Design And Kinematic Performance Research Of Waist Parallel Mechanism Of Quadruped Robot

Quadruped robot is adaptable to complex terrain whose legs landing points are discrete during moving,so its moving ability is better than crawler robot and wheeled robots.The waist structure of quadruped robots,as an important part of them,can effectively increase moving.Conventional quadruped robots usually have no waist structure,and some robots with waist structure adopt passive waist structure or rigid waist structure.This paper mainly introduced that the waist parallel mechanism of the quadruped robot was designed and the motion performance of the parallel mechanism was analyzed,so as to obtain a control method that met the motion law of the waist parallel mechanism.The specific contents were as follows:Firstly,the parallel waist structure of the quadruped robot was designed based on the bionic characteristics of mammals,the 3-UPS/UR(U: Hooke’s hinge,P: moving sub,S: ball sub,R:rotating sub)type was used as the parallel mechanism.The freedom degrees number and mechanism constraints were verified by screw theory and modified G-K formula.And motion requirements of quadruped robot were suitable.Then,the kinematics of the waist parallel mechanism were analyzed.According to the actual waist moving of the quadruped robot,the motion of the parallel mechanism was calculated in MATLAB separately to obtain the inverse solution of the mechanism.The genetic algorithm was used to analyzing the positive solution.Based on the constructed inverse solution formula of the waist parallel mechanism,the working space range of the waist parallel mechanism was obtained by numerical methods.Next,the Lagrangian dynamics equations of the waist parallel mechanism were established and verified in MATLAB,and the kinematics and dynamics of the waist parallel mechanism were simulated and analyzed by ADAMS dynamics analysis software,whose results were also compared with the calculation results of MATLAB to verify the correctness of the model.And the results showed that the model design of the waist parallel mechanism was correct and the kinematics and dynamics simulation results were in accordance with the theoretical calculation.Finally,the control part of the waist parallel mechanism was studied,and the PID control model and the fuzzy PID control model of the waist parallel mechanism were established respectively,and the simulation results were compared,which showed that the fuzzy PID control method is better than the PID control method.The joint simulation of ADAMS and SIMULINK were adopted to obtain the motion change of the waist parallel mechanism of the quadruped robot,and the simulation results showed that the control of the waist parallel mechanism by fuzzy PID can meet the control requirements.