A coupling underactuated hip exoskeleton robot based on TNSEA

Abstract

The application discloses a kind of coupling underdriven hip joint walking exoskeleton based on TNSEA, adopt single motor and help both sides hip joint rotation simultaneously.The exoskeleton includes TNSEA mechanism, MDOF-HRJ-M-AM mechanism, double cable force transmission system and integrated electric control module.TNSEA mechanism is designed by inner and outer ring and spring group, realizes the differentiated torque output of both sides hip joint in the stage of helping, and dynamically compensates the difference of both sides movement coordination.MDOF-HRJ-M-AM mechanism compensates the anatomic alignment deviation between pelvis and exoskeleton in the process of wearing by introducing redundancy degree of freedom.Double cable system efficiently and low frictionally transmits driving force from actuator to both sides hip joint.The application provides a kind of "outer ring RMPC and inner ring PID" combined human-machine collaborative control strategy, can accurately generate target helping torque, realize high-precision tracking of motor, and improve human-machine interaction flexibility.

Description

Technical Field

[0001] This invention belongs to the field of robotics, and in particular relates to an exoskeleton robot designed to enhance the wearer's hip joint mobility and provide hip joint walking assistance. Background Technology

[0002] Researching a wearable, comfortable, and lightweight lower limb exoskeleton robot to assist people with walking difficulties, such as the elderly and patients with hip dysplasia, has enormous social value and application potential.

[0003] However, existing lower limb assistive exoskeleton robots still have many shortcomings. Most current lower limb assistive exoskeletons are complete lower limb structures covering both hip, knee, and ankle joints. These devices are suitable for people with movement disorders in their entire lower limb, enabling precise control of each joint. However, for people with only hip joint movement disorders and unimpaired lower limb nerve function, a large number of drive units leads to a complex and costly exoskeleton structure, increases its weight, and makes the wearer feel burdened during use, affecting comfort and convenience.

[0004] Chinese patent application ZL201610511532.0 discloses a lower limb assistive exoskeleton robot, which includes an upper body structure, a leg structure, a knee joint, and a hip joint. It employs dual motors to directly drive the hip and knee joints. This method of mounting the motors at the joints results in extremely large joint mass and inertia, leading to poor joint compliance and low safety.

[0005] Chinese patent ZL201610060563.9 discloses a lightweight modular walking assistive exoskeleton robot, which includes a back module, two thigh modules, two lower leg modules, and feet. The thigh modules employ two sets of drive units to operate the hip and knee joints. While the thigh and lower leg modules can be assembled as needed, if only hip joint assistance is required, the other modules become meaningless burdens, significantly increasing the wearer's physical exertion and usage burden. Summary of the Invention

[0006] Purpose of the invention: This invention aims to address the shortcomings of existing technologies and solve the problems of large mass, high energy consumption, and lack of coordination between human and machine movements in existing lower limb assistive exoskeletons. It provides a coupled underactuated hip joint exoskeleton robot based on TNSEA, which realizes coordinated and differentiated assistance of a single motor to both hip joints through a specific bidirectional nonlinear series elastic actuator (TNSEA).

[0007] The present invention also provides a method for constructing the TNSEA stiffness curve of the above-mentioned coupled underactuated hip exoskeleton robot based on TNSEA.

[0008] The present invention also provides a method for generating the inner circle trajectory of the TNSEA-based coupled underactuated hip exoskeleton robot described above.

[0009] Technical solution: To achieve the above objectives, the present invention may adopt the following technical solution:

[0010] A coupled underactuated hip exoskeleton robot based on TNSEA (Transverse Nonlinear Series Elastic Actuator), wherein the TNSEA is a bidirectional nonlinear series elastic actuator, includes a lumbar support located at the waist, a TNSEA mechanism connected to the lumbar support, a lumbar wearable device connected to the lumbar support and located in front of the TNSEA mechanism, MDOF-HRJ-M-AM mechanisms located on both sides of the TNSEA mechanism, a dual-set cable force transmission system, and a thigh wearable device connected to the MDOF-HRJ-M-AM mechanism; the MDOF-HRJ-M-AM mechanism... The structure is a multi-degree-of-freedom human-machine joint misalignment adaptation mechanism; the waist support includes a motor mounting plate, a motor mounted in the middle of the motor mounting plate, a motor wall plate fixed to the motor mounting plate and located in front of the motor mounting plate, and a front wall plate fixed to the motor mounting plate and located in front of the motor wall plate; the TNSEA mechanism includes an inner ring main shaft, two TNSEAs coaxially mounted on the inner ring main shaft, the two TNSEAs being located between the front wall plate and the motor wall plate, and the two ends of the inner ring main shaft respectively cooperating with the front wall plate and the motor wall plate through wall plate bearings; The main shaft of the ring is coaxially connected to the output shaft of the motor; each TNSEA includes an outer TNSEA ring, an inner TNSEA ring fixed coaxially with the inner ring main shaft, five sets of springs located between the outer and inner TNSEA rings, and a lasso baffle fixed to the periphery of the outer TNSEA ring; two adjacent springs form a group, and the two springs in each group have different stiffnesses; one end of each spring is connected to the outer TNSEA ring and the other end is connected to the inner TNSEA ring; each MDOF-HRJ-M-AM mechanism includes a bending bearing bracket, The system comprises a drive wheel mounted inside the flexion-extension bearing bracket via a drive wheel bearing, and a hip assist inner groove plate located outside the flexion-extension bearing bracket and fixedly connected to the portion of the drive wheel extending out of the flexion-extension bearing bracket; the dual-cable force transmission system includes at least two sets of steel wire ropes, each set of steel wire ropes being used to connect a TNSEA and an MDOF-HRJ-M-AM mechanism; one end of each set of steel wire ropes is fixedly connected to the outer ring of the TNSEA and the other end is fixedly connected to the outer edge of the drive wheel, used to transmit the rotation of the outer ring of the TNSEA to the drive wheel to cause the drive wheel to rotate.

