Variable stiffness and variable damper for shank joint of exoskeleton robot

Abstract

The utility model discloses a variable stiffness variable damper for a shank joint of an exoskeleton robot, which belongs to the technical field of medical instruments, and comprises a magnetorheological damper I and a magnetorheological damper II, the magnetorheological damper I comprises an upper connecting piece, a piston rod, an electromagnetic coil I and magnetorheological fluid I, the top end of the piston rod is fixedly installed at the center of the upper connecting piece, the first electromagnetic coil is arranged on the outer side of the bottom end of the piston rod in a sleeving mode, the first magnetorheological fluid is arranged on the outer side of the piston rod in a sleeving mode, and the second magnetorheological damper is arranged on the outer side of the first magnetorheological fluid in a sleeving mode. According to the variable-rigidity variable damper for the shank joint of the exoskeleton robot, the variable-rigidity variable damper for the shank joint of the exoskeleton robot is mainly composed of the two magneto-rheological dampers with different damping coefficients and the two springs with different rigidity coefficients, and the walking flexibility and stability of the lower limb exoskeleton rehabilitation robot are improved.

Description

Technical Field

[0001] The utility model relates to the technical field of medical equipment, in particular to a variable stiffness variable damper used for a calf joint of an exoskeleton robot. Background Art

[0002] As an auxiliary device, the lower limb exoskeleton rehabilitation robot mainly helps those who need rehabilitation due to lower limb injuries or functional impairment to restore their walking ability. The robot needs to be adjusted according to the needs and progress of the wearer to help them gradually restore muscle strength, balance and gait control. When people walk, run or are impacted by the outside world, joints and muscles can play a buffering role. However, when the robot is walking, when the swinging leg lands, it will inevitably collide with the ground, and the impact reaction force from the ground will cause a certain degree of vibration from the bottom to the top of the robot. And as the walking speed increases and the stride increases, the ground impact and the upper body vibration of the robot will become more intense. Therefore, reducing the impact of the robot during walking is of great significance to improving the stability, energy efficiency, precision and comfort of the robot.

[0003] In order to overcome the impact of ground impact on the robot and the wearer and make the robot compliant, active compliant control methods have been proposed, mainly controlling external forces through some control algorithms. The active compliant interactive control scheme of lower limb exoskeleton rehabilitation robots based on adaptive adjustment of impedance parameters has been widely used, and the movement of the robot can be adjusted according to the difference between the expected force or torque and the actual perceived force or torque. In addition, mathematical models can be used to describe the dynamics and kinematics of the robot system, and control algorithms can be designed based on these models to optimize the robot's motion trajectory. There are also control algorithms designed by imitating the working principle of the human nervous system to achieve precise control of the robot. Neural network control methods usually combine sensor feedback and model prediction to achieve efficient motion control. In addition to active control methods, the compliance of the robot can also be passively achieved by introducing stiffness and damping structures. For example, a series elastic actuator introduces an elastic element, usually a spring, between the motor and the load to achieve flexible control and movement. In order to break through the limitation of fixed stiffness, variable stiffness actuators (VSAs) have become a research hotspot in recent years, and variable stiffness characteristics can be achieved through different structures.

[0004] Through the analysis of the above research, it is found that the active flexible controller is highly dependent on the accurate dynamic model of the actual robot leg structure. For robots with relatively complex leg structures, this is the main difficulty in achieving active flexibility. The stiffness coefficient and damping coefficient of the passive flexible structure are mostly fixed values, which are difficult to adapt to different ground conditions.

[0005] In recent years, magnetorheological technology has become increasingly mature. Magnetorheological dampers are devices that use the rheological properties of magnetic fluids to achieve damping adjustment. When an external magnetic field is applied, the particles of the magnetic fluid will be rearranged, thereby changing its flow properties and causing a damping effect in the device. At present, magnetorheological dampers are mostly used in automobile suspension systems. By adjusting the magnetic field of the damper, the suspension stiffness and damping effect can be adjusted according to different road conditions and driving requirements. At the same time, magnetorheological dampers are also widely used in buildings, bridges and other fields. In addition, in the field of robotics, magnetorheological dampers can be used to improve the motion control and stability of robots, as well as to reduce their vibration and impact. They have been introduced in robotic arms, bionic legs, bionic joints, and intelligent prostheses. In terms of control strategies, semi-active control and ceiling control are currently more widely used.

