of the rotation angle position of the inner end of the non-linear coil spring 310. The angle difference between the rotation angle position of the inner end of the coil spring and the rotation angle position of the outer end is the number of turns that the non-linear coil spring 310 is compressed. Different numbers of turns compressed result in different elastic torques, and the above non-linear coil spring design method can be used for design and manufacturing. The non-linear coil spring 310 has the characteristic of adapting to the load torque. In this embodiment, when connecting the load, according to the stiffness characteristics of each coil spring segment, each coil spring segment is compressed in the order of increasing stiffness, that is, the coil spring segment with the smallest stiffness is compressed first. If the load torque is greater than the current coil spring torque, the coil spring segment with a larger stiffness is compressed until balance.

[0085] In the stiffness adjustment assembly 320 of the variable stiffness unit 300, the coil spring drive frame 322 is a circular plate provided with a third journal 3221 at the center of the lower end surface. Both the circular plate and the third journal 3221 are provided with central holes matching the central axis 210. The third journal 3221 at the center of the coil spring drive frame 322 is fixedly sleeved on the top end of the central axis 210 through a second set screw 3222, so as to rotate synchronously with the central axis 210. The non-linear coil spring 310 is placed on the upper end surface of the coil spring drive frame 322, and a second pin 3223 for fixing the outer end of the non-linear coil spring 310 is provided on the upper end surface of the coil spring drive frame 322. The load torque is introduced into the non-linear coil spring 310 from the outer end of the non-linear coil spring 310. A gap is left between the outer edge of the coil spring drive frame 322 and the inner side wall of the upper housing 111. The coil spring locking member 321 includes a ratchet and pawl mechanism and a matching stop switch and a return spring; the ratchet and pawl mechanism includes a ratchet 3210 coaxially arranged with the central axis 210, and a positive stop pawl 3213 and a negative stop pawl 3214 that cooperate with the ratchet 3210 through teeth. The central hole of the ratchet 3210 is fixed to the output shaft of the coil spring adjustment motor 323 through a first set screw 3212, so as to rotate synchronously with the output shaft of the coil spring adjustment motor 323. The protruding first pin 3211 on the ratchet 3210 can be inserted into the inner end ring of the non-linear coil spring 310 to achieve a fixed connection. There is relative rotation between the ratchet 3210 and the coil spring drive frame 322, that is, it drives the inner end and the outer end of the non-linear coil spring 310 to rotate relatively, so as to realize the compression or release of the non-linear coil spring 310; one end of the positive stop pawl 3213 and the negative stop pawl 3214 are rotatably connected to the boss 1111 on the lower surface of the top end of the upper housing 111. A positive return spring 3215 and a positive stop switch 3216 are provided between one end of the positive stop pawl 3213 close to the tooth part and the boss 1111, and a negative return spring 3217 and a negative stop switch 3218 are provided between one end of the negative stop pawl 3214 close to the tooth part and the boss 1111. When it is required that the ratchet 3210 remains stationary and does not rotate, the two return springs always remain in a compressed state, so as to provide a thrust for the corresponding stop pawl to approach the ratchet 3210. It should be noted that each stop switch adopts an electromagnetic switch. More specifically, an armature switch can be adopted, which is controlled by the control unit 400. When the armature switch is turned on, it will provide a force for the corresponding stop pawl to move away from the ratchet in contact with the corresponding stop pawl, and this force is greater than the force provided by the return spring, so that the corresponding stop pawl is separated from the ratchet; when the armature switch is turned off, the force provided by it for the corresponding stop pawl disappears, and the corresponding stop pawl contacts the ratchet under the action of the return spring.

[0086] Further, referring to Figure 7In FIGS. (a), (b), and (c), they are schematic diagrams of the working process of the stiffness adjustment assembly 320 of this embodiment. At this time, the outer end of the non-linear coil spring 310 is subjected to a clockwise load torque, where:

[0087] When the load torque is just connected, the stiffness adjustment assembly 320 operates in the mode shown in Figure 7 FIG. (a). The coil spring is compressed and deformed. The outer end of the non-linear coil spring 310 is fixed to the second pin 3223 on the coil spring drive frame 322 and is subjected to the clockwise torque generated by the load. Under the stopping action of the positive stop pawl 3213 on the right side, although the ratchet wheel 3210 is subjected to the clockwise torque generated by the inner end of the non-linear coil spring 310, it can remain stationary, so as to ensure that the counterclockwise elastic torque generated by the non-linear coil spring 310 can balance the clockwise torque generated by the load. If the load reaches the desired working angle (position) at this time, the stiffness adjustment assembly 320 operates in the mode shown in Figure 7 FIG. (c). At this time, both the positive stop pawl 3213 and the negative stop pawl 3214 are engaged with the ratchet wheel 3210 to ensure that the ratchet wheel 3210 is fixed.

