The Research And Application Of Force Control Of Polishing Robot

With the rapid development of economy,the market needs a large number of products with high quality surface.But curved surface polishing almost depend on traditional skilled workers now,there are some disadvantages about this way,such as time consuming,the shortage of labor,harmful for people's health and poor surface quality uniformity.The research on automatic polishing of curved surface is of great significance.an automatic polishing system with an industrial robot and force signal feedback is developed in this paper,and the theory and experiment of curved surface polishing strategy using position-based force/position hybrid control algorithm are carried out.In this paper,the following aspects are studied:(1)The transformation principle of the trajectory of the contact point to the end flange of the robot is studied.Based on the description of robot end pose,the process that getting the polishing path from the contact point trajectory which has been got from UG software through the cutter compensation in workpiece coordinate system is studied;after the coordinate system of robot links are established,and the forward and inverse kinematics of polishing robot is discussed and the transformation from the movement trajectory of cutter to the movement trajectory of end flange of robot is achieved.(2)Adaptive force/position control algorithm that adjusting control parameters according system stiffness is developed.In order to ensure uniformity of the quality of the surface,a method that adjusting spindle speed according to the normal vector of the surface is proposed.the stiffness of polishing system with different polish tool is always different,The force tracking performance of system adopting fixed control parameters is unsatisfactory,facing with this situation,the curve of stiffness changing with expectation force is used to evaluate the stiffness of the system;the adaptive hybrid position/control algorithm that adjust control parameters according to the evaluation of the system stiffness is developed.Force control algorithm is simulated through the Matlab Robot Toolbox and proved effectively.(3)design and development of polishing system software based on the VC++6.0 and LabVIEW software platform is designed and developed.Position control and force control algorithm of robot is developed on VC++6.0 platform,position control is mainly used to track the input command,and position is corrected in the direction of normal vector of workpiece surface through the force control.Collection,process and storage of force and adjustment of spindle speed according to the normal vector of the surface are finished on the LabVIEW software platform.Data exchange are reached between two processes through TCP communication protocol.(4)The Establishment of automatic polishing system and the polishing experiments.The automatic polishing system with robot system,force sensor,acquisition card and so on is established,the polishing experiments are done on the plane and surface samples and the experimental results are analyzed,the correctness of theoretical algorithm is proved.