A humanoid robot and its variable stiffness variable reduction ratio ankle joint device

Abstract

This invention provides a humanoid robot and its variable stiffness, variable reduction ratio ankle joint device, including a linear actuator, a non-standard rocker arm, a rocker arm shaft, an ankle joint shaft, a variable stiffness mechanism, a rocker arm output shaft, and a transmission link. The upper end of the linear actuator is rotatably connected to the top of the lower leg structure, and the lower end is connected to the rocker arm input shaft. The rocker arm input shaft is fixedly connected to one end of the non-standard rocker arm, and the other end of the non-standard rocker arm is rotatably connected to the rocker arm shaft. The rocker arm shaft is fixedly connected to the lower part of the lower leg structure. The non-standard rocker arm is also fixedly connected to the rocker arm output shaft, which is rotatably connected to the upper end of the transmission link. The transmission link is fixedly connected to the variable stiffness mechanism input shaft and rotatably connected to the variable stiffness mechanism. The variable stiffness mechanism is rotatably connected to the ankle joint shaft, which is fixedly connected to the bottom of the lower leg structure. This invention allows for flexible design of the reduction ratio and joint coupling relationship, and can also achieve a change from low stiffness to infinite stiffness.

Description

Technical Field

[0001] This invention relates to the field of humanoid robot technology, specifically to a variable stiffness, variable deceleration ratio humanoid robot ankle joint device. Background Technology

[0002] Humanoid robots, mimicking human appearance and movement, can perform diverse tasks without altering the environment, making them a hot research area in robotics in recent years. Furthermore, innovations in motor technology, sensing technology, and control algorithms, along with continuous progress in related fields, and the significant advantages of electric drive compared to other actuation methods such as hydraulics and pneumatics, have made electrically driven humanoid robots a mainstream research direction. Currently, many electrically driven humanoid robots can achieve stable walking and perform some simple tasks. However, due to limitations in motor power density and torque density, the high-dynamic movement capabilities (such as running and jumping) of humanoid robots are relatively weak. Additionally, compared to humans, electrically driven humanoid robots still lag significantly in energy efficiency, requiring further reductions in energy consumption.

[0003] The ankle joint plays a crucial role in human movement. Its excellent shock absorption, high burst output capacity, and outstanding energy storage capacity are essential for high-dynamic motion. Therefore, the ankle joint design is particularly important for humanoid robots to run, jump, or perform other high-dynamic tasks. However, current humanoid robot ankle joints mostly employ high-rigidity designs, resulting in weak performance in energy storage and shock absorption. Secondly, existing humanoid robot ankle joints do not consider the relationship between joint torque and rotational speed requirements and joint angles during high-dynamic motion, failing to fully utilize the motor's output capacity and thus providing insufficient power during high-dynamic movements. Furthermore, while a few lower-rigidity elastic ankle joints can meet energy storage requirements, they may affect the control precision of joint position, making control difficult and unable to complete complex tasks. Summary of the Invention

[0004] To address the shortcomings of existing technologies, this invention provides a variable stiffness, variable deceleration ratio humanoid robot ankle joint device.

[0005] The present invention achieves the above-mentioned technical objectives through the following technical means.

[0006] A variable stiffness, variable reduction ratio ankle joint device includes a lower leg structural component, a special-shaped rocker arm, a rocker arm shaft, an ankle joint shaft, a variable stiffness mechanism, an upper shaft of a linear actuator, a linear actuator, a rocker arm output shaft, a rocker arm input shaft, a transmission link, and a variable stiffness mechanism input shaft.

[0007] The upper end of the linear actuator is connected to the upper shaft of the linear actuator, and the upper shaft of the linear actuator is interference-fitted with the top of the lower leg structure. The lower end of the linear actuator is connected to the rocker input shaft, and the rocker input shaft is interference-fitted with one end of the irregular rocker. The other end of the irregular rocker is connected to the rocker shaft, and the rocker shaft is interference-fitted with the lower part of the lower leg structure.

[0008] The end of the irregular rocker arm near the input shaft is also interference-fitted with the output shaft. The output shaft is connected to the upper end of the transmission link, and the lower end of the transmission link is interference-fitted with the input shaft of the variable stiffness mechanism. The input shaft of the variable stiffness mechanism is connected to the variable stiffness mechanism.

[0009] The upper part of the variable stiffness mechanism is also connected to the ankle joint pivot, and the ankle joint pivot is interference-fitted to the bottom of the lower leg structure.

[0010] In the above technical solution, the irregular rocker arm, rocker arm shaft, ankle joint shaft, variable stiffness mechanism, rocker arm output shaft, and transmission connecting rod constitute a crank-rocker transmission mechanism; the irregular rocker arm is the rocker arm in the crank-rocker transmission mechanism, the variable stiffness mechanism is the crank in the crank-rocker transmission mechanism, and the lower leg structure is the frame in the crank-rocker transmission mechanism.