[0088] When the load torque increases, the outer end of the non-linear coil spring 310 will continue to rotate clockwise, further compressing the coil spring until torque balance is reached again.

[0089] When the load torque decreases, the outer end of the non-linear coil spring 310 will rotate counterclockwise, relaxing the coil spring until torque balance is reached again.

[0090] After torque balance, if, due to the need of the working angle (position), it is required that the load rotates counterclockwise by a certain angle, that is, it is required that the outer end of the non-linear coil spring 310 rotates counterclockwise by a certain angle, then the stiffness adjustment assembly 320 operates in the mode shown in Figure 7 FIG. (a). At this time, because the negative stop pawl 3214 on the left disengages from the ratchet wheel 3210, the ratchet wheel 3210 can rotate counterclockwise under the drive of the coil spring adjustment motor 323, that is, the inner end of the non-linear coil spring 310 rotates counterclockwise by a certain angle, so as to realize that the load rotates counterclockwise by a certain angle to reach the desired working angle (position).

[0091] Similarly, after torque balance, if, due to the need of the working angle (position), it is required that the load rotates clockwise by a certain angle, that is, it is required that the outer end of the non-linear coil spring 310 rotates clockwise by a certain angle, then the stiffness adjustment assembly 320 operates in the mode shown in Figure 7In the mode shown in Fig. (b), at this time, since the right positive stop pawl 3213 disengages from the ratchet wheel 3210, the ratchet wheel 3210 can rotate clockwise driven by the coil spring adjusting motor 323, that is, the inner end of the non-linear coil spring 310 rotates clockwise by a certain angle, so that the load rotates clockwise by a certain angle to reach the desired working angle (position). It should be noted that since the inner end of the non-linear coil spring 310 is subjected to the coil spring elastic force in the clockwise direction at this time, after the ratchet wheel 3210 rotates clockwise by a certain angle, the right positive stop switch 3216 needs to be immediately released so that the positive stop pawl 3213 engages with the ratchet wheel 3210 to achieve clockwise stopping.

[0092] It can be understood that Figure 7 Fig. shows a typical installation method of the non-linear coil spring 310. If the non-linear coil spring 310 can bear the load torque in the counterclockwise direction according to the design requirements, it is only necessary to install the non-linear coil spring 310 with left-right mirror inversion on the basis of the installation method shown in Fig. (a). At this time, the negative stop pawl 3214 provides the stopping torque for the ratchet wheel 3210. Therefore, the above mechanism can achieve the balance of the load torque in both clockwise (counterclockwise) directions. In the actual application process, the non-linear coil spring 310 should be installed by selecting a suitable installation method according to the acting direction of the load torque.

[0093] It should be noted that the coil spring adjusting motor 323 in this embodiment can be replaced by an adjusting handle, and the inner end rotation angle position of the non-linear coil spring 310 can be adjusted by manually rotating the adjusting handle; the ratchet and pawl mechanism in the coil spring locking member in this embodiment can be replaced by a friction cam mechanism or other similar intermittent motion mechanisms.

[0094] It can be understood that in this embodiment, the load torque is transmitted through the outer end of the non-linear coil spring, that is, the inner end of the coil spring is fixed and the outer end is movable. Compared with the way of transmitting from the inner end, the durability of the coil spring can be increased. Since the curvature radius of the coil spring at the outer ring is larger, the deformation of the coil spring at the outer ring is smaller than that at the inner ring during the working process, which will extend the service life of the coil spring.

[0095] Furthermore, the control unit 400 is disposed within the upper housing 111 of the rack body 110 and is located below the torsion spring drive frame 322. It includes a circuit board 410, a main controller, a rotation angle sensor, and a current sensor disposed on the circuit board 410 (the main controller, current sensor, and rotation angle sensor are not shown in the figure). Both the current sensor and the rotation angle sensor are connected to the main controller. The current sensor can adopt an existing on-board current sensor and is used to detect the current signal of the drive motor 220. The rotation angle sensor is used to collect the rotation angle of the central shaft 210 in real time (the rotation number and rotation speed of the central shaft are reflected by this rotation angle). The circuit board is fixedly connected to the lower housing 112 by bolts. The main controller is used to control the drive motor 220 and each stop switch according to the current signal of the drive motor 220 and the rotation angle signal of the central shaft 210. A wire hole is formed on the side wall of the upper housing 111, and the cable on the circuit board is led out from this wire hole. Optionally, the control unit 400 further includes a dust cover 420 provided with a central through hole. The dust cover 420 is fixedly connected to the rack body 110, and the central through hole of the dust cover 420 is rotatably connected to the third journal 3221 of the first sub-torsion spring drive frame 322 through a fifth bearing e.

