Self-adaptive variable stiffness driving module and application thereof

Abstract

The invention provides a self-adaptive variable-stiffness driving module. The self-adaptive variable-stiffness driving module comprises a rack, a driving unit, a variable-stiffness unit and a control unit, wherein the driving unit, the variable-stiffness unit and the control unit are arranged in the rack; the driving unit comprises a central shaft and a driving motor which are coaxial, and the output end of the driving motor is connected with the external connection end on the rack; the variable stiffness unit comprises a nonlinear coil spring and a stiffness adjusting assembly, the nonlinear coil spring is formed by sequentially connecting a plurality of coil spring sections with different stiffness in an end-to-end mode and integrally formed, the stiffness adjusting assembly is connected with the nonlinear coil spring and the center shaft, and the load of the carrier acts on the nonlinear coil spring through torque transmitted by the center shaft; the rigidity adjusting assembly is used for carrying out one-way or two-way locking and pre-tightening or unloading on the end part of the nonlinear coil spring so as to balance the corresponding load torque and enable a carrier to reach an expected working angle; the control unit is used for controlling the rigidity adjusting assembly and the driving motor, so that the torque of the load, the nonlinear coil spring and the driving motor is balanced, and self-adaptive adjustment of different loads is achieved while power is provided for the carrier.

Description

Technical Field

[0001] The present disclosure relates to the technical field of drivers, and in particular to an adaptive variable stiffness driving module and applications thereof. Background Art

[0002] The robot's joint drive module is the core component of the robot's motion system, responsible for achieving precise joint movement and providing sufficient driving force to ensure that the robot can perform complex tasks. The joint drive module not only improves the robot's flexibility and adaptability, enabling it to operate flexibly in various environments, but also enhances its load capacity and energy efficiency, thereby improving 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 applications, including automated production lines in industrial manufacturing, surgical robots in the medical field, automatic delivery and cleaning robots in the service industry, automated planting and picking equipment in agriculture, robot dogs, exoskeletons, and detection and rescue robots, thereby promoting the overall development of robotics technology and bringing smarter and more efficient robot systems.

[0003] In most application scenarios, the robot's joint drive module usually swings within a certain range. During the movement, it always needs to overcome the weight of the robot arm and the gravity of the load it operates to do work, which brings additional energy consumption (useless work), and then puts forward more stringent index requirements for the output torque of the joint drive module, which has become an important bottleneck restricting the current development of joint drive module technology. With the rapid development of artificial intelligence and robotics technology, joint drive modules with higher load-to-weight ratio (ratio of load to self-weight) and longer battery life are important directions and necessary paths for future technological development. The current high-torque motors used in robot joints mainly use large transmission ratio reducers (such as harmonic and RV reducers) to achieve the drive of large loads, but they cannot solve the problem of useless work done by overcoming the gravity of the robot arm and the load. In actual use, most of the power consumption is used to overcome gravity, which greatly reduces the robot's battery life.

[0004] The so-called gravity balance (compensation) technology in the prior art can offset the gravity effect of the robot arm and its load by using mechanical means such as springs, counterweights or pneumatic devices. This not only reduces the load on the motor and control system, improves control accuracy and response speed, but also improves energy efficiency and stability, extends system life, and reduces operating costs. Gravity balance technology enables the robot arm to respond to different load conditions and working environments more flexibly, thereby effectively solving the key challenges of the robot joint module in the face of high deadweight, heavy load and variable load scenarios. However, through research, it was found that although the existing related gravity balance technology provides gravity balance support force (torque) by introducing elastic elements such as springs and coil springs in parallel or in series with the motor, it is only applicable to constant load (torque) or load (torque) changes. When facing most real working conditions, it still cannot solve the following important problems-how should the joint drive module be adaptively adjusted to optimize energy efficiency when the load changes greatly and the working angle has a limited range. For example, the mass of the load grasped by the robot arm changes greatly or even rapidly over time, and the robot arm produces large torque changes with angle changes. The elastic elements with a single stiffness in the existing related technologies are applicable to a relatively narrow range of working conditions and cannot meet the above requirements. Therefore, it is extremely necessary to carry out innovative design research on the range of changes in load and working angle, and to propose innovative structures and design methods that are adaptive to changes in load and working angle and have variable stiffness. Summary of the invention

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

[0006] To this end, the present invention provides an adaptive variable stiffness drive module, which has a compact structure and can be applied to a larger load (torque) variation range. The stiffness of the module can be automatically adjusted according to the load size to automatically adapt to various working conditions, and can simultaneously meet the rotation angle requirements and output torque requirements of the driven load.

[0007] In order to achieve the above objectives, the present disclosure adopts the following technical solutions:

[0008] A first aspect of the present disclosure provides an adaptive variable stiffness drive module, comprising a frame, and a drive unit, a variable stiffness unit and a control unit arranged in the frame;

[0009] The frame includes a frame body and an external connection terminal arranged on the frame body, through which the load of the carrier is connected and power is provided to the carrier;

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

[0011] The variable stiffness unit comprises a nonlinear coil spring and a stiffness adjustment component. The nonlinear coil spring is composed of a plurality of coil spring segments connected end to end in sequence and integrally formed. The stiffness of two adjacent coil spring segments is different. The stiffness adjustment component is connected between the nonlinear coil spring and the central shaft. The load torque is transmitted to the stiffness adjustment component through the central shaft, and then the torque is applied to one end of the nonlinear coil spring. The stiffness adjustment component changes the working number of coils and the output torque of the nonlinear coil spring by unidirectional or bidirectional locking of one end of the nonlinear coil spring, thereby balancing the corresponding load torque. The stiffness adjustment component pre-tightens or unloads the other end of the nonlinear coil spring. The nonlinear coil spring is designed according to the following steps: the given working curve of the driving module is divided into S segments, the working curve of the driving module is the functional relationship between the rotation angle of the central axis and the torque output through the external end, and the number of segments of the nonlinear coil spring is taken as S; the i-th segment working curve and its slope are respectively used as the working curve and stiffness of the i-th coil spring segment, i=1,2,...,S, and the i-th coil spring segment is designed according to the industry standard JB / T7366-1994 to obtain the parameters of the i-th coil spring segment, including elastic modulus E, section thickness h, section width b and unfolded length l;

[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 achieve a balance among the load torque, the torque of the nonlinear coil spring and the output torque of the drive motor, thereby realizing adaptive adjustment of different loads while providing power for the carrier.

