Research On Magnetorheological Damper For Lower Prosthesis And Its Control Simulation Analysis

As cars have become more popular,more and more traffic accidents have occurred.In addition to other causes such as accidents and local wars,the number of people with physical disabilities is huge,and those with lower limbs account for the majority of amputees.The Magnetorheological damper based lower prosthesis(Magnetorheological damper based lower prosthesis,MDLP)has the advantages of fast response,wide output range,continuous controllable damping force,low energy consumption and stable structure.More and more scholars have begun to study MDLP.In this paper,the walking experiment of healthy people is carried out,and the kinematics and dynamics constitutive equations of the prosthesis during the swing period are derived.The dynamic analysis of the lower prosthesis is carried out,and the structure design of the magnetorheological damper(MRD)is carried out.The magnetic circuit design,the advanced correction circuit was designed for the MRD,the system model of the MRD was established,the virtual prototype of the lower prosthesis was established and the joint simulation was carried out.The specific research contents are as follows:(1)A normal human walking experiment was performed to obtain the movement patterns of the hip,knee and ankle joints of normal people.The kinematics and dynamics equations of the prosthetic swing period were established,and the dynamics analysis software was used to analyze the dynamics of the lower prosthesis.The expected damping force of the MRD of the prosthetic limb during the swinging period was obtained.(2)A multi-section coil double-outlet MRD operating in pure shear mode is designed according to the desired damping force.According to the lightweight requirements of the damper under the background of prosthetic application,an optimization design method combining the damper structure design and the magnetic circuit design is proposed.The structural size of the damper is determined.The finite element analysis software ANSYS is used.The magnetic field finite element analysis of the MRD was carried out to verify the rationality of the MRD structure.(3)The steady-state magnetic field analysis and transient magnetic field analysis are carried out for the MRD.The effects of coil inductance and magnetic circuit eddy current on the current limiting response time and magnetic field response time are analyzed.The results show that the eddy current has a greater influence on the magnetic field response time.The effects of series and parallel connection of multi-section coils on current response time are analyzed.The advanced correction circuit is designed for MRD.The system model of MRD is established by using formula method and BP neural network method respectively.The results show that although the formula method can clearly see the physical meaning of each item,the modeling accuracy of BP neural network method higher.(4)The simulation platform of MRD lower limb prosthesis was established.Two simulation schemes of PID control strategy and self-designed cascade switch structure feedback control strategy were designed to jointly simulate the lower limb prosthesis prototype.The simulation results show that the self-designed cascaded switch structure feedback control simulation of the BP neural network model based on MRD has higher precision.Therefore,the performance of the lower limb prosthetic virtual prototype under the MRD model and control strategy is better.