Abstract
We explore in-hand manipulation, especially pivoting, with a robot hand equipped with a contact area variable surface (CAVS) and a vision-based tactile sensor FingerVision. CAVS is a skin for robots where the surface friction coefficient passively changes according to the external force; during holding objects with a small force, the friction coefficient is low, while the friction coefficient becomes higher when increasing the holding force. FingerVision provides multimodal sensations, including force and slip distributions, and orientation of grasped objects. On our robot hand, CAVS is embedded on the surface of the fingertips, and FingerVision is installed under the CAVS skin. With this hand, we expect a gentle in-hand manipulation of objects where we properly control objects by slipping them on purpose to achieve a desired operation, however an adequate control method for such operations has been unclear. This paper focuses on the control methods of the CAVS+FingerVision hand for pivoting objects as an example of in-hand manipulation. Through the empirical comparisons, we found that a vibration control of fingertips achieves the best accuracy and outperforms a simple fuzzy control, and CAVS outperforms a usual flat skin.