[0011] In the above technical solution, the variable stiffness mechanism includes a variable stiffness leaf spring, a linear bearing, a variable stiffness stop block, a T-type lead screw nut, a variable stiffness fulcrum shaft, a T-type lead screw, an input bearing component, a variable stiffness base, a variable stiffness motor, an optical shaft, and a flat key.

[0012] One end of the variable stiffness leaf spring is fixed on the variable stiffness base, and the other end is fixedly connected to the input bearing member. The input bearing member is hinged to the input shaft of the variable stiffness mechanism.

[0013] The T-shaped lead screw and the optical shaft are located on both sides of the variable stiffness leaf spring; the two ends of the optical shaft are fixedly connected to the variable stiffness base; the two ends of the T-shaped lead screw are rotatably connected to the variable stiffness base, and the end of the T-shaped lead screw with the keyway is embedded with a flat key, which forms an overfit with the motor shaft of the variable stiffness motor.

[0014] The T-shaped lead screw and the optical shaft are respectively fitted with T-shaped lead screw nuts and linear bearings, and the T-shaped lead screw nuts and linear bearings are both installed inside the variable stiffness stop block; the variable stiffness stop block is also fitted on the variable stiffness leaf spring;

[0015] The variable stiffness stop block has two variable stiffness fulcrum shafts fixed inside, which respectively abut against the upper and lower surfaces of the variable stiffness leaf spring.

[0016] In the above technical solution, the two ends of the T-shaped lead screw are fixedly connected to the variable stiffness base through T-shaped lead screw support bearings, and a bearing cap is fixedly connected to the end of the T-shaped lead screw away from the variable stiffness motor to restrict the axial movement of the T-shaped lead screw support bearing.

[0017] In the above technical solution, the variable stiffness base is provided with a limiting block at the end near the input bearing component.

[0018] In the above technical solution, the linear actuator includes an upper shaft fixing component, a pressure sensor, an actuator lead screw guide rail, a motor stator fixing component, a hollow encoder, a linear actuator motor stator, a linear actuator motor rotor, a motor rotor fixing component, a lead screw nut fixing component, a ball screw nut, a ball screw, a linear actuator output component, a deep groove ball bearing, a lead screw support slider, and a pair of angular contact bearings.

[0019] The upper shaft fixing component, pressure sensor, and actuator screw guide rail are connected sequentially from top to bottom; the upper end of the ball screw is located inside the actuator screw guide rail, the screw support slider is installed on the cylindrical surface of the upper end of the ball screw, and the lower end of the ball screw is fixedly connected to the linear actuator output component.

[0020] The motor stator fixing component is fixed on the actuator lead screw guide rail, and the motor rotor fixing shaft is located between the motor stator fixing component and the actuator lead screw guide rail; the outer ring of the deep groove ball bearing is installed on the upper end of the motor stator fixing component, and the inner ring is installed on the outer side of the upper end of the motor rotor fixing component; the inner ring of the angular contact bearing is installed on the actuator lead screw guide rail, and the outer ring is installed on the inner side of the lower end of the motor rotor fixing component.

[0021] The linear actuator motor stator is installed inside the motor stator fixing component, and the linear actuator motor rotor is installed outside the motor rotor fixing component, with the linear actuator motor rotor located inside the linear actuator motor stator.

[0022] The rotor of the hollow encoder is fixed on the motor rotor fixing component, and the stator is fixed on the upper end of the motor stator fixing component;

[0023] The ball screw nut is installed inside the ball screw nut fixing component.

[0024] In the above technical solution, the lead screw support slider is composed of a polytetrafluoroethylene rod and a rubber support frame. The polytetrafluoroethylene rod is glued in the groove on the outside of the rubber support frame, and the polytetrafluoroethylene rod slides in contact with the inner wall of the actuator lead screw guide rail.

[0025] A humanoid robot includes the aforementioned variable stiffness and variable reduction ratio ankle joint device, wherein the lower leg structure is mounted on the lower leg of the humanoid robot at the middle, and the bottom of the variable stiffness mechanism is connected to the foot component.

[0026] The beneficial effects of this invention are:

[0027] (1) The variable stiffness mechanism in this invention moves the leaf spring fulcrum through a motor and a T-screw system, changing the length of the deformable part of the leaf spring to achieve active variable stiffness. Since the length of the deformable part of the leaf spring in this mechanism can be adjusted to near zero, the stiffness variation range can be from low stiffness to infinity, enabling the joint to achieve energy storage and buffering at low stiffness and precise position control at high stiffness. Furthermore, the T-screw in the variable stiffness mechanism has a self-locking capability, eliminating the influence of the load on the variable stiffness motor, thereby reducing the requirements for the output capacity of the variable stiffness motor. Smaller motors can be used to achieve variable stiffness, making the variable stiffness mechanism more compact and lighter, reducing the impact on the dynamic response of the robot's legs. Additionally, the variable stiffness mechanism in this invention has a limiting mechanism, allowing the joint to continue outputting even when the joint load exceeds the load capacity of the variable stiffness mechanism, increasing the output capacity of the variable stiffness joint.

