Research On Structure Design And Force Control Of Lower Limb Flexible Power Suit

Modern warfare has higher and higher requirements for soldiers,in order to pursue stronger marching ability,countries around the world have turned their attention to the research of exoskeleton power suits,especially in terms of flexible power suits that are lighter than rigid power suits.Compared with foreign countries,the lower limb flexible power suit started late in domestic research and is far from reaching the level of actual use,so the development of a flexible power suit that can provide assistance for human walking has certain innovative and practical significance.Therefore,the research purpose of this thesis is to design a new type of lower limb flexible power suit,and design a humanmachine collaborative force control algorithm for it,so as to finally achieve the control purpose of human-host auxiliary and human-machine collaboration,and have a certain assistance effect on human walking.To this end,the following research is done in this thesis.Firstly,this thesis analyzes the physiological structure of human lower limbs,collects human motion data through IMU and plantar pressure sensors,and uses OpenSim to perform inverse kinematics and inverse dynamics simulation to obtain gait motion characteristic parameters.Secondly,this thesis designs a flexible lower limb booster suit with hip flexion and knee flexion as the help object and meets the movement law of human physiological structure,and performs three-dimensional modeling of the auxiliary suit through Solid Works.Then,the ergonomic model is established and the mathematical relationship between joint angle,cord length and motor angle is determined.The Lagrange method was used to model the positive dynamics of the support phase and the swing phase in the humanmachine gait motion,and the change law of torque in the process of wearing and not wearing this flexible power assist suit was comparatively analyzed.Thirdly,the control algorithm of lower limb flexible power suit is designed by using the force control method of motion intention perception and expected torque tracking.In terms of motion intent perception,IMU sensors and plantar pressure sensors are used to obtain the current gait parameters of the person to identify the movement intention and determine the expected assist waveform.In terms of expected force tracking control,an adaptive fuzzy PID inner loop is designed to track the admittance control of the assist curve,and Simulink is used to establish a simulation platform to verify the force following of the control system.Finally,through the selection of key equipment of the prototype,a prototype of the lower limb flexible assist suit was established,and the muscle fatigue experiment was used to prove the auxiliary effect of the lower limb flexible assist suit.The experimental results showed that the muscle activity of the rectus femoris muscle and biceps decreased by 14.55% and 6.70%,respectively,after wearing the flexible power suit of the lower limb.It shows that the lower limb booster designed in this project effectively reduces the fatigue of related muscles and has a good booster effect.