[0006] Lower limb exoskeleton rehabilitation robots need to imitate the natural movement of human lower limbs and provide necessary assistance when needed. Therefore, the structural design needs to take into account the freedom of movement of the knee joint, hip joint, ankle joint and other parts, and ensure that the robot can provide sufficient range and flexibility. With the increase of the stiffness coefficient, the system's impact resistance will be enhanced, but the output bandwidth and output impedance value will become larger and larger, the driver and the load will be close to a rigid connection, and the system stability will be weakened; with the increase of the damping coefficient, the stability of the system will be better and better, but the larger the damping coefficient, the worse the comfort of people when wearing the robot. Based on the design of the overall structure of the lower limb exoskeleton rehabilitation robot, combined with the human walking GRF curve obtained in the above experiment, the maximum ground reaction force is about 1.4 times the body weight. In order to meet the needs of more wearers, the limit pressure that the variable stiffness variable damper can withstand should be greater, and at the same time, the spring bottoming phenomenon can be avoided, which will cause harm to the wearer. However, while meeting the limit pressure, the flexibility of walking should also be considered, so the optimal parameters should be selected to match the human body. Therefore, it is necessary to design a variable stiffness variable damper that meets the above requirements and can be applied to the calf joint of the exoskeleton robot. Utility Model Content

[0007] Aiming at the high stiffness problem of the calf joints of traditional robots, the utility model proposes a variable stiffness and variable damping composed of two magnetorheological dampers with controllable damping and two mold springs with fixed stiffness coefficients, thereby improving the compliance and stability of the walking of the lower limb exoskeleton rehabilitation robot.

[0008] To achieve the above-mentioned purpose, the utility model provides a variable stiffness variable damper for the calf joint of an exoskeleton robot, including a magnetorheological damper 1 and a magnetorheological damper 2, wherein the magnetorheological damper 1 includes an upper connecting piece, a piston rod, an electromagnetic coil 1 and a magnetorheological fluid 1, the top end of the piston rod is fixedly installed at the center of the upper connecting piece, one set of the electromagnetic coil is arranged on the outside of the bottom end of the piston rod, one set of the magnetorheological fluid is arranged on the outside of the piston rod, and the second set of the magnetorheological damper is arranged on the outside of the magnetorheological fluid 1.

[0009] Preferably, the magnetorheological damper 1 also includes a lower connecting piece, a movable plate and an energy storage spring, the lower connecting piece is arranged at the bottom end of the magnetorheological fluid 1, the movable plate is slidably arranged inside the magnetorheological fluid 1, one side of the movable plate is connected to the top end of the energy storage spring, and the bottom end of the energy storage spring is connected to the lower connecting piece.

[0010] Preferably, the second magnetorheological damper includes a second magnetorheological fluid, a second electromagnetic coil and a shell, the second magnetorheological fluid is sleeved on the outside of the first magnetorheological fluid, the second electromagnetic coil is sleeved on the outside of the second magnetorheological fluid, and the second electromagnetic coil is arranged between the first magnetorheological fluid, and the shell is sleeved on the outside of the second electromagnetic coil.

[0011] Preferably, the magnetorheological damper 1 further includes an upper sealing ring and a lower sealing ring, both of which are sleeved on the outside of the magnetorheological fluid 2, and the upper sealing ring and the lower sealing ring are respectively arranged at two ends of the shell.

[0012] Preferably, a spring 1 is sleeved on the outer side of the piston rod and the magnetorheological fluid 1, and the spring 1 is arranged between the upper connecting member and the upper sealing ring.

[0013] Preferably, a second spring is sleeved on the outer side of the first magnetorheological fluid, and the second spring is arranged between the lower sealing ring and the lower connecting piece.

[0014] Preferably, an upper length adjustment hole is provided on the upper connecting member, and a lower length adjustment hole is provided on the lower connecting member.

[0015] Preferably, a cavity is formed between the piston rod and the movable plate.

[0016] Therefore, the utility model adopts a variable stiffness variable damper of the above structure for the calf joint of an exoskeleton robot, which is mainly composed of two magnetorheological dampers with different damping coefficients and two springs with different stiffness coefficients, thereby improving the flexibility and stability of the lower limb exoskeleton rehabilitation robot in walking.