[0096] Furthermore, considering that the motion state, i.e., the pose, of the carrier driven by the drive module in this embodiment will change, including but not limited to the change of one of the attitude angles (including yaw angle, roll angle, and pitch angle) and displacement of the carrier, or the simultaneous change of both, and the change of the carrier pose will be reflected as the change of the load size connected to this drive module through the external connection end 120. In order to achieve the precise tracking of the target pose of the carrier by the drive module, the control unit 400 in this embodiment is further used to control the stiffness adjustment component 320 and the drive motor 220 according to the current pose and target pose of the carrier, combined with the change of the current signal of the drive motor 220 and the rotation angle of the central shaft 210, so that the load torque, the non-linear torsion spring torque, and the driving torque reach balance while ensuring that the carrier can reach the target pose. The control unit 400 in this embodiment further includes an inertial measurement unit (IMU) disposed on the circuit board 410 (the IMU is not shown in the figure), which is used to collect the attitude angle and displacement of the carrier in real time and transmit them to the main controller within the control unit 400. The drive control of the drive motor 220 by the main controller is to add a pose loop of the carrier on the basis of the vector control (Field-Oriented Control, FOC) method. The FOC method adopts a three-loop control, which are the current loop, the speed loop, and the position loop from the inside to the outside. The added pose loop is used to obtain the expected rotation angle of the drive motor 220 according to the deviation between the current pose and the target pose of the carrier, input this expected rotation angle into the position loop in the FOC, and obtain the expected current value for the drive motor to maintain or reach the expected rotation angle through the calculation of the FOC method, so as to achieve the precise tracking of the target pose of the carrier.

[0097] Optionally, referring to Figure 8 Figures (a) and (b) therein, the drive module provided by the embodiments of the present disclosure further includes a handle 130 that cooperates with a pin shaft 121 on an external connection end 120, enabling the drive module of this embodiment to have a manual power generation function. When manual power generation is required, first, the control unit 400 controls each stop switch to separate all stop pawls (3213, 3214) from the teeth of the ratchet wheel 3210. At this time, the inner end of the non-linear spiral spring 310 is in a free state. Then, the handle 130 is connected to the external connection end 120. By rotating the handle 130, power is transmitted in sequence through the external connection end 120, the speed reducer 230, the central shaft 210 to the rotor frame 221. The permanent magnet 222 on the rotor frame 221 and the coil 224 move relative to each other, cutting the magnetic induction lines to generate current, achieving the effect of manual power generation.

[0098] The working process of the drive module of this embodiment is described as follows:

[0099] The load is introduced into this drive module through the external connection end 120. The external connection end 120 is connected to the low-speed shaft of the speed reducer 230. The central shaft 210 serves as the high-speed shaft of the speed reducer 230. The load torque is amplified by the speed reducer 230 and then drives the central shaft 210 to rotate. The spiral spring drive frame 322 is fixedly connected to the top end of the central shaft 210. Therefore, the rotation of the central shaft 210 will drive the spiral spring drive frame 322. The outer end of the non-linear spiral spring 310 is fixedly connected to the spiral spring drive frame 322. The load torque is introduced into the non-linear spiral spring 310 through the spiral spring drive frame 322 and the non-linear spiral spring 310 is pre-tightened with the cooperation of the spiral spring locking member 321, thereby using the non-linear spiral spring 310 to balance most of the load torque. Specifically: the control unit 400 controls the engagement and separation of the ratchet pawl in the spiral spring locking member 321 through the on-off of the electromagnetic switch. When the control unit 400 issues a ratchet pawl separation instruction, the electromagnetic switch is energized. At this time, the pawl is separated from the ratchet under the action of magnetic suction force; when the control unit 400 issues a ratchet pawl engagement instruction, the electromagnetic switch is de-energized. At this time, the pawl is engaged with the ratchet under the action of the return spring. Since the torque generated by the load has been balanced by the non-linear spiral spring 310, at this time, when the drive motor 220 drives the movement of the load, only a smaller torque is required to control the movement of the load, thereby greatly reducing the energy consumption of the drive motor.