[0013] In some embodiments, the stiffness adjustment assembly includes a coil spring inner end adjustment member, a coil spring locking member, and a coil spring driving frame fixedly connected to the central axis; the coil spring inner end adjustment member is arranged at the center of the top cover of the frame body, and is used to adjust the inner end rotation angle of the nonlinear coil spring to achieve pre-tightening or unloading of the inner end of the nonlinear coil spring; the coil spring driving frame can rotate relative to the frame body and is fixedly connected to the outer end of the nonlinear coil spring; the coil spring locking member includes a ratchet pawl mechanism and a matching stop switch and a reset spring, and the ratchet pawl mechanism is connected between the inner end of the nonlinear coil spring and the lower end surface of the top cover of the frame body; each reset spring is always kept in a compressed state, and is used to provide a force for the stop pawl to approach the ratchet wheel; during the stiffness adjustment process of the nonlinear coil spring, the stop switch allows the ratchet wheel to move only in a set direction according to the command of the control unit, so that the number of working turns of the nonlinear coil spring increases or decreases, until the load torque, the torque of the nonlinear coil spring and the output torque of the drive motor are balanced, and the control unit controls the stop switch to lock the inner end of the nonlinear coil spring.

[0014] In some embodiments, the ratchet pawl mechanism includes a ratchet shaft coaxial with the central axis and a ratchet fixedly sleeved on the ratchet shaft, and a positive stop pawl and a negative stop pawl matched with the ratchet through a tooth portion, the inner end of the nonlinear coil spring is fixedly connected to the ratchet shaft, the ends of the positive stop pawl and the negative stop pawl away from their respective tooth portions are rotatably connected to the lower end surface of the top cover of the frame body, a positive return spring and a positive stop switch are provided between an end of the positive stop pawl close to its tooth portion and the lower end surface of the top cover of the frame body, and a negative return spring and a negative stop switch are provided between an end of the negative stop pawl close to its tooth portion and the lower end surface of the top cover of the frame body;

[0015] During the stiffness adjustment process of the nonlinear coil spring, at most only one of the two stop pawls cooperating with the ratchet wheel is in contact with the teeth of the ratchet wheel; when the load torque, the torque of the nonlinear coil spring and the output torque of the drive motor are balanced, the two stop pawls cooperating with the ratchet wheel are both in contact with the teeth of the ratchet wheel.

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

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

[0018] In some embodiments, the control unit also 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 it to the main controller. The main controller performs four-loop control on the drive motor according to the signal collected by the inertial measurement unit to achieve tracking of the target posture of the carrier. The four-loop control adds a posture loop on the basis of the FOC method. The posture loop is used to obtain the expected rotation angle of the drive motor according to the deviation between the current posture of the carrier and the target posture, and the expected rotation angle is used as the input of the FOC method. After calculation by the FOC method, the expected current value of the drive motor to maintain or reach the expected rotation angle is obtained.

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

[0020] In some embodiments, the drive module also includes a handle that cooperates with the external end, so that the drive module has a manual power generation function. When manual power generation is required, the stiffness adjustment component is controlled by the control unit. At this time, one end of the nonlinear coil spring is in a free state, and then the handle is connected to the external end. By rotating the handle, power is transmitted to the mover of the drive motor through the external end and the center axis to generate current.

[0021] In some embodiments, the driving unit, the control unit and the variable stiffness unit are coaxially and layeredly arranged in the frame body, and the carrier and the variable stiffness unit are arranged on both sides of the driving unit; the central axis portion is located inside the driving motor, and the remaining portion of the central axis protrudes from the driving motor.

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

[0023] In some embodiments, the drive unit also includes a reducer arranged between the output end of the drive motor, the external 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 end through the low-speed end of the reducer.

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

[0025] The first aspect of the present disclosure provides an adaptive variable stiffness drive module, which has a large stiffness adjustment range, a small built-in nonlinear coil spring, a simple stiffness adjustment component, a small volume, and a weight comparable to that of an ordinary driver. The coaxial arrangement between the nonlinear coil spring, the stiffness adjustment component, and the control unit makes the drive module compact, low power consumption, and simple to control. The introduction of the nonlinear coil spring enables the drive module to simultaneously meet the rotation angle requirements of the carrier and the torque requirements of the coil spring under compact space constraints. Adaptive adjustment is performed according to different carrier load sizes. Specifically:

[0026] 1. Due to the optimization of the power transmission chain, the nonlinear coil spring has a larger stiffness adjustment range, occupies a smaller volume, and has a weight comparable to that of an ordinary drive.

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

[0028] 3. Compared with linear coil springs with lower stiffness, nonlinear coil springs can withstand greater load torque at the same coil spring outer diameter and number of turns. Compared with linear coil springs with higher stiffness, nonlinear coil springs can rotate the central axis more times at the same coil spring outer diameter and load torque. Therefore, the introduction of nonlinear coil springs enables the drive module to provide a larger central axis rotation angle range and coil spring torque range under the same space constraints.

[0029] 4. The stiffness adjustment component adjusts the stiffness of the nonlinear coil spring by controlling the engagement of the pawl or the contact of the friction wheel in the stiffness adjustment component according to the instructions issued by the control unit, so as to automatically adapt to various working conditions; in addition, the control unit can also control the drive motor according to the real-time motion state of the carrier, so as to realize the accurate tracking of the target posture of the carrier by the drive module.

[0030] The advantages of the present application will be given in part in the following description, and in part will become apparent from the following description, or will be understood through the practice of the present application.

[0031] A second aspect of the present disclosure provides a robot dog, comprising a body, legs, a first connecting member and a second connecting member disposed between the body and the legs, and a plurality of drive modules according to any one of the embodiments of the first aspect of the present disclosure, and a transmission member disposed in the legs, wherein the legs include a thigh and a calf;

[0032] A first driving module, used for providing a driving force for the legs to move within the cross section of the fuselage, the frame body of the first driving module is fixedly connected to the fuselage, and the external end of the first driving module is fixedly connected to the first connecting member;

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

[0034] In some embodiments, the transmission member adopts a belt drive method, including a first pulley, a second pulley, a tensioning pulley and a synchronous belt. The first pulley and the second pulley are both in contact with the synchronous belt. The first pulley is fixedly connected to the external end of the third drive module. The tensioning pulley is rotatably arranged in the middle part of the thigh for tensioning the synchronous belt. The second pulley is rotatably mounted on the pulley shaft and 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.

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

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

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

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

[0039] A fourth aspect of the present disclosure provides an exoskeleton comprising a waist belt, a drive module, a drive module fixing frame and a leg fixing frame;

[0040] The waist belt is fixed to the wearer's waist and is fixedly connected to the drive module fixing frame;

[0041] The leg fixing frame is fixed to the wearer's legs;

[0042] The driving module adopts the driving module described in any embodiment of the first aspect of the present disclosure, and is used to provide driving force for the leg fixing frame. The frame body of the driving module is fixedly connected to the driving module fixing frame, and the external end of the driving module is fixedly connected to the leg fixing frame. BRIEF DESCRIPTION OF THE DRAWINGS

[0043] Figure 1 This is a schematic diagram of the overall structure of an adaptive variable stiffness drive module provided in Example 1 of the present disclosure, wherein the nonlinear coil spring is a planar spiral spring with variable cross-sectional thickness.

