Study On Compliant Control Algorithms Of Lower Limb Assist Exoskeleton

In recent years,the development of military affairs in various countries has been accelerating,and military strategic principles of "future soldiers" have been introduced one after another.This approach mainly focuses on intelligent digital combat platform,including operations,reconnaissance,communications,protection and other aspects,in which the transformation of individual combat equipment is particularly important.Under the requirements of future battlefield variability and complexity,individual soldier can carry all kinds of equipment,adapt to various environments,complete diverse tasks,and inevitably increase the burden of individual soldier,which has a great impact on individual soldier’s physical fitness and mobility.Exoskeleton is a new type of man-machine interactive robot,and its wearability makes it possible to increase the soldier’s load.As an interactive robot with highly human-computer coupling,how to accurately and quickly identify human motion intention and provide assistance to the wearer before harming the wearer are two major problems that need to be solved urgently.To solve this problems,this article studies the two core issues of exoskeleton robot dynamics modeling and compliance control strategy,and designs related experiments for application and verification.Finally,the experimental platform of the lower limb exoskeleton robot is built,and the algorithm is verified on the experimental platform.Firstly,this article introduces the system composition of the lower extremity exoskeleton robot,including the motor drive system,mechanical structure,control system and perception system,and expounds the design requirements and function realization.Then the human anatomy and simplified human model are described and analyzed,and the kinematics and dynamics model of the lower limb exoskeleton robot is established.When the lower limb exoskeleton is in the swing phase,it is simplified as the top fixed and link model;when the lower limb exoskeleton is in the support phase,it is simplified as the bottom fixed three link model.At the same time,in order to verify the accuracy and practicability of the exoskeleton kinematics and dynamics model,the lower limb exoskeleton simulation model is built in the robot simulation environment,and reasonable experiments are designed to verify.Through the comparative analysis of the current mainstream control algorithms,combined with the characteristics of the lower limb exoskeleton robot system and the control requirements,the adaptive impedance control algorithm based on the dynamic model is determined.The foot pressure is used to identify the human motion intention,and the motion data in the off-line motion database of human body is transferred to the exoskeleton impedance controller as the desired trajectory.At the same time,the human-computer interaction force signal is used as the compensation of the impedance control to reduce the delay.Finally,the compliance control algorithm is tested on the experimental platform of the lower extremity exoskeleton robot,and the performance of the exoskeleton system prototype is evaluated.