Multiobjectives Of Attitude Adjusment Mechanism For Climbing Wheelchair Chairs Optimization And Robustness Analysis

In modern society,more and more elderly people and physically handicapped people choose electric wheelchairs as a means of mobility.However,ordinary electric wheelchairs can only run on flat ground or on small slopes.When they encounter obstacles such as stairs,ravines,and stairs,they will change.There is nothing to do.In order to make the wheelchair have the function of going up and down the stairs,obstacles and crossings,based on the analysis of the existing wheelchairs for electric climbing stairs,this subject has designed a wheel-leg compound electric wheelchair.The main research object of this article is the chair posture adjustment mechanism in the wheelchair.It plays the role of adjusting the overall center of gravity of the stair climbing wheelchair.That is to say,the accuracy of the movement is directly related to the safety of the climbing chair during the movement.Therefore,it is necessary for the chair posture adjustment mechanism of a stair climbing wheelchair to performs stress analysis,optimization design,and robustness analysis.The main research content includes the following points:Firstly,by analyzing the movement characteristics and working principles of the seat attitude adjusting mechanism during the movement of a stair climbing wheelchair,it is simplified as a cross four-bar mechanism,and a kinematics model is established with using the closed vector method to simulate the work space and centroid of the mechanism.acceleration curve;The force analysis of the mechanism was performed using the D’Alembert’s principle,and the force conditions at each hinge point were obtained using a matrix solution,which laid the foundation for further optimization of the seat attitude adjustment mechanism.Secondly,by comparing the advantages and disadvantages of the genetic algorithm based on the Analytic Hierarchy Process(AHP)and the improved non-dominating sequence(NSGA-II)genetic algorithm,the former is uncontrollable,and the actual is a single-objective optimization,and the latter can be controlled and truly multi-objective optimization,and based on the centroid acceleration of the seat attitude adjustment mechanism,the received driving torque,and the working space as evaluation indexes,the optimization of the rod length of the mechanism based on the NSGA-II genetic algorithm was selected.In the process,the different optimization sub-objectives are emphasized,and then five groups of design solutions are given.Since this paper focuses on optimizing thecentroid acceleration of the seat attitude adjustment mechanism,this group of bar length results is selected to conduct comparative analysis before and after optimization of each evaluation index.Thirdly,to further study the influence of the joint clearance in the mechanism,adopt the theory of continuous contact between the middle reaming hole and the pin axis in the movement,and regard the joint clearance as the length without the mass,thereby simplifying the cross-bar linkage mechanism into multiple rods and multiples.The degree of freedom mechanism and the closed-vector method and the Lagrange method were used to establish the kinematics and dynamics model of the seat attitude adjustment mechanism when considering the clearance.After that,the seat attitude adjustment mechanism was used with Matlab to check whether the gap was different or not.Consider numerical simulation and comparative analysis under different gaps.At the same time,using effective rod length theory and knowledge of probability theory,the influences of motion pair gap and basic dimension errors in the seat attitude adjustment mechanism on the accuracy and reliability of the motion accuracy are deeply studied.