[0028] (2) During high-dynamic motion, the torque and rotational speed requirements of the ankle joint vary at different angles in humanoid robots. Therefore, a reasonable deceleration ratio and joint angle coupling relationship can improve the output capability of the joint in high-dynamic motion. This invention uses a combination of linear actuator drive and four-bar linkage to achieve the coupling of the deceleration ratio and joint angle of the ankle joint device. In addition, this invention has many design parameters related to the deceleration ratio, which enhances the flexibility of deceleration ratio design and enables the realization of various deceleration ratio and joint angle coupling relationships to obtain the optimal configuration suitable for the ankle joint of high-dynamic robots. Furthermore, a reasonable deceleration ratio design can reduce the performance requirements of the joint drive motor, which accounts for a large proportion of the mass. At the same time, this invention places the drive motor closer to the knee joint, reducing the rotational inertia of the ankle joint device relative to the knee joint, thereby improving the dynamic response capability of the knee joint.

[0029] (3) In this invention, the ball screw end of the linear actuator uses a slider composed of rubber and polytetrafluoroethylene (PTFE) as a support. The PTFE rods serve as the contact surface, and the rubber as the support frame. This not only ensures the smooth movement of the slider along the guide rail but also utilizes the properties of rubber to eliminate vibration during the screw's movement and the gap between the slider and the guide rail. Furthermore, since the multiple PTFE rods are in line contact with the guide rail, and the support frame is elastic, the requirements for the cylindrical surface machining accuracy of the slider are reduced. Attached Figure Description

[0030] Figure 1 This is a schematic diagram of the ankle joint device of the humanoid robot with variable stiffness and variable deceleration ratio described in the present invention.

[0031] Figure 2 This is a side view of the variable stiffness, variable reduction ratio humanoid robot ankle joint device described in this invention.

[0032] Figure 3(a) is a schematic diagram of the bionic foot dorsiflexion of the humanoid robot with variable stiffness and variable deceleration ratio described in this invention;

[0033] Figure 3(b) is a schematic diagram of the normal state of the bionic foot of the humanoid robot with variable stiffness and variable deceleration ratio described in this invention;

[0034] Figure 3(c) is a schematic diagram of the bionic foot plantar flexion of the humanoid robot with variable stiffness and variable deceleration ratio described in this invention;

[0035] Figure 4 This is a side view of the irregularly shaped joystick described in this invention;

[0036] Figure 5 This is a cross-sectional view of the linear actuator described in this invention;

[0037] Figure 6 This is a structural diagram of the lead screw supporting slider described in this invention;

[0038] Figure 7 This is a structural diagram of the variable stiffness mechanism described in this invention;

[0039] Figure 8 This is an exploded view of the variable stiffness mechanism described in this invention;

[0040] Figure 9 This is a simplified diagram of the variable stiffness mechanism of the present invention.

[0041] Figure 10 This is a cross-sectional view of the variable stiffness mechanism described in this invention.

[0042] In the diagram: 101 - Lower leg structural component, 102 - Foot component, 103 - Ankle joint pivot centerline, 202 - Irregular rocker arm, 203 - Rocker arm pivot, 204 - Ankle joint pivot, 205 - Variable stiffness mechanism, 207 - Upper pivot of linear actuator, 208 - Linear actuator, 209 - Rocker arm output pivot, 210 - Crank-rocker transmission mechanism, 211 - Rocker arm input pivot, 212 - Transmission connecting rod, 213 - Variable stiffness mechanism Stiffness mechanism input shaft, 403-rocker shaft mounting hole, 409-rocker output shaft mounting hole, 411-rocker input shaft mounting hole, 501-upper shaft fixing part, 502-pressure sensor, 503-actuator lead screw guide rail, 504-motor stator fixing part, 505-hollow encoder, 506-motor rotor cover, 507-linear actuator motor stator, 508-linear actuator motor rotor, 509 - Motor stator cover, 510 - Motor rotor fixing component, 511 - Ball screw nut fixing component, 512 - Ball screw nut, 513 - Ball screw nut cover, 514 - Ball screw, 515 - Linear actuator output component, 516 - Deep groove ball bearing, 517 - Screw support slider, 518 - Angular contact bearing pair, 601 - PTFE rod, 602 - Rubber support frame, 801 - Fixed end leaf spring pressure plate 802-Variable stiffness leaf spring, 803-Linear bearing, 804-Variable stiffness stop block, 805-T-type lead screw nut, 806-Variable stiffness fulcrum shaft, 807-Bearing cover, 808-T-type lead screw support bearing, 809-T-type lead screw, 810-Input bearing component, 811-Leaf spring moving end pressure plate, 812-Variable stiffness base, 813-Variable stiffness motor, 814-Optical shaft, 815-Flat key, 816-Limit stop block. Detailed Implementation

[0043] The present invention will be further described below with reference to the accompanying drawings and specific embodiments, but the scope of protection of the present invention is not limited thereto.

