A parallel drive module with adaptive variable stiffness and its application

Abstract

A parallel drive module with adaptive variable stiffness provided by the present disclosure includes a frame and a drive unit, a variable stiffness unit, and a control unit located therein; the drive unit includes a 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 elastic element and a stiffness adjustment component, the non-linear elastic element includes two sub-coil springs connected in parallel through the stiffness adjustment component, the stiffness adjustment component is also connected to the central shaft, the torque transmitted by the load of the carrier through the central shaft acts on the non-linear elastic element, and the stiffness adjustment component performs one-way or two-way locking and pre-tightening or unloading on the outer end of the non-linear elastic element 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 component and the drive motor to balance the torques of the load, the non-linear elastic element, and the drive motor, and to 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 particularly to a parallel drive module with adaptive variable stiffness and its applications. Background Art

[0002] The joint drive module of a robot is the 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 the work efficiency and endurance. Through real-time monitoring and adjustment, the joint drive module also improves the safety and reliability of the robot, which is particularly important in scenarios that require collaboration with humans. 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, automated 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 robot technology 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). Furthermore, this places more stringent 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 robot technology, joint drive modules with higher payload ratios (the ratio of load to self-weight) and longer endurance are an important direction and the only way for future technological 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, 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 the energy efficiency and stability, extends the system life, and reduces the operating cost. The gravity balance technology enables the robotic arm to more flexibly respond to 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 volute 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 torque changes as the robotic arm changes its angle. In the existing related technologies, the applicable working condition range of the elastic element with a single stiffness is relatively narrow and cannot meet the above requirements. Therefore, it is extremely necessary to carry out innovative design research on the change 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 have 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 parallel drive module with adaptive variable stiffness provided in the first aspect of this disclosure has a compact structure, can be applicable to a large load (moment) change 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 requirements of the rotation angle and output torque of the driven carrier.

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

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

[0009] 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;

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

[0011] The parallel-type variable stiffness unit includes a non-linear elastic element and a stiffness adjustment component. The non-linear elastic element is composed of a first sub-coil spring and a second sub-coil spring which are connected in parallel through the stiffness adjustment component and have the same number of working turns. The stiffness adjustment component is also connected to the central shaft. The load torque is transmitted to the stiffness adjustment component through the central shaft, and then the torque acts on the inner ends of the sub-coil springs. The stiffness adjustment component locks the outer ends of the non-linear elastic element unidirectionally or bidirectionally to change the number of working turns and the output torque of each sub-coil spring, so as to balance the corresponding load torque. The stiffness adjustment component pre-tightens or unloads the outer ends of each sub-coil spring to make the carrier reach the desired working angle;

[0012] The control unit is used to control the stiffness adjustment component and the drive motor according to the current signal of the drive motor and the rotation angle signal of the central shaft, so as to balance the load torque, the torque of the non-linear elastic element and the output torque of the drive motor, and realize the adaptive adjustment of different loads while providing power for the carrier.

[0013] In some embodiments, the first sub-coil spring is arranged closer to the central shaft than the second sub-coil spring. Each sub-coil spring is a linear coil spring, or a non-linear coil spring, or one is a linear coil spring and the other is a non-linear coil spring. The non-linear coil spring is a flat spiral spring formed by connecting multiple coil spring segments end to end and integrally, and the stiffness of adjacent two coil spring segments is different. The stiffness adjustment component includes a first stiffness adjustment mechanism and a second stiffness adjustment mechanism. A partition plate fixedly connected to the frame body is provided inside the frame body;

[0014] The first stiffness adjustment mechanism includes a first sub-spring locking member and a first sub-spring fixing bracket. The first stiffness adjustment mechanism and the first sub-spring are located on one side of the partition facing the central axis. The second stiffness adjustment mechanism includes a second sub-spring locking member and a second sub-spring fixing bracket. The second stiffness adjustment mechanism and the second sub-spring are located on one side of the partition facing away from the central axis. Each sub-spring locking member respectively includes a ratchet and pawl mechanism, a matching stop switch and a return spring. All the ratchet and pawl mechanisms share a ratchet shaft. The ratchet shaft is coaxial and fixedly connected with the central axis and is rotatably connected to the frame body. The first ratchet and pawl mechanism is connected between the outer end of the first sub-spring and the lower end surface of the partition. The second ratchet and pawl mechanism is connected between the outer end of the second sub-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 corresponding stop pawl to approach its respective ratchet. During the adjustment process of the non-linear elastic element, each stop switch enables each ratchet to move only in the same single direction according to the instruction of the control unit, so that the number of working turns of the two sub-springs both increases or both decreases. Until the load torque, the torque of the non-linear elastic element and the output torque of the drive motor reach balance, the control unit controls the corresponding stop switch to lock the outer ends of the two sub-springs.

[0015] In some embodiments, the non-linear elastic element is designed according to the following steps:

[0016] The working curve of the given parallel drive module is divided into S segments. The working curve of the parallel drive module is the functional relationship between the rotation angle of the central axis and the torque output through the external connection end.

[0017] Let the number of spring segments contained in the first sub-spring be P, and the number of spring segments contained in the second sub-spring be Q. Both P and Q are positive integers greater than or equal to 1, and satisfy S≥P, S≥Q. When the number of spring segments of the sub-spring is taken as 1, the sub-spring is a linear spring. When the number of spring segments of the sub-spring is greater than 1, the sub-spring is a non-linear spring.

[0018] For the i-th segment of the working curve, i = 1, 2,..., S, the torque at a certain rotation angle φ on this segment of the working curve is taken as the sum of the torques of the first sub-spring and the second sub-spring at the rotation angle φ, and the slope of the working curve at the rotation angle φ is taken as the sum of the stiffnesses of the first sub-spring and the second sub-spring at the rotation angle φ, so as to obtain the respective working curves of the first sub-spring and the second sub-spring within the rotation angle range corresponding to the i-th segment of the working curve.

[0019] According to the working curves of the first sub-coil spring and the second sub-coil spring respectively, each coil spring segment in the first sub-coil spring and the second sub-coil spring is designed in accordance with the industry standard JB / T7366-1994 to obtain the parameters of each coil spring segment, including the elastic modulus E, the cross-sectional thickness h, the cross-sectional width b, and the developed length l.

[0020] In some embodiments, the first ratchet and pawl mechanism includes a first ratchet rotatably sleeved on the ratchet shaft, a first positive stop pawl and a first negative stop pawl that cooperate with the first ratchet through teeth. On the outer periphery of the first ratchet, there is the first sub-coil spring fixing frame integrally formed with the first ratchet. The inner end and the outer end of the first sub-coil spring are respectively fixedly connected to the ratchet shaft and the first sub-coil spring fixing frame. The ends of the first positive stop pawl and the first negative stop pawl away from their respective teeth are rotatably connected to the end face of the partition facing the first sub-coil spring fixing frame. Between the end of the first positive stop pawl close to its tooth and the partition, there is a first positive return spring and a first positive stop switch. Between the end of the first negative stop pawl close to its tooth and the partition, there is a first negative return spring and a first negative stop switch;

[0021] The second ratchet and pawl mechanism includes a second ratchet rotatably sleeved on the ratchet shaft, a second positive stop pawl and a second negative stop pawl that cooperate with the second ratchet through teeth. On the outer periphery of the second ratchet, there is the second sub-coil spring fixing frame integrally formed with the second ratchet. The inner end and the outer end of the second sub-coil spring are respectively fixedly connected to the ratchet shaft and the second sub-coil spring fixing frame. The ends of the second positive stop pawl and the second negative stop pawl away from their respective teeth are rotatably connected to the end face of the top cover of the machine frame body facing the second sub-coil spring fixing frame. Between the end of the second positive stop pawl close to its tooth and the top cover of the machine frame body, there is a second positive return spring and a second positive stop switch. Between the end of the second negative stop pawl close to its tooth and the top cover of the machine frame body, there is a second negative return spring and a second negative stop switch;

[0022] During the adjustment process of the non-linear elastic element, at most only one of the two stop pawls cooperating with the same ratchet contacts the teeth of the ratchet; when the load torque, the torque of the non-linear elastic element, and the output torque of the driving motor reach balance, both of the two stop pawls cooperating with the same ratchet contact the teeth of the ratchet.