[0100] Embodiment 2

[0101] Referring to Figure 9 、 Figure 10a and Figure 10b, in this embodiment, the coil spring adjusting motor 323 and the ratchet and pawl mechanism in the stiffness adjusting component 320 in Embodiment 1 are replaced with a worm and worm gear mechanism. An adjusting frame 344 is added between the worm and worm gear mechanism and the coil spring driving frame 322, and an inner end fixing frame 345 is added between the inner end of the non-linear coil spring 310 and the central shaft 210 to achieve that when the inner end of the non-linear coil spring 310 rotates clockwise or counterclockwise under the action of a load, it always maintains a self-locking state. In the stiffness adjusting component 320 of this embodiment, the worm and worm gear mechanism includes a worm adjusting motor 343, a worm 341, and a worm gear 342. The worm adjusting motor 343 is fixed on the top cover of the middle upper housing 111 of the frame 100. The output shaft of the worm adjusting motor 343 is fixedly connected to one end of the worm 341 through a third set screw 3411 to achieve torque transmission. One end of the worm 341 is rotatably connected to the top cover of the upper housing 111. The worm gear 342 is rotatably connected to the top cover of the upper housing 111 through a bearing and meshes with the worm 341. The worm gear 342 is fixedly connected to the coil spring driving frame 322. The coil spring driving frame 322 is provided with a protruding pin for inserting into the outer end of the non-linear coil spring 310 to achieve the fixed connection between the outer end of the coil spring and the worm gear 342. The worm gear 342 is provided with three first counterbore holes distributed in a circumferential manner. One end of the adjusting frame 344 facing the worm gear 342 is formed with three first bosses evenly distributed in a circumferential manner and each with a threaded hole, and each first boss corresponds to a first counterbore hole on the worm gear 342 respectively. Thus, the worm gear 342 and the adjusting frame 344 are fixedly connected through a first bolt 3441; the adjusting frame 344 is also provided with three second counterbore holes distributed in a circumferential manner. One end of the coil spring driving frame 322 facing the adjusting frame 344 is formed with three second bosses each with a threaded hole, and each second boss corresponds to a second counterbore hole on the adjusting frame 344 respectively. Thus, the adjusting frame 344 and the coil spring driving frame 322 are fixedly connected through a second bolt 3442. The coil spring driving frame 322 is rotatably connected to the central shaft 210 through a bearing; the outer end of the non-linear coil spring 310 is fixedly connected to the coil spring driving frame 322, and the inner end of the non-linear coil spring 310 is fixedly connected to the inner end fixing frame 345. The inner end fixing frame 345 is fixedly connected to the top end of the central shaft 210 through a set screw. There is relative rotation between the worm gear 342 and the inner end fixing frame 345, that is, it drives the inner end and the outer end of the non-linear coil spring 310 to rotate relative to each other, thereby realizing the compression or release of the non-linear coil spring 310. In this embodiment, the worm and worm gear mechanism has a self-locking characteristic. It can be understood that the outer end of the non-linear coil spring 310 is restricted by the worm gear 342 and can remain stationary at any angle (position) unless the worm 341 rotates to drive the worm gear 342 and then drive the outer end of the non-linear coil spring 310 to rotate. The worm and worm gear transmission usually has a large transmission ratio. It can be understood that only a small driving torque is required to drive the worm 341 to drive the worm gear 342, and then drive the outer end of the non-linear coil spring 310.In addition to rotating by controlling the worm to adjust the motor 343, the worm 341 can also be rotated manually.

[0102] Similar to Embodiment 1, when the load torque changes (increases or decreases), the inner end of the non-linear coil spring 310 will be driven by the load torque to rotate (clockwise or counterclockwise), while the outer end of the non-linear coil spring 310 remains stationary due to the self-locking limitation of the worm and worm gear. It can be understood that the non-linear coil spring 310 will be compressed or released, so as to achieve the balance between the load torque and the elastic torque of the coil spring.

[0103] After the torque is balanced, if it is required that the load rotates a certain angle (clockwise or counterclockwise) due to the need of the working angle (position), that is, it is required that the central axis 210 drives the inner end of the non-linear coil spring 310 to rotate a certain angle (clockwise or counterclockwise). The adjustment method is to rotate the outer end of the non-linear coil spring 310 a certain angle (clockwise or counterclockwise), and the balanced torque can be transmitted to the inner end of the non-linear coil spring 310, so that the central axis drives the load to rotate. At this time, the worm 341 can be rotated manually, or the worm 341 can be driven to rotate by the worm adjustment motor 343, so that the outer end of the non-linear coil spring 310 rotates a certain angle in the desired direction (clockwise or counterclockwise), so that the load rotates a certain angle to reach the desired working angle (position).

[0104] The rest of this embodiment is the same as that of Embodiment 1 and will not be elaborated here.

[0105] Embodiment 3

[0106] See Figure 11 In (a) and (b), this embodiment applies the drive module provided in Embodiment 1 to a robotic dog. The robotic dog includes a body 2, legs, a first connecting member 5, a second connecting member 6 and a number of drive modules (11, 12 and 13) provided according to Embodiment 1 disposed between the body 2 and the legs, and a transmission member 7 disposed inside the legs. The legs include a thigh 3 and a calf 4;

[0107] The first drive module 11 is used to provide the driving force for the legs to move within the cross-section of the body. The frame body of the first drive module 11 is fixedly connected to the body 2, and the external connection end of the first drive module 11 is fixedly connected to the first connecting member 5;

[0108] The first connecting member 5, the second driving module 12, the second connecting member 6, and the third driving module 13 are sequentially connected and coaxially arranged. The second driving module 12 is used to provide the driving force for the thigh 3 to move in the sagittal plane of the fuselage. The third driving module 13 is used to provide the driving force for the calf 4 to move in the sagittal plane of the fuselage. The frame body of the second driving module 12 is fixedly connected to the first connecting member 5. The external connection end of the second driving module 12 is fixedly connected to one end of the second connecting member 6. The frame body of the third driving module 13 is fixedly connected to the end of the thigh 3 close to the fuselage 2. The external connection end of the third driving module 13 is connected to the calf 4 through a transmission member 7 disposed inside the thigh 3.

