Research On Hybrid Coordinated Control Of SCARA Robot's Path Tracking

The SCARA robot widely used in assembly and handling industries due to its large flexibility in the plane and strong rigidity in the vertical direction.In recent years,the manufacturing has developed rapidly,and the development of robots has been raised to the national level.People have put forward higher and higher requirements for robot control speed,control precision and stability.In this paper,the SCARA robot driven by the permanent magnet synchronous motor is taken as the research object,and the kinematics and dynamics analysis of the robot are carried out.The robot control is decomposed into two parts: the robot body control subsystem and the PMSM control subsystem.After the energy control,signal control and smooth switching control researches are performed for each control subsystem,the energy control,signal control and smooth switching control for SCARA robot driven by PMSM are researched.MATLAB/Simulink simulation software is used to simulate and verify.Firstly,the SCARA robot model is established based on D-H method.The forward kinematics equation and inverse kinematics solution of SCARA robot are derived by analytical method.The joint space trajectory planning of SCARA robot is carried out by cubic spline interpolation algorithm.The kinematics equations and trajectory planning of SCARA robots are simulated and verified by MATLAB software.The 3D model of the SCARA robot is established in ADAMS,and the constraints are added to the model.The feasibility of reducing the SCARA robot model from 4 degrees of freedom to 2 degrees of freedom is verified by simulation.The Lagrangian method is used to derive the dynamic equation of the 2 degree of freedom SCARA robot.Secondly,the robot body control subsystem is studied.(1)Consider the robot body as a multi-port energy conversion device,establish a port-controlled Hamiltonian model,determine the desired Hamiltonian function of the closed-loop system,design the closed-loop system controller by using the state error port-controlled Hamiltonian principle,and obtain the control torque required for the robot body path tracking;(2)Consider the robot body as a multi-port signal conversion device,establish a signal control model,design the signal controller of the robot body by using the back step method,and obtain the control torque required for the robot body path tracking.(3)A smooth switching control strategy is designed to smooth the switching between energy control torque and signal control torque.The tracking error Gaussian function which is a new smooth switching control strategy is proposed in this paper.The significance of the new strategy is that smooth switching can be performed as long as there is tracking error,then continuous and smooth change of control torque can be achieved.(4)Analyze the stability of the robot body energy control,signal control and smooth switching control system by the Lyapunov method and LaSalle invariance principle.The simulation results of MATLAB/Simulink simulation platform prove that adopting the energy and signal smooth switching control strategy in the robot body control subsystem can improve the dynamic response speed of the system at low speed while ensuring the steady state performance of the system.Thirdly,some research is done on the PMSM subsystem.(1)Establish the PMSM speed servo Hamiltonian model for driving the i-th joint of the robot,design the i-th PMSM energy controller by using the principle of state error PCH and obtain the control voltage required for tracking speed of the i-th PMSM at the desired load torque.(2)In order to improve the dynamic response speed of the PCH controller,the design idea of the state error PCH controller with adaptive damping injection is proposed.(3)Use back step methods to design the PMSM speed servo signal controller of the i-th joint and obtain the control voltage required for tracking speed.(4)Use the smooth switching control strategy to smoothly switch the energy control voltage and the signal control voltage to achieve continuous and smooth change of the control voltage.(5)Connect the two PMSM signal control systems in parallel to form the signal control system of the PMSM subsystem,which is used to prove that two PCHD systems in parallel are still PCHD systems and so do the two PMSM energy control systems.(6)Analyze the stability of the single PMSM energy control,signal control and smooth switching control system by the Lyapunov method and LaSalle invariance principle,and so do the PMSM energy control,signal control and smooth switching control subsystem.The simulation results of MATLAB/Simulink simulation platform porve that adopting the energy and signal smooth switching control strategy in the PMSM can make the system have both good steady state performance and fast dynamic response.Finally,the research on PMSM-driven SCARA robot energy and signal smoothing switching control is carried out.(1)Cascade the energy control system of the robot body and the energy control system of the PMSM subsystem to form the PMSM-driven SCARA robot energy control system,and prove that the two PCHD systems are still PCHD systems after cascading.(2)Cascade the signal control system of the robot body and the signal control system of the PMSM subsystem to form the PMSM-driven SCARA robot signal control system.(3)Use the smooth switching control strategy to organize the PMSM-driven SCARA robot energy control system and the signal control system as the PMSM-driven SCARA robot energy and signal smoothing switching system,in order to achieve continuous and smooth variation of the control voltage.(4)Analyze the stability of the PMSM-driven SCARA robot energy control,signal control and smooth switching control system by the Lyapunov method and LaSalle invariance principle.The simulation results of MATLAB/Simulink simulation platform prove that the PMSMA-driven SCARA robot energy and signal smooth switching control system has faster tracking speed and good steady-state performance.