[0023] In some embodiments, after torque balance, if it is required that the carrier continue to rotate by an angle α in the original rotation direction due to the need of the working angle, first make the two detent pawls cooperating with each ratchet be in a state opposite to that before torque balance, so that the outer ends of the sub-coil springs rotate by an angle α, the inner ends of the sub-coil springs will follow the outer ends of the sub-coil springs to rotate by an angle α, and then use the detent pawls to make each ratchet be in a two-way lock-up state;

[0024] After torque balance, if it is required that the carrier rotate in the reverse direction by an angle β in the original rotation direction due to the need of the working angle, first make the two detent pawls cooperating with each ratchet be in the same state as before torque balance, and use the driving motor to drive the carrier to rotate in the reverse direction in the original rotation direction, so that each sub-coil spring is unloaded. Until when the elastic torque of each sub-coil spring is zero, use the driving motor to drive the carrier to continue to rotate in the reverse direction in the original rotation direction by an angle β, thereby driving the outer ends of the sub-coil springs to rotate in the reverse direction in the original rotation direction of the carrier by an angle β. At this time, first use the detent pawls to make each ratchet be in a two-way lock-up state, then make the two detent pawls cooperating with each ratchet be in the same state as before torque balance, connect the load torque, the inner ends of the sub-coil springs rotate in the original rotation direction of the carrier, the sub-coil springs are compressed and deformed, and the outer ends of the sub-coil springs rotate in the reverse direction in the original rotation direction of the carrier by an angle β, so that the torque reaches balance again, and finally use the detent pawls to make each ratchet be in a two-way lock-up state.

[0025] In some embodiments, replace the ratchet and pawl mechanism in each sub-coil spring locking member with a friction cam mechanism.

[0026] In some embodiments, the parallel drive module further includes a handle cooperating with the external connection end, so that the parallel drive module has a manual power generation function. When manual power generation is required, control each stop switch through the control unit to separate all detent pawls from the tooth parts of the corresponding ratchets. At this time, the outer ends of all sub-coil springs are in a free state, then connect the handle to the external connection end, and by rotating the handle, power is transmitted through the external connection end and the central shaft to the mover of the driving motor to generate current.

[0027] 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 driving motor in real time, and the main controller is used to control the driving motor and each stop switch according to the rotation angle signal of the central shaft and the current signal of the driving motor.

[0028] In some embodiments, the control unit further includes an inertial measurement unit disposed on the circuit board, which is 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, 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.

[0029] 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.

[0030] In some embodiments, the drive unit, the control unit, and the parallel variable stiffness unit are coaxially and hierarchically arranged in the frame body, and the carrier and the parallel 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.

[0031] In some embodiments, the frame body includes an upper housing and a lower housing that are fixedly connected and coaxially arranged with the central shaft. The drive motor and the central shaft are both located inside the lower housing, and the upper end of the central shaft protrudes from the upper end surface of the lower housing. The external connection end is rotatably arranged at the center of the lower end surface of the lower housing through a bearing; the parallel variable stiffness unit and the control unit are both located inside the upper housing.

[0032] In some embodiments, the drive unit further includes a 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 reducer, and the output end of the drive motor is connected to the external connection end through the low-speed end of the reducer.

[0033] Compared with the prior art, the present disclosure has the following characteristics and beneficial effects:

[0034] An adaptive variable stiffness parallel drive module provided by an embodiment of the present disclosure has a large stiffness adjustment range. The nonlinear elastic element composed of a nonlinear coil spring is small, occupies a small volume, the stiffness adjustment component is simple, and the weight is comparable to that of a common driver. The coaxial arrangement among the nonlinear elastic element, 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 nonlinear elastic element enables the drive module to meet the requirements of the carrier's rotation angle and the output torque of the drive module under compact space constraints. According to different carrier load sizes, it can be adaptively adjusted to achieve precise tracking of the carrier's target pose. Specifically:

[0035] 1. Due to the optimization of the power transmission chain, the drive module of the present disclosure has a large stiffness adjustment range, occupies a small volume, and the weight is comparable to that of a common driver.

[0036] 2. The stiffness adjustment component, the nonlinear elastic element and the drive unit are coaxially matched, and the carrier and the nonlinear elastic element are located on both sides of the drive unit instead of on 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.

[0037] 3. Compared with a linear coil spring with a smaller stiffness, the nonlinear elastic element can bear a greater load torque under the same outer diameter of the coil spring and the number of rotation turns. Compared with a linear coil spring with a larger stiffness, the nonlinear elastic element 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 nonlinear elastic element enables the drive module to provide a larger rotation angle range and output torque range of the central axis under the same space constraints.

[0038] 4. The stiffness adjustment component adjusts the stiffness of the nonlinear elastic element 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 perform closed-loop control on the drive motor according to the real-time motion state of the carrier to achieve precise tracking of the carrier's target pose by the drive module.

[0039] Some of the advantages of the present application will be given in the following description, some will become obvious from the following description, or be understood through the practice of the present application.

[0040] A robot dog provided in the second aspect of the present disclosure includes a fuselage, legs, a first connecting member, a second connecting member and a plurality of parallel 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 in the legs. The legs include a thigh and a calf;

[0041] The first parallel 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 parallel drive module is fixedly connected to the fuselage, and the external connection end of the first parallel drive module is fixedly connected to the first connecting member;

[0042] The first connecting member, the second parallel drive module, the second connecting member, and the third parallel drive module are sequentially connected and coaxially arranged. The second parallel drive module is used to provide the driving force for the thigh to move within the sagittal plane of the fuselage, and the third parallel drive module is used to provide the driving force for the calf to move within the sagittal plane of the fuselage. The frame body of the second parallel drive module is fixedly connected to the first connecting member, the external connection end of the second parallel drive module is fixedly connected to one end of the second connecting member, the frame body of the third parallel drive module is fixedly connected to the end of the thigh close to the fuselage, and the external connection end of the third parallel drive module is connected to the calf through the transmission member disposed within the thigh.

[0043] In some embodiments, the transmission member adopts a belt drive mode, including 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 parallel drive module. The tension pulley is rotatably disposed in the middle of the thigh for tensioning the synchronous belt. The second pulley is rotatably sleeved on the pulley shaft and fixedly connected to the end of the calf close to the thigh, and the pulley shaft is fixedly connected to the end of the thigh close to the calf.

[0044] A robotic arm provided in the third aspect of the present disclosure includes a base, a fixed frame, a first arm, a second arm, a robotic claw, and two parallel drive modules according to any one of the embodiments of the first aspect of the present disclosure;

[0045] 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 provided within the base;

[0046] The first parallel drive module is disposed between the fixed frame and the first arm, and is used to provide the driving force for the first arm. The frame body of the first parallel drive module is fixedly connected to the fixed frame, and the external connection end of the first parallel drive module is fixedly connected to one end of the first arm;

[0047] The second parallel drive module is disposed between the first arm and the second arm for providing driving force to the second arm. The frame body of the second parallel drive module is fixedly connected to the other end of the first arm, and the external connection end of the second parallel drive module is fixedly connected to one end of the second arm. The other end of the second arm is connected to the robotic claw.

[0048] An exoskeleton provided in the fourth aspect of the present disclosure includes a waistband, a drive module, a drive module fixing bracket, and a leg fixing bracket.

[0049] The waistband is fixed to the waist of the wearer and fixedly connected to the drive module fixing bracket.

[0050] The leg fixing bracket is fixed to the leg of the wearer.

[0051] The drive module adopts the parallel drive module according to any one of the embodiments of the first aspect of the present disclosure for providing driving force to the leg fixing bracket. The frame body of the parallel drive module is fixedly connected to the drive module fixing bracket, and the external connection end of the parallel drive module is fixedly connected to the leg fixing bracket. Description of the Drawings

[0052] Figure 1 It is a schematic diagram of the overall structure of a parallel drive module with adaptive variable stiffness provided in Embodiment 1 of the present disclosure.