[0017] The technical solution of the utility model is further described in detail below through the accompanying drawings and embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 It is a structural schematic diagram of an embodiment of a variable stiffness variable damper for a calf joint of an exoskeleton robot according to the utility model;

[0019] Figure 2 It is a cross-sectional view of an embodiment of a variable stiffness variable damper for a calf joint of an exoskeleton robot according to the utility model;

[0020] Figure 3 This is a structural diagram of the utility model used on the calf joint of an exoskeleton robot;

[0021] Reference numerals

[0022] 1. Magnetorheological damper 1; 11. Upper connecting piece; 12. Piston rod; 13. Electromagnetic coil 1; 14. Magnetorheological fluid 1; 15. Lower connecting piece; 16. Moving plate; 17. Energy storage spring; 18. Upper sealing ring; 19. Lower sealing ring; 2. Magnetorheological damper 2; 21. Magnetorheological fluid 2; 22. Electromagnetic coil 2; 23. Housing; 3. Spring 1; 4. Spring 2; 5. Upper length adjustment hole; 6. Lower length adjustment hole. DETAILED DESCRIPTION

[0023] The technical solution of the utility model is further described below through the accompanying drawings and embodiments.

[0024] Unless otherwise defined, the technical terms or scientific terms used in the present invention shall have the usual meanings understood by persons with ordinary skills in the field to which the present invention belongs. The words "first", "second" and similar words used in the present invention do not indicate any order, quantity or importance, but are only used to distinguish different components. Words such as "include" or "comprise" and the like mean that the elements or objects appearing before the word include the elements or objects listed after the word and their equivalents, without excluding other elements or objects. Words such as "connect" or "connected" and the like are not limited to physical or mechanical connections, but may include electrical connections, whether direct or indirect. "Up", "down", "left", "right" and the like are only used to indicate relative positional relationships. When the absolute position of the described object changes, the relative positional relationship may also change accordingly.

[0025] Example

[0026] like Figure 1-3 As shown, the utility model provides a variable stiffness variable damper for the calf joint of an exoskeleton robot, comprising a magnetorheological damper 1 and a magnetorheological damper 2. The magnetorheological damper 2 is sleeved on the magnetorheological damper 1 and can slide on the magnetorheological damper 1, while isolating the spring 1 3 from the spring 2 4.

[0027] The magnetorheological damper 1 includes an upper connecting member 11, a piston rod 12, an electromagnetic coil 13 and a magnetorheological fluid 14. The top of the piston rod 12 is fixedly installed at the center of the upper connecting member 11, the electromagnetic coil 13 is sleeved on the outside of the bottom end of the piston rod 12, the magnetorheological fluid 14 is sleeved on the outside of the piston rod 12, and the magnetorheological damper 2 is sleeved on the outside of the magnetorheological fluid 14. The magnetorheological damper 1 also includes a lower connecting member 15, a movable plate 16 and an energy storage spring 17. The lower connecting member 15 is arranged at the bottom of the magnetorheological fluid 14, the movable plate 16 is slidably arranged inside the magnetorheological fluid 14, one side of the movable plate 16 is connected to the top of the energy storage spring 17, and the bottom of the energy storage spring 17 is connected to the lower connecting member 15. A cavity is formed between the piston rod 12 and the movable plate 16.

[0028] The magnetorheological damper 1 further includes an upper sealing ring 18 and a lower sealing ring 19 , both of which are sleeved on the outside of the magnetorheological fluid 14 , and the upper sealing ring 18 and the lower sealing ring 19 are respectively arranged at both ends of the housing 23 .

[0029] The upper connecting member 11 is provided with an upper length adjustment hole 5, and the lower connecting member 15 is provided with a lower length adjustment hole 6. The upper connecting member 11 is mainly connected to the knee joint, and the lower connecting member 15 is mainly connected to the ankle joint. The upper length adjustment hole 5 and the lower length adjustment hole 6 on the connecting member can adapt to people with different leg lengths.

[0030] The magnetorheological damper 2 includes a magnetorheological fluid 21, an electromagnetic coil 22 and a shell 23. The magnetorheological fluid 21 is sleeved on the outside of the magnetorheological fluid 14, the electromagnetic coil 22 is sleeved on the outside of the magnetorheological fluid 21, and the electromagnetic coil 22 is set between the magnetorheological fluids 14, and the shell 23 is sleeved on the outside of the electromagnetic coil 22.

[0031] The piston rod 12 and the magnetorheological fluid 14 are sleeved with a spring 13, which is arranged between the upper connecting piece 11 and the upper sealing ring 18. The magnetorheological fluid 14 is sleeved with a spring 24, which is arranged between the lower sealing ring 19 and the lower connecting piece 15.

