Abstract
We propose a fundamental control method for anthropomorphic hands with fruitful passivity, preparing eighteen primitive grasping styles every form of object (spherical, cylindrical, rectangular parallelepiped) and make transition control among several styles corresponding to desired handling. Also, we constructed a control method utilizing passivity for making grasping and handling a circular cross-section object stably. In the first phase of grasping, this method allows robotic hands to esteem the position of object the moment touching at finger cushion and to re-grasp it more stably by making gradients at thumb and index finger parallel. During the handling phase after grasping, the method also enables to maintain gradients at thumb and index finger contacting with an object to be parallel for achieving high stability, based on adaptively coordinated-handling control in between active PIP joint and mechanically passive DIP one. Experimental experiments demonstrating that TWENDY-ONE hand successfully grasps various sized object with the pre-defined grasping styles and adaptively handles a cylindrical object using multi-fingers by transit among the styles even if no size information is given and also handles an object from finger cushion-grasping to palm one while keeping stability confirms the usefulness of the control methods.