[0053] Figure 2 It is a schematic longitudinal sectional view of a parallel drive module with adaptive variable stiffness provided in Embodiment 1 of the present disclosure.

[0054] Figure 3 Is Figure 1 An exploded view of the drive unit in the shown parallel drive module.

[0055] Figure 4 Is Figure 1 An exploded view of the parallel variable stiffness unit in the shown parallel drive module from the first perspective.

[0056] Figure 5 Is Figure 1 An exploded view of the parallel variable stiffness unit in the shown parallel drive module from the second perspective.

[0057] Figure 6 In (a), (b), and (c) are schematic diagrams of the working process of the stiffness adjustment component of the parallel variable stiffness unit in the parallel drive module provided in Embodiment 1 of the present disclosure.

[0058] Figure 7 In (a) and (b) are respectively Figure 1Schematic diagram of the structure of the parallel drive module in the manual power generation mode and the state diagram of its internal stiffness adjustment component.

[0059] Figure 8 Among them, (a) and (b) are respectively the overall structure diagram and cross-sectional view of applying the parallel drive module provided in Embodiment 1 of the present disclosure to a quadruped robot.

[0060] Figure 9 It is a schematic diagram of applying the parallel drive module provided in Embodiment 1 of the present disclosure to a robotic arm.

[0061] Figure 10 It is a schematic diagram of applying the parallel drive module provided in Embodiment 1 of the present disclosure to an exoskeleton.

[0062] In the figure:

[0063] 100 is a frame, 110 is a frame body, 111 is an upper housing, 111a is a partition, 1111 is a second boss, 1112 is a first 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;

[0064] 200 is a drive unit, 210 is a central shaft, 220 is a drive motor, 221 is a rotor bracket, 2211 is a first journal, 222 is a permanent magnet, 223 is a winding bracket, 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;

[0065] 300 is a parallel variable stiffness unit, 310 is a non-linear elastic element, 311 is a first sub-coil spring, 312 is a second sub-coil spring, 320 is a stiffness adjustment component, 321 is a first sub-coil spring locking member, 3211 is a first ratchet wheel, 3212 is a first positive stop pawl, 3213 is a first negative stop pawl, 3214 is a first positive return spring, 3215 is a first positive stop switch, 3216 is a first negative return spring, 3217 is a first negative stop switch, 3218 is a set screw, 3219 is a first bearing bush, 322 is a first sub-coil spring fixing bracket, 3221 is a first pin, 323 is a second sub-coil spring locking member, 3231 is a second ratchet wheel, 3232 is a second positive stop pawl, 3233 is a second negative stop pawl, 3234 is a second positive return spring, 3235 is a second positive stop switch, 3236 is a second negative return spring, 3237 is a second negative stop switch, 3239 is a second bearing bush, 324 is a second sub-coil spring fixing bracket, 3241 is a second pin, 325 is a ratchet shaft;

[0066] 400 is the control unit, 410 is the circuit board, and 420 is the dust cover;

[0067] a is the first bearing, b is the second bearing, c is the third bearing, d is the fourth bearing, e is the fifth bearing, f is the sixth bearing, and g is the seventh bearing;

[0068] 11 is the first parallel drive module in the robot dog, 12 is the second parallel drive module in the robot dog, 13 is the third parallel drive module in the robot dog, 2 is the fuselage, 3 is the thigh, 4 is the calf, 5 is the first connecting piece, 6 is the second connecting piece, 7 is the transmission part, 71 is the first pulley, 72 is the second pulley, 73 is the tension pulley, 74 is the timing belt, and 75 is the pulley shaft;

[0069] 11’ is the first parallel drive module in the robotic arm, 12’ is the second parallel 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, and 5’ is the robotic claw;

[0070] 01 is the waist belt, 02 is the parallel drive module in the exoskeleton, 03 is the drive module fixing bracket, and 04 is the leg fixing bracket. Detailed implementation manners

[0071] 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. All other embodiments obtained by those of ordinary skill in the art based on the embodiments in the present application without creative efforts shall fall within the protection scope of the present application.

[0072] For 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.

[0073] 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.

[0074] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled 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.

[0075] Embodiment 1

[0076] See Figure 1 、 Figure 2 An adaptive variable stiffness parallel drive module provided in this embodiment includes a frame 100, as well as a drive unit 200, a parallel variable stiffness unit 300, and a control unit 400 disposed within the frame 100. Among them,

[0077] The frame 100 includes a frame body 110 and an external connection end 120 provided on the frame body 110, accesses the load of the carrier through the external connection end 120, and provides power to the carrier;

[0078] The drive unit 200 includes a central shaft 210 and a drive motor 220 coaxially arranged, and the drive motor 220 drives the central shaft 210 to rotate, and then is connected to the external connection end 120 through a speed reducer 230;

[0079] The parallel variable stiffness unit 300 includes a non-linear elastic element 310 and a stiffness adjustment component 320. The non-linear elastic element 310 is composed of a first sub-coil spring 311 and a second sub-coil spring 312 that are connected in parallel through the stiffness adjustment component 320 and have the same number of working turns. The stiffness adjustment component 320 is also connected to the central shaft 210. 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 the inner ends of the sub-coil springs. The stiffness adjustment component 320 changes the number of working turns and the output torque of each sub-coil spring by unidirectionally or bidirectionally locking the outer ends of the sub-coil springs, so as to balance the corresponding load torque. The stiffness adjustment component 320 pre-tightens or unloads the outer ends of the sub-coil springs to make the carrier reach the desired working angle;

[0080] The control unit 400 is used to control the stiffness adjustment component 320 and the drive motor 220 according to the current signal of the drive motor 220 and the rotation speed signal of the central shaft 210, so that the load torque, the torque of the non-linear elastic element 310, and the output torque of the drive motor 220 (hereinafter, the output torque of the drive motor will be simply referred to as "driving torque") reach balance among the three, and realize the adaptive adjustment of different loads while providing power to the carrier.

[0081] Furthermore, the frame body 110 serves as a base for providing support and positioning for other components within the drive 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 coaxially arranged with the central shaft 210. The drive motor 220 and the central shaft 210 are both located within 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 provided at the center of the lower end surface of the lower shell 112 through a third bearing c. The parallel variable stiffness unit 300 and the control unit 400 are both located within the upper shell 111.

[0082] Further, referring 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 output shaft of currently commercially available motors is built into the motor housing, while in this disclosed embodiment, the central axis 210 replaces the output shaft of the commercially available motor, facilitating connection with the parallel type variable stiffness unit 300. Most of the central axis 210 is located within 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 within the rotor frame 221. The permanent magnet 222 is fixed to the inner sidewall of the rotor frame 221, and the coil 224 is wound around the winding frame 223. At the center of the upper end surface of the rotor frame 221, a first journal 2211 with a through hole is formed. Part of the first journal 2211 protrudes from the upper end surface of the rotor frame 221 and part is located inside the rotor frame 221. The outer sidewall of the first journal 2211 protruding from the upper end surface of the rotor frame 221 is rotatably connected to the inner sidewall of the second journal 1121 at the center of the upper end surface of the lower housing 112 through a first bearing a, and the outer sidewall 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, a magnetic field is generated. Under the action of the magnetic field, the permanent magnet 222 drives the rotor frame 221 to rotate, and 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 the external connection end 120 is driven to rotate through the speed reducer 230, realizing the external output of power.

[0083] Optionally, referring to Figure 3, the drive unit 200 further includes a speed reducer 230 disposed between the output end of the drive motor 220 and the external connection end 120, which is used to reduce the rotational speed of the output end of the drive motor 220 to amplify the output torque. The output end of the drive motor 220 is the central shaft 210, 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 drive motor 220 is sufficient to overcome the change in the load torque. At this time, there is no need 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, which includes an internal gear ring 234, a planetary carrier 231, a sun gear 232 and a plurality of 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, and a plurality of planetary shafts 2311a are provided on the planetary carrier body 2311 and are circumferentially distributed 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 cycloid pinwheel speed reducers, etc., which will not be exemplified and elaborated here.

