Dynamic characteristics of planar bending actuator embedded with shape memory alloy

Planar bending actuators embedded with a shape memory alloy (SMA) are a novel type of actuator capable of outputting high bending angle and bending moment. This actuator has a simple structure and high power–weight ratio, which enable it to have wide-ranging applications in the field of biomimetic robots, including biomimetic fish fins and soft robots. However, the existing mechanical model of planar bending actuators embedded with SMA is still quasi-static. Thus, the dynamic characteristics of this kind of actuator cannot be effectively described. Therefore, actuators are difficult to control during the deflection process. To effectively describe this process, a dynamic model of the actuator must be built. This paper aims to identify the dynamic characteristics of the actuator. First, a dynamic model for planar bending actuators embedded with a single SMA wire is established. Second, before SMA wire application, the constitutive characteristics are identified to obtain the necessary parameters for simulation. Third, stable planar bending actuators are fabricated for experiments on characteristics, and then the process flow chart of the planar bending actuator is developed to ensure consistency of the properties of all actuators. Finally, the actuator characteristics obtained experimentally are presented in comparison with those obtained by theoretical simulation. Analysis of the experimental data and simulation results indicates that the planar bending actuator performs better in pulse current heating mode, and that bending angle can be accurately predicted.