Coupled Bending Inwards Motion and Control Strategy Analysis of a Cable-Driven Underactuated Finger

Abstract

Motion strategy analysis at the pre-bending stage is a fundamental component of underactuated finger grasp research. This study presents the pre-bending motion strategy and corresponding analysis of cable driving forces a 3-DOF underactuated finger comprising cable truss units. The structure and four motion strategies at the pre-bending stage are illustrated. The equivalent joint-driven and quasi-static motion models are established in the case where one or two cable driving forces drive the finger. Quasi-static motion model is established, and four typical quasi-static coupled motion space and distributions of corresponding cable driving forces are analysed. In accordance with the kinetic energy theorem and Lagrange's dynamical method, a sampled and general dynamic model is established. Through matrix transformation, a hypothetical "PPA" type dynamic model is obtained. On the basis of the "PPA" dynamic model, three grasping control strategies at pre-bending stage are carried out. Valid simulations and experiments are conducted to verify the accuracy of the coupled bend inwards motion and control strategy. INDEX TERMS coupled motion, control strategy, quasi-static motion, cable-driven finger, underactuated mechanismThis work is licensed under a Creative Commons Attribution-NonCommercial-NoDerivatives 4.