[0109] Further, there are 4 legs in total in the robot dog of this embodiment ( Figure 11 only one leg of the robot dog is shown), which are respectively located at the four corners of the fuselage 2. A first driving module 11 is respectively arranged at the four corners of the fuselage 4 to provide the driving force for a corresponding leg of the robot dog to move in the cross-section plane of the fuselage through the first driving module 11. There are 8 bolt holes on the frame body of the first driving module 11 and it is fixedly connected to the fuselage 2 through bolts; there are 3 bolt holes on the external connection end of the first driving module 11 and it is fixedly connected to the first connecting member 5 through bolts. The first connecting member 5 is the part directly acted on by the first driving module 11, and the movement in the cross-section plane is transmitted to the leg of the robot dog through this part. The first connecting member 5 and the second driving module 12 are fixedly connected through 8 bolt holes on the frame body of the second driving module 12 and the matching bolts. The second driving module 12 is used to control the movement of the thigh 3. It is fixedly connected to the first connecting member 5 through 8 bolt holes on the frame body of the second driving module 12 and the matching bolts. There are 3 bolt holes on the external connection end of the second driving module 12 and it is fixedly connected to the second connecting member 6 through bolts. The second connecting member 6 is the part directly acted on by the second driving module 12, and the power is transmitted to the thigh 3 through this part. The second connecting member 6 is located between the thigh 3 and the third driving module 13. The second connecting member 6 and the third driving module 13 are fixedly connected through 8 bolt holes on the frame body of the third driving module 13 and the matching bolts. The third driving module 13 is used to provide the driving force for the calf 4 to move in the sagittal plane of the fuselage. It is located outside the second connecting member 6 and between the second connecting member 6 and the thigh 3. The third driving module 13 and the thigh 3 are fixedly connected through 8 bolt holes on the frame body of the third driving module 13 and the matching bolts. There are 3 bolt holes on the external connection end of the third driving module 13 and it is connected to the transmission member 7 through bolts, and the power is transmitted to the calf 4 through this transmission member 7.

[0110] Furthermore, the transmission member 7 of this embodiment adopts a belt drive method, including a first pulley 71, a second pulley 72, a tension pulley 73, and a synchronous belt 74. Both the first pulley 71 and the second pulley 72 are in contact and cooperation with the synchronous belt 74. The first pulley 71 is fixedly connected to the external connection end of the third drive module 13. The tension pulley 73 is rotatably arranged in the middle of the thigh 3 for tensioning the synchronous belt 74 to improve the transmission efficiency. The second pulley 72 is rotatably sleeved on the pulley shaft 75 and fixedly connected to one end of the calf 4 close to the thigh 3. The pulley shaft 75 is fixedly connected to one end of the thigh 3 close to the calf 4.

[0111] It can be understood that for the robot dog provided in this embodiment, due to the adoption of the non-linear coil spring, the power consumption of the drive motor can be reduced, which is suitable for working conditions with large loads. In addition, since the drive module in this embodiment has the ability of adaptive adjustment for different loads, for example, the robot dog can adaptively adjust the stiffness in various working conditions such as variable-speed forward movement, jumping, uphill, undulating, etc. to meet the requirements of different working conditions. Moreover, when power is off, due to the existence of the non-linear coil spring, the robot dog will not be unloaded instantly and still plays a supporting role for the fuselage. The drive module in this embodiment is integrated with an IMU to real-time collect the pose states at each joint of the robot dog's leg. The control unit in the drive module can perform closed-loop control on the drive motor according to this pose state to achieve precise tracking of the target pose at each joint of the robot dog's leg.

[0112] Embodiment 4

[0113] See Figure 12 , in this embodiment, the drive module provided in Embodiment 1 is applied to a robotic arm. The robotic arm includes a base 2', a fixing frame 3', a first arm 41', a second arm 42', a robotic claw 5', and two drive modules (11' and 12') provided according to Embodiment 1;

[0114] The fixing frame 3' is installed on the base 2'. A motor for driving the fixing frame 3' to rotate around the axis of the base 2' is provided in the base 2' (this motor is not shown in Figure 12 ).

[0115] The first drive module 11' is arranged between the fixing frame 3' and the first arm 41' for providing driving force for the first arm 41'. The frame body of the first drive module 11' is fixedly connected to the fixing frame 3'. The external connection end of the first drive module 11' is fixedly connected to one end of the first arm 41';

[0116] The second driving module 12' is disposed between the first arm 41' and the second arm 42' and is used to provide driving force for the second arm 42'. The frame body of the second driving module 12' is fixedly connected to the other end of the first arm 41', the external connection end of the second driving module 12' is fixedly connected to one end of the second arm 42', and the other end of the second arm 42' is connected to the mechanical claw 5'.

