Large Scale Optical Polishing Robot’s Local Polishing Trajectory Planning

With the advance of microelectronics, and optical communications, and aerospace, and astronomical technology, the optical manufacturing technology which has a long history develops rapidly. Along with the Computer Controlled Optical Surfacing(CCOS) technology matured increasingly, it has been widely used in large scale optical element processing. But for the high precision large scale aspheric workpiece, due to the brittleness of materials and optical itself’s strict requirement of the precision, there is a big gap to meet demand. At the same time, the important technology of industrial robots has breakthrough after decades of progress. It can improve the production’s efficiency and reduce the requirement for operators. It’s very suitable for mass production.Large scale optical polishing robot is an effective means to realize the automation of large-caliber optical aspherical lapping, it can finish the later polishing period processing in high quality and low cost. In the later period of polishing, the peak area is discrete and uncertain, local polishing trajectory is trajectory that polishing machine traversing all high points in this region. Therefore, on the basis of the craft requirements, how to plan out a trajectory which is shorter and joint angle changed smoothly is the main problem of this article to solve. This subject comes from the "863" project "large-scale optical intelligence and polishing robot". In this paper, the research work includes the following several parts:① Introduce polishing robot processing craft and provide the process background. According to the Preston theory, it builds the mathematical model of polishing robot CCOS planetary polishing machine. Then gets the removal function and analyze the main effect parameters. At last, using convolution iteration method and Fourier transform algorithm to calculate the dwell time function and comparing the two algorithms.② Research the polishing robot kinematics theory. Based on the analysis of the large scale optical polishing robot’s structure, it establishing the link coordinate system and obtained D-H parameters. Then by solving the robot kinematics equation and inverse- kinematics, it can be clearly corresponded the relationship between Cartesian space position and posture to each joint angle in joint space.③ Research the polishing robot’s local trajectory planning. Firstly, according to the surface error to divide contour level, and determine the peak area. Secondly, it as the scope of the removal function to be the grid spacing, then to determine the robot trajectory point. Thus it can translate trajectory planning into traveling salesman problem. Finally, it can use ant colony algorithm and cubic polynomial differential algorithm respectively to planning the trajectory in Cartesian and joints space. Realizing the request that robot has a shorter movement distance and the joint angle changed smoothly.④ The polishing robot experiment research. Introduce the polishing process and the large scale optical robot system. On the premise of craft requirement, as an example of the 1.9M diameter parabolic mirror, using of local polishing trajectory to experiment. The result fulfills the requirements of process precision and the processing task. It verifies the local polishing method’s feasibility.