[0084] Further, referring to Figure 4 , Figure 5 , in the parallel variable stiffness unit 300 of this embodiment, the non-linear elastic element 310 is composed of two sub-coil springs connected in parallel. The two sub-coil springs have the same number of working turns, that is, they have the same angular range during rotation. Each sub-coil spring is layered in the upper layer housing 111 of the frame body 110, and the first sub-coil spring 311 is arranged closer to the central shaft 210 than the second sub-coil spring 312. Each sub-coil spring is a linear coil spring, or a non-linear coil spring, or one is a linear coil spring and the other is a non-linear coil spring; the non-linear coil spring is a flat spiral spring formed by connecting multiple coil spring segments end to end and integrally formed, and the stiffness of adjacent two coil spring segments is different. The non-linear elastic element 310 is designed according to the following steps:

[0085] Step 1: Segment the working curve of the given parallel drive module. The working curve of the parallel drive module is the functional relationship between the rotation angle (independent variable) of the central axis 210 and the torque output through the external connection end 120 (dependent variable). The number of segments S is determined according to the attitude control accuracy and stiffness adjustment accuracy requirements of the carrier. The higher the accuracy requirements, the larger the number of segments S, and S is a positive integer greater than or equal to 2.

[0086] Step 2: Let the number of coil spring segments contained in the first sub-coil spring 311 be P, and the number of coil spring segments contained in the second sub-coil spring 312 be Q. Both P and Q are positive integers greater than or equal to 1, and satisfy S≥P, S≥Q. When the number of coil spring segments of the sub-coil spring is taken as 1, the sub-coil spring is a linear coil spring. When the number of coil spring segments of the sub-coil spring is greater than 1, the sub-coil spring is a non-linear coil spring.

[0087] Step 3: For the i-th segment of the working curve, i = 1, 2,..., S, take the torque at a certain rotation angle φ on this segment of the working curve as the sum of the torques of the first sub-coil spring 311 and the second sub-coil spring 312 at the rotation angle φ, and take the slope of the working curve at the rotation angle φ as the sum of the stiffnesses of the first sub-coil spring 311 and the second sub-coil spring 312 at the rotation angle φ, so as to obtain the respective working curves of the first sub-coil spring 311 and the second sub-coil spring 312 within the rotation angle range corresponding to the i-th segment of the working curve.

[0088] Step 4: Design the P coil spring segments of the first sub-coil spring 311 and the Q coil spring segments of the second sub-coil spring 312 respectively according to the industry standard JB / T7366 - 1994 according to the respective working curves of the first sub-coil spring 311 and the second sub-coil spring 312 to obtain the parameters of each coil spring segment, including elastic modulus E, cross-sectional thickness h, cross-sectional width b, and developed length l.

[0089] Step 5: The overall dimensions of each sub-coil spring obtained according to the above design steps in the free state should meet the set space requirements. If not, it is necessary to return to Step 2, adjust the parameters P and Q, and re-design.

[0090] 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 (the specific adjustment process will be given below), in most application cases, when the relationship between the carrier 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 approximately conforming to the set function curve according to the above steps.

[0091] In this embodiment, there are two linear coil springs with different stiffnesses. The coil spring with a larger stiffness is used as the first sub-coil spring 311, and the coil spring with a smaller stiffness is used as the second sub-coil spring 312 and is arranged above the first sub-coil spring 311. The stiffness of the non-linear coil spring 310 is obtained by the parallel connection of the first sub-coil spring 311 and the second sub-coil spring 312, and the first sub-coil spring 311 and the second sub-coil spring 312 with different stiffnesses can be selected and combined according to actual needs.

[0092] In the parallel-type variable stiffness unit 300 of this embodiment, a stiffness adjustment mechanism is configured for each sub-coil spring. The two stiffness adjustment mechanisms together constitute the stiffness adjustment assembly 320 in the parallel-type variable stiffness unit 300, and both are coaxial with the central axis 210. Each stiffness adjustment mechanism is controlled by the control unit 400 to adjust the stiffness of the coil spring. Specifically, through each stiffness adjustment mechanism, the corresponding sub-coil spring is locked or unloaded until the total elastic moment generated by the non-linear elastic element 310 reaches the load moment and then remains balanced. The first stiffness adjustment mechanism includes a first sub-coil spring locking member 321 and a first sub-coil spring fixing bracket 322. The second stiffness adjustment mechanism includes a second sub-coil spring locking member 323 and a second sub-coil spring fixing bracket 324. A partition 111a is further provided in the upper housing 111 to divide the upper housing 111 into an upper space and a lower space. The first stiffness adjustment mechanism and the first sub-coil spring 311 are located in the lower space of the upper housing 111, and the second stiffness adjustment mechanism and the second sub-coil spring 312 are located in the upper space of the upper housing 111. The partition 111a is a circular plate provided with a central hole, and a first boss 1112 for installing the first sub-coil spring locking member 321 is provided on the lower end surface of the partition 111a. The outer end of the partition 111a is fixedly connected to the upper housing 111 by screws. A second boss 1111 for installing the second sub-coil spring locking member 323 is provided on the lower end surface of the top cover of the upper housing 111.

[0093] The first sub-coil spring locking member 321 and the second sub-coil spring locking member 323 each include a ratchet and pawl mechanism, a matching stop switch and a return spring. The ratchet and pawl mechanisms in the first sub-coil spring locking member 321 and the second sub-coil spring locking member 323 share a ratchet shaft 325. The ratchet shaft 325 is a stepped shaft. The top end of the ratchet shaft 325 is rotatably connected to the frame body 110 through a fifth bearing e provided at the central hole of the upper housing 111. The bottom end of the ratchet shaft 325 is fixedly connected to the top end of the central shaft 210 through a set screw 3218. The angular difference between the inner end rotation angle position and the outer end rotation angle position of the sub-coil spring is the number of turns by which the sub-coil spring is compressed. Different numbers of compressed turns 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 has the characteristic of adapting to the load torque. In this embodiment, when a load is connected, according to the stiffness characteristics of each coil spring segment, the coil spring segments are compressed in order from the smallest stiffness to the largest 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 equilibrium is reached.

