The Design Of The Control System And Gait Implementation Of The Lower Limb Exoskeleton Robot

The lower limb exoskeleton robot which is a complicated system combining Bionics Technology,Biomedical Technology,Artificial Intelligence Technology,Automatic Control Technology,Data Fusion Technology and many other technologies according to the specific functions and tasks has become one of the most popular research fields in recent years.It can not only carry the loads instead of people,but also can be used to treat patients with rehabilitation training according to the planned gait in advance.Therefore,the lower limb exoskeleton robot has a promising prospect of application in rehabilitation,military,disaster assistance field and so on.This thesis carries out an exploratory research on the gait control of the lower extremity exoskeleton robot which is self-designed by the research group,which includes the following aspects:(1)First,the cubic spline interpolation method is adopted to achieve the parametric motion curves of each joint according to the characteristics of the mechanical mechanism of the lower limb exoskeleton robot.Then,the PSO algorithm is employed to optimize the motion curves of each joint in order to maximize the ZMP stability margin.Finally,the simulation experiment verifies that the optimized gait has greater ZMP stability margin,robustness to greater external disturbances,smooth position and angle curves,no severe oscillations and complies with the laws of human walking.(2)The errors caused by the mechanical devices of the lower limb exoskeleton robot,the external disturbances and other factors will lead to the bad performance,or even hurt the human being.Therefore,the PD controller based on the gravity compensation and the RBF network adaptive controller based on the model uncertainty are designed to correct the errors.Finally,the Matlab/Simulink software is applied for the simulation experiment and the result indicates that the RBF network adaptive controller based on the model uncertainty is better at the control precision,the rate of convergence and the target trajectory tracking.(3)The control system of the lower limb exoskeleton robot is designed based on the TwinCAT software and the communications of the modules are connected by EtherCAT protocol.The RBF adaptive outer loop compensation control based on the MTI sensor further enhances the performance of the trajectory tracking.The experiment which is carried out on the physical prototype verifies that the design of the control system is reasonable and the control method is feasible.The flexion and extension motion of the hip joint of the lower limb exoskeleton robot is preliminarily achieved.