[0011] Furthermore, the lumbar support also includes lumbar plates fixed to both sides of the lumbar wearable device; the MDOF-HRJ-M-AM mechanism also includes an auxiliary degree-of-freedom integrated block, a hip assist plate hinged to the auxiliary degree-of-freedom integrated block, an inner hip flexion-extension bearing bracket, and an outward swing-inward adduction main degree-of-freedom connecting block; the hip assist inner groove plate is provided with a long recess extending along the length direction of the hip assist inner groove plate, and a sliding screw is provided to pass through the through hole of the hip assist plate and connect to the long recess of the hip assist inner groove plate, so that the hip assist plate and the hip assist... The relative length of the inner groove plate is adjustable; one end of the auxiliary degree of freedom integrated block is hinged to the hip assist plate through the flexion and extension degree of freedom internal thread stud, and the other end of the auxiliary degree of freedom integrated block is hinged to the thigh wear piece through the outward swing and inward adduction degree of freedom internal thread stud, and the axis of the flexion and extension degree of freedom internal thread stud is perpendicular to the axis of the outward swing and inward adduction degree of freedom internal thread stud; the inner hip flexion and extension bearing bracket is hinged to the outward swing and inward adduction main degree of freedom connecting block through the outward swing and inward adduction main degree of freedom internal thread stud, and the outward swing and inward adduction main degree of freedom connecting block is fixedly connected to the waist plate.

[0012] Furthermore, the stiffness values ​​of the five sets of springs are as follows: the stiffness values ​​of the first set of springs are 4.0702 N / mm and 5.7028 N / mm, the stiffness values ​​of the second set of springs are 5.7028 N / mm and 2.3562 N / mm, the stiffness values ​​of the third set of springs are 1.4234 N / mm and 1.1230 N / mm, the stiffness values ​​of the fourth set of springs are 2.1582 N / mm and 1.9610 N / mm, and the stiffness values ​​of the fifth set of springs are 5.7028 N / mm and 4.0702 N / mm; the first set of springs, the second set of springs, the third set of springs, the fourth set of springs, and the fifth set of springs are arranged sequentially around the inner ring of TNSEA.

[0013] Furthermore, the rotation range of the motor output shaft is -70° to +70°.

[0014] Furthermore, an absolute magnetic encoder is provided to measure the hip joint angle. The absolute magnetic encoder consists of a chip and a magnet. The chip is located on the outside of the inner hip flexion-extension bearing bracket, and the magnet is installed in a groove in the center of the drive wheel.

[0015] Furthermore, an airbag-type force sensor is provided at the hip joint, and is placed in the groove of the thigh wearable component corresponding to the thigh flexor and extensor muscles, respectively, to sense the contraction pressure of the human thigh muscles.

[0016] Furthermore, the double-sleeve force transmission system also includes a sleeve and several sleeve stops; the sleeve is used to contain and protect the steel wire rope, and the sleeve stops are installed on both sides of the bottom of the sleeve stop plate; one end of the sleeve is fixedly connected to the inside of the sleeve stop plate, and the other end of the sleeve is fixed between the outer hip flexion-extension bearing bracket and the inner hip flexion-extension bearing bracket; the sleeve stop plate is fixedly connected to the wall panel and the motor wall panel.

[0017] Furthermore, the connection between the TNSEA outer ring and the steel wire rope is secured with screws; when the human hip joint is in the non-assisted phase, the TNSEA outer ring does not generate strong tension, and the steel wire rope is in a relaxed or slightly tensioned state so that the rotation of the human hip joint is not interfered with by the exoskeleton robot; when in the motor-assisted phase, the TNSEA outer ring deflects and tightens the steel wire rope, transmitting the driving torque to the drive wheel through the dual-set cable force transmission system for assistance.

[0018] This invention also provides a method for constructing the TNSEA stiffness curve of the coupled underactuated hip exoskeleton robot based on TNSEA, wherein the target torque is reduced proportionally, and the analytical basis functions of output torque and equivalent stiffness are constructed by combining a groupless spring with geometric deformation and Hooke's law.

[0019] ;

[0020] ;

[0021] Let be the equivalent rotational stiffness of a single spring group in the TNSEA mechanism. Within the single spring group, the stiffnesses of the two springs are set sequentially as follows: , ; Indicates the first Spring assembly; initial position, spring inclination angle is The spring length is The inner radius is The outer radius is The difference in rotation angle between the inner and outer rings is ;

[0022] The overall equivalent stiffness of the TNSEA mechanism is determined. Next, extreme points within the actual assist demand range are extracted to generate a "moment-angle characteristic point" matrix. Initial spring parameters and preliminary stiffness curves are obtained through least-squares error interpolation. Then, the Pareto multi-objective optimization algorithm is introduced to iteratively optimize the parameters, constructing a piecewise nonlinear stiffness curve containing a low-stiffness, small-angle tolerance domain and a high-stiffness, large-angle assist difference domain. Finally, for the zero-position parasitic torque caused by the asymmetric spring optimization solution, the initial spring installation angle is compensated in reverse to ensure absolute compliance at zero position. A linear combination of multiple standard spring components is used to perform a secondary replacement fitting of the ideal curve, ultimately completing the full design of this nonlinear stiffness system.

[0023] This invention also provides a method for generating the inner circle trajectory of the TNSEA-based coupled underactuated hip exoskeleton robot, wherein the target assist torque is calculated by calling the outer ring RMPC controller. , ,in This is the optimal control input at the current moment; For robustness gain; The actual system error is obtained at the current sampling time k, based on all measurement information up to time k. The nominal tracking error is the system's prediction based on the nominal model at time k.

[0024] Map the target assist torque to the desired steering angle control command of the TNSEA inner ring (24). , ,in The actual rotation angle of the outer ring (30) of TNSEA; The difference in rotation angle between the inner and outer rings of TNSEA;

[0025] If the current features do not meet the assistance conditions, the system enters the follow-up phase and further determines the specific follow-up scenario type based on the aforementioned features. The discriminant is defined as follows: ,in This refers to the angular velocity of the human hip joint. Angular velocity threshold; For thigh muscle strength; Threshold for judging muscle strength; This represents the exoskeleton assist coefficient, where 1 indicates assist and 0 indicates follow-up. The exoskeleton motion scene coefficient is 1, which means that one hip joint is in the extension and braking phase, and 0 means that both hip joints are in the assisted swing phase.

