Research On Adaptive Control Of Exoskeleton Serial Elastic Actuator

Exoskeleton actuator are mostly driven by conventional actuator(direct drive)or motor integrated harmonic speed reducers.Because the effect between the exoskeleton and the environment is different from other robots,it directly acts on human muscles and joints.For the safety and endurance of machine interaction,this paper studies the advantages of Series Elastic Actuator(SEA)as an exoskeleton drive source.This article is based on a detailed study of SEA’s papers on research hotspots in physical modeling,control algorithms,energy storage and application,etc.,starting from the actual needs of the exoskeleton for the actuator,focusing on the basic theoretical research of SEA and adding yourself Innovations,so as to conduct research on the core features of SEA.First,a complete SEA system dynamics model is constructed,including the SEA model and the human-robot interaction model on the load side.In view of the shortcomings of the current SEA dynamics model that does not consider the load-end dynamics model or only regards the load-end as a pure inertial link(oversimplification of the load-end dynamics model),this paper proposes two linear and non-linear human-robot interaction models.Then the SEA dynamic model and human-robot interaction model are combined to propose a complete SEA dynamic model.According to the complete SEA model,the effects of springs with different stiffness on SEA force output bandwidth,"transparency" and tracking accuracy are analyzed in detail.Then,an adaptive force controller is designed based on two complete dynamic models,linear and nonlinear,and the stability of the system is strictly proved by Lyapunov theory.Finally,the force tracking accuracy,robustness and The antiinterference ability verifies the control effect of the controller,which is in accordance with the theoretical analysis.Next,a double-joint SEA model of a hybrid system of exoskeleton SEA and human lower limbs was established.The model was simplified and equivalent to a double-joint robot arm model.An adaptive position controller based on RBF neural network was designed.Matlab and simulink simulation verified the good position tracking ability and anti-jamming ability of the control system to assist human body movement.Finally,the energy storage and energy saving characteristics of SEA are analyzed,and the energy saving characteristics of the output end of SEA are studied in depth.The analysis of dynamic differential equations and Matlab simulation confirm that SEA does have energy saving effects compared to conventional drives.