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CN-121973154-A - Upper limb exoskeleton robot with gravity compensation function, control method and system

CN121973154ACN 121973154 ACN121973154 ACN 121973154ACN-121973154-A

Abstract

The invention provides an upper limb exoskeleton robot with gravity compensation, a control method and a system, wherein the upper limb exoskeleton robot comprises an upper limb exoskeleton mechanism and a gravity balancing device, the gravity balancing device is integrated in the upper limb exoskeleton mechanism and comprises a multi-link mechanism and an elastic piece, and parameters of the rod length, a hinge point position, an elastic coefficient and an initial length of the multi-link mechanism of the gravity balancing device are optimized through an algorithm to provide self-adaptive gravity compensation in a working space of the upper limb exoskeleton mechanism. The gravity balance device optimized by the algorithm reduces the energy consumption of the motor, improves the gravity compensation precision and the system flexibility, and solves the problems that the contact force sensing precision is insufficient and the human-computer interaction process presents a feeling of hardness and cannot meet the requirements of rehabilitation training on the flexibility due to feedback adjustment only by the current loop estimated moment.

Inventors

  • Xiao feiyun
  • HUANG CHENG

Assignees

  • 合肥工业大学

Dates

Publication Date
20260505
Application Date
20260209

Claims (10)

  1. 1. An upper extremity exoskeleton robot with gravity compensation, comprising: The upper limb exoskeleton mechanism comprises a back plate and a shoulder joint connecting rod, wherein the shoulder joint connecting rod is in rotary connection with the back plate through a first shoulder joint module, and the first shoulder joint module is configured to control the swing of the shoulder joint connecting rod; A gravity balancing device configured to provide adaptive gravity compensation within a working space of the upper limb exoskeleton mechanism, the gravity balancing device comprising a first link, a second link, and a tension spring; Two ends of the first connecting rod are respectively hinged with the first shoulder joint module to form a hinge point A, and one end of the second connecting rod is hinged with the second shoulder joint module to form a hinge point B; The other end of the second connecting rod and the shoulder joint connecting rod form a hinge point C; the hinge center of the first shoulder joint module is D so as to form a four-bar linkage ABCD; Two ends of the tension spring respectively form a hinge point E with the first connecting rod and a hinge point F with the shoulder joint connecting rod.
  2. 2. The upper extremity exoskeleton robot of claim 1 wherein said upper extremity exoskeleton mechanism further comprises a second shoulder joint module, a big arm, an elbow joint module and a small arm connected in sequence, and wherein said first shoulder joint module, said second shoulder joint module and said elbow joint module provide pivoting for said shoulder joint links, said big arm and said small arm, respectively, and wherein said gravity balancing device is integrated in said first shoulder joint module to provide adaptive gravity compensation within a working space of said first shoulder joint module.
  3. 3. The upper extremity exoskeleton robot of claim 2 wherein said upper extremity exoskeleton mechanism comprises three degrees of freedom, shoulder abduction and adduction, swing of said large arm and swing of said small arm, respectively, said gravity balancing device loading the weight of said first shoulder module traction shoulder abduction and adduction.
  4. 4. The upper extremity exoskeleton robot of claim 1 wherein the distance between the hinge point EF at both ends of the extension spring and the hinge point a on the shoulder module is greater than the distance between the hinge point BC on the first and second links and the hinge point a on the shoulder module.
  5. 5. The upper extremity exoskeleton robot of claim 1 wherein the lever length, hinge point position, and spring coefficient and initial length of the elastic member of the four bar linkage ABCD are configured to be obtained by a parameter optimization algorithm comprising: Establishing a first shoulder joint moment of gravity about the joint rotation angle Is a gravitational moment function of (2) And spring force is transferred through four-bar mechanism to generate elastic compensation moment function ) Wherein For the rotation angle of the target structure in the gravity balancing device, Parameters to be optimized comprise the length of the rod, the position of the hinge point, the elastic coefficient of the elastic piece and the initial length; constructing an objective function with a ratio of the minimized maximum residual gravity moment to the maximum gravity moment; adopting particle swarm optimization algorithm to parameter according to the objective function Global optimization is performed, and the individual extremum and the global extremum are tracked by iteratively updating the speed and position of the particles, and finally the optimal parameter combination P for minimizing the objective function T (P) is converged.
