Fuzzy Logic Position Control of a Shape Memory Alloy Wire (original) (raw)
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Force control of a shape memory alloy wire using fuzzy controller
Modeling, Signal Processing, and Control for Smart Structures 2008, 2008
An experimental setup is designed and fabricated to measure the force induced by voltage in an SMA wire. Using autoregressive model with exogenous input (ARX) method for system identification of the experimental data, two appropriate transfer functions of the force in SMA wire versus the applied voltage during each of heating and cooling processes were derived. Afterwards, a conventional PID controller and a self-tuning fuzzy PID controller were designed to control the force in SMA wire. The latter control algorithm is used by tuning the parameters of the PID controller thereby integrating fuzzy inference and producing a fuzzy adaptive PID controller, which is used to improve the force control performance. The responses of the system with the both designed controllers for different inputs are simulated and compared to each other. At the end, simulation results show that in force control of the SMA wire, self-tuning fuzzy PID controllers are more efficient than conventional PID controllers.
Evolving Fuzzy Models of Shape Memory Alloy Wire Actuators
2021
This paper suggests Takagi-Sugeno-Kang (TSK) fuzzy models that characterize the position of Shape Memory Alloy (SMA) wire actuators. The systems dynamics are important because, since SMA wire actuators are included in control systems in various critical applications, the position control systems have to ensure very good performance indices. The output of these systems, viewed as controlled processes, is the position of the SMA wire actuators, and the input is the current signal which supplies the actuator, i.e., it flows through the wire. Starting with these two input and output signals directly related to the process, different numbers of additional TSK fuzzy model inputs and outputs obtained from past inputs and/or outputs are considered. The structures and parameters of the fuzzy models are evolved by an incremental online identification algorithm. Two evolving TSK fuzzy models are derived, they are next tested against the experimental data and compared. The experimental results ...
Study and Modeling Behavior of Shape Memory Alloy Wire
2017
From early 20s till today, advancement in the technology is highly speeded up. Every innovation talks about the incorporation of intelligence and smartness into the system. This smartness is added by various materials categorized as smart materials. One of the materials from the same category is Shape Memory Alloy (SMA). Proper expected functioning of the material and system, it is necessary to know the behavior of the material. Hence the material is studied and later mathematically modeled to track the response of material for an input. The type of excitation and excitation duration plays a very crucial role, Hence a material is excited with various signals such as DC, triangular and trapezoidal wave for which a respective temperature profile is obtained. Change in temperature from 50 to 100 0 C leads to phase transformation. The temperature dependent transformation is mathematically modeled using different mathematical functions and Liang and Rogers, Duhem models are compared with...
Shape memory alloy (SMA) actuators exhibit considerable hysteresis between the supply voltage (conventionally used in resistive heating) and strain characteristics of the SMA. Hence, it is not easy to control the strain of a thin-SMA wire, unless a model is developed that can match the actuator's nonlinearities for predicting the supply voltage required by the SMA system accurately. The work presented in this paper proposes the use of a black-box technique called the adaptive neurofuzzy inference system (ANFIS) to study the hysteretic behavior of SMAs. The input parameters for such an ANFIS model would be a physical variable at time t and at a time t + n, where n is a time shift. The present work studies the effect of a time shift on the actuator nonlinearities for two ANFIS models. One of the models studies the relationship between the desired displacement of an SMA and the supply voltage across the SMA, while the other model predicts the actual displacement of an SMA from the feedback temperature. A novel SMA–Constantan thermocouple records the feedback temperature.
Smart Materials and Structures, 2012
This paper presents an experimental investigation of position control of a shape memory alloy (SMA) wire actuator with adaptive and modulated adaptive controllers. The transfer function model of the SMA wire actuator is determined from the experimental open loop response. Adaptive controllers, namely LMS–GSPI, RLS–GSPI and Kalman–GSPI, and modulated adaptive controllers using pulse width modulation (PWM) are designed. The performances of these controllers are experimentally investigated for the position control of an SMA wire actuator with and without thermal disturbance. Experimental results demonstrate that the modulated adaptive controllers outperform adaptive controllers.
