Research On Gait Planning And Motion Control Of Lower Limb Prosthesis With Magnetorheological Damper

The lower limb prosthesis not only needs to realize the compensation of walking function,but also needs to maintain the movement coordination with the wearer.The existing prosthesis products are mostly passive prosthesis,with large volume,high energy consumption and insufficient stability.With the development of smart materials,a new type of magnetorheological damping lower limb prosthesis represented by magnetorheological fluid has the advantages of low power consumption,high sensitivity,and adjustable damping force,and has been widely used in the field of lower limb prosthetics.In view of the shortcomings of the existing prosthetic products,a new type of lower limb prosthesis with magnetorheological(MR)damper is designed by combining four-bar linkage and MR damper.Taking the minimum deviation of the actual trajectory curve and the target trajectory as the objective function,the length of the four-bar knee joint mechanism,the length of the thigh bar and the length of the leg bar were optimized respectively,and the parameter design of the lower limb prosthesis with MR damper was completed;Based on the parameter design of MR damping lower limb prosthesis,the virtual prototype model of lower limb prosthesis was established by Solid Works.Based on the central pattern generator theory,the gait planning of lower limb prosthesis was carried out by coupling Rayleigh oscillator,and the joint angle curves of hip joint and knee joint were obtained.To verify the rationality of the obtained joint angle curves,motion simulation of lower limb prosthetics was performed using the dynamic simulation software—Solidworks motion;The stepping motor is used as the joint motor of lower limb prosthesis.Based on PID control theory,Labview hose computer and STM32 controller,the closed-loop control system of joint motor is built,and the closed-loop control experiment of joint motor is carried out;In order to realize the simulation of normal walking gait of lower limb prosthesis,based on the closed-loop control experiment,the joint angle curve obtained from gait planning is taken as the target trajectory curve,and the joint motor is controlled to follow the target trajectory curve,and the motion control of lower limb prosthesis joint motor is studied.