  6. 6. The upper extremity exoskeleton robot of claim 5 wherein said gravity moment function is: Wherein m is the mass of the whole arm and load of the exoskeleton, and r is the distance from the mass center to the hinge point A on the first shoulder joint module; the spring compensation moment is that the length of the spring is calculated through the geometric relation And arm of force Obtaining Wherein L0 is the free length of the spring; The objective function is: , wherein, The angle range is [ -pi/2, pi/2 ].
  7. 7. A method of compliant control of an upper extremity exoskeleton robot with gravity compensation, applied to an upper extremity exoskeleton robot as claimed in any one of claims 1 to 6, comprising: Collecting current value, speed and position signals of a motor encoder of the shoulder joint module in real time in a fixed sampling period, filtering the current and speed values, eliminating high-frequency noise, and obtaining a filtered current signal I_filtered; Based on Newton-Euler recursion dynamics algorithm, inputting joint position theta and speed V, and calculating gravity moment G (q) and Coriolis moment in real time And calculating the compensation moment provided by the passive gravity balancing device according to the current joint angle theta by combining with the optimization parameters of the passive gravity balancing device ; Using motor torque constants Calculating the output torque of the motor Re-passing through dynamic model Resolving man-machine interaction moment Wherein Is the moment of inertia; will interact with the moment The input of the admittance controller is provided, by simulating a second-order mass-damping-spring system, the dynamic equation is that Solving a track adjustment quantity theta_e and a differential term thereof by a numerical integration method; will originally expect the track Trace adjustment amount output by admittance controller Superposition to generate final joint position instruction And the motor is driven by a PID position closed-loop controller to accurately track the instruction, and the gravity balancing device provides basic gravity compensation.
  8. 8. The method for compliant control of an upper extremity exoskeleton robot of claim 7, wherein said admittance controller resolving step comprises: Taking interaction torque tau_h estimated based on a current loop as input of an admittance controller, wherein the tau_h improves the signal-to-noise ratio due to passive gravity compensation, and can accurately reflect the intention of a user; Admittance controller follows second order system equations Real-time calculation is carried out through Euler discretization, and the track adjustment quantity is output Wherein M_d, B_d, K_d are adjustable admittance parameters; output the admittance controller The method is used for correcting an original expected track theta_d, generating theta_cmd, enabling the exoskeleton to adapt to external interaction force, and achieving natural man-machine cooperation; and inputting the theta_cmd into a PID controller, generating a motor driving signal through proportional, integral and differential operations, realizing high-precision position tracking, continuously counteracting gravity interference by a passive gravity balancing device, and reducing the motor load.
  9. 9. The method according to claim 8, wherein in the admittance control calculation step, admittance parameters m_d, b_d, k_d are adjusted online to change the degree of compliance of the exoskeleton to external interaction forces.
  10. 10. An upper extremity exoskeleton robot compliance control system with gravity compensation, applied to an upper extremity exoskeleton robot as claimed in any one of claims 1 to 6, and operating the upper extremity exoskeleton robot compliance control method of any one of claims 7 to 9, the control system comprising: The signal filtering module is used for collecting and filtering encoder signals of current, speed and position of the robot joint motor in real time; The calculation module is used for calculating real-time dynamic moment comprising gravity moment, coriolis moment and inertia moment based on Newton-Euler algorithm and integrating the passive compensation moment of the gravity balancing device; the interaction torque module calculates the output torque of the motor through the motor torque constant and the filter current, and combines the real-time dynamic torque and the passive compensation torque to output pure interaction torque; an admittance control module for converting the net interaction torque into a trajectory adjustment by simulating a second order mass-damping-spring system, and And the instruction synthesis module is used for superposing the expected track and the track adjustment quantity and driving the joint motor to track the position through the PID controller.