[0044] This invention proposes a variable stiffness, variable reduction ratio humanoid robot ankle joint device, primarily addressing the needs of high-dynamic humanoid robot ankle joints. For example... Figure 1 As shown, the ankle joint device is fixed to the humanoid robot's lower leg through mounting holes on the lower leg structure 101, and serves as the ankle joint of the humanoid robot, connected to the foot component 102. The ankle joint device has one degree of freedom, namely, the foot component 102 can rotate around the ankle joint's rotation axis centerline 103, which can realize plantar flexion and dorsiflexion movements of the humanoid robot's foot.

[0045] like Figure 2As shown, the ankle joint device consists of a lower leg structure 101, a shaped rocker arm 202, a rocker arm shaft 203, an ankle joint shaft 204, a variable stiffness mechanism 205, a foot component 102, an upper shaft 207 for a linear actuator, a linear actuator 208, a rocker arm output shaft 209, a rocker arm input shaft 211, a transmission link 212, and an input shaft 213 for the variable stiffness mechanism. The lower leg structure 101 is screwed to the humanoid robot's lower leg. The upper end of the linear actuator 208 is connected to the upper shaft 207 for a linear actuator via a rotating bearing. The upper shaft 207 is fixed to the top of the lower leg structure 101 by an interference fit. The lower end of the linear actuator 208 is connected to the rocker arm input shaft 211 by a rotating bearing. The rocker arm input shaft 211 and one end of the shaped rocker arm 202 are fixed by an interference fit. The other end of the irregularly shaped rocker arm 202 is connected to the rocker arm shaft 203 via a rotary bearing. The rocker arm shaft 203 is fixedly connected to the lower part of the lower leg structure 101 by an interference fit. The irregularly shaped rocker arm 202 is fixedly connected to the rocker arm output shaft 209 by an interference fit. The rocker arm output shaft 209 is connected to the upper end of the transmission link 212 via a rotary bearing. The lower end of the transmission link 212 is fixedly connected to the variable stiffness mechanism input shaft 213 by an interference fit. The variable stiffness mechanism input shaft 213 is connected to the variable stiffness mechanism 205 via a rotary bearing. The variable stiffness mechanism 205 is connected to the ankle joint shaft 204 via a rotary bearing. The ankle joint shaft 204 is fixedly connected to the bottom of the lower leg structure 101 by an interference fit. The foot component 102 is fixedly connected to the variable stiffness mechanism 205 by screws.

[0046] The crank-rocker transmission mechanism 210 comprises the irregularly shaped rocker arm 202, rocker arm shaft 203, ankle joint shaft 204, variable stiffness mechanism 205, rocker arm output shaft 209, and transmission connecting rod 212. The irregularly shaped rocker arm 202 is the rocker arm in the crank-rocker transmission mechanism 210, the variable stiffness mechanism 205 is the crank in the crank-rocker transmission mechanism 210, and the lower leg structure 101 is the frame in the crank-rocker transmission mechanism 210. The irregularly shaped rocker arm 202 serves as the input to the crank-rocker transmission mechanism 210, and the variable stiffness mechanism 205 serves as the output of the crank-rocker transmission mechanism 210.

[0047] The specific operation of the ankle joint device is as follows: The linear actuator 208 drives the rocker input shaft 211 to move. The rocker input shaft 211 drives the irregular connecting rod 202 and the rocker output shaft 209 in the crank-rocker transmission 210 to rotate around the rocker shaft 203. The transmission connecting rod 212, which is hinged to the rocker output shaft 209, transmits the power to the variable stiffness mechanism 205. The variable stiffness mechanism 205 drives the foot component 102, which is fixed to it, to rotate, ultimately realizing the plantar flexion and dorsiflexion movements of the humanoid robot's ankle joint. Figures 3(a), (b), and (c) are schematic diagrams of the movement of the ankle joint device. (a) shows the bionic foot dorsiflexion, (b) shows the normal state of the bionic foot, and (c) shows the bionic foot plantar flexion.

[0048] Figure 4 This is a side view of the irregularly shaped joystick 202. In the figure, 403, 409, and 411 are the mounting holes for the joystick shaft, the joystick output shaft, and the joystick input shaft, respectively. α is the angle between the straight line defined by the centers of the joystick shaft mounting holes 403 and 409 and the straight line defined by the centers of the joystick shaft mounting holes 403 and 411.

