Bi-directional Smart Linear Actuator with Synergistic Bias

Abstract:
A light and the compact bi-directional actuator is designed based on shape memory alloy (SMA) technology. This bi-directional controlled SMA wire integrated differentially configured compliant linear actuator shows significantly improved actuation speed when compared to the traditional bias and differential type SMA actuator configurations for bidirectional movement. The structure of the actuator comprises a pair of antagonistic/differential SMA based actuator modules, each created using SMA wire(s) and passive compression spring, assembled about the guide shaft. The differential arrangement and synergistic biasing enable to increase the actuation speed and obtain the bidirectional translational movement; the compression spring is employed to reduce the total stiffness of the SMA based actuator module and to provide restoring force to the de-activated SMA wire. The mechanical design offers a direct linear and compliant actuation, without involving additional components. The basic performance characteristics of the actuator are obtained experimentally. Further, the trajectory tracking of the control signals are observed from its estimated model.