[0117] It can be understood that for the robotic arm provided in this embodiment, since it is equipped with the driving module provided in the present disclosure embodiment, the robotic arm of this embodiment has the following characteristics: 1. The non-linear coil spring in the driving module of this robotic arm can reduce the power consumption of the driving motor and is applicable to working conditions with large loads; 2. This embodiment can adapt to the working conditions. For example, when the load grasped by the robotic arm is a non-constant load, it can adaptively adjust the stiffness of the driving module to meet different working conditions; 3. When power is cut off, the mechanical device can be protected due to the existence of the non-linear coil spring; 4. The IMU is integrated in the driving module of this embodiment to collect the pose states at the joints of the robotic arm in real time. The control unit in the driving module can perform closed-loop control on the driving motor according to the pose states to achieve precise tracking of the target poses at the joints of the robotic arm.

[0118] Embodiment 5

[0119] See Figure 13 , in this embodiment, the driving module provided in Embodiment 1 is applied to an exoskeleton. The exoskeleton includes a waistband 01, a driving module 02, a driving module fixing bracket 03, and a leg fixing bracket 04;

[0120] The waistband 01 is fixed to the waist of the wearer and can be fixedly connected to the driving module fixing bracket 03 through a buckle;

[0121] The leg fixing bracket 04 is fixed to the leg of the wearer, so that the power of the driving module 02 is transmitted to the leg. It is located at the lower part of the exoskeleton of this embodiment, at the position in contact with the leg of the wearer;

[0122] The driving module 02 adopts the driving module provided in Embodiment 1 of the present disclosure and is used to provide driving force for the leg fixing bracket 04. The driving module 02 is fixedly connected to the driving module fixing bracket 03 through 8 bolt holes on the frame body of the driving module 02 and the matching bolts, and the driving module 02 is fixedly connected to the top of the leg fixing bracket 04 through 3 bolt holes on the external connection end of the driving module 02 and the matching bolts.

[0123] It can be understood that the exoskeleton provided in this embodiment has the following characteristics due to the driving module provided in the present disclosure being configured therein: 1. The non-linear coil spring in the driving module of this exoskeleton can reduce the power consumption of the driving motor and is applicable to working conditions with large loads; 2. This embodiment can adapt to the working conditions. For example, when the load carried by the exoskeleton is a non-constant load, it can adaptively adjust the stiffness of the driving module to meet different working conditions; 3. The mechanical device can be protected due to the presence of the non-linear coil spring; 4. The IMU is integrated in the driving module of this embodiment to collect the pose state at the joints of the exoskeleton in real time. The control unit in the driving module can perform closed-loop control on the driving motor according to this pose state to achieve precise tracking of the target pose at the joints of the exoskeleton.

[0124] In the present invention, the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples", etc., mean that the specific features, structures, materials, or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials, or characteristics described can be combined in a suitable manner in any one or more embodiments or examples. In addition, without contradiction, those skilled in the art can combine and combine the different embodiments or examples described in this specification and the features of the different embodiments or examples.

[0125] Although the above embodiments have been shown and described, it can be understood that the above embodiments are exemplary and should not be construed as limiting the present application. Any changes, modifications, substitutions, and variations made by those of ordinary skill in the art to the above embodiments are within the protection scope of the present application.

Claims

1. An adaptive variable stiffness drive module, characterized in that, It includes a frame, as well as a driving unit, a variable stiffness unit and a control unit arranged within the frame; The frame includes a frame body and an external connection end provided on the frame body. The load of the carrier is connected through the external connection end, and power is provided to the carrier; The driving unit includes a central shaft and a driving motor arranged coaxially. The power output by the driving motor is transmitted to the external connection end through the central shaft; The variable stiffness unit includes a non-linear coil spring and a stiffness adjustment component. The non-linear coil spring is formed by sequentially connecting multiple coil spring segments end to end and integrally molding, and the stiffness of adjacent two coil spring segments is different; the stiffness adjustment component is connected between the non-linear coil spring and the central shaft. The load torque is transmitted to the stiffness adjustment component through the central shaft, and then the torque acts on one end of the non-linear coil spring. The stiffness adjustment component locks one end of the non-linear coil spring unidirectionally or bidirectionally to change the number of working turns and output torque of the non-linear coil spring, so as to balance the corresponding load torque. The stiffness adjustment component pre-tightens or unloads the other end of the non-linear coil spring, and enables the carrier to reach the desired working angle; The non-linear coil spring is designed according to the following steps: divide the working curve of the given driving module into S segments. The working curve of the driving module is the functional relationship between the rotation angle of the central shaft and the torque output through the external connection end. Take the number of segments of the non-linear coil spring as S; take the i-th working curve and its slope as the working curve and stiffness of the i-th coil spring segment respectively, where i = 1, 2,..., S, and design the i-th coil spring segment according to the industry standard JB / T7366-1994 to obtain the parameters of the i-th coil spring segment, including elastic modulus E, cross-sectional thickness h, cross-sectional width b and unfolded length l; The control unit is used to control the stiffness adjustment component and the driving motor according to the current signal of the driving motor and the rotation angle signal of the central shaft, so that the load torque, the torque of the non-linear coil spring and the output torque of the driving motor reach balance, and realize the adaptive adjustment of different loads while providing power to the carrier.

