Design and Evaluation of Three-Phalange Underactuated Adaptive LSDH Finger

Abstract

The design of the terminal operation tool of the in-orbit service of the space station faces the difficult problem of complicated operation in a small space. Anthropomorphic hand tools operation has long been a controversial topic, partly because of dexterity and adaptive capabilities. Here, we propose a novel underactuated hand named linkage spline dexterous hand (LSDH). The underactuated LSDH finger can adapt to irregular objects without requiring complicated parallel linkages. Furthermore, the grasping process of the finger is composed of two sequential steps: initial parallel pinching and indirect adaptive grasping. To delve into the intricacies of the grasping mechanism exhibited by the finger, kinematics, force analysis, and performance evaluation are performed. The contact force between the object and the middle phalange can reach 20 N, marking an advancement compared to the recent literature. To evaluate the performance of the LSDH finger, the dexterity and the workspace of the LSDH finger are analyzed. It only requires one motor to drive the movement of three phalanges to adapt to different shapes and different sizes (diameter 30 mm–60 mm). When the length of the proximal phalange and the proximal shaft rotation angle get the max value, the dexterity can reach the best effect. The dexterity of the finger is up to 0.9 after various size optimizations under the size limitation.