Design Optimization Of Robot End-effector Tool And Path Planning For Robot-assisted Polishing System

Polishing is one of key procedures in machining, which can not only increase surface finish and improve surface quality, but also positively affect the local stress concentration. Polishing workpieces with complicated surfaces is still preformed manually in present-day. This process is always time-consuming and labor-consuming and also demands for high-level polishing technology and rich polishing experience. Some useless workpieces are sometimes produced due to mistakes made in the process of polishing. The automatic polishing system can solve the above problems caused by manual polishing, and thus satisfy the needs of high efficient machining with great quality for contemporary consumers. Compared to machine tool, robot has many merits including the larger reachable workspace, multiple degrees of freedom and low cost, so that it has better polishing performance and capability of machining workpieces with more complex surfaces, and has potential to be widely used in automatic polishing system. But because of the technology complexity of developing and applying robot-assisted polishing automatic system, including designing and manufacturing required hardware, designing efficient tool path, and holding the stable polishing force, designing the complicate motion of polishing tool, automatic implementation of polishing plan and setting up all-round and complex feedback system, the abroad and home automatic polishing systems put into market are rare. The purpose of our research is studying some problems confronted when building robot-assisted polishing free-form surfaces automatic system, mainly containing the following aspects:After fully understanding the requirements of designing polishing tool based on polishing technology, a robot end-effector polishing tool held by the arm of robot is designed. It provides the conditions for polishing with compliance and thus achieving better polishing performance. Furthermore, the multiple-objective optimization based on the integration of ADAMS and iSIGHT is executed, in order to provide the theoretical basis for structure improvement and adjustment of this robot end-effector polishing tool.After fully understanding the requirements of planning polishing path based on the needs of high efficient, high quality machining, a plan for arranging polishing path is presented, which has capability of producing uniform polishing path covering free-form surfaces, and thus solves the problem of planning polishing path automatically. Furthermore, a simulation based on this approach is done in MATLAB and verifies the efficiency of this method.A control method of force tracking is presented to satisfy the needs of holding stable polishing force when polishing. This method is using the force difference to modify position difference of inner loop, which may not only maintain the stable polishing force, also could ensure the executive body polishing along the accurate path. Additionally, a block diagram is built in Simulink and the robot model is set up in SimMechanics of Simulink in order to verify the feasibility of the proposed method.This study plays a role in providing theoretical value for setting up robot-assisted polishing free-form surfaces automatic system in order to satisfy the needs of high efficient machining and high quality products.