A worming torque actuator using shape memory alloys SMA

In this paper a new torque motor based on shape memory alloys (SMA) is developed. A mechanism has been designed to convert rotary movement to linear. A mathematical model of the mechanism is derived for prediction of angle of twist for a given constant load. This mechanism has been placed in a vehicle as an engine to produce necessary force for movement. Due to the long recovery time of SMA's, the bias spring provides bias force to make SMA spring return to its original configuration. This mechanism has discontinuous movement and it can be simulated with worming movement. In order to resolve this problem and to achieve continuous movement a new mechanism is introduced by placing several SMA's spring without any bias in the mechanism. A controller is necessary to establish a harmony between springs. The main advantage of this design is to provide large forces and momentum by small springs.