Study On The Key Technology Of Polishing Robot

The plumbing and sanitary products with complex curved surface usually need to be polished manually.There are some problems such as unstable polishing quality and poor consistency of the products.In addition,noise and metal dust generated in the production process will harm the health of the workers which makes the plumbing and sanitary industry recruit difficulties and pay higher wages.All these problems can be resolved effectively by using robots to polish.In view of this,a six-freedom polishing robot is developed under the support of National Hi-tech Research and Development Program of China(863 Program)entitled ‘Research and application demonstration of polishing robot and automatic production line',Major Project of Science and Technology of Fujian Province entitled ‘Research and industrialization of intelligent robotic polishing system'.A robotic polishing unit constructed by the polishing robot and a group of polishing machines will be joined to a robotic polishing production line to polish the plumbing and sanitary products automatically.According to the technological requirements and the instantaneous change of impact force during the course of polishing,this paper presents the design indexes of polishing robot,plans and designs its mechanical structure.The parallelogram structure is adopted at joint 2 and joint 3 in order to enhance the stiffness.The driving motors of these two joints are installed at the waist of the robot,thus decreasing the additional load and entire inertia of the robotic system effectively,improving the dynamic characteristics of the system.The movement of polishing robot end is controlled by three motors mounted at the end of the upper arm,thus decreasing the wrist weight and improving its flexibility.Aiming at the selection of key components in the development of polishing robots,this paper proposes an iterative design method based on dynamic simulation which resolves the problems of large computation and error-prone existing in the past design process of industrial robots,thus improving the efficiency and reliability of the development.In order to guarantee that the mechanical parts of the polishing robot will not fail under the extreme working conditions,the finite element analysis software is used to analyze and check the strength of the key components,and to carry out the dynamic simulation and modal testing for the polishing robot,so as to get its vibration frequency and modal.The polishing path of workpiece is obtained by artificial teaching,and the execution time of each path segment is given by the operator according to his experience.If the execution time is long,it will affect the polishing efficiency of the robot.If the execution is short,the robot will not complete the specified movement within the expected time due to its performance deficiency.Disregard for the dynamic performance of the robot will make the mechanical system wear excessively by constant vibration and shock,thereby reducing the life of the polishing robot.Aiming at this problem,this paper proposes a time optimal trajectory planning method based on the improved teaching and learning optimization algorithm.This algorithm can determine the shortest execution time of each path segment on the basis of satisfying the robotic dynamics constriants and resolve the uncertainty for determining the execution time,and can improve the efficiency of the polishing robot.Finally,the experimental study for the developed polishing robot is carried out,that is,the construction experiment of robot sand casting system,the test experiment of polishing robot parameters,the experiment of time optimal trajectory planning,the construction and polishing experiment of robotic polishing production line.The experimental results testify the correctness of the theoretical analysis and technical methods.