Design And Research Of Lower Limb Assisted Exoskeleton Based On Standing Process

Exoskeleton as a kind of augmentation assistant device has been widely studied in recent years.By collecting human motion information,it combines the external power of mechanical device with human intelligence to achieve the effect of active or passive assistant human action.At present,the research of exoskeleton technology is not mature enough,which mainly has the problems of high energy consumption and poor balance stability after wearing.This paper based on the actual application and the human erection process,studied and designed a wearable lower limb assist exoskeleton,and explored the stability problem caused by wearing exoskeleton.The prediction of human erection and instability of backward pitch is completed by using exoskeleton force/position feedback and assisted the human body complete corresponding action.The main contents of this paper are as follows:Firstly,based on human biomechanics,analyzed the characteristics of joint motion in the process of standing up;established the mathematical model of human centroid,and collected the parameters of standing up by optical capture equipment.To solve the problem that the collected discrete data can not well represent the human motion law,the Boltzmann function is used to fit and reconstruct the joint motion angles based on the least square method.Obtained the planning trajectory of joint angular displacement by planning.In addition,established the simulation prototype of human erection process by using motion simulation software.Secondly,carried out the design and structural optimization of the auxiliary standing exoskeleton.In order to reduce the space occupied by the structure and improve the assistant thrust effect,established a five-bar model of the lower extremity assisted exoskeleton support structure,and carried out the multi-objective optimization of the length of each bar based on Pareto dominance theory.The design of each part of the exoskeleton was carried out,and established the three-dimensional model of the prototype by Pro/E.Exoskeleton knee power,actuator and so on are selected to complete the processing and assembly of exoskeleton structure.Then,analyzed the balance stability of the assistant standing process.Based on ZMP theory,used the human erection model established in ADAMS to analyze the stability of the normal erection and the planned trajectory of the erection movement.In addition,because the wearing of exoskeleton is not stable in mechanical analysis,explored the influence of the upper body's backward motion in the sagittal plane on the overall stability.Based on the COP information of foot sole and the angle information of hip joint,proposed the prediction method of human standing and dumping and the corresponding control algorithm of exoskeleton response.Finally,built an exoskeleton control and debugging platform.On this basis,carried out an auxiliary stand-up experiment and a backward tilt test to verify the reliability of the exoskeleton system and the feasibility of the algorithm.Experiments show that the designed exoskeleton can effectively play an auxiliary stand-up effect,and can quickly respond to human movements when sagittal instability occurs.