Implementation of robot finger using shape memory alloys and electrical motors

This paper introduces a mechanical structure and control technique of a second robot finger as a system integration. The finger has been developed as element of a robot hand which has 20 joints and 16 degrees of freedom in order to express fingerspelling. The first joint of the finger is driven by small DC servo motor and the second and third joints are driven by shape-memory alloy (SMA) wires. The hand system consists of four parts of "hand mechanism", "drive device", "control unit" and "man-machine interface". In order to implement cooperative smooth motions, the control system is designed based on experimental results related to system identification, and the position trajectory refernce is designed considering time delay on the SMA. Finally, we report the simulation and experimental control results to evaluate the presented system.