[0094] The first sub-coil spring locking member 321 includes a first ratchet wheel 3211 rotatably sleeved on the ratchet shaft 325 through a first bearing bush 3219, a first positive stop pawl 3212 and a first negative stop pawl 3213 that cooperate with the first ratchet wheel 3211 through tooth portions, a first positive return spring 3214 and a first positive stop switch 3215 disposed between one end of the first positive stop pawl 3212 near the tooth portion and the first boss 1112 of the partition plate 111a, and a first negative return spring 3216 and a first negative stop switch 3217 disposed between one end of the first negative stop pawl 3213 near the tooth portion and the first boss 1112 of the partition plate 111a. One ends of the first positive stop pawl 3212 and the first negative stop pawl 3213 away from their respective tooth portions are rotatably connected to the first boss 1112 of the partition plate 111a. A first sub-coil spring fixing bracket 322 integrally formed with the first ratchet wheel 3211 is provided on the outer periphery of the first ratchet wheel 3211. A first pin 3221 for fixing the outer end of the first sub-coil spring 311 is provided on the lower end surface of the first sub-coil spring fixing bracket 322. The inner end of the first sub-coil spring 311 is fixedly connected to the ratchet shaft 325. An eighth bearing h is provided at the central hole of the partition plate 111a, and the partition plate 111a is rotatably sleeved on the ratchet shaft 325 through the seventh bearing g. The second sub-coil spring locking member 323 includes a second ratchet wheel 3231 rotatably sleeved on the ratchet shaft 325 through a second bearing bush 3239, a second positive stop pawl 3232 and a second negative stop pawl 3233 that cooperate with the second ratchet wheel 3231 through tooth portions, a second positive return spring 3234 and a second positive stop switch 3235 disposed between one end of the second positive stop pawl 3232 near the tooth portion and the second boss 1111 on the lower end surface of the top cover of the upper housing 111, and a second negative return spring 3236 and a second negative stop switch 3237 disposed between one end of the second negative stop pawl 3233 near the tooth portion and the second boss 1111 on the lower end surface of the top cover of the upper housing 111. One ends of the second positive stop pawl 3232 and the second negative stop pawl 3233 away from their respective tooth portions are rotatably connected to the second boss 1111 on the lower end surface of the top cover of the upper housing 111. A second sub-coil spring fixing bracket 324 integrally formed with the second ratchet wheel 3231 is provided on the outer periphery of the second ratchet wheel 3231. A second pin 3241 for fixing the outer end of the second sub-coil spring 312 is provided on the lower end surface of the second sub-coil spring fixing bracket 324. The inner end of the second sub-coil spring 312 is fixedly connected to the ratchet shaft 325.Each reset spring always remains in a compressed state and is used to provide a force for each stop pawl to approach the corresponding ratchet wheel. Taking the first sub-wound spring locking member 321 as an example: During the stiffness adjustment process, by switching the states of the two stop switches, only one of the first positive stop pawl 3212 and the first negative stop pawl 3213 contacts the tooth part of the first ratchet wheel 3211. Thus, the first ratchet wheel 3211 can only rotate in a single direction, causing the first sub-wound spring 311 to be in a pre-tightened or unloaded state (in this embodiment, it is stipulated that when the first ratchet wheel 3211 and the second ratchet wheel 3231 rotate counterclockwise, the sub-wound spring is in a pre-tightened compressed state and the elastic torque increases; when the first ratchet wheel 3211 and the second ratchet wheel 3231 rotate clockwise, the sub-wound spring is in an unloaded state and the elastic torque decreases). When the first ratchet wheel 3211 rotates in the opposite direction, the tooth part of the first ratchet wheel 3211 will be resisted by the stop pawl currently in contact with the first ratchet wheel 3211. Thus, the first ratchet wheel 3211 is in a stopped state, so that the first ratchet wheel 3211 can only rotate in a single direction. When the torque reaches equilibrium, both the first positive stop pawl 3212 and the first negative stop pawl 3213 contact the tooth part of the first ratchet wheel 3211, locking the outer end of the first sub-wound spring 311, thereby keeping the current elastic torque unchanged. It should be noted that each stop switch uses an electromagnetic switch. More specifically, an armature switch can be used. Controlled by the control unit, when the armature switch is turned on, it will provide a force for the corresponding stop pawl to move away from the ratchet wheel in contact with the corresponding stop pawl, and this force is greater than the force provided by the reset spring, so that the corresponding stop pawl is separated from the ratchet wheel; when the armature switch is turned off, the force it provides for the corresponding stop pawl disappears, and the corresponding stop pawl contacts the ratchet wheel under the action of the reset spring.

[0095] In this embodiment, the characteristics of the parallel wound spring are that the two sub-wound springs participate in the stiffness adjustment synchronously. The total elastic torque of the parallel wound spring is determined by the elastic torques of the two sub-wound springs. When the load increases, the stiffness adjustment components of the two sub-wound springs will simultaneously adjust the elastic torques of the corresponding sub-wound springs, increasing the total elastic torque of the non-linear elastic element 310. When the load decreases, the stiffness adjustment components of the two sub-wound springs will simultaneously adjust the total elastic torques of the corresponding sub-wound springs, decreasing the total elastic torque of the non-linear elastic element 310.

[0096] Further, referring to Figure 6 (a), (b), and (c) therein, which are schematic diagrams of the working process of the stiffness adjustment component 320 of this embodiment. The two sub-wound springs participate in the stiffness adjustment synchronously. At this time, the inner ends of the first sub-wound spring 311 and the second sub-wound spring 312 are subjected to a counterclockwise load torque, where:

[0097] When the load torque is just applied, the stiffness adjustment component 320 operates as shown in Figure 6In the mode shown in (a), the coil spring is compressed and deformed. The outer end of the first sub-coil spring 311 is fixed to the first pin 3221 on the first sub-coil spring fixing bracket 322 (the first sub-coil spring fixing bracket 322 is integrally formed with the first ratchet wheel 3211), that is, the outer end of the first sub-coil spring 311 moves synchronously with the first ratchet wheel 3211. The inner end of the first sub-coil spring 311 is fixed to the ratchet shaft 325 and is subjected to the counterclockwise torque generated by the load. The first positive stop pawl 3212 on the right separates from the tooth part of the first ratchet wheel 3211, and the first negative stop pawl 3213 on the left contacts the tooth part of the first ratchet wheel 3211, so that the outer end of the first sub-coil spring 311 is locked and immovable under the action of the counterclockwise torque generated by the load. At the same time, the outer end of the second sub-coil spring 312 is fixed to the second pin 3241 on the second sub-coil spring fixing bracket 324 (the second sub-coil spring fixing bracket 324 is integrally formed with the second ratchet wheel 3231). The inner end of the second sub-coil spring 312 is fixed to the ratchet shaft 325 and is subjected to the counterclockwise torque generated by the load. The second positive stop pawl 3232 on the right separates from the tooth part of the second ratchet wheel 3231, and the second negative stop pawl 3233 on the left contacts the tooth part of the second ratchet wheel 3231, so that the outer end of the second sub-coil spring 312 is locked and immovable under the action of the counterclockwise torque generated by the load. Thus, the outer ends of the first sub-coil spring 311 and the second sub-coil spring 312 are both locked and immovable, and the clockwise reverse elastic torque generated by the two together can balance the counterclockwise torque generated by the load. If the load reaches the desired working angle (position) at this time, the stiffness adjustment assembly 320 works in the mode as shown in Figure 6 In the mode shown in (c). At this time, both the first positive stop pawl 3212 and the first negative stop pawl 3213 are engaged with the first ratchet wheel 3211 to ensure that the first ratchet wheel 3211 is fixed, and both the second positive stop pawl 3232 and the second negative stop pawl 3233 are engaged with the second ratchet wheel 3231 to ensure that the second ratchet wheel 3231 is fixed.

[0098] When the load torque increases, the inner ends of the first sub-coil spring 311 and the second sub-coil spring 312 will continue to rotate counterclockwise, further compressing the coil spring until torque balance is reached again.

[0099] When the load torque decreases, the inner ends of the first sub-coil spring 311 and the second sub-coil spring 312 will rotate clockwise to relax the coil spring until torque balance is reached again.

[0100] After torque balance, if it is required that the load rotates counterclockwise by a certain angle due to the need of the working angle (position), that is, it is required that the inner ends of the two sub-coil springs rotate counterclockwise by a certain angle, then the stiffness adjustment assembly 320 is in the mode as shown in Figure 6Work in the mode shown in Fig. (b) for a short period of time. During this time, the first negative stop pawl 3213 and the second negative stop pawl 3233 on the left disengage from the first ratchet wheel 3211 and the second ratchet wheel 3231 respectively. The two ratchet wheels rotate counterclockwise by a certain angle under the elastic torque of the coil spring, so as to realize that the outer end of the sub-coil spring rotates counterclockwise by a corresponding angle. Since the torque is already in balance, the inner ends of the sub-coil springs will rotate by the same angle as the outer ends of the sub-coil springs rotate counterclockwise, so as to make the load reach the desired working angle. Then, control the first negative stop pawl 3213 and the second negative stop pawl 3233 to quickly lock the first ratchet wheel 3211 and the second ratchet wheel 3231 bidirectionally, to prevent the outer end of the coil spring from rotating counterclockwise beyond the desired angle (position); if the rotation angle is less than the desired working angle, continue to make the stiffness adjustment component 320 work in the mode as shown in Figure 6 Repeat the operation in the mode shown in Fig. (b), so as to realize that the outer end of the coil spring rotates counterclockwise by a certain angle to reach the desired working angle (position), and once again reach the balance between the load torque and the coil spring torque.