[0044] Figure 2 It is a schematic longitudinal section diagram of an adaptive variable stiffness drive module provided in Example 1 of the present disclosure.

[0045] Figure 3 yes Figure 1 Explosion diagram of the drive unit in the drive module shown.

[0046] Figure 4 yes Figure 1 The explosion diagram of the variable stiffness unit in the drive module shown in the first perspective.

[0047] Figure 5 yes Figure 1 The explosion diagram of the variable stiffness unit in the drive module shown in the second perspective.

[0048] Figure 6 It is a schematic diagram of the overall structure of another adaptive variable stiffness drive module provided in Example 1 of the present disclosure, wherein the nonlinear coil spring is a planar spiral spring with variable cross-sectional width.

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

[0050] Figure 8 In (a) and (b), they are Figure 1 The schematic diagram of the structure of the drive module when it is in manual power generation mode and the schematic diagram of the state of its internal stiffness adjustment component are shown.

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

[0052] Fig.10a yes Fig. 9 AA section view in .

[0053] Fig.10b yes Fig. 9 A partial enlarged schematic diagram of the driving module.

[0054] Fig.11 (a) and (b) are respectively a schematic diagram and a cross-sectional view of the overall structure of applying the driving module provided in Example 1 of the present disclosure to a robot dog.

[0055] Fig.12 It is a structural schematic diagram of applying the drive module provided in Example 1 of the present disclosure to a robotic arm.

[0056] Fig.13 It is a structural schematic diagram of applying the drive module provided in Example 1 of the present disclosure to an exoskeleton.

[0057] In the figure:

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

[0059] 200 is a driving unit, 210 is a central shaft, 220 is a driving motor, 221 is a rotor frame, 2211 is a first journal, 222 is a magnetic steel, 223 is a winding frame, 224 is a coil, 230 is a reducer, 231 is a planetary frame, 231a is a bolt hole, 2311 is a planetary frame body, 2311a is a planetary shaft, 2312 is a planetary frame top cover, 232 is a sun gear, 233 is a planetary gear, and 234 is an inner gear ring;

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

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

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

[0063] 11 is the first driving module in the robot dog, 12 is the second driving module in the robot dog, 13 is the third driving module in the robot dog, 2 is the body, 3 is the thigh, 4 is the calf, 5 is the first connecting member, 6 is the second connecting member, 7 is the transmission member, 71 is the first pulley, 72 is the second pulley, 73 is the tensioning wheel, 74 is the synchronous belt, and 75 is the pulley shaft;

[0064] 11' is the first driving module in the robot arm, 12' is the second driving module in the robot arm, 2' is the base, 3' is the fixing frame, 41' is the first arm, 42' is the second arm, and 5' is the robot claw;

[0065] 01 is the waist belt, 02 is the drive module in the exoskeleton, 03 is the drive module fixing frame, and 04 is the leg fixing frame. DETAILED DESCRIPTION

[0066] The following will be combined with the drawings in the embodiments of the present application to clearly and completely describe the technical solutions in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0067] In order to better describe and illustrate the embodiments of the present application, reference may be made to one or more drawings, but the additional details or examples used to describe the drawings should not be considered as limiting the scope of the invention of the present application, any of the currently described embodiments or preferred methods.

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

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

[0070] Example 1

[0071] See also Figure 1 , Figure 2 The embodiment provides an adaptive variable stiffness driving module, comprising a frame 100, and a driving unit 200, a variable stiffness unit 300 and a control unit 400 arranged in the frame 100; wherein,

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

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

[0074] The variable stiffness unit 300 includes a nonlinear coil spring 310 and a stiffness adjustment component 320. The nonlinear coil spring 310 is a plane spiral spring formed by connecting multiple coil springs in sequence end to end and integrally formed. The stiffness of two adjacent coil spring sections is different. The stiffness adjustment component 320 is connected between the central shaft 210 and the nonlinear coil spring 310. The load torque is transmitted to the stiffness adjustment component 320 through the reducer 230 and the central shaft 210, and then the torque is applied to one end (such as the outer end) of the nonlinear coil spring 310. The stiffness adjustment component 320 changes the working number of the nonlinear coil spring 310 and the output torque by unidirectionally or bidirectionally locking one end of the nonlinear coil spring 310, thereby balancing the corresponding load torque. The stiffness adjustment component 320 pre-tightens or unloads the other end (such as the inner end) of the nonlinear coil spring 310 to enable the carrier to reach a desired working angle.

[0075] 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 angle signal of the central shaft 210, so as to achieve a balance among the load torque, the torque of the nonlinear coil spring 310 and the output torque of the drive motor 220 (hereinafter the output torque of the drive motor is referred to as "drive torque"), thereby realizing adaptive adjustment of different loads while providing power for the carrier.

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

[0077] Further, see Figure 3, the driving motor 220 serves as the power source of the driving module of this embodiment, and provides power for the carrier. In this embodiment, the driving motor 220 uses a brushless DC motor, which is different from the currently commercially available motors in that its rotating central axis. The central axis of the currently commercially available motor is generally built into the motor housing, while in the embodiment of the present disclosure, the central axis 210 is used to replace the high-speed axis of the commercially available motor, which is convenient for connection with the variable stiffness unit 300. Most of the central axis 210 is located in the driving motor 220, and the top of the central axis 210 protrudes from the top of the driving motor 220. The driving motor 220 of this embodiment includes a rotor frame 221 and a magnet 222, a winding frame 223 and a coil 224 located in the rotor frame 221. The magnet 222 is fixed to the inner side wall of the rotor frame 221, and the coil 224 is wound on the winding frame 223. A first journal 2211 with a through hole is formed at the center of the upper end surface of the rotor frame 221. The first journal 2211 partially protrudes from the upper end surface of the rotor frame 221 and partially is located inside the rotor frame 221. The outer side wall of the first journal 2211 protruding from the upper end surface of the rotor frame 221 is rotatably connected to the inner side wall of the second journal 1121 at the center of the upper end surface of the lower shell 112 through the first bearing a. The outer side wall of the first journal 2211 located inside the rotor frame 221 is rotatably connected to the planetary carrier top cover 2312 through the second bearing b. At the same time, the external connection end 120 is also rotatably connected to the lower end of the lower shell 112 through the third bearing c. When the coil 224 is energized, a magnetic field is generated. The magnet 222 drives the rotor frame 221 to rotate under the action of the magnetic field. The rotation of the rotor frame 221 then drives the central shaft 210 circumferentially fixed thereto to rotate synchronously. One end of the central shaft 210 is a gear (the gear is the sun gear 232 in the reducer 230), which then drives the external end 120 to rotate through the reducer 230 to achieve external power output.

