Research On Robot Motion Planning And Constant Force Control Method For Grinding Based On Floating Platform

At present,most enterprises use manual grinding to process small hardware.In order to improve the level of grinding automation and product consistency,robot grinding technology is gradually introduced into manufacturing.However,the existing robot grinding systems have some problems,such as insufficient robot stiffness,low position control accuracy,and original workpiece errors and fixture positioning errors during grinding processing,which cause poor surface quality.In addition,the robot grinding assisted path is mainly manual teaching,which is labor-intensive,inefficient,and difficult to respond to the changes of the processing environment.In view of these problems of the robot grinding system,on the one hand,this paper conducts research on the constant force controlled grinding method for curved surface workpiece;on the other hand,it studies the motion planning method for robot grinding auxiliary stroke.In order to improve the machining accuracy and overall machining efficiency of the robot grinding system,so as to promote the development of robot grinding applications.This article analyzes the characteristics of the current robot grinding system,separates the robot force control and position control,and develops a robot grinding system based on a floating platform to improve the control accuracy of the robot grinding system.The classic kinematics model of a six-degree-of-freedom series robot is established,and then the forward and inverse solutions of the kinematics are analyzed.In order to improve the efficiency and accuracy of the solution,and to avoid the singular points in the grinding trajectory of the robot,a IKFast kinematics model of the robot was established,the forward and inverse solution algorithm of IKFast kinematics was analyzed,and the inverse solution of the singular position in the robot grinding path is simulated and verified.The correct inverse solution of the singular position of the robot is obtained,which improves the stability of the robot grinding path design.Aiming at the insufficient processing efficiency of the robot grinding system,a method of motion planning for robot grinding assisted stroke was studied.The basic principles of the motion planning algorithm based on sampling are analyzed.The sampling and collision detection are the main modules that affect the efficiency of the planning algorithm.This article will focus on these two parts.Based on AABB and OBB,a robot collision detection model was established,and simulation verification was performed through the collision detection library FCL.In order to improve the search efficiency of the RRT algorithm,an improved RRT algorithm is proposed by limiting the sampling neighborhood of nodes near obstacles and adaptively adjusting the size of the neighborhood according to the number of successful node expansions to reduce the number of unnecessary collision detections.The post-processing algorithm is used to trim the path length and smooth the path.The effectiveness of the above algorithm is verified by two-dimensional environment simulation.In order to improve the control effect of robot grinding system and the machining accuracy of workpiece surface,research on constant force controlled grinding methods was carried out.Based on the analysis of the processing principle of a single abrasive particle,a mathematical model of the force on the robot end workpiece and grinding plate is established.Aiming at the problem of poor adaptability of fixing PID control parameters widely used in industry,a control method of fuzzy logic self-adjusting PID parameters is designed,which can control different errors and error changes in sections.It can perform segmented control on different errors and error changes.In order to improve the anti-interference ability of the system,various parts of the PID are improved,an extended state observer is designed,a linear auto-disturbance disturbance control method is proposed,and the closed-loop stability of the system is proven.The simulation and comparison experiments verify that the method has good dynamic performance and steady-state quality.Then,the validity of the robot grinding system with or without floating platform is verified by experiments,and various constant force control methods are compared and analyzed to verify the effect of linear auto disturbance rejection control on improving the grinding force control and the degree of improving the surface roughness of the grinding workpiece.Therefore,it is proved that the robot grinding system of floating platform can promote the robot grinding technology.In order to verify the feasibility and effectiveness of the motion planning method and constant force control strategy,a ROS-based robot grinding motion planning simulation and experiment platform and a floating platform-based robot grinding experiment platform were set up respectively.First,a large number of robot grinding motion planning simulation experiments are performed,and the data are analyzed to verify the effectiveness of the improved RRT algorithm proposed in this paper for improving the efficiency of the planning algorithm,and the physical experiments are used to verify the effectiveness of the post-processing algorithm for improving the path quality of the robot.Then,the effectiveness of the robotic grinding system of the floating platform in this paper is verified through experiments with and without floating platforms.Various constant force control methods are compared and analyzed to verify the effect of the linear auto-disturbance disturbance control on improving the grinding force control and the degree of improvement of the surface roughness of the ground workpiece.Therefore,it is proved that the robot grinding system of the floating platform in this paper promotes the robot grinding technology.