Single-joint driving system of bionic finger based on shape memory alloy

This paper presents the design and domination of single-joint driving system of bionic finger based on shape memory alloy (SMA). A pre-shaped SMA wire is employed as the finger skeleton and the joint. To realize bending and stretching the proposed finger flexibly, a couple of thermoelectric devices (TEDs), being as a drive, touch a certain location of the SMA wire which acts as the joint of the finger heating and cooling the wire directly. In order to control angles of the finger joint accurately and rapidly, the model of relationship between the temperature and the corresponding angle of the finger are developed. A control strategy based PI control is discussed to improve the dynamic response time of the system. Several experiments are used to evaluate the dynamic and steady state performances, and the results show that the proposed driving system controls bend and stretch of the finger with satisfied static accuracy and rapid dynamic response.