[0078] See also Figure 3The reducer 230 disposed between the output end of the driving motor 220 and the external connection end 120 is used to reduce the rotation speed of the output end of the driving motor 220 to amplify the output torque. The output end of the driving motor 220 is the central shaft 210, and the gear 232 at one end thereof is the high-speed input end of the reducer 230, and the low-speed output end of the reducer 230 is the external connection end 120. When the load torque changes little over time during use, the torque generated by the driving motor 220 is sufficient to overcome the change in the load torque. At this time, it is not necessary to reduce the motor speed to amplify the output torque, and the reducer 230 can be omitted. The reducer 230 of this embodiment is a planetary gear reducer, including an inner ring gear 234, a planet carrier 231, a sun gear 232 and a plurality of planetary gears 233; the inner ring gear 234 is fixedly connected to the lower shell 112 and meshes with the inner surface of each planetary gear 233; the planet carrier 231 includes a planet carrier body 2311 and a planet carrier top cover 2312 that are fixedly connected, the planet carrier body 2311 is the external connection end 120, and the planet carrier body 2311 is provided with a plurality of planetary gears 232 and a plurality of planetary gears 233; The planetary gears 233 are respectively sleeved on the corresponding planetary shafts 2311a through the 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 is used as the axle of the sun gear 232 and is integrally formed with the sun gear 232. The planetary carrier body 2311 and the planetary carrier top cover 2312 are provided with a plurality of bolt holes 231a, and the two are fixedly connected by bolts to form the planetary carrier 231. In addition to the planetary gear reducer, the reducer 230 includes other types of reducers such as but not limited to RV reducers, harmonic gear reducers or cycloidal pinwheel reducers, which are not given examples and repeated here.

[0079] Further, see Figure 4 , Figure 5 In the variable stiffness unit 300 of this embodiment, the nonlinear coil spring 310 is disposed in the upper shell 111 of the frame body 110, and is a single plane spiral spring formed by connecting multiple sections of rectangular steel strips (each steel strip is a corresponding coil spring section) in sequence and integrally formed. The nonlinear coil spring 310 is designed according to the following steps:

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

[0081] The i-th (i=1,2,...,S) working curve and its slope are respectively used as the working curve and stiffness of the i-th coil spring segment, and the i-th coil spring segment is designed according to the industry standard JB / T7366-1994 to obtain the parameters of the i-th coil spring segment, including elastic modulus E, cross-sectional thickness h, cross-sectional width b and unfolded length l. In this embodiment, the elastic modulus E, cross-sectional width b and unfolded length l of each coil spring segment are assumed to be equal, and the nonlinear coil spring 310 meets the working curve requirements of the driving module by changing the cross-sectional thickness h of each coil spring segment, that is, the nonlinear coil spring in this embodiment is a plane scroll spring with a variable cross-sectional thickness, see Figure 1 and Figure 2 Similarly, the elastic modulus E, cross-sectional thickness h and unfolded length l of each coil spring segment can be made equal, and a plane scroll spring with a variable cross-sectional width b can be used, such as Figure 6 shown.

[0082] It should be noted that the overall size of the nonlinear coil spring 310 obtained according to the above design steps in the free state should meet the set space requirements. If not, it needs to be redesigned.

[0083] It can be understood that since there is a proportional relationship between the rotation angle of the external terminal 120 connected to the load and the rotation angle of the central axis 210 (reducer power transfer ratio), and the initial rotation angle of the inner ring of the coil spring can be adjusted by the coil spring adjustment motor 323 in the stiffness adjustment component 320, in most applications, when the load angle range and working torque relationship are required to meet the set function curve, even in a limited installation space, a nonlinear coil spring 310 that approximately meets the set function curve can still be designed according to the above steps.

[0084] In the variable stiffness unit 300 of this embodiment, the stiffness adjustment component 320 includes a coil spring locking member 321, a coil spring driving frame 322 and a coil spring adjustment motor 323. The coil spring adjustment motor 323 is arranged at the center of the top cover of the upper shell 111 of the frame body 110, and the output end of the coil spring adjustment motor 323 is connected to the inner end of the nonlinear coil spring 310. The coil spring adjustment motor 323 is controlled by the control unit 400 to adjust the inner end angular position of the nonlinear coil spring 310. The angle difference between the inner end angular position and the outer end angular position of the coil spring is the number of compressed turns of the nonlinear coil spring 310. Different numbers of compressed turns generate different elastic moments, and the nonlinear coil spring design method can be used for design and manufacturing. The nonlinear coil spring 310 has the characteristic of adaptive load torque. In this embodiment, when the load is connected, the coil spring segments are compressed in order from small to large stiffness according to the stiffness characteristics of each coil spring segment, 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 larger stiffness is compressed until balance is achieved.

[0085] In the stiffness adjustment component 320 of the variable stiffness unit 300, the coil spring driving frame 322 is a circular plate with a third shaft neck 3221 at the center of the lower end surface, and the circular plate and the third shaft neck 3221 are both provided with a center hole matching the central axis 210. The third shaft neck 3221 at the center of the coil spring driving frame 322 is fixedly sleeved on the top end of the central axis 210 by a second set screw 3222, so as to rotate synchronously with the central axis 210. The nonlinear coil spring 310 is placed on the upper end surface of the coil spring driving frame 322, and the upper end surface of the coil spring driving frame 322 is provided with a second column pin 3223 for fixing the outer end of the nonlinear coil spring 310. The load torque is transmitted from the outer end of the nonlinear coil spring 310 into the nonlinear coil spring 310, and a gap is left between the outer edge of the coil spring driving frame 322 and the inner side wall of the upper shell 111. The coil spring locking member 321 includes a ratchet pawl mechanism and a matching stop switch and a reset spring; the ratchet pawl mechanism includes a ratchet 3210 coaxially arranged with the central axis 210, and a positive stop pawl 3213 and a negative stop pawl 3214 that cooperate with the ratchet 3210 through the teeth. The center hole of the ratchet 3210 is fixed to the output shaft of the coil spring adjustment motor 323 by a first set screw 3212, so as to rotate synchronously with the output shaft of the coil spring adjustment motor 323. The first pin 3211 protruding from the ratchet 3210 can be inserted into the inner end ring of the nonlinear coil spring 310 to achieve a fixed connection. The ratchet 3210 and the coil spring driving frame 322 can rotate relative to each other, that is, the inner end and the outer end of the nonlinear coil spring 310 are driven to rotate relative to each other, thereby achieving compression or release of the nonlinear coil spring 310. One end of the positive stop pawl 3213 and the negative stop pawl 3214 can be rotatably connected to the boss 1111 on the lower surface of the top end of the upper shell 111. A positive return spring 3215 and a positive stop switch 3216 are provided between one end of the positive stop pawl 3213 close to the tooth portion and the boss 1111, and a negative return spring 3217 and a negative stop switch 3218 are provided between one end of the negative stop pawl 3214 close to the tooth portion and the boss 1111. When the ratchet 3210 needs to be stationary and not rotated, the two return springs are always kept in a compressed state, so as to provide a thrust for the corresponding stop pawl to approach the ratchet 3210. It should be noted that each stop switch adopts an electromagnetic switch, more specifically, an armature switch, which is controlled by the control unit 400. When the armature switch is turned on, it will provide a force for the corresponding stop pawl to move away from the ratchet in contact with the corresponding stop pawl, and the force is greater than the force provided by the reset spring, thereby separating the corresponding stop pawl from the ratchet; when the armature switch is disconnected, the force it provides to the corresponding stop pawl disappears, and the corresponding stop pawl contacts the ratchet under the action of the reset spring.

