Mini Robot Fingers Using Shape Memory Alloy

This paper presents the development of an Intelligent Mini Robot Fingers by using the Shape Memory Alloy (SMA). Taking into consideration the advantages of the SMA, a prototype of mini robot fingers is developed which will be actuated by the SMA. The mini robot fingers has 4 fingers with 3 degrees of freedom (DOF) in each finger. Hence, 12 DOFs of robot fingers are developed to allow a greater flexibility. The SMA is an actuator that permits the elimination of motor to control the movement of the robot fingers. In this study, thin SMA is selected due to low resistance, low current requirement and able cooling within a short period. The function of SMA in each finger is similar to the muscle-tendons structure of the human hand. Robot finger flexion is performed by contraction force of SMA using the characteristic of electrical resistance of SMA. The mini robot fingers have articulated fingers with cable tie (as spring) mounted on the backside of each finger. These cable ties provide the necessary, restoring force for SMA contraction as well as open the fingers for relaxation. From experiments, the grip force is 0.2 N, and can support the object up to 20 grams.