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

The paper studies the fuzzy logic controller for a shape memory alloy (SMA) biomimetic (tentacle type) robotic structure. A tentacle manipulator is a manipulator with a great flexibility, with a distributed mass and torque that can take any arbitrary shape. Considering the influences of the environment temperature, for SMA actuation, a special attention has to be paid to the adaptation of control strategy to external condition. First, are presented experimental results related to SMA physical characterizations using 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 commented. Fuzzy logic approach conducts to suitable for the tentacle SMA based structure, considering the repeatability of the results. The proposed control strategy is based on the Direct Sliding Mode Control (DSMC), which controls the trajectory, towards the switching line and then the motion is forced 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 time response and simple structure, but not guarantee the repeatability of the results as proposed DSMC controller.