[0049] This ankle joint device employs a linear actuator 208 and a crank-rocker transmission mechanism 210, thus the reduction ratio (linear motor speed / ankle joint speed) is coupled with the ankle joint rotation angle. The parameters affecting the coupling relationship between the ankle joint angle and the reduction ratio in this invention include: the lead screw in the linear actuator 208; the positions of the linear actuator fixed shaft 207 and the rocker shaft 203 relative to the ankle joint; the distance between the center of the rocker shaft 203 and the center of the rocker output shaft 209; the distance between the center of the rocker output shaft 209 and the center of the crank input shaft 213; the distance between the center of the rocker shaft 203 and the center of the rocker input shaft 211; and the included angle α. Figure 4 This device has many design parameters related to the reduction ratio, which enhances the flexibility of reduction ratio design and enables the coupling relationship between various reduction ratios and joint angles, thus obtaining the optimal configuration suitable for the ankle joint of a high-dynamic robot.

[0050] Figure 5 This is a cross-sectional view of the linear actuator 208. The linear actuator 208 in this invention is a power device that uses a motor and a ball screw working in tandem. The motor rotor drives the rotation of the ball screw nut, thereby enabling the screw to move linearly. Through this mechanism, the distance between axis a and axis b can be precisely controlled to achieve linear output, wherein axis a is hinged to... Figure 2 The axis of the upper rotating shaft 207 of the linear actuator, axis b is Figure 2The joystick input shaft 211 is aligned with the axis of the joystick. The combination of the motor and ball screw provides the robot with an efficient, precise, stable, and reliable drive system, enabling the robot to perform complex tasks in various working environments. Furthermore, the ball screw has good return drive capability, which helps to mitigate impact forces.

[0051] like Figure 5 As shown, the linear actuator 208 mainly consists of an upper shaft fixing component 501, a pressure sensor 502, an actuator lead screw guide rail 503, a motor stator fixing component 504, a hollow encoder 505, a motor rotor cover 506, a linear actuator motor stator 507, a linear actuator motor rotor 508, a motor stator cover 509, a motor rotor fixing component 510, a lead screw nut fixing component 511, a ball screw nut 512, a lead screw nut cover 513, a ball screw 514, a linear actuator output component 515, a deep groove ball bearing 516, a lead screw support slider 517, and an angular contact bearing pair 518. The upper shaft fixing member 501 is fixed to the upper end of the pressure sensor 502 by screws; the pressure sensor 502 is fixed to the upper end of the actuator screw guide rail 503 by screws; the actuator screw guide rail 503 is a hollow structure, and the upper end of the ball screw 514 is located inside the actuator screw guide rail 503; the screw support slider 517 is installed on the cylindrical surface of the upper end of the ball screw 514, and its movement on the ball screw 514 is restricted by screws and washers; the linear actuator output member 515 is fixed to the lower end of the ball screw 514 by the lower end thread and thread adhesive; the ball screw nut 512 is installed inside the ball screw nut fixing member 511 and is pressed by the threaded engagement between the ball screw nut cover 513 and the ball screw nut fixing member 511; the inner ring of the angular contact bearing pair 518 is installed on the actuator screw guide rail 503, and the outer ring is installed on... The motor rotor fixing part 510 is located inside the lower end of the motor rotor fixing part 510 and is pressed by the ball screw nut fixing part 511 and screws; the outer ring of the deep groove ball bearing 516 is installed on the upper end of the motor stator fixing part 504 and the inner ring is installed on the outer side of the upper end of the motor rotor fixing part 510; the motor stator fixing part 504 is fixed to the actuator screw guide rail 503 by screws; the linear actuator motor stator 507 is installed inside the motor stator fixing part 504 and is pressed by screws and the motor stator cover 509; the rotor of the hollow encoder 505 is fixed on the motor rotor fixing part 510 and the stator is fixed to the upper end of the motor stator fixing part 504 by screws; the linear actuator motor rotor 508 is installed outside the motor rotor fixing part 510 and is pressed by screws and the motor rotor cover 506; the linear actuator motor rotor 508 is located inside the linear actuator motor stator 507.

[0052] The specific working condition of the linear actuator 208 is as follows: the upper shaft fixing part 501, pressure sensor 502, actuator lead screw guide rail 503, motor stator fixing part 504, linear actuator motor stator 507, and motor stator cover 509 are fixed together. During the operation of the linear actuator 208, these components are stationary relative to the linear actuator itself. The motor rotor cover 506, linear actuator motor rotor 508, motor rotor fixed shaft 510, ball screw nut fixing part 511, ball screw nut 512, and ball screw nut cover 513 are fixedly connected together. When the linear actuator is working, these components rotate with the linear actuator motor rotor 508, that is, they rotate relative to the upper shaft fixing part 501, pressure sensor 502, actuator screw guide rail 503, motor stator fixing part 504, linear actuator motor stator 507, and motor stator cover 509. Angular contact bearing pair 518 and deep groove ball bearing 516 provide rotational support for them. Hollow encoder 505 measures the rotational data of linear actuator motor rotor 508.

[0053] Because the linear actuator output component 515 is hinged to the rocker input shaft 211 and fixedly connected to the ball screw 514, the ball screw 514 cannot rotate with the ball screw nut 512, but can only move linearly relative to the ball screw nut 512. When the linear actuator is working, the linear actuator motor rotor 508 drives the ball screw nut 512 to rotate, which in turn drives the ball screw 514 to move linearly, thereby driving the linear actuator output component 515 to move and achieve linear output. The screw support slider 517 provides support to prevent the screw from vibrating during operation.