[0101] Similarly, after the torque is balanced, if the load needs to rotate clockwise by a certain angle due to the need of the working angle (position), that is, the inner ends of the two sub-coil springs need to rotate clockwise by a certain angle, the stiffness adjustment component 320 works in the mode as shown in Figure 6 Fig. (a). At this time, the driving motor 220 drives the load to rotate clockwise to unload the coil spring. When the elastic torque of the coil spring is zero, the driving motor 220 continues to drive the coil spring to rotate clockwise by a certain angle, so as to push the outer end of the coil spring to rotate clockwise by a corresponding angle. At this time, the first negative stop pawl 3213 and the second negative stop pawl 3233 do not prevent the first ratchet wheel 3211 and the second ratchet wheel 3231 from rotating clockwise. When the outer end of the coil spring reaches the desired angle (position), control the first positive stop pawl 3212 and the second positive stop pawl 3232 to lock the first ratchet wheel 3211 and the second ratchet wheel 3231 to ensure that the outer end of the coil spring is locked at the desired angle (position). Then, continue to make the stiffness adjustment component 320 repeat the operation in the mode as shown in Figure 6 Fig. (a), connect the load torque, the inner end of the coil spring rotates counterclockwise, and the coil spring is compressed and deformed, so as to realize that the outer end of the coil spring rotates clockwise by a certain angle to reach the desired working angle (position), and once again reach the balance between the load torque and the coil spring torque. Finally, use the stop pawls to make each ratchet wheel in a bidirectional lock state.

[0102] It can be understood that Figure 6 Fig. shows a typical installation method of the nonlinear elastic element 310 (mainly including the first sub-coil spring 311 and the second sub-coil spring 312). If they can bear the load torque in the clockwise direction according to the design requirements, it is necessary to Figure 6On the basis of the installation method shown in (a), the first sub-coil spring 311 and the second sub-coil spring 312 can be installed by simultaneously mirroring and flipping them left and right. At this time, the positive detent pawl provides the braking torque for each ratchet wheel. Therefore, the above mechanism can achieve the load torque balance in both clockwise and counterclockwise directions. In the actual application process, the appropriate installation method should be selected according to the acting direction of the load torque to install the non-linear elastic element 310.

[0103] It should be noted that in this embodiment, the ratchet and pawl mechanism in the coil spring locking member can be replaced by a friction cam mechanism or other similar intermittent motion mechanisms.

[0104] Further, the control unit 400 is arranged in the upper housing 111 of the frame body 110 and is located below the first sub-coil spring fixing bracket 322. It includes a circuit board 410, and a main controller, a rotation angle sensor, and a current sensor (the main controller, the rotation angle sensor, and the current sensor are not shown in the figure) arranged on the circuit board 410. The current sensor and the rotation angle sensor are both 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 number of rotations and the 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 opened 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-proof cover 420 provided with a central through hole. The dust-proof cover 420 is fixedly connected to the frame body 110, and the central through hole of the dust-proof cover 420 is rotatably connected to the ratchet shaft 325 through a sixth bearing f.

[0105] Furthermore, considering that the motion state, i.e., the pose, of the carrier driven by the driving 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 driving module through the external connection end 120. To achieve the precise tracking of the target pose of the carrier by the driving module, the control unit 400 in this embodiment is further configured to control the stiffness adjustment component 320 and the driving motor 220 according to the current pose and the target pose of the carrier, combined with the current signal of the driving motor 220 and the change of the rotation angle of the central axis 210, so that the load torque, the non-linear elastic element 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, not shown in the figure) disposed on the circuit board 410, which is used to collect the attitude angle and displacement of the carrier in real time and transmit them to the main controller in the control unit 400. The driving control of the driving motor 220 by the main controller is to add a pose loop of the carrier on the basis of the Field-Oriented Control (FOC) method. The FOC method adopts 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 desired rotation angle of the driving motor 220 according to the deviation between the current pose and the target pose of the carrier, input the desired rotation angle into the position loop in the FOC, and obtain the desired current value for the driving motor to maintain or reach the desired rotation angle through the calculation of the FOC method, so as to achieve the precise tracking of the target pose of the carrier.

[0106] Optionally, referring to Figure 7 (a) and (b) in the figure, the parallel-type driving module provided by the embodiment of the present disclosure further includes a handle 130 that cooperates with the pin shaft 121 on the external connection end 120, so that the parallel-type driving module in this embodiment has a manual power generation function. When manual power generation is required, first, the control unit 400 is used to control each stop switch to separate all the stop pawls (3212, 3213, 3232, 3233) from the tooth parts of the corresponding ratchets (3211, 3231). At this time, the outer ends of the first sub-winding spring 311 and the second sub-winding spring 312 are in a free state, and the inner ends are connected to the central axis 210 through the ratchet shaft 325. Then, the handle 130 is connected to the external connection end 120. By rotating the handle 130, the power is transmitted in sequence through the external connection end 120, the reducer 230, the central axis 210 to the rotor frame 221. The relative movement between the permanent magnet 222 and the coil 224 on the rotor frame 221 cuts the magnetic induction lines to generate current, achieving the effect of manual power generation.

[0107] The working process of the driving module in this embodiment is described as follows:

[0108] The load is introduced into the present 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 drives the central shaft 210 to rotate after being amplified by the speed reducer 230. The ratchet shaft 325 is fixedly connected to the top end of the central shaft 210. Therefore, the rotation of the central shaft 210 will drive the ratchet shaft 325. The inner ends of the first sub-winding spring 311 and the second sub-winding spring 312 are both fixedly connected to the ratchet shaft 325. The load torque is introduced into the inner ends of the first sub-winding spring 311 and the second sub-winding spring 312 simultaneously through the ratchet shaft 325, and the first sub-winding spring 311 and the second sub-winding spring 312 are pre-tightened respectively under the cooperation of the first sub-winding spring locking member 321 and the second sub-winding spring locking member 323, so as to balance most of the load torque by using the first sub-winding spring 311 and the second sub-winding spring 312. Specifically: the control unit 400 controls the engagement and separation of the ratchet pawl in the first sub-winding spring locking member 321 through the on-off of the electromagnetic switch to achieve one-way or two-way locking of the outer end of the first sub-winding spring 311. At the same time, the engagement and separation of the ratchet pawl in the second sub-winding spring locking member 323 are controlled to achieve one-way or two-way locking of the outer end of the second sub-winding spring 312. When the control unit 400 issues a ratchet pawl separation instruction, the electromagnetic switch is energized, and at this time, the pawl is separated from the ratchet under the action of the magnetic suction force; when the control unit 400 issues a ratchet pawl engagement instruction, the electromagnetic switch is de-energized, and at this time, the pawl is engaged with the ratchet under the action of the return spring. Since the torque generated by the load of the carrier has been balanced by the non-linear elastic element 310, at this time, when the driving motor 220 drives the movement of the carrier again, only a smaller torque is required to regulate the movement of the load, thereby greatly reducing the energy consumption of the driving motor.

[0109] Embodiment 2

[0110] See Figure 8 In (a) and (b) below, in this embodiment, the parallel drive module provided in Embodiment 1 is applied to a robot dog. The robot dog includes a fuselage 2, legs, a first connecting member 5, a second connecting member 6 and a number of parallel drive modules (11, 12 and 13) provided according to Embodiment 1 disposed between the fuselage 2 and the legs, and a transmission member 7 disposed inside the legs. The legs include a thigh 3 and a calf 4;

[0111] The first parallel drive module 11 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 parallel drive module 11 is fixedly connected to the fuselage 2, and the external connection end of the first parallel drive module 11 is fixedly connected to the first connecting member 5;

[0112] The first connecting member 5, the second parallel drive module 12, the second connecting member 6, and the third parallel drive module 13 are connected in sequence and coaxially arranged. The second parallel drive module 12 is used to provide the driving force for the thigh 3 to move in the sagittal plane of the fuselage. The third parallel drive 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 parallel drive module 12 is fixedly connected to the first connecting member 5. The external connection end of the second parallel drive module 12 is fixedly connected to one end of the second connecting member 6. The second connecting member 6 is fixedly connected to the frame body of the third parallel drive module 13. The frame body of the third parallel drive module 13 is fixedly connected to the end of the thigh 3 close to the fuselage 2. The external connection end of the third parallel drive module 13 is connected to the calf 4 through a transmission member 7 arranged in the thigh 3.