[0026] With the goal of minimizing the disturbance torque on human movement, based on the relationship of the rotation angles of the outer rings (30) of the two-sided TNSEA, the following is achieved:

[0027] For scenarios involving two-sided swinging, a weighted allocation of the outer ring rotation angles on both sides is adopted;

[0028] For single-sided braking scenarios, it directly follows the turning angle of the outer wheel on one side;

[0029] Calculate the expected rotation angle of the inner ring (24) of TNSEA under the servo state. , The outer circle (30) of the TNSEA associated with the right hip; The outer circle (30) of the TNSEA associated with the left hip;

[0030] The desired rotation angle of the TNSEA inner circle (24) generated above adaptively. The tracking error is calculated by comparing the actual measured inner ring rotation angle of the TNSEA, and this error is input into the inner loop PID controller, which ultimately outputs the target preset assist torque; the PID control law is as follows: , , , These are the proportional term coefficient, integral term coefficient, and differential term coefficient, respectively. The TNSEA inner ring (24) corner tracking error is represented by... Obtain, among which This refers to the actual rotation angle of the inner circle 24 of the TNSEA mechanism.

[0031] Beneficial effects: Compared with existing technologies, the present invention has the following advantages:

[0032] (1) The coupling underdrive scheme of a single motor simultaneously assisting both hip joints is adopted, which greatly reduces the number of motors and drivers, and reduces the overall weight and energy consumption.

[0033] (2) The innovative TNSEA mechanism has segmented stiffness characteristics. It maintains low stiffness in the small angle tolerance range to adapt to individual gait differences, and provides high stiffness in the large angle assistance difference range to ensure torque matching of bilateral hip joint flexion and extension, perfectly matching the law of human natural gait.

[0034] (3) Equipped with MDOF-HRJ-M-AM mechanism, it automatically compensates for human-machine joint axis misalignment, is compatible with different individual differences, improves the naturalness of multi-degree-of-freedom movement, and avoids stress concentration of rods through external clamp locking sleeve design, which greatly improves the comfort of wearing, the safety of physical human-machine interaction and the overall reliability of the system.

[0035] (4) A dual-loop control architecture combining “outer loop RMPC and inner loop PID” is adopted, and Kalman filter is used to improve the control accuracy and robustness of the exoskeleton robot, while also improving the smoothness of human-machine interaction. Attached Figure Description

[0036] Figure 1 This is an isometric view of the overall structure of the present invention.

[0037] Figure 2 This is a front view of the overall structure of the present invention.

[0038] Figure 3 This is a rear view of the overall structure of the present invention.

[0039] Figure 4 This is a front view of the overall symmetrical TNSEA mechanism of the present invention.

[0040] Figure 5 This is an assembly isometric drawing of the TNSEA mechanism of the present invention.

[0041] Figure 6 This is an exploded isometric view of the TNSEA mechanism of the present invention.

[0042] Figure 7 This is an exploded isometric view of the MDOF-HRJ-M-AM mechanism of the present invention.

[0043] Figure 8 This is an isometric view of the dual-cable force transmission system of the present invention.

[0044] Figure 9 This is a schematic diagram of the motor drive structure of the present invention.

[0045] Figure 10 This is a schematic diagram of the spring assembly distribution of the present invention.

[0046] Figure 11 This is a diagram showing the relationship between the TNSEA stiffness curves before and after optimization and the positions of relevant optimization variables in the curves.

[0047] Figure 12 This is a logic block diagram for generating the inner loop expected trajectory in this invention.

[0048] The components are named as follows:

[0049] Electrical control box structure I, TNSEA mechanism II, MDOF-HRJ-M-AM mechanism III, double-sleeve force transmission system IV, waist support piece 1, thigh support piece 2, wall panel 3, encoder mounting plate 4, absolute magnetic encoder 5, air pressure sensor 6, motor mounting plate 7, compensation plate 8, waist plate 9, motor 10, lasso stop block 11, motor wall panel 12, front wall panel 121, lasso stop plate 13, absolute magnetic encoder 14, encoder mounting plate 15, electrical control box cover 16, battery 17, electrical control box 18, waist plate 19, external swing and internal retraction main degree of freedom internal thread stud 20, lasso 21, motor connecting flange 22. Outer ring cage bearing; 23. TNSEA inner ring; 24. Spring pin; 25. Inner ring spindle; 26. Bearing; 27. Outer ring cage; 28. Spring; 29. ​​TNSEA outer ring; 30. Wire rope clamping screw; 31. Inner ring flat key; 32. Hip assist inner groove plate; 33. Outer hip flexion and extension bearing bracket; 34. Bearing; 35. Drive wheel; 36. Bearing; 37. Inner hip flexion and extension bearing bracket; 38. Outward swing and inward retraction main degree of freedom connecting block; 39. Sliding screw; 40. Hip assist plate; 41. Nut; 42. Auxiliary degree of freedom integrated block; 43. Flexion and extension degree of freedom internal thread stud; 44. Outward swing and inward retraction degree of freedom internal thread stud; 45. Detailed Implementation

[0050] The specific embodiments of the present invention will be described in detail with reference to the accompanying drawings.

[0051] In this invention, "left" and "right" refer to the left and right parts of the structure when worn by the wearer.

[0052] like Figures 1 to 3 As shown, this invention is a coupled underactuated hip exoskeleton robot based on TNSEA, comprising an electrical control box structure I, a TNSEA mechanism II, an MDOF-HRJ-M-AM mechanism III, a dual-cable force transmission system IV, a waist wearable component 1, a thigh wearable component 2, and a waist support. In this invention, "TNSEA" is a bidirectional nonlinear series elastic actuator, and "MDOF-HRJ-M-AM mechanism" is a multi-degree-of-freedom human-machine joint misalignment adaptation mechanism.

[0053] The waist support includes a motor mounting plate 7, a motor 10 mounted in the middle of the motor mounting plate 7, a motor wall plate 12 fixed to the motor mounting plate 7 and located in front of the motor mounting plate 7, and a front wall plate 121 fixed to the motor mounting plate 7 and located in front of the motor wall plate 12. The waist wear piece 1 is connected to the waist plate 9 groove by screws and can adjust the left and right waist positions. The thigh wear piece 2 is connected to the auxiliary degree of freedom integrated block 43 by an external swing and internal retraction degree of freedom internal thread stud 45. The electrical control box structure I of the present invention is connected to the lasso baffle 13 by screws. The electrical control box structure I is formed by the connection of the electrical control box cover 16 and the electrical control box 18 to form a receiving space, which is mainly used to accommodate the inverter of the control motherboard, battery 17 and sensors such as the air pressure sensor 6. The control motherboard, battery and some sensor inverters are installed in the electrical control box 18 by screws or interference fit.