[0086] Further, see Figure 7(a), (b), and (c) are schematic diagrams of the working process of the stiffness adjustment component 320 of this embodiment. At this time, the outer end of the nonlinear coil spring 310 is subjected to a clockwise load torque, wherein:

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

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

[0089] When the load torque decreases, the outer end of the nonlinear coil spring 310 rotates counterclockwise to relax the coil spring until the torque balance is reached again.

[0090] After the torque is balanced, if the load is required to rotate counterclockwise by a certain angle due to the working angle (position), that is, the outer end of the nonlinear coil spring 310 is required to rotate counterclockwise by a certain angle, then the stiffness adjustment component 320 works as follows: Figure 7 In the mode shown in (a), at this time, because the negative stop pawl 3214 on the left is disengaged from the ratchet 3210, the ratchet 3210 can rotate counterclockwise under the drive of the coil spring adjustment motor 323, that is, the inner end of the nonlinear coil spring 310 rotates counterclockwise by a certain angle, thereby achieving the load rotating counterclockwise by a certain angle to reach the desired working angle (position).

[0091] Similarly, after the torque is balanced, if the load is required to rotate clockwise by a certain angle due to the working angle (position), that is, the outer end of the nonlinear coil spring 310 is required to rotate clockwise by a certain angle, then the stiffness adjustment component 320 works as follows: Figure 7In the mode shown in (b), at this time, because the positive stop pawl 3213 on the right is disengaged from the ratchet 3210, the ratchet 3210 can rotate clockwise under the drive of the coil spring adjustment motor 323, that is, the inner end of the nonlinear coil spring 310 rotates clockwise by a certain angle, so that the load rotates clockwise by a certain angle to reach the desired working angle (position). It should be noted that, because the inner end of the nonlinear coil spring 310 is subjected to the clockwise coil spring elastic force at this time, when the ratchet 3210 rotates clockwise by a certain angle, the right positive stop switch 3216 needs to be released immediately to make the positive stop pawl 3213 engage with the ratchet 3210 to achieve clockwise stop.

[0092] Understandably, Figure 7 7 (a) shows a typical installation method of the nonlinear coil spring 310. If the nonlinear coil spring 310 is required to bear a load moment in the counterclockwise direction according to the design requirements, the nonlinear coil spring 310 needs to be mirror-inverted and installed based on the installation method shown in 7 (a). At this time, the negative stop pawl 3214 provides a stop torque for the ratchet wheel 3210. Therefore, the above mechanism can achieve load moment balance in both clockwise and counterclockwise directions. In actual application, the nonlinear coil spring 310 needs to be installed in a suitable installation method according to the direction of the load moment.

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

[0094] It can be understood that in this embodiment, the load torque is transmitted through the outer end of the nonlinear coil spring, that is, the inner end of the coil spring is fixed and the outer end is movable, which can increase the durability of the coil spring compared to the inner end transmission method. Since the coil spring curvature radius at the outer ring is larger, the deformation of the coil spring at the outer ring is smaller than that at the inner ring during operation, which will extend the service life of the coil spring.

[0095] Further, the control unit 400 is arranged in the upper shell 111 of the frame body 110 and is located below the coil spring drive frame 322, including a circuit board 410, a main controller, an angle sensor and a current sensor (the main controller, the current sensor and the angle sensor are not shown in the figure) arranged on the circuit board 410, the current sensor and the angle sensor are both connected to the main controller, the current sensor can adopt an existing on-board current sensor, which is used to detect the current signal of the drive motor 220, the angle sensor is used to collect the angle of the central shaft 210 in real time (the angle reflects the number of rotations and the speed of the central shaft), the circuit board is fixedly connected to the lower shell 112 by bolts, and 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 angle signal of the central shaft 210. A wire hole is opened on the side wall of the upper shell 111, and the cables on the circuit board are led out from the wire hole. Optionally, the control unit 400 further includes a dust cover 420 having a central through hole, the dust cover 420 is fixedly connected to the frame body 110, and the central through hole of the dust cover 420 is rotatably connected to the third shaft neck 3221 of the first sub-coil spring driving frame 322 through a fifth bearing e.

[0096] Furthermore, considering that the motion state, i.e., the posture, of the carrier driven by the driving module of this embodiment will change, including but not limited to changes in one of the attitude angle (including yaw angle, roll angle and pitch angle) and displacement of the carrier, or changes in both, and the change in the posture of the carrier will be reflected in the change in the size of the load connected to the driving module through the external terminal 120, in order to achieve accurate tracking of the target posture of the carrier by the driving module, the control unit 400 of this embodiment is also used to control the stiffness adjustment component 320 and the driving motor 220 according to the current posture and target posture of the carrier, and in combination with the current signal of the driving motor 220 and the change in the rotation angle of the central axis 210, so as to balance the load torque, nonlinear coil spring torque and driving torque while ensuring that the carrier can reach the target posture. The control unit 400 of this embodiment also includes an inertial measurement unit (IMU, which is not shown in the figure) arranged on the circuit board 410, which is used to collect the attitude angle and displacement of the carrier in real time and transmit it to the main controller in the control unit 400. The main controller controls the drive motor 220 by adding a posture loop of the carrier on the basis of the vector control (Field-Oriented Control, FOC) method. The FOC method adopts three-loop control, which are a current loop, a speed loop and a position loop from the inside to the outside. The added posture loop is used to obtain the expected rotation angle of the drive motor 220 according to the deviation between the current posture of the carrier and the target posture, and the expected rotation angle is input into the position loop in the FOC. After calculation by the FOC method, the expected current value of the drive motor to maintain or reach the expected rotation angle is obtained, thereby realizing accurate tracking of the target posture of the carrier.

[0097] Alternatively, see Figure 8 In (a) and (b), the drive module provided by the embodiment of the present disclosure also includes a handle 130 that cooperates with the pin shaft 121 on the external terminal 120, so that the drive module of this embodiment has a manual power generation function. When manual power generation is required, first, the control unit 400 controls each stop switch to separate all the stop pawls (3213, 3214) from the teeth of the ratchet 3210. At this time, the inner end of the nonlinear coil spring 310 is in a free state, and then the handle 130 is connected to the external terminal 120. By rotating the handle 130, the power is transmitted to the rotor frame 221 through the external terminal 120, the reducer 230, and the central shaft 210 in sequence. The magnet 222 on the rotor frame 221 and the coil 224 move relative to each other, cutting the magnetic flux lines to generate current, thereby achieving the manual power generation effect.