[0032] When the utility model is in use, during the walking process of the exoskeleton robot, spring 13 is compressed downward, driving the upper sealing ring 18 and the lower sealing ring 19 to compress spring 2 4, and then the upper connecting member 11, the piston rod 12 and the electromagnetic coil 13 also move downward, driving the moving plate 16 to move downward through the piston rod 12 and the cavity, and then compressing the energy storage spring 17, thereby improving the flexibility and stability of the exoskeleton robot during walking.

[0033] Working principle: This device has two main connection modes. When the current applied to the magnetorheological damper 2 is small enough, it is the connection mode 1. At this time, the magnetorheological damper 2 can slide relative to the magnetorheological damper 1. At this time, whether it is stimulated by human body force or ground excitation, springs 1 and 2 will deform to form a series mechanism; when the current applied to the magnetorheological damper 2 is large enough, it is the connection mode 2, which prevents sliding relative to the magnetorheological damper 1 and is in a static state. At this time, when external excitation is applied, only spring 1 deforms. Therefore, the variable stiffness system of the entire structure changes its damping value by adjusting the current of the magnetorheological damper 2, and finally changes the connection mode of the spring to achieve a change in the stiffness coefficient, while the variable damping system is achieved by adjusting the current applied to the magnetorheological damper 1.

[0034] Therefore, the utility model adopts a variable stiffness variable damper of the above structure for the calf joint of an exoskeleton robot, which is composed of two magnetorheological dampers with different damping coefficients and two springs with different stiffness coefficients, thereby improving the flexibility and stability of the lower limb exoskeleton rehabilitation robot in walking.

[0035] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the utility model rather than to limit it. Although the utility model has been described in detail with reference to the preferred embodiments, ordinary technicians in this field should understand that they can still modify or replace the technical solution of the utility model with equivalents, and these modifications or equivalent replacements cannot cause the modified technical solution to deviate from the spirit and scope of the technical solution of the utility model.

Claims

1. A variable stiffness variable damper for the calf joint of an exoskeleton robot, characterized in that: It comprises a magnetorheological damper 1 and a magnetorheological damper 2, wherein the magnetorheological damper 1 comprises an upper connecting member, a piston rod, an electromagnetic coil 1 and a magnetorheological fluid 1, wherein the top end of the piston rod is fixedly mounted at the center of the upper connecting member, a set of the electromagnetic coil is arranged on the outer side of the bottom end of the piston rod, a set of the magnetorheological fluid is arranged on the outer side of the piston rod, and the magnetorheological damper 2 is arranged on the outer side of the magnetorheological fluid 1.

2. The variable stiffness variable damper for the calf joint of an exoskeleton robot according to claim 1, characterized in that: The magnetorheological damper 1 also includes a lower connecting piece, a movable plate and an energy storage spring. The lower connecting piece is arranged at the bottom end of the magnetorheological fluid 1, and the movable plate is slidably arranged inside the magnetorheological fluid 1. One side of the movable plate is connected to the top end of the energy storage spring, and the bottom end of the energy storage spring is connected to the lower connecting piece.

3. The variable stiffness variable damper for the calf joint of an exoskeleton robot according to claim 2, characterized in that: The second magnetorheological damper includes a second magnetorheological fluid, a second electromagnetic coil and a shell. The second magnetorheological fluid is sleeved on the outside of the first magnetorheological fluid, the second electromagnetic coil is sleeved on the outside of the second magnetorheological fluid, and the second electromagnetic coil is arranged between the first magnetorheological fluids, and the shell is sleeved on the outside of the second electromagnetic coil.

4. The variable stiffness variable damper for the calf joint of an exoskeleton robot according to claim 3, characterized in that: The magnetorheological damper 1 also includes an upper sealing ring and a lower sealing ring, both of which are sleeved on the outside of the magnetorheological fluid 2, and the upper sealing ring and the lower sealing ring are respectively arranged at two ends of the shell.

5. The variable stiffness variable damper for the calf joint of an exoskeleton robot according to claim 4, characterized in that: A spring 1 is sleeved on the outer side of the piston rod and the magnetorheological fluid 1, and the spring 1 is arranged between the upper connecting piece and the upper sealing ring.

6. The variable stiffness variable damper for the calf joint of an exoskeleton robot according to claim 4, characterized in that: A second spring is sleeved on the outer side of the first magnetorheological fluid, and the second spring is arranged between the lower sealing ring and the lower connecting piece.

7. The variable stiffness variable damper for the calf joint of an exoskeleton robot according to claim 2, characterized in that: The upper connecting member is provided with an upper length adjustment hole, and the lower connecting member is provided with a lower length adjustment hole.

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