[0054] like Figures 4 to 6 The diagram shows the TNSEA mechanism of the present invention. The TNSEA mechanism II includes an inner ring spindle 26 and two TNSEAs coaxially mounted on the inner ring spindle 26. The two TNSEAs are arranged coaxially, one in front of the other, as shown below. Figure 4 As shown. Two TNSEAs are located between the front wall plate 121 and the motor wall plate 12. The two ends of the inner ring spindle 26 are respectively connected to the front wall plate 121 and the motor wall plate 12 through the wall plate bearings 27. The inner ring spindle 26 is coaxially connected to the output shaft of the motor 1. Each TNSEA includes an outer ring 30, an inner ring 24 coaxially fixed with the inner ring spindle 26, five sets of springs 29 located between the outer ring 30 and the inner ring (24), and a lasso baffle 13 fixed around the outer ring 30.

[0055] The motor connecting flange 22 is directly connected to the motor 10, and the motor connecting flange 22 is coaxially connected to the main shaft 26, enabling the motor output torque to be transmitted to the main shaft. Simultaneously, the motor is fixedly connected to the motor mounting plate 7 to maintain motor stability. The motor mounting plate 7 is then connected to the compensation plate 8 to achieve the connection between the back structure and the waist structure. The middle section of the inner ring main shaft 26 forms a torque transmission pair with the TNSEA inner ring 24 via the inner ring key 32. The outer ring cage bearing 23 is assembled between the outer ring cage 28 and the inner ring main shaft 26. The core function of the bearing 27 is to support the inner ring main shaft 26 and position it on the motor wall plate 12 to reduce the relative friction between the main shaft and the wall plate during rotation. Figure 9 As shown. The outer ring 30 of the TNSEA is equipped with wire rope clamping screws 31 for securing the wire rope (not shown) inside the sling. Two connection points of the single spring 29 on the inner ring 24 of the TNSEA are distributed at a 36° angle around the center of the inner ring to avoid motion interference, and are respectively arranged in countersunk grooves machined on both sides of the inner ring 24 of the TNSEA. The spring 29 is pre-tensioned and positioned by spring pins 25. (As shown...) Figure 4 As shown, the two TNSEA mechanisms are assembled in a central mirror symmetry manner with the cross section at the axial step of the inner ring spindle 26 as the symmetry reference plane. The inner rings of the two TNSEA mechanisms are connected to the same inner ring spindle through a flat key.

[0056] The most important aspect of the TNSEA mechanism is the construction of its stiffness curve. Firstly, using the OpenSim human motion simulation platform, the mirror symmetry characteristics and motion differences of the two hip joints during the gait cycle are quantified. Key torque and angle feature points are extracted, resulting in two core design indicators: a "20° angle difference" and a "5Nm torque difference." The "20° angle difference" provides space for asynchronous movement of the two legs, eliminating the motion constraints and interference caused by rigid synchronous drive from a single motor. The "5Nm torque difference" allows for uneven force distribution between the left and right legs based on their actual force requirements at different gait stages. Secondly, based on lightweight requirements, the required output torque of the motor is reduced by 20%, and five sets of springs are used in conjunction with geometric deformation and Hooke's law to construct analytical basis functions for the output torque and equivalent stiffness. Equation (1.1) represents the equivalent rotational stiffness of a single set of springs in the TNSEA mechanism. Within a single spring group, the stiffnesses of the two springs are set sequentially as follows: , ; Indicates the first Spring assembly; initial position, spring inclination angle is The spring length is The inner radius is The outer radius is The difference in rotation angle between the inner and outer rings is Equation (1.2) represents the total equivalent stiffness of the TNSEA mechanism. Secondly, extreme points within the actual assist demand range are extracted to generate a "moment-angle feature point" matrix. Initial spring parameters and preliminary stiffness curves are obtained through least-squares error interpolation. Next, the Pareto multi-objective optimization algorithm is introduced to iteratively optimize the parameters, constructing a piecewise nonlinear stiffness curve that includes a low-stiffness, small-angle tolerance domain (±10°) and a high-stiffness, large-angle assist difference domain, thereby balancing motion flexibility and differentiated assist stability. For example... Figure 11 As shown, the TNSEA stiffness curves before and after optimization and the positional relationship of related optimization variables in the curves are shown. The parameters of the spring can be designed through the optimized stiffness curves. The blue solid line in sub-figure (1) is the theoretical total stiffness fitting curve of the TNSEA mechanism after optimization by the Pareto multi-objective algorithm. Finally, for the zero-position parasitic torque caused by the optimization solution of the asymmetric spring, the initial installation angle of the spring is compensated in reverse to ensure the absolute compliance of the zero position. The ideal curve is then fitted by a linear combination of multiple standard spring parts, and the complete design of the nonlinear stiffness system is finally completed.

[0057]

[0058]

[0059] Please combine Figure 1 , Figure 3 , Figure 7 and Figure 8 As shown, each MDOF-HRJ-M-AM mechanism (Ⅲ) includes a flexion-extension bearing bracket, a drive wheel 36 mounted inside the flexion-extension bearing bracket via a drive wheel bearing 35, and a hip assist inner groove plate 33 located outside the flexion-extension bearing bracket and fixedly connected to the portion of the drive wheel extending out of the flexion-extension bearing bracket. The dual-cable force transmission system (Ⅳ) includes at least two sets of steel wire ropes (not shown), each set of steel wire ropes being used to connect one TNSEA and one MDOF-HRJ-M-AM mechanism Ⅲ; one end of each set of steel wire ropes is fixedly connected to the outer ring 30 of the TNSEA and the other end is fixedly connected to the outer edge of the drive wheel 36, so as to transmit the rotation of the outer ring 30 of the TNSEA to the drive wheel 36 to rotate the drive wheel 36.

[0060] Specifically, such as Figure 7 As shown, in the MDOF-HRJ-M-AM mechanism, the auxiliary degree of freedom integrated block 43 is connected to the hip assist plate 41 through the flexion and extension degree of freedom internal threaded stud 44. The sliding screw 40 passes through the through hole of the hip assist plate 41 and is connected to the long recess of the hip assist inner groove plate 33, allowing it to slide and adjust in the groove, so that the position and length of the left and right hip assist plates can be adjusted to accommodate users with different thigh lengths.

