Development of a Miniature Robot Finger with a Variable Stiffness Mechanism Using Shape Memory Alloy

Abstract

This paper describes a miniature robot finger which uses shape memory alloy as the actuator. Aiming at developing robot hands to perform human work instead of men, numerous researches have been conducted. By miniaturizing robot hands, execution of more detailed work becomes possible. In developing miniature robot hands for dexterous manipulation, it is necessary to consider miniaturizing and simplification. The miniature robot finger proposed in this paper is driven by shape memory alloy (SMA) wires. The structure of the robot finger imitates the musculoskeletal system of humans, since SMA wires exhibit nonlinear features similar to human muscles. Highly precise position control of fingertip is performable by using SMA owing to its shape memory effect. Force control of the fingertip is performed by measuring the tension of the SMA wire. We used strain gages to measure tension. We confirmed that stiffness control of the finger joint can be conducted by controlling tension of the SMA simultaneously.