| The number of amputated patients caused by accidental work injuries,traffic accidents,frequent natural disasters,etc.is increasing,and the demand for knee prosthetic auxiliary medical equipment is also increasing.At present,the prosthetic limbs in the country are mostly passive prostheses.The wearer will have fatigue due to wearing time,and the passive prosthesis can not follow the movement of the normal leg,resulting in abnormal walking gait and large bone wear on the disabled side.High-performance knee prostheses capable of providing active torque and following normal leg movements have long been an urgent medical device for patients with lower extremity amputation,so develop an active knee joint that can coordinate normal leg movements and has high cost performance.Prosthetic products are extremely necessary.Aiming at these situations,the paper establishes the model of human lower limb joint torque,designs the structure of knee joint elastic actuator,and studies the tracking control algorithm of human walking gait trajectory.The main contents are as follows:(1)First,a dynamic analysis of the human lower limb model(thigh and calf)was performed.By simplifying the lower limbs of the human body into a two-bar linkage mechanism,the Lagrange energy method is used to model the driving torque of the lower limb hip joint and knee joint,and the driving torque of the hip joint and the knee joint and the joint are established.The equal angle between the angle of motion,angular velocity and angular acceleration lays the theoretical foundation for the torque control of the knee joint.(2)An elastic element is added between the power output end and the actuator end of the prosthesis.The elastic element can store and release energy and play a certain buffering effect,so that the prosthesis has a certain bionic property,and the impedance effect generated by the SEA can also be the wearer is more comfortable during walking.This structure is referred to herein as the Series Elastic Actuator(SEA).The prosthesis model was established according to the ratio of 1:1 using Creo2.0 and Catia three-dimensional software.The prosthesis prototype was constrained in Adams dynamics software.The output power of the prosthetic motor under different stiffness was simulated and simulated.The results show that when the SEA spring stiffness is at 2.1E+05N/m,the output power of the prosthetic motor is the smallest.(3)In order to facilitate the research of trajectory tracking control algorithm for artificial limbs,a mannequin model with prosthetic prototype was created by using Creo2.0 and CatiaV5R20 software,and the human-machine hybrid model was derived from Adams.A control algorithm is established to control the model created by the virtual prototype,and such a joint simulation platform is built.And using the 3D gait capture instrument,the driving data of the human-machine hybrid model and the desired trajectory to be tracked are obtained.(4)The dynamic prosthesis needs to effectively control the prosthetic power source to coordinate with the healthy side legs.The dynamic prosthesis studied in this paper uses DC motor drive to drive the prosthetic movement by controlling the input torque of the prosthetic motor.By constructing a joint simulation experiment control platform,the PID control algorithm and the linear synovial control algorithm are used to track and control the trajectory of the prosthesis under the control of the single-leg model.It is found that the linear synovial control algorithm has strong adaptability to the unsynchronized trajectory.The antiinterference ability is strong and the convergence speed is fast.In the research of man-machine hybrid model control method,the RBF neural network adaptive control strategy and the delaybased fast terminal synovial membrane control strategy are mainly compared and the latter trajectory is found.The tracking error is about 5° smaller than the former in most of the time,and the walking control of the human-machine hybrid model can be realized.Finally,the experimental control platform is built in the paper,and the artificial limb single-leg model control algorithm is experimentally verified.The tracking error is within ±15°,and the trajectory tracking error is large.The main reason for the large error is the relative sliding between the parts of the prosthetic prosthesis,the gap between the gear transmission and the controller algorithm parameters.It is applied to the experiment without modification in the experimental environment.In the subsequent experiments,the algorithm parameter values are needed.Correction and improved design of parts. |
