An open-architecture-based hybrid control method with a weak coupling between position feedback-loop and force feedback-loop (application to a mold polishing robot)

Cutter location (CL) data with normal vectors can be used for not only a desired trajectory of tool's translational motion but also desired force directions for a mold polishing robot. In this paper, such normalized tool vectors are systematically generated from 3-axis CL data. The resultant CL data allow the polishing robot with an abrasive tool to realize a teaching-less operation of position and force. The present robot can also control the polishing force consisting of the contact and kinetic friction forces. During the polishing of a mold, a position feedback loop has a delicate contribution to the force feedback loop in Cartesian space so that a stable force control and an accurate pick feed control can be simultaneously achieved. The effectiveness and validity of the proposed robot have been proved by actual polishing experiments using a duralumin mold with curved surface.