Research On Lightweight Parameter Matching Method Of Quadruped Robot Hydraulic Drive System

The combination of legged robot and hydraulic system enables the robot to have large load bearing and quick response ability,which has great application potential in military and civil fields.The hydraulic drive system is one of the most important subsystems of the legged robot,which is responsible for driving each joint according to the requirements,so as to realize the various gait movement of the robot.It includes a hydraulic oil source(providing high-pressure)and hydraulic drive units(driving the joint movement of the robot).If the hydraulic drive system can not meet the requirements of the robot’s force and velocity in various gaits,it will seriously restrict the robot’s motion ability.Therefore,the performance of the hydraulic drive system is one of the decisive factors of robot performance.In order to make the hydraulic drive system meet the motion requirements of the robot,the parameter matching method is the key during the initial design stage.The weight of the robot is also one of the important factors affecting its performance.Due to the large weight ratio of the hydraulic drive system,it has great lightweight potential.Therefore,if a lightweight parameter matching method for the hydraulic drive system of the legged robot can be studied,it will help the robot to reduce weight,improve its load-bearing ability,dynamic performance and endurance ability,and also benefit energy conservation and emission reduction.This paper aims to study a lightweight parameter matching method for the hydraulic drive system of a quadruped robot,focusing on the following research works:(1)The hydraulic driving principle of the quadruped robot is designed and analyzed.The hydraulic drive system of the quadruped robot is designed using the principle of lightweight,and a novel leg structure of rotary oil distribution is proposed(the hydraulic quadruped robot composed of this kind of leg is called YYBZ quadruped robot).The gaits(foot end trajectory)of the quadruped robot are planned.And the dynamics simulation of the quadruped robot is carried out to obtain the rotating load trajectory of each joint.Aiming at the lightweight of the hydraulic drive system of the quadruped robot,the key technologies of the lightweight matching method of hydraulic drive system parameters are analyzed in combination with the parameter types and characteristics.(2)The lightweight matching method of power mechanism with four-quadrant load is studied.The concept of system effective pressure of the valve-controlled hydraulic system is defined to describe the output characteristics of the power mechanism.A four-quadrant load equivalent method is proposed to simplify the four-quadrant load matching.The position control system of the power mechanism and its performance indexes are analyzed,and a method to determine the parameters of feedback parameters and feed-forward parameters is proposed,which can obtain the corrected system parameters.Combining the lightweight requirements and the driving requirements,a lightweight load matching index is proposed.A lightweight load matching method is designed.And a parameter correction method is proposed for the power mechanism parameters after the load matching.(3)The lightweight optimization method of the joint hinge point position for the quadruped robot is studied.Aiming at the quadruped robot single leg with the series hinged form,a general mathematical model is established to represent the hinge point position of the leg.The general expressions of equivalent mass of hydraulic drive units are derived and the mass expressions of hydraulic drive system is established.For the hinge point position,the constraint system of hinge point position and its optimization index are proposed.An intelligent optimization algorithm is used to optimize the position of the joint hinge point to lightweight the quadruped robot leg.(4)The lightweight matching and design method of hydraulic drive system for quadruped robot is studied.Combining the lightweight load matching method and the hinge point position optimization method,a lightweight parameter matching method for the quadruped robot hydraulic drive system is proposed based on particle swarm optimization,and the corresponding automatic matching program is designed.Based on the above automatic matching program,the lightweight parameters match of the hydraulic drive system of the YYBZ quadruped robot is carried out.And the joint hinge point position,hydraulic drive unit parameters and hydraulic oil source flow curve are obtained.Then the3 D design of the hydraulic drive system of the YYBZ quadruped robot is carried out.(5)The lightweight hydraulic drive system of the quadruped robot is verified.The hydraulic drive unit experimental system is established.And the lightweight matching method of power mechanism with four-quadrant load is verified.The single-leg experimental system of the YYBZ quadruped robot is established.And the motion boundary of the robot joint and the weight reduction effect of the robot are verified.Compared with the traditional hydraulic quadruped robot single leg,the motion performance of the YYBZ quadruped robot single leg is verified.The YYBZ quadruped robot is established,and some experiments under different working conditions are carried out to verify that the hydraulic drive system of the YYBZ quadruped robot meets the design requirements.