Research On Decoupling Control Of Lower Limb Rehabilitation Robot Based On Inverse System Approach

Focusing on the lower limb rehabilitation robots,this dissertation optimizes the electrical system of a new generation of lower rehabilitation robots to tackle shortcomings of previous generation of the robots developed by laboratory.On the basis of inverse system theory,three degree of freedom dynamics of these robots is decoupled linearly and linearity controller is designed.Trajectory tracking of each joint is achieved and simulated by control algorithm of the fuzzy intelligent PID.Firstly,this paper summarizes some problems posed by these robots developed by laboratory in application process,designs a new electrical system for the new robots in terms of system's stability and reliability and utilizes Lagrange equation to establish dynamics models of three joints of the lower limb rehabilitation robots and human-machine coupling based on six-axis force sensor.Secondly,according to three-link dynamics featuring non-linearity and couple between input and output,linear feedback decoupling is realized by adopting the nonlinear inverse system to prove a reversible kinetic model,build up the inverse system of kinetic model on analytic method and formulate a pseudo linear system.Tracking control of each joint is obtained by designing linear controller,which is verified by simulation.Then,given that parameter accuracy of dynamic model posed by its torque control of each joint and friction uncertainty caused by uncertain disturbance the lowers may encounter during the process of rehabilitation,this paper engineers a much better approach jointed with negative feedback and PID regulator to eliminate system errors.On this basis,intelligent fuzzy algorithm is introduced to establish a fuzzy adaptive PID controller and improve the system's dynamic characteristics.And it is feasible by simulation.Finally,this paper builds electrical system for the lowers' single leg of the new generation.All sensors are calibrated and precision of systemic track is tested by experiment.It also resolves the problem that parameters of dynamic model are changed due to the change of the length of leg.The method of the quality parameters of three joint manipulators is determined by experiment and simulation software.