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

[0099] The load is transmitted to the driving module through the external terminal 120, and the external terminal 120 is connected to the low-speed shaft of the reducer 230. The central shaft 210 serves as the high-speed shaft of the reducer 230. The load torque is amplified by the reducer 230 and drives the central shaft 210 to rotate. The coil spring driving frame 322 is fixedly connected to the top of the central shaft 210. Therefore, the rotation of the central shaft 210 will drive the coil spring driving frame 322. The outer end of the nonlinear coil spring 310 is fixedly connected to the coil spring driving frame 322. The load torque is transmitted to the nonlinear coil spring 310 through the coil spring driving frame 322 and is then applied to the coil spring. The nonlinear coil spring 310 is pre-tightened with the cooperation of the locking member 321, so that the nonlinear coil spring 310 is used to balance most of the load torque. Specifically, the control unit 400 controls the engagement and separation of the ratchet pawl in the coil spring locking member 321 by turning on and off the electromagnetic switch. When the control unit 400 issues a ratchet pawl separation command, the electromagnetic switch is powered on, and the pawl is separated from the ratchet under the action of the magnetic attraction; when the control unit 400 issues a ratchet pawl engagement command, the electromagnetic switch is powered off, and the pawl is engaged with the ratchet under the action of the reset spring. Since the torque generated by the load has been balanced by the nonlinear coil spring 310, at this time, the load movement is driven by the drive motor 220, and only a small torque is required to regulate the load movement, thereby greatly reducing the energy consumption of the drive motor.

[0100] Example 2

[0101] See also Fig. 9 , Fig.10a and Fig.10bIn this embodiment, the coil spring adjustment motor 323 and the ratchet pawl mechanism in the stiffness adjustment component 320 in Example 1 are replaced with a worm gear mechanism, an adjustment frame 344 is added between the worm gear mechanism and the coil spring driving frame 322, and an inner end fixing frame 345 is added between the inner end of the nonlinear coil spring 310 and the central axis 210, so as to achieve the self-locking state at any time when the inner end of the nonlinear coil spring 310 rotates in the clockwise direction or counterclockwise direction under the action of the load. The worm gear mechanism in the stiffness adjustment assembly 320 of this embodiment includes a worm adjustment motor 343, a worm 341 and a worm wheel 342. The worm adjustment motor 343 is fixed on the top cover of the upper shell 111 in the frame 100. The output shaft of the worm adjustment motor 343 is fixedly connected to one end of the worm 341 through a third set screw 3411 to achieve torque transmission. One end of the worm 341 is rotatably connected to the top cover of the upper shell 111. The worm wheel 342 is rotatably connected to the top cover of the upper shell 111 through a bearing and meshes with the worm 341. The worm wheel 342 is fixedly connected to the coil spring drive frame 322. The coil spring drive frame 322 is provided with a protruding pin for inserting the outer end of the nonlinear coil spring 310 to achieve fixed connection between the outer end of the coil spring and the worm wheel 342. The worm wheel 342 is provided with three first countersunk holes distributed circumferentially, and one end of the adjustment frame 344 facing the worm wheel 342 is formed with three first bosses with threaded holes evenly distributed circumferentially, and each first boss corresponds to a first countersunk hole on the worm wheel 342, so that the worm wheel 342 and the adjustment frame 344 are fixedly connected by the first bolt 3441; the adjustment frame 344 is also provided with three second countersunk holes distributed circumferentially, and one end of the coil spring drive frame 322 facing the adjustment frame 344 is formed with three first bosses with threaded holes The second bosses are respectively corresponding to a second countersunk hole on the adjustment frame 344, so that the adjustment frame 344 is fixedly connected to the coil spring driving frame 322 through the second bolt 3442, and the coil spring driving frame 322 is rotatably connected to the central shaft 210 through the bearing; the outer end of the nonlinear coil spring 310 is fixedly connected to the coil spring driving frame 322, and the inner end of the nonlinear coil spring 310 is fixedly connected to the inner end fixing frame 345, and the inner end fixing frame 345 is fixedly connected to the top of the central shaft 210 through a set screw. There is relative rotation between the worm gear 342 and the inner end fixing frame 345, that is, the inner end and the outer end of the nonlinear coil spring 310 are driven to rotate relative to each other, thereby realizing the compression or release of the nonlinear coil spring 310. In this embodiment, the worm gear mechanism has a self-locking characteristic. It is understandable that the outer end of the nonlinear coil spring 310 is restricted by the worm wheel 342 and can remain motionless at any angle (position) unless the worm 341 rotates to drive the worm wheel 342 and then drive the outer end of the nonlinear coil spring 310. The worm gear transmission usually has a large transmission ratio. It is understandable that only a small rotational torque is required to drive the worm 341 to achieve the drive of the worm wheel 342 and then drive the outer end of the nonlinear coil spring 310.The worm 341 can be rotated manually in addition to being rotated by controlling the worm adjusting motor 343 .

[0102] Similar to Example 1, when the load torque changes (increases or decreases), the inner end of the nonlinear coil spring 310 will be driven by the load torque to rotate (clockwise or counterclockwise), while the outer end of the nonlinear coil spring 310 remains stationary due to the self-locking restriction of the worm gear. It can be understood that the nonlinear coil spring 310 will be compressed or released, thereby achieving a balance between the load torque and the elastic torque of the coil spring.

[0103] After the torque is balanced, if the load is required to rotate a certain angle (clockwise or counterclockwise) due to the need of the working angle (position), that is, the central shaft 210 is required to drive the inner end of the nonlinear coil spring 310 to rotate a certain angle (clockwise or counterclockwise). The adjustment method is to rotate the outer end of the nonlinear coil spring 310 (clockwise or counterclockwise) by a certain angle so that the balancing torque can be transmitted to the inner end of the nonlinear coil spring 310, and then the central shaft drives the load to rotate. At this time, the worm 341 can be driven to rotate manually, or the worm adjustment motor 343 can be used to drive the worm 341 to rotate, so that the outer end of the nonlinear coil spring 310 rotates a certain angle in the desired direction (clockwise or counterclockwise), thereby causing the load to rotate a certain angle to achieve the desired working angle (position).