[0054] Figure 6 This is a structural diagram of the ball screw support slider 517, which consists of 12 polytetrafluoroethylene (PTFE) rods 601 and a rubber support frame 602. The 12 PTFE rods 601 are glued to slots in the rubber support frame 602. The ball screw support slider 517 provides support for the linear motion of the ball screw 514 through the sliding contact between the 12 PTFE rods 601 and the actuator ball screw guide rail 503. In addition, due to the elasticity of the rubber support frame 602, the position of the PTFE rods 601 in the slots of the rubber support frame 602 can be appropriately changed, which can eliminate the gap between the PTFE rods 601 and the actuator ball screw guide rail 503 and provide a certain preload pressure to avoid the impact force generated by the gap between the slider and the guide rail. Due to the good damping properties of rubber, the rubber support frame 602 can suppress and reduce the vibration of the ball screw 514 during the movement.

[0055] Figure 7 This is a structural diagram of a variable stiffness mechanism. Axis c represents the connection between the variable stiffness mechanism and... Figure 2 The ankle joint pivot 204 is the hinge axis of rotation, and the d-axis is the variable stiffness mechanism. Figure 2 The variable stiffness mechanism in the middle has an input shaft 213 hinged to the rotation axis of the rotation. Figure 2 The foot component 102 is fixed to the bottom of the variable stiffness mechanism by screws.

[0056] Figure 8 This is an exploded view of the variable stiffness mechanism, which consists of a fixed-end leaf spring pressure plate 801, a variable stiffness leaf spring 802, a linear bearing 803, a variable stiffness stop block 804, a T-type lead screw nut 805, a variable stiffness fulcrum shaft 806, a bearing cover 807, a T-type lead screw support bearing 808, a T-type lead screw 809, an input bearing component 810, a leaf spring moving end pressure plate 811, a variable stiffness base 812, a variable stiffness motor 813, a light shaft 814, and a flat key 815.

[0057] One end of the variable stiffness leaf spring 802 is fixed to the variable stiffness base 812 near the c-axis via a fixed end leaf spring pressure plate 801 and screws. The input bearing 810 is fixed to the other end of the variable stiffness leaf spring 802 via screws and a leaf spring moving end pressure plate 811. The cylindrical surfaces at both ends of the T-screw 809 are interference-fitted to the inner ring of the T-screw support bearing 808. The outer ring of the T-screw support bearing 808 is fixed in the mounting hole of the variable stiffness base 812. The bearing cap 807 is fixed to one bearing mounting hole of the T-screw 809 via screws to restrict the axial movement of the bearing. The motor housing of the variable stiffness motor 813 is fixed to the other bearing mounting hole of the T-screw 809 via screws and... The motor housing restricts the axial movement of the bearing; a flat key 815 is embedded at one end of the T-screw 809 with a keyway, forming an overfit with the motor shaft of the variable stiffness motor 813, and preventing relative movement between them through the key; both ends of the optical shaft 814 are fixed to the variable stiffness base 812 through an interference fit, and the axial movement of the optical shaft is restricted by nuts at both ends of the optical shaft 814; the T-screw nut 805 moves on the T-screw 809, and the linear bearing 803 slides on the optical shaft 814; the T-screw nut 805 and the linear bearing 803 are installed inside the variable stiffness stop 804 and fixed by adhesive; the variable stiffness stop 804 also has a through hole for the variable stiffness leaf spring 802 to pass through, such as Figure 8 As shown, the T-shaped lead screw 809 and the optical axis 814 are located on both sides of the stiffness leaf spring 802; the variable stiffness stop block 804 is also fixedly connected to two variable stiffness fulcrum shafts 806, which are located on the upper and lower sides of the variable stiffness leaf spring 801 respectively, and are tangent to the variable stiffness leaf spring 801 during the movement of the variable stiffness stop block 804.

[0058] Figure 9This is a simplified diagram of the variable stiffness mechanism's variable stiffness principle. The lower leg structure 101 is connected to the variable stiffness base 812 via an ankle joint pivot 204; the transmission link 212 is hinged to the variable stiffness leaf spring 802 via the variable stiffness mechanism input pivot 213; the leftmost end of the variable stiffness leaf spring 802 is fixed to the variable stiffness base 812; the housing of the variable stiffness motor 813 is fixed to the variable stiffness base 812; and the T-shaped lead screw 809 is connected to the pivot of the variable stiffness motor 813 and rotates with the variable stiffness mechanism. The shaft of the motor 813 rotates; the T-type lead screw nut 805 is installed on the T-type lead screw 809 and moves with the rotation of the T-type lead screw 809; the variable stiffness fulcrum shafts 806 are fixed to the T-type lead screw nut 805 through connecting parts and move with the T-type lead screw nut 805, and the two variable stiffness fulcrum shafts 806 are divided into upper and lower fulcrums, which respectively support the upper and lower surfaces of the variable stiffness leaf spring 802; the elastically deformable part L is the part of the variable stiffness leaf spring 802 that can deform.