Description

Upper limb exoskeleton robot with gravity compensation function, control method and system Technical Field The invention relates to the technical field of rehabilitation medical robots, in particular to an upper limb exoskeleton robot with gravity compensation, a control method and a control system. Background In the field of medical rehabilitation, the number of patients with limb dyskinesia is continuously increased, wherein the demand of the group with limited upper limb functions caused by factors such as stroke, spinal cord injury and the like on rehabilitation training equipment is urgent. The existing upper limb exoskeleton robot faces remarkable technical bottlenecks in the neural rehabilitation, senile assistance and industrial assistance scenes. The shoulder joint is used as a main bearing joint, and gravity moment generated in the movement process of the shoulder joint is required to be counteracted by continuously outputting redundant moment by the driving motor, so that the energy consumption of the motor is greatly increased, and meanwhile, the dynamic response capability and movement flexibility of the control system are weakened. The current gravity balance technology is realized by adopting a spring or a connecting rod mechanism, but the design of structural parameters generally depends on manual experience, and a systematic optimization method is lacked, so that the matching error of gravity moment and balance moment under different joint angles is larger, and the requirement of multi-gesture movement is difficult to adapt. In addition, in order to realize safe and natural man-machine cooperation, the existing admittance control strategy cannot effectively fuse the real-time compensation effect of the mechanical balance moment, and feedback adjustment is carried out only through the current loop estimated moment, so that the contact force perception precision is insufficient, the man-machine interaction process presents a feeling of hardness, and the core requirement of rehabilitation training on flexibility cannot be met. These problems limit the improvement of exoskeleton devices in training effect, wearing comfort and system energy efficiency together, and development of a novel gravity compensation mechanism and a control architecture is needed. Disclosure of Invention The invention provides an upper limb exoskeleton robot with gravity compensation, a control method and a system, which have the advantages of reducing energy consumption, improving gravity compensation precision and system flexibility through an algorithm-optimized gravity balancing device, and are used for solving the problems that the contact force sensing precision is insufficient and the human-computer interaction process presents a feeling of hardness and cannot meet the requirements of rehabilitation training on flexibility due to feedback adjustment only through current loop estimated moment. The invention provides an upper limb exoskeleton robot with gravity compensation, which comprises an upper limb exoskeleton mechanism and a gravity balancing device, wherein the exoskeleton mechanism comprises a back plate and shoulder joint connecting rods, the shoulder joint connecting rods are in rotary connection with the back plate through first shoulder joint modules, the first shoulder joint modules are configured to control swinging of the shoulder joint connecting rods, the gravity balancing device is configured to provide self-adaptive gravity compensation in a working space of the upper limb exoskeleton mechanism, the gravity balancing device comprises a first connecting rod, a second connecting rod and a tension spring, two ends of the first connecting rod are hinged with the first shoulder joint modules respectively to form a hinge point A, one end of the second connecting rod is hinged with the first shoulder joint modules to form a hinge point B, the other end of the second connecting rod is hinged with the shoulder joint connecting rods to form a hinge point C, the hinge center of the first shoulder joint is D to form a four-bar mechanism ABCD, and two ends of the tension spring are hinged with the first connecting rods respectively to form a hinge point E, and the shoulder joint connecting rods are hinged with the second connecting rods to form a hinge point F. In an embodiment of the invention, the upper limb exoskeleton mechanism further comprises a second shoulder joint module, a big arm, an elbow joint module and a small arm which are sequentially connected, wherein the first shoulder joint module, the second shoulder joint module and the elbow joint module respectively provide pivoting for the shoulder joint connecting rod, the big arm and the small arm, and the gravity balancing device is integrated in the first shoulder joint module to provide self-adaptive gravity compensation in a working space of the first shoulder joint module. In an embodiment of the present invention, the upper extremity exoskele