[0113] Further, there are 4 legs in total in the robot dog of this embodiment ( Figure 8 only one leg of the robot dog is shown), which are respectively located at the four corners of the fuselage 2. A first parallel drive 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 parallel drive module 11. There are 8 bolt holes on the frame body of the first parallel drive 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 parallel drive 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 parallel drive 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 parallel drive module 12 are fixedly connected through 8 bolt holes on the frame body of the second parallel drive module 12 and the matching bolts. The second parallel drive 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 parallel drive module 12 and the matching bolts. There are 3 bolt holes on the external connection end of the second parallel drive 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 parallel drive 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 parallel drive module 13. The second connecting member 6 and the third parallel drive module 13 are fixedly connected through 8 bolt holes on the frame body of the third parallel drive module 13 and the matching bolts. The third parallel drive 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 parallel drive module 13 and the thigh 3 are fixedly connected through 8 bolt holes on the frame body of the third parallel drive module 13 and the matching bolts. There are 3 bolt holes on the external connection end of the third parallel drive 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.

[0114] 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 parallel 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.

[0115] It can be understood that for the robotic dog provided in this embodiment, due to the adoption of non-linear elastic elements, the power consumption of the driving motor can be reduced, which is applicable to working conditions with larger loads. In addition, since the drive module in this embodiment has the ability of adaptive adjustment for different loads, for example, the robotic 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 cut off, due to the existence of non-linear elastic elements, the robotic dog will not be instantly unloaded 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 of each joint of the robotic dog's leg. The control unit in the drive module can perform closed-loop control on the driving motor according to this pose state to achieve precise tracking of the target pose of each joint of the robotic dog's leg.

[0116] Embodiment 3

[0117] See Figure 9 , in this embodiment, the parallel drive module provided in Embodiment 1 is applied to a robotic arm, which includes a base 2', a fixed frame 3', a first arm 41', a second arm 42', a robotic claw 5', and two parallel drive modules (11' and 12') provided according to Embodiment 1;

[0118] The fixed frame 3' is installed on the base 2'. A motor for driving the fixed frame 3' to rotate around the axis of the base 2' is provided in the base 2' (this motor is not shown in Figure 9 );

[0119] The first parallel drive module 11' is arranged between the fixed frame 3' and the first arm 41' for providing driving force for the first arm 41'. The frame body of the first parallel drive module 11' is fixedly connected to the fixed frame 3'. The external connection end of the first parallel drive module 11' is fixedly connected to one end of the first arm 41';

[0120] The second parallel drive module 12' is disposed between the first arm 41' and the second arm 42' for providing driving force to the second arm 42'. The frame body of the second parallel drive module 12' is fixedly connected to the other end of the first arm 41', and the external connection end of the second parallel drive module 12' is fixedly connected to one end of the second arm 42'. The other end of the second arm 42' is connected to the robotic gripper 5'.

[0121] It can be understood that for the robotic arm provided in this embodiment, since it is internally configured with the parallel drive module provided in this disclosure embodiment, the robotic arm of this embodiment has the following characteristics: 1. The non-linear elastic element in the drive module of this robotic arm can reduce the power consumption of the drive motor and is applicable to working conditions with large loads; 2. This embodiment can adapt to 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 drive 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 elastic element; 4. The IMU is integrated in the drive module of this embodiment to collect the pose states at each joint of the robotic arm in real time. 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 robotic arm.

[0122] Embodiment 4

[0123] See Figure 10 , in this embodiment, the parallel drive module provided in Embodiment 1 is applied to an exoskeleton. The exoskeleton includes a waistband 01, a drive module 02, a drive module fixing bracket 03, and a leg fixing bracket 04;

[0124] The waistband 01 is fixed to the waist of the wearer and can be fixedly connected to the drive module fixing bracket 03 through a buckle;

[0125] The leg fixing bracket 04 is fixed to the leg of the wearer, so that the power of the drive 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;

[0126] The drive module 02 adopts the parallel drive module provided in Embodiment 1 of this disclosure for providing driving force to the leg fixing bracket 04. The drive module 02 is fixedly connected to the drive module fixing bracket 03 through 8 bolt holes on the frame body of the drive module 02 and the matching bolts, and the drive 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 drive module 02 and the matching bolts.

[0127] It can be understood that the exoskeleton provided in this embodiment, due to the parallel drive module provided in the present disclosure being configured therein, has the following characteristics: 1. The non-linear elastic element in the drive module of this exoskeleton can reduce the power consumption of the drive motor and is applicable to working conditions with large loads; 2. This embodiment can adapt to working conditions. For example, when the load carried by the exoskeleton is a non-constant load, it can adaptively adjust the stiffness of the drive module to meet different working conditions; 3. The mechanical device can be protected due to the presence of the non-linear elastic element; 4. The IMU is integrated in the drive module of this embodiment to collect the pose state at the joints of the exoskeleton in real time. 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 the joints of the exoskeleton.

[0128] 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 different embodiments or examples.

[0129] 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 limitations on 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 scope of protection of the present application.

Claims

1. A parallel drive module with adaptive variable stiffness, characterized in that It includes a frame, as well as a driving unit, a parallel 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 parallel variable stiffness unit includes a non-linear elastic element and a stiffness adjustment component. The non-linear elastic element is composed of a first sub-coil spring and a second sub-coil spring that are connected in parallel through the stiffness adjustment component and have the same number of working turns. The stiffness adjustment component is also connected to the central shaft. The load torque is transmitted to the stiffness adjustment component through the central shaft, and then the torque acts on the inner ends of each sub-coil spring. The stiffness adjustment component locks the outer ends of the non-linear elastic element unidirectionally or bidirectionally to change the number of working turns and the output torque of each sub-coil spring, so as to balance the corresponding load torque. The stiffness adjustment component pre-tightens or unloads the outer ends of each sub-coil spring to make the carrier reach the desired working angle; 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 elastic element and the output torque of the driving motor reach balance, and realize the adaptive adjustment of different loads while providing power for the carrier; The first sub-coil spring is arranged closer to the central shaft than the second sub-coil spring. Each sub-coil spring is a linear coil spring, or a non-linear coil spring, or one is a linear coil spring and the other is a non-linear coil spring; the non-linear coil spring is a flat spiral spring formed by connecting multiple coil spring segments end to end and integrally, and the stiffness of adjacent two coil spring segments is different; the stiffness adjustment component includes a first stiffness adjustment mechanism and a second stiffness adjustment mechanism; a partition plate fixedly connected to the frame body is arranged within the frame body; The first stiffness adjustment mechanism includes a first sub-spring locking member and a first sub-spring fixing bracket. The first stiffness adjustment mechanism and the first sub-spring are located on one side of the partition facing the central axis. The second stiffness adjustment mechanism includes a second sub-spring locking member and a second sub-spring fixing bracket. The second stiffness adjustment mechanism and the second sub-spring are located on the side of the partition facing away from the central axis. Each sub-spring locking member respectively includes a ratchet and pawl mechanism, a matching stop switch and a return spring. All the ratchet and pawl mechanisms share a ratchet shaft. The ratchet shaft is coaxial and fixedly connected with the central axis and is rotatably connected with the frame body. The first ratchet and pawl mechanism is connected between the outer end of the first sub-spring and the lower end face of the partition. The second ratchet and pawl mechanism is connected between the outer end of the second sub-spring and the lower end face 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 corresponding stop pawl to approach its respective ratchet. During the adjustment process of the non-linear elastic element, each stop switch enables each ratchet to move only in the same single direction according to the instruction of the control unit, so that the number of working turns of the two sub-springs both increases or both decreases. Until the load torque, the torque of the non-linear elastic element and the output torque of the driving motor reach balance, the control unit controls the corresponding stop switch to lock the outer ends of the two sub-springs.

