Underactuated Finger Closing Motion Control Using Dual Drive Actuation

Abstract

In this paper, a novel technique to prescribe and control the closing motion of a linkage-driven underactuated finger is presented. Since an underactuated, a.k.a self-adaptive, finger generally only has one actuator for a given number of degrees of freedom, its closing motion before making contact with an object is typically imposed by its mechanical design and cannot be changed once the finger is built. In the literature, several closing motions for underactuated fingers have been proposed each one having its own merits and in each case, associated to a particular mechanical layout. In this work, the authors propose a novel design of a partially compliant underactuated finger based on a dual drive actuation system where two motors, which can be used independently or in combination, move the finger. Each of these motors prescribes a different closing motion which has been selected amongst the most commonly found in the literature. In order to characterize the behavior and performances of this finger, a kinetostatic analysis is carried on and a lumped compliance model is developed. The geometry of the finger is then optimized using a genetic algorithm in order to achieve the desired kinematic motions.