2. The drive module according to claim 1, wherein The stiffness adjustment component includes an inner end adjuster of the coil spring, a coil spring locking component and a coil spring driving frame fixedly connected to the central shaft; the inner end adjuster of the coil spring is arranged at the center of the top cover of the frame body and is used to adjust the inner end rotation angle of the non-linear coil spring to realize the pre-tightening or unloading of the inner end of the non-linear coil spring; the coil spring driving frame can rotate relative to the frame body and is fixedly connected to the outer end of the non-linear coil spring; the coil spring locking component includes a ratchet and pawl mechanism and a matching stop switch and a return spring. The ratchet and pawl mechanism is connected between the inner end of the non-linear coil spring and the lower end surface of the top cover of the frame body; each return spring always remains in a compressed state and is used to provide a force for the stop pawl to approach the ratchet; During the stiffness adjustment process of the non-linear coil spring, the stop switch enables the ratchet to move only in the set direction according to the instruction of the control unit, increasing or decreasing the number of working turns of the non-linear coil spring until the balance is achieved among the load torque, the torque of the non-linear coil spring, and the output torque of the driving motor. Then, the control unit controls the stop switch to lock the inner end of the non-linear coil spring.

3. The drive module according to claim 2, wherein The ratchet and pawl mechanism includes a ratchet shaft coaxial with the central shaft, a ratchet fixedly sleeved on the ratchet shaft, a forward stop pawl and a reverse stop pawl that cooperate with the ratchet through tooth parts. The inner end of the non-linear coil spring is fixedly connected to the ratchet shaft. One end of the forward stop pawl and the reverse stop pawl, which is far from their respective tooth parts, is rotatably connected to the lower end surface of the top cover of the frame body. Between one end of the forward stop pawl close to its tooth part and the lower end surface of the top cover of the frame body, there are a forward return spring and a forward stop switch. Between one end of the reverse stop pawl close to its tooth part and the lower end surface of the top cover of the frame body, there are a reverse return spring and a reverse stop switch. During the stiffness adjustment process of the non-linear coil spring, at most only one of the two stop pawls cooperating with the ratchet contacts the tooth part of the ratchet. When the balance is achieved among the load torque, the torque of the non-linear coil spring, and the output torque of the driving motor, both of the two stop pawls cooperating with the ratchet contact the tooth part of the ratchet.

4. The drive module according to claim 1, wherein The stiffness adjustment assembly includes a coil spring locking member, a coil spring driving frame rotatably connected to the central shaft, an adjustment frame connected between the coil spring locking member and the coil spring driving frame, and an inner end fixing frame connected between the inner end of the non-linear coil spring and the central shaft. The coil spring locking member is used to maintain a self-locking state at any time when driving the inner end of the non-linear coil spring to rotate clockwise or counterclockwise. The stiffness adjustment assembly includes a worm adjustment member, a worm, and a worm gear connected in sequence. The worm adjustment member is arranged on the top cover of the frame body and is used to adjust the rotation angle of the outer end of the non-linear coil spring, realizing pre-tightening or unloading of the outer end of the non-linear coil spring, so as to meet the expected working angle requirement of the carrier after torque balance. The worm gear is fixedly connected to the coil spring driving frame through the adjustment frame. The outer end and the inner end of the non-linear coil spring are respectively fixedly connected to the coil spring driving frame and the inner end fixing frame. The inner end fixing frame is fixedly connected to the central shaft.

5. The drive module according to claim 1, characterized in that, The control unit includes a circuit board, a main controller, a rotation angle sensor, and a current sensor arranged on the circuit board. The circuit board is fixedly connected to the frame body. The rotation angle sensor is used to measure the rotation angle of the central shaft in real time. The current sensor is used to measure the current of the driving motor in real time. The main controller is used to control the driving motor and the stiffness adjustment assembly according to the rotation angle signal of the central shaft and the current signal of the driving motor.

6. The drive module according to claim 5, characterized in that, The control unit further includes an inertial measurement unit disposed on the circuit board, which is used to collect the attitude angle and displacement of the carrier in real time and transmit them to the main controller. The main controller performs four-loop control on the drive motor according to the signals collected by the inertial measurement unit to achieve tracking of the target pose of the carrier. The four-loop control adds a pose loop on the basis of the FOC method. The pose loop is used to obtain the desired rotation angle of the drive motor according to the deviation between the current pose and the target pose of the carrier, and use this desired rotation angle as the input of the FOC method. After calculation by the FOC method, the desired current value for the drive motor to maintain or reach the desired rotation angle is obtained.

