Enhancement of force control performance of macro-micro system based polishing robot with gravity compensation

In a fine mold manufacturing process, the polishing process plays an important role in enhancing the surface quality and is performed manually by skilled workers. However, there are many problems such as decrease in skilled workers, health hazards due to scattering of abrasives, and difference in surface quality due to difference in the proficiency. Hence, there is a strong demand for automation of the polishing process at present. In this research, a robot polishing system that applies macro-micro mechanism is proposed. The functional polishing module of the end effector is developed and attached to the hand of the serial link robot. Tool path and posture are controlled in a serial link robot as a macro mechanism, and polishing force and tool rotation speed are controlled in the developed polishing module as micro mechanism. This mechanism ideally controls position, force, and rotation speed at the same time. An interlocking control system for position and force has already been constructed. In this paper, we constructed gravity compensation and evaluated the force control performance of the constructed system. Through the evaluation, the followability of the estimated reaction force to the command force and the validity of the actual force behavior measured by the force sensor were evaluated.