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چكيده انگليسي :

71 Modeling and Design of a Controller for a Finger Actuated by Shape Memory Alloys Hadi Karimi H Karimi@me iut ac ir Date of Submission July 20 2011 Department of mechanical engineering Isfahan University of Technology Isfahan 84156 83111 Iran Degree M Sc Language Farsi Mehdi Keshmiri MehdiK@cc iut ac ir Mahmoud Kadkhodaei Kadkhodaei@cc iut ac ir Abstract Shape memory alloys are a group of smart materials which are of a lot interest in different fields such as robotics One of their applications in robotic systems is manufacturing the actuators for prosthetic hands and fingers Some of these actuators advantages are mechanical simplicity small size high power to weigh ratio and silent performance Shape memory alloys have a complex electro thermo mechanical dynamic and due to which their modeling is difficult In fact the main problem for the modeling is that their temperature and stress change simultaneously So choosing a proper model which can predict shape memory alloys behavior in presence of temperature stress dependency is so important The kinetics and constitutive models are needed to model shape memory alloys The kinetics model shows the phase transformation and the constitutive model presents the relationship between stress strain and temperature Nonlinear hysteresis and uncertainties makes shape memory alloys actuators control difficult Modeling of shape memory alloys in a way to be used in control algorithm choosing a proper control method to compensate for hysteresis and overcome the uncertainties problem as well as kinetics of the robot finger and eventually studying the results are the main parts of this research In this study for investigating the shape memory alloys behavior and controllers performance a rotary manipulator which is actuated with shape memory alloys is modeled Also changing the temperature of the SMAs is done by joule heating The simulations are done with MATLAB software For the rotary manipulator mentioned some control algorithms are designed First a position based PID controller is designed and it is found that this controller cannot perform well for all the desired angular positions set points Also the performance of the controller is not good for tracking Regarding that the temperature and transformation of shape memory alloys depends on the stress choosing the stress as the set point can be so efficient So a sliding mode controller based on the stress of the SMA wire is designed The results show better performance for this controller than the PID one for both regulation and tracking By studying the results it is found that choosing different values for the slope of sliding surface have an effect on the performance of the controller So to have a better performance a fuzzy tuner is designed for tuning the slope of sliding surface The position error is the input for the fuzzy tuner and the slope of sliding surface is the output The better performance of the controller than the previously designed controllers is showed Finally to study the robustness of the fuzzy sliding mode controller the performance of the controller is investigated by considering the moment of inertia damping coefficient and heat convection coefficient as the uncertainties The performance of the proposed controllers is studied for both a 1DOF and a 3 link rotary manipulator which are actuated with shape memory alloys The results show that the sliding mode controller cannot perform well for all set points for the 3 link manipulator but the fuzzy sliding mode controller does have a good performance for all set points Key words shape memory alloys sliding mode controller fuzzy tuner Robustness

كريمي، هادي

مدل سازي و طراحي كنترل كننده براي يك انگشت داراي آلياژهاي حافظه دار

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