A compact and flexible actuator based on shape memory alloy springs

Abstract

A new structure of compact flexible actuator based on shape memory alloy (SMA) springs is presented. Three SMA springs, which are trained to shrink as the phase transition occurs, are embedded off-axially and movably in a silicone rubber rod solidified at room temperature. The spatial bending, which is accomplished through heating SMA springs by suitable current, could restore flexibly as soon as heating is stopped. Thus, the compact, flexible, integrative actuator is built. Being possessed of the merits such as high load—weight ratio, low energy dissipation, and direct driving, the actuators can implement simple drive, precise operation, and flexible movement. On the basis of the analysis of an elastic rod with distributed and concentrated loads, the design of the rod and SMA springs is investigated. Subsequently, the manufacture of the prototype is carried out and the control system is implemented. Finally, the experiments are carried out to validate the virtues of the actuators.