Precise position control using shape memory alloy wires
Turkish Journal of Electrical Engineering Computer Sciences, 2010
Shape memory alloys (SMAs) are active metallic "smart" materials used as actuators and sensors in high technology smart systems . The term shape memory refers to ability of certain materials to "remember" a shape, even after rather severe deformations: once deformed at low temperatures, these materials will stay deformed until heated, whereupon they will return to their original, pre-deformed "learned" shape .
2010
The paper introduces a contribution in the design of adaptive controllers. A PID adaptive controller derived using the mathematical formulas of model reference adaptive control (MRAC) combined with the self tuning adaptive control (STC). The controller tested in the position control of shape memory alloy (SMA) wire and enhanced by experiment to an Enhanced adaptive controller which is more robust and consistent than other classical adaptive controllers derived based on mathematical means. This controller is used to tune the parameters of a PI controller that could control the position of an SMA wire actuator. The performance of both the enhanced adaptive controller and the PI controller are compared under different sets of excitation frequencies of input current to the SMA wire showing robust control and low percentages of error rates.
A Temperature-based Controller for a Shape Memory Alloy Actuator
Journal of Vibration and Acoustics, 2005
This paper presents a robust nonlinear control that uses a state variable estimator for control of a single degree of freedom rotary manipulator actuated by shape memory alloy (SMA) wire. A model for SMA actuated manipulator is presented. The model includes nonlinear dynamics of the manipulator, a constitutive model of the shape memory alloy, and the electrical and heat transfer behavior of SMA wire. The current experimental setup allows for the measurement of only one state variable which is the angular position of the arm. Due to measurement difficulties, the other three state variables, arm angular velocity and SMA wire stress and temperature, cannot be directly measured. A modelbased state estimator that works with noisy measurements is presented based on the extended Kalman filter (EKF). This estimator estimates the state vector at each time step and corrects its estimation based on the angular position measurements. The estimator is then used in a nonlinear and robust control algorithm based on variable structure control (VSC). The VSC algorithm is a control gain switching technique based on the arm angular position (and velocity) feedback and EKF estimated SMA wire stress and temperature. Using simulation it is shown that the state vector estimates help reduce or avoid the undesirable and inefficient overshoot problem in SMA one-way actuation control.
Self-sensing shape memory alloy wire actuators using Kalman filters
2017
Shape Memory Alloys (SMA) are known to undergo large deformation at low temperature and can recover the same while subjected to high temperature. This ability offers SMA as a potential candidate for actuation. They offer large displacement, typically 4-5% of the length in case of wire, and considerable force, equivalent to 300-400 MPa, at low operating speed, in the range of 0.1-10 Hz. The SMA based actuators are found to be very promising in case of miniature applications, where, size, weight and smooth operating conditions are important. Out of all the forms available, SMA wire based actuators are mostly used, because these can easily be activated through resistive heating. In addition, the SMA materials exhibit nonlinear and hysteretic behavior; offering challenges in terms of controlling the actuators for practical applications. In literature, sophisticated control algorithms have been proposed, requiring one or more feedback sensors. The introduction of feedback sensors makes s...
Dynamic control of plate with embedded shape memory alloy wires
Smart materials such as shape memory alloys (SMAs) and piezoelectric ceramics are increasingly being used in vibration control applications. In this paper, the alteration of the natural frequency of composite structures using embedded NiTiNOL-based shape memory alloy wires will be presented. The governing equations will be solved analytically and numerically to show the effect of recovery stresses acting in wires and the subsequent effect it has on stiffness of the plate and hence its natural frequency. The results showed that the natural frequencies of composite plate change slightly at a temperature above the austenite finish temperature of the embedded pre-strained SMA wires. Different SMA wires arrangements will be studied in order to optimize the control strategy.