Research On Kinematic Control Of Hydraulically Driven Six-degree-of-freedom Manipulator

As one of the symbols of industrial modernization,industrial robots are widely used in all walks of life.It can replace human beings to complete the work requirements under various complex working conditions,and the safety,reliability and efficiency brought by it are increasingly recognized by people.Hydraulic drive is widely used in engineering machinery and equipment because of its large power-to-weight ratio,large speed range,compact structure and flexibility,which makes more and more researchers conduct in-depth research on its motion characteristics and control characteristics.Based on the working conditions of the coal mine working environment,this paper takes the hydraulic-driven six-degree-of-freedom manipulator as the research object,combines the typical motion trajectory of the manipulator,and studies the manipulator from the four aspects of kinematics,trajectory planning,dynamics and control strategy,and builds an experimental platform to verify the effectiveness of the control system optimization algorithm and the feasibility of trajectory planning.Firstly,according to the intelligent operation requirements of the manipulator,the motion trajectory is planned.The D-H method is used to establish the forward kinematics model of the manipulator.Combined with the forward kinematics model and the Monte Carlo algorithm,the workspace of the manipulator is analyzed to provide a theoretical basis for the reachable space for trajectory planning.The algebraic method is used to solve the inverse kinematics of the manipulator.Combined with the numerical expression of each joint angle,the trajectory planning of the typical plane trajectory and space trajectory of the manipulator is studied by cubic polynomial and quintic polynomial interpolation strategies.Considering the force impact and motion smoothness between the joints of the manipulator,the trajectory planning of the manipulator is carried out by high-order polynomial interpolation.Secondly,the dynamic modeling of the manipulator is crucial to improve the motion control accuracy and stability of the manipulator.In this paper,the Lagrange method is used to establish the dynamic equation of the manipulator,which provides a theoretical basis for the dynamic simulation of the manipulator.Based on the quintic polynomial trajectory planning of typical spatial curves,the dynamic simulation of the manipulator under no-load and load of 50 kg is carried out,and the driving force distance of each joint of the manipulator under two states is obtained.Thirdly,the hydraulic system of the manipulator is studied in detail,and the mathematical models of valve controlled cylinder and valve controlled hydraulic motor are established.The simulation model of the manipulator hydraulic control system is built by AMESim,and the control strategy based on PID control algorithm is proposed.The no-load and load conditions of the manipulator are simulated,and the response characteristics of the control system are analyzed.Finally,the motion control accuracy and stability of the manipulator under no-load and load conditions are verified by using the manipulator experimental platform.The experimental results show that the maximum no-load working error of the manipulator is between 2 % and the maximum error of the load 50 kg is between 3 %.The proposed control strategy can meet the accuracy requirements of the manipulator.