2. The parallel drive module according to claim 1, wherein Design the non-linear elastic element according to the following steps: Divide the working curve of the given parallel drive module into S segments. The working curve of the parallel drive module is the functional relationship between the rotation angle of the central axis and the torque output through the external connection end. Let the number of spring segments contained in the first sub-spring be P, and the number of spring segments contained in the second sub-spring be Q. Both P and Q are positive integers greater than or equal to 1, and satisfy S≥P, S≥Q. When the number of spring segments of the sub-spring is taken as 1, the sub-spring is a linear spring. When the number of spring segments of the sub-spring is greater than 1, the sub-spring is a non-linear spring. For the i-th segment of the working curve, i = 1, 2,..., S, take the torque at a certain rotation angle φ on this segment of the working curve as the sum of the torques of the first sub-spring and the second sub-spring at this rotation angle φ, and take the slope of the working curve at this rotation angle φ as the sum of the stiffnesses of the first sub-spring and the second sub-spring at the rotation angle φ, so as to obtain the respective working curves of the first sub-spring and the second sub-spring within the rotation angle range corresponding to the i-th segment of the working curve. Design each spring segment in the first sub-spring and the second sub-spring respectively according to the respective working curves of the first sub-spring and the second sub-spring in accordance with the industry standard JB / T7366-1994 to obtain the parameters of each spring segment, including the elastic modulus E, the cross-sectional thickness h, the cross-sectional width b and the unfolded length l.

3. The parallel drive module according to claim 1, characterized in that, The first ratchet pawl mechanism includes a first ratchet rotatably sleeved on the ratchet shaft, a first positive stop pawl and a first negative stop pawl that cooperate with the first ratchet through tooth portions. An integrally formed first sub-winding spring fixing bracket with the first ratchet is provided on the outer periphery of the first ratchet. The inner end and the outer end of the first sub-winding spring are fixedly connected to the ratchet shaft and the first sub-winding spring fixing bracket respectively. One ends of the first positive stop pawl and the first negative stop pawl, which are far from their respective tooth portions, are rotatably connected to the end surface of the partition facing the first sub-winding spring fixing bracket. A first positive return spring and a first positive stop switch are provided between one end of the first positive stop pawl close to its tooth portion and the partition. A first negative return spring and a first negative stop switch are provided between one end of the first negative stop pawl close to its tooth portion and the partition; The second ratchet pawl mechanism includes a second ratchet rotatably sleeved on the ratchet shaft, a second positive stop pawl and a second negative stop pawl that cooperate with the second ratchet through tooth portions. An integrally formed second sub-winding spring fixing bracket with the second ratchet is provided on the outer periphery of the second ratchet. The inner end and the outer end of the second sub-winding spring are fixedly connected to the ratchet shaft and the second sub-winding spring fixing bracket respectively. One ends of the second positive stop pawl and the second negative stop pawl, which are far from their respective tooth portions, are rotatably connected to the end surface of the top cover of the frame body facing the second sub-winding spring fixing bracket. A second positive return spring and a second positive stop switch are provided between one end of the second positive stop pawl close to its tooth portion and the top cover of the frame body. A second negative return spring and a second negative stop switch are provided between one end of the second negative stop pawl close to its tooth portion and the top cover of the frame body; During the adjustment process of the non-linear elastic element, at most only one of the two stop pawls cooperating with the same ratchet contacts the tooth portion of the ratchet; when the load torque, the torque of the non-linear elastic element, and the output torque of the driving motor reach balance, both of the two stop pawls cooperating with the same ratchet contact the tooth portion of the ratchet.

4. The parallel drive module according to claim 3, characterized in that After the torque balance, if it is required that the carrier continues to rotate by an angle α in the original rotation direction due to the need of the working angle, first make the two stop pawls cooperating with each ratchet in a state opposite to that before the torque balance, so that the outer ends of the sub-winding springs rotate by an angle α, and the inner ends of the sub-winding springs will follow the outer ends of the sub-winding springs to rotate by an angle α, and then use the stop pawls to make each ratchet in a two-way locking state; After the torque is balanced, if it is required that the carrier rotates in the reverse direction by an angle β due to the need of the working angle, first make the two detent pawls cooperating with each ratchet in the same state as before the torque balance, and use the driving motor to drive the carrier to rotate in the reverse direction along the original rotation direction, so that each sub-coil spring is unloaded. Until when the elastic torque of each sub-coil spring is zero, use the driving motor to drive the carrier to continue to rotate in the reverse direction along the original rotation direction by an angle β, thereby pushing the outer ends of each sub-coil spring to rotate in the reverse direction by an angle β along the original rotation direction of the carrier. At this time, first use the detent pawls to make each ratchet in a two-way locking state, then make the two detent pawls cooperating with each ratchet in the same state as before the torque balance, connect the load torque, the inner ends of each sub-coil spring rotate along the original rotation direction of the carrier, each sub-coil spring is compressed and deformed, and the outer ends of each sub-coil spring rotate in the reverse direction by an angle β along the original rotation direction of the carrier, so that the torque reaches balance again. Finally, use the detent pawls to make each ratchet in a two-way locking state.

5. The parallel drive module according to claim 1, characterized in that Replace the ratchet and pawl mechanism in each sub-coil spring locking member with a friction cam mechanism.

6. The parallel drive module according to claim 1, characterized in that The parallel drive module further includes a handle cooperating with the external connection end, so that the parallel drive module has a manual power generation function. When manual power generation is required, the control unit controls each stop switch to separate all the detent pawls from the tooth parts of the corresponding ratchets. At this time, the outer ends of all the sub-coil springs are in a free state. Then connect the handle to the external connection end, and by rotating the handle, the power is transmitted to the mover of the driving motor through the external connection end and the central shaft to generate current.

7. The parallel drive module according to claim 1, wherein 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, and 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 each stop switch according to the rotation angle signal of the central shaft and the current signal of the driving motor.

8. The parallel drive module according to claim 7, wherein The control unit further includes an inertial measurement unit arranged 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 driving motor according to the signals collected by the inertial measurement unit to realize the tracking of the target pose of the carrier. The four-loop control is to add a pose loop on the basis of the FOC method. The pose loop is used to obtain the desired rotation angle of the driving 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 driving motor to maintain or reach the desired rotation angle is obtained.

9. The parallel drive module according to claim 7, wherein, The control unit further includes a dust cover fixedly connected to the frame body, and the circuit board is located below the dust cover.

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

11. The parallel 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 driving 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 parallel variable stiffness unit and the control unit are both located inside the upper shell.

12. The parallel drive module according to claim 1, wherein The driving unit further includes a speed reducer arranged between the output end of the driving motor, the external connection end, and the central shaft. The output end of the driving motor is connected to the central shaft through the high-speed end of the speed reducer, and the output end of the driving motor is connected to the external connection end through the low-speed end of the speed reducer.

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

14. The robotic dog according to claim 13, characterized in that, The transmission member adopts a belt drive method 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 parallel 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 a 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.

15. A robotic arm, characterized in that, It includes a base, a fixed frame, a first arm, a second arm, a mechanical claw, and two parallel driving modules according to any one of claims 1 to 12. The fixing bracket is installed on the base, and a motor for driving the fixing bracket to rotate around the axial direction of the base is arranged in the base; The first parallel drive module is arranged between the fixing bracket and the first arm for providing driving force for the first arm. The frame body of the first parallel drive module is fixedly connected with the fixing bracket, and the external connection end of the first parallel drive module is fixedly connected with one end of the first arm; The second parallel drive module is arranged between the first arm and the second arm for providing driving force for the second arm. The frame body of the second parallel drive module is fixedly connected with the other end of the first arm, and the external connection end of the second parallel drive module is fixedly connected with one end of the second arm. The other end of the second arm is connected with the mechanical claw.

16. An exoskeleton, characterized in that, It includes a belt, a drive module, a drive module fixing bracket and a leg fixing bracket; The belt is fixed to the waist of the wearer and fixedly connected with the drive module fixing bracket; The leg fixing bracket is fixed to the leg of the wearer; The drive module adopts the parallel drive module according to any one of claims 1 to 12 for providing driving force for the leg fixing bracket. The frame body of the parallel drive module is fixedly connected with the drive module fixing bracket, and the external connection end of the parallel drive module is fixedly connected with the leg fixing bracket.

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