[0061] One end of the auxiliary degree-of-freedom integrated block 43 is connected to the hip assist plate 41 via a flexion-extension degree-of-freedom internal threaded stud 44. Rotation around the stud allows for angle adjustment in the flexion-extension degree-of-freedom direction. The other end is connected to the thigh wear structure via an outward swing / adduction degree-of-freedom internal threaded stud 45. Rotation around the stud allows for angle adjustment in the outward swing / adduction degree-of-freedom direction. The inner hip flexion-extension bearing bracket 38 is fixed to the outward swing / adduction main degree-of-freedom connecting block 39 via an outward swing / adduction main degree-of-freedom internal threaded stud 20 to achieve outward swing / adduction degree-of-freedom function. Simultaneously, it is connected to the outer hip flexion-extension bearing bracket 34 via screws, providing a stable rotational support foundation for the hip joint flexion-extension movement of the exoskeleton. The outward swing / adduction main degree-of-freedom connecting block 39 is fixed to the waist plate 9 via screws, connecting the lower limbs to the waist wear structure. The MDOF-HRJ-M-AM mechanism has left and right sides corresponding to the two hip joints of the human body.

[0062] like Figure 8 The diagram shows the double-sling force transmission system mechanism of the present invention. One end of each of the two steel wire ropes is fixed to the outer ring 30 of the TNSEA via a steel wire rope clamping screw 31, and the other end is also connected to the drive wheel 36 via a clamping screw. One end of the lasso 21 is fixed to the inside of the lasso stop block 11 via a locking screw, and the other end is also fixed to the cavity formed by the outer hip flexion-extension bearing bracket 34 and the inner hip flexion-extension bearing bracket 38 via a locking screw. Meanwhile, the lasso stop block 11 is placed in a guide groove and pre-tightened by connecting it to the lasso baffle 13 via a pre-tightening screw. By adjusting the screwing length of the pre-tightening screw, the spatial position of the lasso stop block 11 in the guide groove can be changed. The lasso baffle 13 is fixed to the wall plate 3 and the motor wall plate 12 via a screw. The wire rope inlet and outlet of the lasso stop 11 and lasso baffle 13 are tangent to the inner ring 24 of the TNSEA. Similarly, the drive wheel 36 is also tangent to the wire rope inlet and outlet formed by the outer hip flexion-extension bearing bracket 34 and the inner hip flexion-extension bearing bracket 38. By accurately positioning the lasso inlet and outlet, the deflection control accuracy of the lasso is ensured. The double lasso force transmission system mechanism has two sets, left and right, corresponding to the left and right hip joints. The two lasso baffles are fixed in place with the positions of the two TNSEA outer rings 30, and the two drive wheels are also fixed in place with the positions of the hip flexion-extension bearing brackets on both sides.

[0063] The sensors of this invention include three absolute magnetic encoders and a barometric pressure sensor. Two absolute magnetic encoders 14 are respectively mounted on the left and right inner hip flexion-extension bearing brackets 38. The encoder magnets are embedded in a dedicated groove in the drive wheel 36 (i.e., the rotation center of the hip joint shaft end) using a transition fit process. The chip is fastened between the left and right encoder mounting plates 15 through threaded holes to form an assembly. This assembly is then threadedly connected to the left and right inner hip flexion-extension bearing brackets 38 for fixation, preventing loosening during movement. Another absolute magnetic encoder 5 is fixed to the back mechanism. Similarly, the magnet is embedded in a dedicated groove in the rotation center of the inner ring main shaft 26. The chip is fastened between the encoder mounting plates 4 through threaded holes to form an assembly. This assembly is then threadedly connected to the wall plate 3 coaxial with the inner ring main shaft 26. The barometric pressure sensor 6 is mounted in the switch hole of the electrical control box 18 via an interference fit. Meanwhile, in the experiment, a self-made airbag force sensor was assembled on the mounting groove of the thigh wearable component. The airbag was glued and fixed in the groove with double-sided adhesive to limit relative displacement and ensure a tight fit.

[0064] like Figure 12 The diagram shown is a logic block diagram for generating the inner loop desired trajectory according to the present invention. First, the system acquires real-time angular velocity data of the human hip joint and thigh muscle force data using an encoder and a self-made airbag sensor. Based on preset angular velocity and muscle force thresholds, it identifies and determines the gait phase and follow-up scene. If the current features meet the assistance determination conditions, the system determines to enter the assistance stage. At this time, it calls the outer loop RMPC controller to calculate the target assistance torque. The target assist torque is calculated from the actual control law of RMPC in equation (1.9), where This is the optimal control input at the current moment; For robustness gain; The actual system error is obtained at the current sampling time k, based on all measurement information up to time k. The nominal tracking error is predicted by the system based on the nominal model at time k; then, the torque-rotation inverse function of TNSEA is used. As shown in equation (1.5), the target torque is mapped to the desired steering angle control command of the inner ring 24 of TNSEA. ,in The actual rotation angle of the TNSEA outer ring 30 is measured by the encoder. The difference in rotation angle between the inner and outer rings of the TNSEA mechanism; the torque-rotation angle inverse function of the TNSEA. Depend on Figure 11 The torque-rotation angle curve is obtained from the above. If the current feature does not meet the assist condition, the system enters the follow-up stage and further determines the specific follow-up scenario type based on the above features. The discriminant is defined as shown in equation (1.6), where This refers to the angular velocity of the human hip joint. Angular velocity threshold; For thigh muscle strength; Threshold for judging muscle strength; This represents the exoskeleton assist coefficient, where 1 indicates assist and 0 indicates follow-up. Here, represents the exoskeleton homing scenario coefficient. 1 indicates homing scenario 1, where one hip joint is in the extension braking phase, and 0 indicates homing scenario 2, where both hip joints are in the assisted swing phase. With the goal of minimizing the interference torque on human movement, based on the relationship of the outer 30° rotation angle of both TNSEA rings (e.g., directly following the outer 30° rotation angle for the single-sided braking scenario, or using a weighted allocation of the outer 30° rotation angles for the double-sided swing scenario), as shown in equations (1.7) and (1.8), the desired rotation angle of the motor corresponding to the inner 24° of the TNSEA ring in the homing state is calculated. Equation (1.8) is the design formula for the desired hip joint trajectory in scenario 1. For the TNSEA outer ring with a 30° rotation angle related to the right hip, such as when the left leg is in the braking phase of upright turning and extension, and the right leg is in the swing-assisted phase, this design enables... The assist side has no interfering torque, while the braking side bears all the interfering torque, which conforms to the biomechanical characteristics of human gait; Equation (1.7) is the design formula for the expected trajectory of the hip joint in scenario 2. For the TNSEA outer ring 30° angle related to the left hip, the formula appears to be an equal distribution of the outer ring angles on both sides, but the actual distribution of the disturbance torque is not equal. Because the stiffness characteristics of the TNSEA mechanism are bidirectionally nonlinear, the side with a larger stiffness coefficient will naturally bear a larger disturbance torque. This distribution method is adapted to the real-time pose stiffness characteristics of both hip joints, ensuring that the overall disturbance torque is minimized. Finally, the system compares the adaptively generated TNSEA inner ring 24° desired angle with the actual measured inner ring angle to obtain the tracking error, and inputs this error into the inner loop PID controller, ultimately achieving the goal of accurately outputting the preset assist torque. The PID control law is shown in equation (1.3). , , These are the proportional term coefficient, integral term coefficient, and differential term coefficient, respectively. This represents the tracking error of the TNSEA inner ring 24-degree angle; Equation (1.4) is... The calculation formula, where This is the actual rotation angle of TNSEA's inner ring 24.

