Research On Compliance Control Strategy Of Industrial Robot For Weld Grinding

With the acceleration of intelligent transformation in the manufacturing industry,industrial robots have been widely used in the welding and forming fields of plane and curved surfaces such as ships,high-speed railways and aircraft,gradually replacing manual work to complete some highly repetitive tasks.However,due to the complexity of the weld surface of large components after welding,it is necessary to reduce the stress at the welding while smoothly removing the excess materials,which requires high precision polishing.At present,the welding metal materials are still mainly removed by manual polishing processing.But manual grinding and polishing labor intensity,low efficiency,poor working environment,difficult to ensure the consistency of processing quality and other factors,urgent need of industrial robots instead of manual grinding and polishing work.This paper takes the welding seam grinding and polishing robot as the research object,starting from the force control method,in order to ensure the grinding and polishing processing accuracy of industrial robots,a compliance control strategy based on intelligent control theory algorithm is proposed,in order to ensure the stability of force tracking during the grinding and polishing process,and then improve the quality and accuracy of welding seam grinding and polishing.The main research contents of this paper are as follows:1.Taking the weld grinding and polishing robot as the object,the relationship between the end effector of the robot and the base coordinate system is established through coordinate transformation.The robot model is established according to D-H parameters,and its forward and inverse kinematics are analyzed.An optimization method is proposed for the inverse kinematics multi solution problem.The correctness of the robot model is verified using MATLAB Robotics Toolbox,and its workspace is analyzed,It provides a theoretical basis for controlling the robot to carry2.The control method of grinding force in the process of grinding and polishing robot is studied,and the position based impedance control with good robustness is selected to realize the compliance control during the grinding and polishing process.The impedance control system model based on position is established through Simulink,and the influence on the control system performance is studied by changing the impedance control parameters: inertia coefficient M,damping coefficient B,stiffness coefficient K,so as to provide a basis for the combination of intelligent control algorithm and traditional impedance control methods to adapt to dynamic environment changes.3.The optimization strategy of impedance control parameters based on intelligent control algorithm is studied.Based on the Simulink platform of MATLAB,the PSO algorithm and DE algorithm are improved.The PSO-DE hybrid control algorithm is obtained by mixing the algorithms in parallel.The impedance parameters are iteratively optimized.The fitness function is designed by comprehensively considering the overshoot,steady-state time,steady-state error and other factors of the control system.The intelligent algorithm is used to iterate to find the optimal solution of the objective function.The effectiveness of the compliance control strategy is verified by comparison.4.Based on Xin Song SR50 B industrial robot and 6-axis force sensor,an experimental platform for weld grinding and polishing force tracking is built.When there is compliance control strategy,different types of welds in the industry are ground and polished,and contact force data in the process of grinding and polishing are recorded.The force tracking effect of the control system is compared to verify the stability and accuracy of the variable impedance parameter control system optimized based on intelligent optimization algorithm in the process of weld grinding and polishing.