Development On Shape-adaptive Polishing Robot For Large Free-form Surface

At present, in the aerospace industry, marine and automotive manufacturing, the polishing of large free-form surfaces is still performed manually. Manual polishing has the disadvantages of low efficiency, high labor intensity, and poor processing capacity, which restrict the advance of the industries. Because the large polishing equipment matching with workpiece is costly, there are some contradictories on system stability, working range and accuracy. Therefore, it's become effective to develop new automation polishing technology and equipments based on new ideas to adapt to large free-form surface precision polishing demand, which are both to meet the project requirements and consistent with economic needs.Based on abundant data, this thesis designs structure of a small robot which can be adaptive to the changes of large free-form surface curvature, and move freely on the surface to polishing. By analyzing features of large free-form surface and the arm movement of human in manual polishing, the thesis determine the technical composition of the robot. The polishing robot is constructed of two-wheel drive and support wheel. The support wheel is instead of grinding plate. Therefore, the driving wheels of the robot are independently driven while the grinding plate which is in ring surface as the third pivot. Tool system uses two-axis rotating in space to form an omnidirectional wrist to adapt to the changes of surface.This thesis establishes the kinematic model of travel mechanism and polishing tool of robot, analyzes the motion characteristics and processing of polishing robot, and establishes the equation of its posture change. The virtual prototyping of the polishing robot and tool system are created based on ADAMS. By simulation experiment on two typical free-form surfaces---sine surface and arc surface, the adaptive capability, tracking capability and the polishing surface pressure of the tool system and polishing robot are analyzed. An experiment prototype robot is built to investigate the tracking capacity of the polishing robot. And a set of LabVIEW software is programmed for data acquisition and motion control of the travel mechanism. According to the movement of robot in the inclined plane experiments, the investigation results demonstrate the polishing robot has good adaptive and move capability.