Rotational Angle Trajectory Tracking of a Twisted Polymeric Fiber Actuator by the Combination of a Model-Based Feed-Forward and Estimated Temperature Feedback

In this letter, an angular trajectory tracking controller for a twisted polymeric fiber (TPF) actuator by the combination of a model-based feed-forward and estimated temperature feedback is proposed. TPF actuator is one of the soft actuators that can produce a rotational motion, which is made by twisting a nylon yarn and thermally treating it. Adding a feed-forward controller with a feedback controller makes it possible to reduce a phase lag and realizes a higher frequency response compared with using only the feedback controller when performing a time-dependent trajectory tracking. First, temperature-angle, resistance-temperature, and voltage-temperature models are composed, respectively, and then combined in order to design a feedforward controller. Next, parameter estimation is performed through experiments using the prototype of a rotational actuation module. Finally, trajectory-tracking experiments are conducted using a prototype to demonstrate that the proposed method can improve the tracking performance by reducing the phase lag.