[0059] When the humanoid robot is working, the linear actuator 208 provides a force along the transmission link 212 to the variable stiffness leaf spring 802, generating pressure (or tension) on the right end of the variable stiffness leaf spring 802. The lower (or upper) surface of the variable stiffness leaf spring 802 generates pressure on the lower fulcrum (upper fulcrum), and the lower fulcrum transmits the pressure to the variable stiffness T-screw nut 805. The T-screw nut 805 generates pressure (or tension) on the T-screw 809, thereby driving the variable stiffness base 812 (i.e., the foot component 102) to rotate, realizing the plantar flexion and dorsiflexion movements of the humanoid robot's foot. The elastic element of the variable stiffness leaf spring 802 will deform under pressure (or tension). Since the variable stiffness fulcrum shaft 806 restricts the deformation of the variable stiffness leaf spring 802, only the elastically deformable part L of the variable stiffness leaf spring 802 undergoes deformation. Since the other parts are made of high-stiffness materials, the overall stiffness of the joint is determined by the length of the elastically deformable portion L. According to the relationship between the effective length and stiffness of the variable stiffness leaf spring 802, changing the position of the variable stiffness fulcrum shaft 806 to lengthen the elastically deformable portion L results in a decrease in joint stiffness, and vice versa. Therefore, by controlling the variable stiffness motor 813 and manipulating the position of the variable stiffness fulcrum shaft 806, the length of the elastically deformable portion L is changed, thus achieving a change in joint stiffness. When the variable stiffness fulcrum shaft 806 is at the leftmost position of the variable stiffness leaf spring 802, the joint has its lowest stiffness, determined by the leaf spring dimensions and the length of L. When the variable stiffness fulcrum shaft 806 is at the rightmost position of the variable stiffness leaf spring 802, the elastically deformable portion L approaches zero, therefore the stiffness approaches infinite stiffness.

[0060] Figure 10The figure shows a cross-sectional view of the variable stiffness mechanism. To prevent the leaf spring from deforming beyond its working range and causing damage, a limiting block 816 is designed on the variable stiffness base 812. The limiting block 816 not only protects the elastic element in the variable stiffness mechanism from damage due to overload, but also allows the joint output to exceed the torque load of the elastic element in the variable stiffness mechanism.

[0061] The embodiments described above are preferred embodiments of the present invention, but the present invention is not limited to the above embodiments. Any obvious improvements, substitutions or modifications that can be made by those skilled in the art without departing from the essence of the present invention shall fall within the protection scope of the present invention.

Claims

1. A variable stiffness, variable gear ratio ankle device, characterized by, The lower leg structure (101), the special-shaped rocker (202), the rocker rotation shaft (203), the ankle rotation shaft (204), the variable stiffness mechanism (205), the upper end rotation shaft of the linear actuator (207), the linear actuator (208), the rocker output rotation shaft (209), the rocker input rotation shaft (211), the transmission connecting rod (212) and the variable stiffness mechanism input rotation shaft (213) are included. The upper end of the linear actuator (208) is connected to the upper end rotation shaft of the linear actuator (207), the upper end rotation shaft of the linear actuator (207) is in interference connection with the top of the lower leg structure (101), the lower end of the linear actuator (208) is connected to the rocker input rotation shaft (211), the rocker input rotation shaft (211) is in interference connection with one end of the special-shaped rocker (202), the other end of the special-shaped rocker (202) is connected to the rocker rotation shaft (203), and the rocker rotation shaft (203) is in interference connection with the lower part of the lower leg structure (101). The end of the special-shaped rocker (202) close to the rocker input rotation shaft (211) is also in interference connection with the rocker output rotation shaft (209), the rocker output rotation shaft (209) is connected to the upper end of the transmission connecting rod (212), the lower end of the transmission connecting rod (212) is in interference connection with the variable stiffness mechanism input rotation shaft (213), and the variable stiffness mechanism input rotation shaft (213) is connected to the variable stiffness mechanism (205). The upper part of the variable stiffness mechanism (205) is also connected to the ankle rotation shaft (204), and the ankle rotation shaft (204) is in interference connection with the bottom of the lower leg structure (101). The variable stiffness mechanism (205) includes a variable stiffness plate spring (802), a linear bearing (803), a variable stiffness block (804), a T-shaped screw nut (805), a variable stiffness fulcrum shaft (806), a T-shaped screw (809), an input carrier (810), a variable stiffness base (812), a variable stiffness motor (813), an optical shaft (814) and a flat key (815). One end of the variable stiffness plate spring (802) is fixed to the variable stiffness base (812), and the other end is fixedly connected to the input carrier (810), and the input carrier (810) is hinged to the variable stiffness mechanism input rotation shaft (213). The T-shaped screw (809) and the optical shaft (814) are located on the two sides of the variable stiffness plate spring (802) respectively, the two ends of the optical shaft (814) are fixedly connected to the variable stiffness base (812), the two ends of the T-shaped screw (809) are rotationally connected to the variable stiffness base (812), and the end of the T-shaped screw (809) with a key groove is embedded with the flat key (815) to form a transition fit with the motor shaft of the variable stiffness motor (813). The T-shaped screw (809) and the optical shaft (814) are respectively sleeved with the T-shaped screw nut (805) and the linear bearing (803), and the T-shaped screw nut (805) and the linear bearing (803) are both installed in the variable stiffness block (804); and the variable stiffness block (804) is also sleeved on the variable stiffness plate spring (802). The variable stiffness stop block (804) is internally fixed with two variable stiffness fulcrum shafts (806) respectively pressing against the upper and lower surfaces of the variable stiffness leaf spring (802).

