Parametric Research on Underactuated Tendon-Driven Grasping Mechanism for Space Capture Operation

Space objects always stay in rotation mode with various nutation according to their different inertia parameters during free flying. It is hard for designing a grasping mechanism to capture a rotating target with unknown velocity and unknown size. An under-actuated tendon-driven grasping mechanism is designed and researched in this paper, and which could handle the uncertainties during the capturing using its structural flexibility and strong adaption to space unknown rotating objects for taking the advantage of under-actuation. The under-actuated grasping mechanism consists of four fingers, and each finger has four joints, but driven by only one tendon and four pre-designed springs, which make it a typical under-actuated mechanism. The partial feedback linearization method is modified for the control with time varying constraints and the parametric design method is proposed to complete the tracking control of multiple joint angle using a single driven tendon, and which is validated by the simulation of the whole capturing procedure.