[0065]

[0066]

[0067]

[0068]

[0069]

[0070]

[0071]

[0072] The working principles of the TNSEA mechanism, MDOF-HRJ-M-AM mechanism, and double-set cable force transmission system mechanism of the present invention are as follows:

[0073] The TNSEA mechanism is a flexible link between the motor and the double-sling transmission system. Its principle is to transmit and buffer torque through the deformation of spring 29. When the power of motor 10 is transmitted to the inner ring 24 of the TNSEA, a relative rotational angle is created between the inner ring 24 and the outer ring 30 of the TNSEA. This relative rotation stretches spring 29, and the tangential component of the tension force drives the outer ring 30 of the TNSEA to output torque. Figure 10 As shown, the TNSEA mechanism achieves nonlinear stiffness output by asymmetrically configuring five sets of springs with different stiffnesses. The first set of springs is 291, with stiffness values ​​of 4.0702 N / mm and 5.7028 N / mm; the second set of springs is 292, with stiffness values ​​of 5.7028 N / mm and 2.3562 N / mm; the third set of springs is 293, with stiffness values ​​of 1.4234 N / mm and 1.1230 N / mm; the fourth set of springs is 294, with stiffness values ​​of 2.1582 N / mm and 1.9610 N / mm; and the fifth set of springs is 295, with stiffness values ​​of 5.7028 N / mm and 4.0702 N / mm.

[0074] In the early stages of walking, when the relative angle of the two hip joints changes little and is in a fine-tuning phase, the TNSEA mechanism is low-stiffness, allowing the two hip joints to perform small-amplitude, different movements without interfering with each other. When the human body is preparing to take a stride, it is in a large-angle force exertion phase, and the TNSEA mechanism is high-stiffness. The torque of the motor 10 can be transmitted to the outer ring 30 of the TNSEA through the spring assembly, and then to the steel cable, which is then transmitted to the hip joint through the double-sleeve force transmission system to provide assistance. The output shaft of the motor 10 is coaxially connected to the inner ring main shaft 26, and its output shaft reciprocates and rotates within a limited, small angle range. Specifically, the rotation angle range of the output shaft of the motor 10 is set to -70° to +70°. The angle range is determined by the biomechanical range of motion of the human hip joint and the target rotation angle of the motor (i.e., the desired rotation angle of the inner ring 24 of the TNSEA) according to formula (1.5).

[0075] The principle of the MDOF-HRJ-M-AM mechanism is to adaptively resolve and compensate for the translational and rotational misalignment between the exoskeleton mechanical structure and the actual rotation center of the human hip joint during dynamic walking by introducing passive redundant degrees of freedom. During wear and walking, the human-machine joint center is prone to shift. Therefore, this mechanism is designed with a sliding guide pair consisting of a hip-assist inner groove plate 33 and a hip-assist plate 41. During exoskeleton flexion and extension, the hip-assist plate 41 can slide freely along the groove without obstruction. This linear translational redundant degree of freedom passively compensates for the link length deviation caused by misalignment of the human-machine joint. Simultaneously, the mechanism connects two revolute joints (i.e., the internal threaded stud 44 for flexion and extension degrees of freedom and the internal threaded stud 45 for outward and inward swing degrees of freedom) through an auxiliary degree of freedom integrated block 43. During human movement, these two revolute joints act as rotational redundant degrees of freedom, allowing the wearable components to undergo slight passive deflections in different rotational planes. In general, the flexion-extension degree of freedom has an angle adjustment margin of -10 to 10° and a length adjustment margin of -80 to 80 mm; in the swing / adduction degree of freedom, the angle adjustment margin is -10 to 10° and the length adjustment margin is -10 to 10 mm. Through the passive coordination of the above redundant degrees of freedom, the mechanism can eliminate human-machine motion interference in real time and adaptively, greatly reducing the constraint force and pulling sensation experienced by the user during movement, and is compatible with anatomical alignment deviations of users of different body types.

[0076] The principle of the dual-cable force transmission system is to use two steel wire ropes to form a pull-pull transmission structure, transmitting the torque of the motor 10 to the hip joint over a long distance with low resistance. One end of each steel wire rope is fixed to the inner ring 24 of the TNSEA, and the other end is connected to the drive wheel 36. During movement, one steel wire rope is constantly taut to transmit tension, which in turn drives the hip assist inner groove plate 33 to rotate to provide auxiliary assistance. A lasso 21 is fitted around the outside of the steel wire rope. When the steel wire rope is stretched, the lasso restricts its movement trajectory, preventing the steel wire rope from cutting and wearing against the holes. At the same time, the lasso stop 11 and the preload screw change the position of the lasso stop 11 by rotating a long stroke, thereby adjusting the spatial curvature of the lasso and achieving precise tightening and optimization of the steel wire rope.

[0077] The present invention provides a coupled underactuated hip exoskeleton robot based on TNSEA, which is worn on the human hip joint. It uses a single drive motor 10 on the back as the drive source, and distributes the torque through the inner ring main shaft 26 of the TNSEA mechanism to drive the outer rings 30 of TNSEA on both sides respectively. Then, through the double-sling steel wire rope group fixed on the outer rings 30 of TNSEA, the driving force is transmitted across the joint to the hip joint structure of the exoskeleton via the lasso 21, which drives the drive wheel 36 at the hip joint structure to rotate. This causes the thigh brace of the MDOF-HRJ-M-AM mechanism connected to the drive wheel 36 to drive the thigh to rotate around the human hip joint.

