Fuzzy Logic Controller for Shape Memory Alloy Tendons Actuated Biomimetic Robotic Structure

Abstract

The paper studies the fuzzy logic controller for a shape memory alloy (SMA) biomimetic (tentacle type) robotic structure. A tentacle manipulator is a mani pulator with a great flexibility, with a distribute d mass and torque that can take any arbitrary shape. Considering the influ ences of the environment temperature, for SMA actuation, a special attention has to be paid to the adaptation of contr ol strategy to external condition. First, are prese nted experimental results related to SMA physical characterizations u sing Thermal Analysis Methods. In the next section SMA tentacle's robotic structure conventional control (P, PI, PD, and PID controller) is tested and the results are c ommented. Fuzzy logic approach conducts to suitable for the tentacl e SMA based structure, considering the repeatabilit y of the results. The proposed control strategy is based on the Direc t Sliding Mode Control (DSMC), which controls the trajectory, towards the switching line and then the motion is f orced directly to the origin, on the switching line . A fuzzy controller is proposed and the fuzzy rules are established by using the DSMC procedures. In conclusions conventional control structures offer good performances in term of the t ime response and simple structure, but not guarante e the repeatability of the results as proposed DSMC controller.