2. A variable stiffness, variable-ratio ankle device according to claim 1, wherein, The special-shaped rocker (202), the rocker rotating shaft (203), the ankle joint rotating shaft (204), the variable stiffness mechanism (205), the rocker output rotating shaft (209) and the transmission connecting rod (212) constitute a crank rocker transmission mechanism (210); the special-shaped rocker (202) is a rocker in the crank rocker transmission mechanism (210); the variable stiffness mechanism (205) is a crank in the crank rocker transmission mechanism (210); and the lower leg structural member (101) is a rack in the crank rocker transmission mechanism (210).

3. The variable stiffness, variable-ratio ankle device of claim 1, wherein, The T-shaped screw rod (809) is fixed at both ends with the variable stiffness base (812) through T-shaped screw rod support bearings (808), and the end of the T-shaped screw rod (809) away from the variable stiffness motor (813) is fixed with a bearing gland (807) for limiting the axial movement of the T-shaped screw rod support bearings (808).

4. A variable stiffness, variable ratio ankle device according to claim 3, wherein, The variable stiffness base (812) is provided with a limiting stop block (816) near one end of the input bearing (810).

5. A variable stiffness, variable ratio ankle device according to claim 3, wherein, The optical axis (814) is limited in the axial movement through nuts at both ends.

6. The variable stiffness, variable-ratio ankle device of claim 1, wherein, The linear actuator (208) comprises an upper end shaft fixing member (501), a pressure sensor (502), an actuator screw rod guide rail (503), a motor stator fixing member (504), a hollow encoder (505), a linear actuator motor stator (507), a linear actuator motor rotor (508), a motor rotor fixing member (510), a screw rod nut fixing member (511), a ball screw nut (512), a ball screw (514), a linear actuator output member (515), a deep groove ball bearing (516), a screw rod support sliding block (517) and an angular contact bearing pair (518). The upper end shaft fixing member (501), the pressure sensor (502) and the actuator screw rod guide rail (503) are sequentially connected from top to bottom; the upper end of the ball screw (514) is located inside the actuator screw rod guide rail (503), the screw rod support sliding block (517) is mounted on the cylindrical surface of the upper end of the ball screw (514), and the lower end of the ball screw (514) is fixed with the linear actuator output member (515); The motor stator fixing member (504) is fixed on the actuator screw rod guide rail (503), the motor rotor fixing member (510) is located between the motor stator fixing member (504) and the actuator screw rod guide rail (503); the outer ring of the deep groove ball bearing (516) is mounted on the upper end of the motor stator fixing member (504), and the inner ring is mounted on the upper end of the motor rotor fixing member (510); the inner ring of the angular contact bearing pair (518) is mounted on the actuator screw rod guide rail (503), and the outer ring is mounted on the lower end of the motor rotor fixing member (510); The linear actuator motor stator (507) is installed inside the motor stator fixing member (504), the linear actuator motor rotor (508) is installed outside the motor rotor fixing member (510), and the linear actuator motor rotor (508) is located inside the linear actuator motor stator (507); The rotor of the hollow encoder (505) is fixed on the motor rotor fixing member (510), and the stator is fixed on the upper end of the motor stator fixing member (504); The ball screw nut (512) is installed inside the ball screw nut fixing member (511).

7. A variable stiffness, variable ratio ankle device according to claim 6, wherein, The screw support slider (517) is composed of a polytetrafluoroethylene rod (601) and a rubber support frame (602), the polytetrafluoroethylene rod (601) is adhered to the clamping groove on the outside of the rubber support frame (602), and the polytetrafluoroethylene rod (601) is in sliding contact with the inner wall of the actuator screw guide rail (503).

8. A humanoid robot, characterized by The variable stiffness variable deceleration ratio ankle joint device comprises the variable stiffness variable deceleration ratio ankle joint device of any one of claims 1-7, the middle part of the shank structure member (101) is installed on the humanoid robot shank, and the bottom of the variable stiffness mechanism (205) is connected to the foot member (102).

Images