Research On Position Impedance Of Hydraulic Quadruped Robot Based On Position Impedance

Foot robots need only a few supporting points to move,so they are more flexible and have been widely used in fire rescue and field material transportation.Compared with biped and hexapod robots,quadruped robots can simultaneously meet the advantages of good stability,simple structure and easy control.Therefore,the research on quadruped robots has become the focus of the research on quadruped robots.The contact between the foot robot and the ground is a single point contact when walking,which will produce huge impact force when moving.Excessive impact force will affect the running stability of the machine and even cause damage to the machine body.Therefore,on the basis that the robot meets the requirements of position accuracy,the robot legs should be "soft-landed".In this paper,the hydraulic quadruped robot experimental platform is taken as the research object,and the compliance control of its single leg is studied.In this paper,the following research work has been carried out:(1)Establishment of robot dynamics model and hydraulic system model.Taking the laboratory hydraulic quadruped robot platform as the research object,according to its leg structure,the force relationship between the actuator and the connecting rod is analyzed,the equivalent load model of the cylinder valve drive unit is deduced,and the block diagram of the equivalent hydraulic system and the closed-loop transfer function of the actuator are obtained,which provide theoretical guidance for the follow-up compliance control research and simulation experiments.(2)Research on compliance control method.The main control method of compliance control is impedance control.This paper expounds the principle of impedance control,analyzes the influence of impedance control parameters on the system,and analyzes the error of impedance control.An adaptive control algorithm based on position impedance and an adaptive-fuzzy control algorithm based on position impedance are proposed to make up for the deficiency of the original impedance control.(3)Joint simulation and result analysis.The joint simulation platform of ADAMS and MATLAB is built,and the single leg simulation model of the robot is built.Firstly,the adaptive control based on position impedance and the position impedance control are simulated under the same parameters.Finally,the simulation experiments based on the adaptive control based on position impedance and the adaptive-fuzzy control based on position impedance are compared to obtain the foot force output curves under different environmental stiffnesses,which verifies the rationality of the control algorithm and provides a reference for subsequent prototype experiments.(4)Verification of physical experiments.The physical experiment table of the laboratory is used to carry out physical prototype experiments on the two control methods.Two control methods are used to control the single leg of the physical prototype,and one-leg touchdown experiments are carried out in different environments to obtain the tracking curve of foot end force.Analysis of experimental data to verify the results of joint simulation further proves the effectiveness and feasibility of the proposed control scheme.