Analytical Description of SMA Actuator Dynamics based on Fermi-Dirac Function

K. Kluszczyński and M. Kciuk Silesian University of Technology, Faculty of Electrical Engineering, Chair of Mechatronics, Akademicka 10a, 44-100 Gliwice, Poland

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The paper deals with possible application of the very promising SMART material - shape memory alloy. At the beginning the laboratory stand for investigation on dynamic behaviour of a SMA linear actuator is presented and results of measurements for the chosen SMA actuator F2000 are depicted and discussed. In the next stage the authors propose to use the so-called Fermi-Dirac function for description of SMA linear actuator dynamics. Applying this function for determining basic performance curve: shortening Δ L versus time t for different loads F requires proper modification of the Fermi-Dirac function and its conversion: in the one-parameter family (with parameter F). Coefficients of this family are determined with the help of Hooke-Jeeves optimization algorithm and on the basis of experimental findings separately for activation and deactivation process. The both derived expressions were validated by additional laboratory investigations. Finally, the elaborated descriptions was employed in design procedure of a robot gripper. It was shown that the results of measurements for the gripper prototype are in satisfactory agreement with the results of calculations.

DOI: 10.12693/APhysPolA.131.1274 PACS numbers: 87.85.St, 71.20.Gj, 71.20.Be