[0078] This design is based on the mirror-symmetric movement characteristics of the two hip joints during normal walking. When one thigh flexes forward, the other inevitably extends backward. Through a special double-cable-and-pull cross-connection wiring system, it ensures that only a single motor is needed to provide opposite-direction assist outputs to both hip joints simultaneously. The five sets of tension coil springs in the TNSEA mechanism ensure that when the gait is being finely adjusted or there are small differences in the movement of the two legs, the stiffness generated by spring deformation is extremely low. The inner and outer rings of the TNSEA mechanism exhibit a low-coupling tolerance, and the slight autonomous rotation of the human hip joint is not interfered with by the rigid drive of the motor. When the hip joint is in a large-angle assist phase, the relative angle between the inner and outer rings of the TNSEA increases, the springs are stretched sharply, and the stiffness increases dramatically. This allows the motor's assist to be efficiently transmitted to the hip joint through the high-stiffness springs and steel cables for precise assistance. As the single-step movement is about to end and the legs are brought together, the relative angle between the inner and outer rings of the TNSEA decreases, the stretched spring rebounds and releases energy, assisting the legs in decelerating. The stiffness of the TNSEA mechanism returns to the low-coupling tolerance state at the beginning, and the exoskeleton enters the next half-gait cycle, providing the same compliant assistance to the other hip joint.

[0079] This design, based on the human gait hip joint angle cycle, selects approximately one-fifth of the gait cycle length between the 0-20% and 50-70% phases (producing a maximum angle difference of approximately 20°) as the assist phase for the exoskeleton drive motor. Its maximum designed assist effect is approximately 20% (about 5 N·m) of the actual torque of a normal adult hip joint. Simultaneously, considering the characteristics of the TNSEA mechanism, this design selects a small-angle tolerance phase for the exoskeleton, corresponding to a small torque input (approximately ±1.4 N·m, or about 3% of the peak torque of a normal adult hip joint) and a movement angle difference boundary approaching 20° (±10°), to ensure flexibility and adaptability of movement.

[0080] For those skilled in the art, various other corresponding changes and modifications can be made based on the technical solutions and concepts described above, and all such changes and modifications should fall within the protection scope of the claims of this invention.

Claims

1. A coupled underactuated hip exoskeleton robot based on TNSEA, wherein the TNSEA is a bidirectional nonlinear series elastic actuator, characterized in that: It includes a lumbar support located at the waist, a TNSEA mechanism (II) connected to the lumbar support, a waist wearable piece (1) connected to the lumbar support and located in front of the TNSEA mechanism (II), an MDOF-HRJ-M-AM mechanism (III) located on both sides of the TNSEA mechanism (II), a double-set cable force transmission system (IV), and a thigh wearable piece (2) connected to the MDOF-HRJ-M-AM mechanism (III); the MDOF-HRJ-M-AM mechanism is a multi-degree-of-freedom human-machine joint misalignment adaptation mechanism; The waist support includes a motor mounting plate (7), a motor (10) installed in the middle of the motor mounting plate (7), a motor wall panel (12) fixed to the motor mounting plate (7) and located in front of the motor mounting plate (7), and a front wall panel (121) fixed to the motor mounting plate (7) and located in front of the motor wall panel (12). The TNSEA mechanism (II) includes an inner ring main shaft (26) and two TNSEAs coaxially mounted on the inner ring main shaft (26). The two TNSEAs are located between the front wall plate (121) and the motor wall plate (12). The two ends of the inner ring main shaft (26) are respectively connected to the front wall plate (121) and the motor wall plate (12) through wall plate bearings (27). The inner ring main shaft (26) is coaxially connected to the output shaft of the motor (10). Each TNSEA includes an outer ring (30), an inner ring (24) coaxially fixed with the inner ring spindle (26), five sets of springs (29) located between the outer ring (30) and the inner ring (24), and a lasso baffle (13) fixed around the outer ring (30); two adjacent springs form a group, and the two springs in each group have different stiffnesses; one end of each spring is connected to the outer ring (30) and the other end is connected to the inner ring (24); Each MDOF-HRJ-M-AM mechanism (Ⅲ) includes a flexion-extension bearing bracket, a drive wheel (36) mounted inside the flexion-extension bearing bracket via a drive wheel bearing (35), and a hip assist inner groove plate (33) located outside the flexion-extension bearing bracket and fixedly connected to the portion of the drive wheel extending out of the flexion-extension bearing bracket. The dual-set cable force transmission system (Ⅳ) includes at least two sets of steel wire ropes, each set of steel wire ropes is used to connect a TNSEA and an MDOF-HRJ-M-AM mechanism (Ⅲ); one end of each set of steel wire ropes is fixedly connected to the outer ring (30) of the TNSEA and the other end is fixedly connected to the outer edge of the drive wheel (36) to transmit the rotation of the outer ring (30) of the TNSEA to the drive wheel (36) to make the drive wheel (36) rotate.

2. The coupled underactuated hip exoskeleton robot based on TNSEA according to claim 1, characterized in that: The lumbar support also includes a lumbar plate (9) fixed to both sides of the lumbar wear piece (1); the MDOF-HRJ-M-AM mechanism (Ⅲ) also includes an auxiliary degree of freedom integrated block (43), a hip assist plate (41) hinged to the auxiliary degree of freedom integrated block (43), an inner hip flexion and extension bearing bracket (38), and an outward swing and inward adduction main degree of freedom connecting block (39); the hip assist inner groove plate (33) is provided with a long recess extending along the length direction of the hip assist inner groove plate (33), and a sliding screw (40) is provided to pass through the through hole of the hip assist plate (41) and connect to the long recess of the hip assist inner groove plate (33), so that the relative length of the hip assist plate (41) and the hip assist inner groove plate (33) is adjustable; One end of the auxiliary degree of freedom integrated block (43) is hinged to the hip assist plate (41) through the flexion and extension degree of freedom internal thread stud (44), and the other end of the auxiliary degree of freedom integrated block (43) is hinged to the thigh wear piece (2) through the outward swing and inward adduction degree of freedom internal thread stud (45), and the axis of the flexion and extension degree of freedom internal thread stud (44) is perpendicular to the axis of the outward swing and inward adduction degree of freedom internal thread stud (45); The inner hip flexion and extension bearing bracket (38) is hinged to the outer swing and inner retraction main degree of freedom connecting block (39) through the outer swing and inner retraction main degree of freedom internal thread stud (20), and the outer swing and inner retraction main degree of freedom connecting block (39) is fixedly connected to the waist plate (9).

