Realization of Precision Hand Finishing Process by Grinding Force Control Based on Hand Stiffness Estimation

Abstract

Compared with machining by automation, handwork is suitable for the high-variety low-volume manufacturing because it requires a lower cost and a lead time. However, high concentration machining should be implemented in handwork. Furthermore, mistakes generated by a disturbance from the tool rotation results in unless products and wasted materials. This study aims to address as development of the finish machining support system that make it possible to realize high accuracy machining for machining without machining mistakes. Specifically, in this study we developed the fixture-type machining support robot with the parallel link system to achieve good usability and highly accurate machining. We deal with the debburing process at the slit. The feature of this process is that the tool rotational direction is orthogonal to the feed direction. Therfore, the influence of the griding force on the worker's hand becomes more serious and have to be solved. Moreover we estimate the operator's hand stiffness from the machining force and the position of the end effector during grinding. Then, the grinding force is controlled based on the estimated worker's hand stiffness. As a result, the influence of the grinding force on the worker's hand is suppressed, and the decrease of the machining accuracy in handwork is suppressed. Finally, the effectiveness of the proposed method is shown by the grinding experiments and the user test results.