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

[0105] Example 3

[0106] See also Fig.11 In (a) and (b), this embodiment is to apply the driving module provided in Embodiment 1 to a robot dog, the robot dog comprises a body 2, legs, a first connecting member 5 and a second connecting member 6 arranged between the body 2 and the legs, and a plurality of driving modules (11, 12 and 13) provided according to Embodiment 1, and a transmission member 7 arranged in the legs, the legs comprising a thigh 3 and a calf 4;

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

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

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

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

[0111] It can be understood that the robot dog provided in this embodiment, due to the use of nonlinear coil springs, can reduce the power consumption of the drive motor and is suitable for working conditions with larger loads; in addition, since the drive module in this embodiment has the ability to adaptively adjust for different loads, for example: the robot dog can adaptively adjust the stiffness in various working conditions such as speed change, jumping, uphill, and ups and downs to meet the requirements of different working conditions; furthermore, when the power is off, the presence of the nonlinear coil spring can prevent the robot dog from being unloaded instantly and still play a supporting role for the fuselage; the drive module of this embodiment is integrated with an IMU to collect the posture state of each joint of the robot dog's legs in real time, and the control unit in the drive module can perform closed-loop control of the drive motor according to the posture state to achieve accurate tracking of the target posture at each joint of the robot dog's legs.

[0112] Example 4

[0113] See also Fig.12 This embodiment applies the driving module provided in Embodiment 1 to a robot arm, which includes a base 2', a fixing frame 3', a first arm 41', a second arm 42', a robot claw 5' and two driving modules (11' and 12') provided in Embodiment 1;

[0114] The fixing frame 3' is mounted on the base 2', and a motor is provided in the base 2' for driving the fixing frame 3' to rotate around the axial direction of the base 2' (the motor is Fig.12 not shown);

[0115] The first driving module 11' is disposed between the fixing frame 3' and the first arm 41', and is used to provide driving force for the first arm 41'. The frame body of the first driving module 11' is fixedly connected to the fixing frame 3', and the external end of the first driving module 11' is fixedly connected to one end of the first arm 41'.

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

[0117] It can be understood that the robotic arm provided in the present embodiment has the following characteristics because the driving module provided in the present disclosure embodiment is configured therein: 1. The nonlinear coil spring in the driving module of the robotic arm can reduce the power consumption of the driving motor and is suitable for working conditions with larger loads; 2. The present embodiment can adapt to working conditions, for example: the load grasped by the robotic arm is a non-constant load, and the stiffness of the driving module can be adaptively adjusted to meet different working conditions; 3. When the power is off, the mechanical device can be protected due to the presence of the nonlinear coil spring; 4. The driving module of the present embodiment is integrated with an IMU to collect the posture state of each joint of the robotic arm in real time. The control unit in the driving module can perform closed-loop control of the driving motor according to the posture state to achieve accurate tracking of the target posture at each joint of the robotic arm.

[0118] Example 5

[0119] See also Fig.13 This embodiment is to apply the driving module provided in the embodiment 1 to an exoskeleton, and the exoskeleton includes a waist belt 01, a driving module 02, a driving module fixing frame 03 and a leg fixing frame 04;

[0120] The waist belt 01 is fixed to the waist of the wearer and can be fixedly connected to the drive module fixing frame 03 via a buckle;

[0121] The leg fixing frame 04 is fixed to the wearer's legs so that the power of the driving module 02 is transmitted to the legs. The leg fixing frame 04 is located at the lower part of the exoskeleton of this embodiment, where it contacts the wearer's legs.

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

[0123] It can be understood that the exoskeleton provided in this embodiment has the following characteristics because the drive module provided in the embodiment of the present disclosure is configured therein: 1. The nonlinear coil spring in the drive module of the exoskeleton can reduce the power consumption of the drive motor and is suitable for working conditions with larger loads; 2. The present embodiment can adapt to working conditions, for example: the load carried by the exoskeleton is a non-constant load, and the stiffness of the drive module can be adaptively adjusted to meet different working conditions; 3. The presence of the nonlinear coil spring can protect the mechanical device; 4. The drive module of this embodiment is integrated with an IMU to collect the posture state of the exoskeleton joints in real time. The control unit in the drive module can perform closed-loop control of the drive motor according to the posture state to achieve accurate tracking of the target posture at the exoskeleton joints.

[0124] In the present invention, the terms "one embodiment", "some embodiments", "examples", "specific examples", or "some examples" etc. mean that the specific features, structures, materials or characteristics described in conjunction 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 described specific features, structures, materials or characteristics may be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art may combine and combine the different embodiments or examples described in this specification and the features of the different embodiments or examples, without contradiction.

[0125] Although the above embodiments have been shown and described, it is to be understood that the above embodiments are exemplary and are not to be construed as limitations on the present application. Changes, modifications, substitutions and variations of the above embodiments by those of ordinary skill in the art are all within the scope of protection of the present application.

Claims

1. A drive module with adaptive variable stiffness, characterized in that: It comprises a frame, and a driving unit, a variable stiffness unit and a control unit arranged in the frame; The frame includes a frame body and an external connection terminal arranged on the frame body, through which the load of the carrier is connected and power is provided to the carrier; The driving unit comprises a coaxially arranged central shaft and a driving motor, and the power output by the driving motor is transmitted to the external end through the central shaft; The variable stiffness unit comprises a nonlinear coil spring and a stiffness adjustment component, wherein the nonlinear coil spring is composed of a plurality of coil spring segments connected end to end in sequence and integrally formed, and the stiffness of two adjacent coil spring segments is different; the stiffness adjustment component is connected between the nonlinear coil spring and the central shaft, and the load torque is transmitted to the stiffness adjustment component through the central shaft, and then the torque is applied to one end of the nonlinear coil spring; the stiffness adjustment component changes the working number of coils and the output torque of the nonlinear coil spring by unidirectional or bidirectional locking of one end of the nonlinear coil spring, thereby balancing the corresponding load torque; the stiffness adjustment component pre-tightens or unloads the other end of the nonlinear coil spring, and enables the carrier to reach a desired working angle; The nonlinear coil spring is designed according to the following steps: the given working curve of the driving module is divided into S segments, the working curve of the driving module is the functional relationship between the rotation angle of the central axis and the torque output through the external end, and the number of segments of the nonlinear coil spring is taken as S; the i-th segment working curve and its slope are respectively used as the working curve and stiffness of the i-th coil spring segment, i=1,2,...,S, and the i-th coil spring segment is designed according to the industry standard JB / T7366-1994 to obtain the parameters of the i-th coil spring segment, including elastic modulus E, section thickness h, section width b and unfolded length l; 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 achieve a balance among the load torque, the torque of the nonlinear coil spring and the output torque of the drive motor, thereby realizing adaptive adjustment of different loads while providing power for the carrier.