3. The coupled underactuated hip exoskeleton robot based on TNSEA according to claim 1, characterized in that: The stiffness values ​​of the five groups of springs (29) are as follows: the stiffness values ​​of the first group of springs (291) are 4.0702 N / mm and 5.7028 N / mm, the stiffness values ​​of the second group of springs (292) are 5.7028 N / mm and 2.3562 N / mm, the stiffness values ​​of the third group of springs (293) are 1.4234 N / mm and 1.1230 N / mm, the stiffness values ​​of the fourth group of springs (294) are 2.1582 N / mm and 1.9610 N / mm, and the stiffness values ​​of the fifth group of springs (295) are 5.7028 N / mm and 4.0702 N / mm. The first group of springs (291), the second group of springs (292), the third group of springs (293), the fourth group of springs (294), and the fifth group of springs (295) are arranged sequentially around the inner ring (24) of TNSEA.

4. The coupled underactuated hip exoskeleton robot based on TNSEA according to claim 1, characterized in that: The rotation range of the output shaft of the motor (10) is -70° to +70°.

5. The coupled underactuated hip exoskeleton robot based on TNSEA according to claim 1, characterized in that: An absolute magnetic encoder (5) is also provided to measure the hip joint angle. The absolute magnetic encoder (5) consists of a chip and a magnet. The chip is located on the outside of the inner hip flexion and extension bearing bracket (38), and the magnet is installed in the groove in the center of the drive wheel (36).

6. The coupled underactuated hip exoskeleton robot based on TNSEA according to claim 1, characterized in that: An airbag-type force sensor (46) is provided at the hip joint and is placed in the groove of the thigh wearable component corresponding to the thigh flexor and extensor muscles, respectively, to sense the contraction pressure of the human thigh muscles.

7. The coupled underactuated hip exoskeleton robot based on TNSEA according to claim 1, characterized in that: The double-sling force transmission system (Ⅳ) also includes a sling (21) and several sling blocks (11); the sling (21) is used to contain and protect the wire rope, and the sling blocks (11) are installed on both sides of the bottom of the sling baffle (13); one end of the sling (21) is fixed inside the sling block (11), and the other end of the sling (21) is fixed between the outer hip flexion and extension bearing bracket (34) and the inner hip flexion and extension bearing bracket (38); the sling baffle (13) is fixed to the wall panel (3) and the motor wall panel (12).

8. The coupled underactuated hip exoskeleton robot based on TNSEA according to claim 7, characterized in that: The TNSEA outer ring (30) is tightened with screws at the connection with the wire rope. When the human hip joint is in the non-assisted phase, the TNSEA outer ring (30) does not generate strong tension, and the wire rope is in a relaxed or slightly tense state so that the human hip joint rotation is not interfered with by the exoskeleton robot. When in the motor-assisted phase, the TNSEA outer ring (30) deflects and tightens the wire rope, and transmits the driving torque to the drive wheel (36) through the double cable force transmission system for assistance.

9. A method for constructing the TNSEA stiffness curve of a coupled underactuated hip exoskeleton robot based on TNSEA according to claim 1, characterized in that, The target torque is reduced proportionally, and analytical basis functions for the output torque and equivalent stiffness are constructed using a combination of non-grouped springs, geometric deformation, and Hooke's law. ； ； Let be the equivalent rotational stiffness of a single spring group in the TNSEA mechanism. Within the single spring group, the stiffnesses of the two springs are set sequentially as follows: , ; Indicates the first Spring assembly; initial position, spring inclination angle is The spring length is The inner radius is The outer radius is The difference in rotation angle between the inner and outer rings is ; The overall equivalent stiffness of the TNSEA mechanism is determined. Next, extreme points within the actual assist demand range are extracted to generate a "moment-angle characteristic point" matrix. Initial spring parameters and preliminary stiffness curves are obtained through least-squares error interpolation. Then, the Pareto multi-objective optimization algorithm is introduced to iteratively optimize the parameters, constructing a piecewise nonlinear stiffness curve containing a low-stiffness, small-angle tolerance domain and a high-stiffness, large-angle assist difference domain. Finally, for the zero-position parasitic torque caused by the asymmetric spring optimization solution, the initial spring installation angle is compensated in reverse to ensure absolute compliance at zero position. A linear combination of multiple standard spring components is used to perform a secondary replacement fitting of the ideal curve, ultimately completing the full design of this nonlinear stiffness system.

10. A method for generating the inner circle trajectory of a coupled underactuated hip exoskeleton robot based on TNSEA according to claim 1, characterized in that, The target assist torque is calculated by calling the outer loop RMPC controller. , ,in This is the optimal control input at the current moment; For robustness gain; The actual system error is obtained at the current sampling time k, based on all measurement information up to time k. The nominal tracking error is the system's prediction based on the nominal model at time k. Map the target assist torque to the desired steering angle control command of the TNSEA inner ring (24). , ,in The actual rotation angle of the outer ring (30) of TNSEA; The difference in rotation angle between the inner and outer rings of TNSEA; If the current features do not meet the assistance conditions, the system enters the follow-up phase and further determines the specific follow-up scenario type based on the aforementioned features. The discriminant is defined as follows: ,in The angular velocity of the human hip joint; Angular velocity threshold; For thigh muscle strength; Threshold for judging muscle strength; This represents the exoskeleton assist coefficient, where 1 indicates assist and 0 indicates follow-up. The exoskeleton motion scene coefficient is 1, which means that one hip joint is in the extension and braking phase, and 0 means that both hip joints are in the assisted swing phase. With the goal of minimizing the disturbance torque on human movement, based on the relationship of the rotation angles of the outer rings (30) of the two-sided TNSEA, the following is achieved: For scenarios involving two-sided swinging, a weighted allocation of the outer ring rotation angles on both sides is adopted; For single-sided braking scenarios, it directly follows the turning angle of the outer wheel on one side; Calculate the expected rotation angle of the inner ring (24) of TNSEA under the servo state. , The outer circle (30) of the TNSEA associated with the right hip; The outer circle (30) of the TNSEA associated with the left hip; The desired rotation angle of the TNSEA inner circle (24) generated above adaptively. The tracking error is calculated by comparing the actual measured inner ring rotation angle of the TNSEA, and this error is input into the inner loop PID controller, which ultimately outputs the target preset assist torque; the PID control law is as follows. , , , These are the proportional term coefficient, integral term coefficient, and differential term coefficient, respectively. The TNSEA inner ring (24) corner tracking error is represented by... Obtain, among which The actual rotation angle of the inner circle (24) of the TNSEA mechanism.

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