7. The drive module according to claim 5, characterized in that The control unit further includes a dust cover fixedly connected to the frame body, and the circuit board is located below the dust cover.

8. The drive module according to claim 1, wherein The drive module further includes a handle that cooperates with the external connection end, enabling the drive module to have a manual power generation function. When manual power generation is required, the stiffness adjustment component is controlled by the control unit. At this time, one end of the non-linear coil spring is in a free state, and then the handle is connected to the external connection end. By rotating the handle, power is transmitted through the external connection end and the central shaft to the mover of the drive motor to generate current.

9. The drive module according to claim 1, wherein, The drive unit, the control unit, and the variable stiffness unit are coaxially and hierarchically arranged in the frame body, and the carrier and the variable stiffness unit are respectively arranged on both sides of the drive unit; a part of the central shaft is located inside the drive motor, and the remaining part of the central shaft protrudes from the drive motor.

10. The drive module according to claim 1, wherein The frame body includes an upper shell and a lower shell that are fixedly connected and coaxially arranged with the central shaft. The drive motor and the central shaft are both located inside the lower shell, and the upper end of the central shaft protrudes from the upper end surface of the lower shell. The external connection end is rotatably arranged at the center of the lower end surface of the lower shell through a bearing; the variable stiffness unit and the control unit are both located inside the upper shell.

11. The drive module according to claim 1, characterized in that, The drive unit further includes a speed reducer disposed between the output end of the drive motor and the external connection end and the central shaft. The output end of the drive motor is connected to the central shaft through the high-speed end of the speed reducer, and the output end of the drive motor is connected to the external connection end through the low-speed end of the speed reducer.

12. A robotic dog, characterized in that, It includes a fuselage, legs, a first connecting member, a second connecting member, and a plurality of drive modules according to any one of claims 1 to 11 disposed between the fuselage and the legs, and transmission members disposed inside the legs. The legs include a thigh and a calf. A first drive module is used to provide the driving force for the leg to move within the cross-section of the fuselage. The frame body of the first drive module is fixedly connected to the fuselage, and the external connection end of the first drive module is fixedly connected to the first connecting member. The first connecting member, the second driving module, the second connecting member, and the third driving module are sequentially connected and coaxially arranged. The second driving module is used to provide a driving force for the thigh to move in the sagittal plane of the fuselage, and the third driving module is used to provide a driving force for the calf to move in the sagittal plane of the fuselage. The frame body of the second driving module is fixedly connected to the first connecting member, the external connection end of the second driving module is fixedly connected to one end of the second connecting member, the frame body of the third driving module is fixedly connected to the end of the thigh close to the fuselage, and the external connection end of the third driving module is connected to the calf through the transmission member arranged in the thigh.

13. The robotic dog according to claim 12, characterized in that, The transmission member adopts a belt drive mode and includes a first pulley, a second pulley, a tension pulley, and a synchronous belt. Both the first pulley and the second pulley are in contact and cooperation with the synchronous belt. The first pulley is fixedly connected to the external connection end of the third driving module. The tension pulley is rotatably arranged in the middle of the thigh and is used to tension the synchronous belt. The second pulley is rotatably sleeved on the pulley shaft and is fixedly connected to the end of the calf close to the thigh. The pulley shaft is fixedly connected to the end of the thigh close to the calf.

14. A robotic arm, characterized in that, It includes a base, a fixed frame, a first arm, a second arm, a mechanical claw, and two driving modules according to any one of claims 1 to 11. The fixed frame is installed on the base, and a motor for driving the fixed frame to rotate around the axis of the base is arranged in the base. The first driving module is arranged between the fixed frame and the first arm and is used to provide a driving force for the first arm. The frame body of the first driving module is fixedly connected to the fixed frame, and the external connection end of the first driving module is fixedly connected to one end of the first arm. The second driving module is arranged between the first arm and the second arm and is used to provide a driving force for the second arm. The frame body of the second driving module is fixedly connected to the other end of the first arm, the external connection end of the second driving module is fixedly connected to one end of the second arm, and the other end of the second arm is connected to the mechanical claw.

15. An exoskeleton, characterized in that, It includes a waist belt, a driving module, a driving module fixing frame, and a leg fixing frame. The waist belt is fixed to the waist of the wearer and is fixedly connected to the driving module fixing frame. The leg fixing frame is fixed to the leg of the wearer. The driving module adopts the driving module according to any one of claims 1 to 11 and is used to provide a driving force for the leg fixing frame. The frame body of the driving module is fixedly connected to the driving module fixing frame, and the external connection end of the driving module is fixedly connected to the leg fixing frame.

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