Robotics Research toward Explication of Everyday Physics

Abstract

It is commonly recognized now at the end of the 20th century that a general 6- or 7-degree-of-freedom robot equipped with an endeffector with simple structure is clumsy in performing a variety of ordinary tasks that a human encounters in his or her everyday life. In this paper, it is claimed that the clumsiness manifests the lack of our knowledge of everyday physics. It is then shown that even dynamics of a set of dual fingers grasping and manipulating a rigid object are not yet formulated when the fingers’ ends are covered by soft and deformable material. By illustrating this typical problem of everyday physics, it is pointed out that explication of everyday physics in computational (or mathematical) languages is inevitable for consideration of how to endow a robot with dexterity and versatility. Once kinematics and dynamics involved in such everyday tasks are described, it is then possible to discover a simple but fine control structure without the need of much computation of kinematics and dynamics. Simplicity of the control structure implies robustness against parameter uncertainties, which eventually allows the control to perform tasks with dexterity and versatility by using visual or tactile sensing feedback. Thus, a key to uncover the hidden secret of dexterity is to characterize complicated dynamics of such a robotic task as seen when a set of multifingers with multijoints covered by deformable material interacts physically with objects or an environment. It is pointed out throughout the paper that some of the generic characteristics of dynamics that everyday physics encounters must be “passivity,” “approximate Jacobian matrix of coordinates transformation,” “feedback loops from sensation to action,” “impedance matching,” and “static friction.”