2. The driving module according to claim 1, characterized in that: The stiffness adjustment assembly includes a coil spring inner end adjustment member, a coil spring locking member, and a coil spring driving frame fixedly connected to the central axis; the coil spring inner end adjustment member is arranged at the center of the top cover of the frame body, and is used to adjust the inner end rotation angle of the nonlinear coil spring to achieve pre-tightening or unloading of the inner end of the nonlinear coil spring; the coil spring driving frame can rotate relative to the frame body and is fixedly connected to the outer end of the nonlinear coil spring; the coil spring locking member includes a ratchet pawl mechanism and a matching stop switch and a reset spring, and the ratchet pawl mechanism is connected between the inner end of the nonlinear coil spring and the lower end surface of the top cover of the frame body; each reset spring is always kept in a compressed state, and is used to provide a force for the stop pawl to approach the ratchet direction; During the stiffness adjustment process of the nonlinear coil spring, the stop switch allows the ratchet to move only in the set direction according to the instructions of the control unit, thereby increasing or decreasing the number of working turns of the nonlinear coil spring until a balance is reached among the load torque, the torque of the nonlinear coil spring and the output torque of the drive motor. The control unit then controls the stop switch to lock the inner end of the nonlinear coil spring.

3. The driving module according to claim 2, characterized in that: The ratchet pawl mechanism comprises a ratchet shaft coaxial with the central axis and a ratchet wheel fixedly sleeved on the ratchet shaft, and a positive stop pawl and a negative stop pawl matched with the ratchet wheel through a tooth portion, the inner end of the nonlinear coil spring is fixedly connected to the ratchet shaft, the ends of the positive stop pawl and the negative stop pawl away from their respective tooth portions are rotatably connected to the lower end surface of the top cover of the frame body, a positive return spring and a positive stop switch are provided between an end of the positive stop pawl close to its tooth portion and the lower end surface of the top cover of the frame body, and a negative return spring and a negative stop switch are provided between an end of the negative stop pawl close to its tooth portion and the lower end surface of the top cover of the frame body; During the stiffness adjustment process of the nonlinear coil spring, at most only one of the two stop pawls cooperating with the ratchet wheel is in contact with the teeth of the ratchet wheel; when the load torque, the torque of the nonlinear coil spring and the output torque of the drive motor are balanced, the two stop pawls cooperating with the ratchet wheel are both in contact with the teeth of the ratchet wheel.

4. The driving module according to claim 1, characterized in that: The stiffness adjustment component includes a coil spring locking member, a coil spring driving frame rotatably connected to the central axis, an adjustment frame connected between the coil spring locking member and the coil spring driving frame, and an inner end fixing frame connected between the inner end of the nonlinear coil spring and the central axis; the coil spring locking member is used to maintain a self-locking state at any time when the inner end of the nonlinear coil spring is driven to rotate in a clockwise direction or a counterclockwise direction; the worm gear mechanism includes a worm adjusting member, a worm and a worm wheel connected in sequence; the worm adjusting member is arranged on the top cover of the frame body, and is used to adjust the rotation angle of the outer end of the nonlinear coil spring to achieve pre-tightening or unloading of the outer end of the nonlinear coil spring, so as to meet the desired working angle requirement of the carrier after the torque is balanced; the worm wheel is fixedly connected to the coil spring driving frame through the adjustment frame; the outer end and the inner end of the nonlinear coil spring are respectively fixedly connected to the coil spring driving frame and the inner end fixing frame; the inner end fixing frame is fixedly connected to the central axis.

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

6. The driving module according to claim 5, characterized in that: The control unit also 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 drive motor according to the signal collected by the inertial measurement unit to achieve tracking of the target posture of the carrier. The four-loop control is to add a posture loop on the basis of the FOC method. The posture loop is used to obtain the expected rotation angle of the drive motor according to the deviation between the current posture of the carrier and the target posture, and the expected rotation angle is used as the input of the FOC method. After calculation by the FOC method, the expected current value of the drive motor to maintain or reach the expected rotation angle is obtained.

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

8. The driving module according to claim 1, characterized in that: The drive module also includes a handle that matches the external end, so that the drive module has a manual power generation function. When manual power generation is required, the stiffness adjustment component is controlled by the control unit. At this time, one end of the nonlinear coil spring is in a free state, and then the handle is connected to the external end. By rotating the handle, power is transmitted to the mover of the drive motor through the external end and the central axis to generate current.

9. The driving module according to claim 1, characterized in that: The driving unit, the control unit and the variable stiffness unit are coaxially and layeredly arranged in the frame body, and the carrier and the variable stiffness unit are arranged on both sides of the driving unit; the central axis portion is located inside the driving motor, and the remaining portion of the central axis protrudes from the driving motor.

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

11. The driving module according to claim 1, characterized in that: The drive unit also includes a reducer arranged between the output end of the drive motor, the external 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 end through the low-speed end of the reducer.

12. A robot dog, characterized in that: It comprises a body, a leg, a first connecting member and a second connecting member arranged between the body and the leg, and a plurality of driving modules according to any one of claims 1 to 11, and a transmission member arranged in the leg, wherein the leg comprises a thigh and a calf; A first driving module, used for providing a driving force for the legs to move within the cross section of the fuselage, the frame body of the first driving module is fixedly connected to the fuselage, and the external end of the first driving module is fixedly connected to the first connecting member; The first connecting member, the second driving module, the second connecting member and the third driving module are connected in sequence and coaxially arranged. The second driving module is used to provide a driving force for the thigh to move in the sagittal plane of the fuselage. The third driving module is used to provide a driving force for the calf to move in the sagittal plane of the fuselage. The frame body of the second driving module is fixedly connected to the first connecting member, the external end of the second driving module is fixedly connected to one end of the second connecting member, the frame body of the third driving module is fixedly connected to one end of the thigh close to the fuselage, and the external end of the third driving module is connected to the calf through the transmission member arranged in the thigh.

13. The robot dog according to claim 12, characterized in that: The transmission member adopts a belt drive method, including a first pulley, a second pulley, a tensioning pulley and a synchronous belt. The first pulley and the second pulley are both in contact with the synchronous belt. The first pulley is fixedly connected to the external end of the third drive module. The tensioning pulley is rotatably arranged in the middle part of the thigh for tensioning the synchronous belt. The second pulley is rotatably mounted on the pulley shaft and fixedly connected to one end of the calf close to the thigh. The pulley shaft is fixedly connected to one end of the thigh close to the calf.

14. A robotic arm, characterized in that: It comprises a base, a fixing frame, a first arm, a second arm, a mechanical claw and two driving modules according to any one of claims 1 to 11; The fixing frame is mounted on the base, and a motor is provided in the base for driving the fixing frame to rotate around the axial direction of the base; The first driving module is disposed between the fixing frame and the first supporting arm, and is used to provide driving force for the first supporting arm. The frame body of the first driving module is fixedly connected to the fixing frame, and the external end of the first driving module is fixedly connected to one end of the first supporting arm. The second driving module is arranged between the first arm and the second arm, and is used to provide driving force for the second arm. The frame body of the second driving module is fixedly connected to the other end of the first arm, the external end of the second driving module is fixedly connected to one end of the second arm, and the other end of the second arm is connected to the mechanical claw.

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

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