Development of an Extended Kalman Filter for Self-Sensing Application of Shape Memory Alloy Wire Actuator

2015 ◽  
Author(s):  
H. Gurung ◽  
S. Karmakar ◽  
A. Banerjee
Keyword(s):  
Heat Transfer ◽  
Kalman Filter ◽  
Shape Memory Alloy ◽  
Shape Memory ◽  
Convective Heat Transfer ◽  
Extended Kalman Filter ◽  
Convective Heat ◽  
Electrical Resistance ◽  
System Response ◽  
Sensing Application

This paper presents the development of an Extended Kalman Filter (EKF) for self-sensing application of Shape Memory Alloy (SMA) wire actuator. The EKF is used to estimate the end displacement of a SMA wire actuated compliant link using the electrical resistance variation of SMA. The model of the system is developed by coupling the stress-deformation relation of the link along the direction of the SMA actuator with the phenomenological model of the SMA wire. In EKF, the stress and temperature of SMA comprise the state vector and its electrical resistance is considered as output. The developed EKF is validated, by comparing the estimated system response with that of the model for a given input signal. The effects of the process and measurement noise on the estimation error have also been studied. An experimental setup is developed to measure the change in electrical resistance of the SMA wire, voltage drop across the same, and the associated end-displacement of the compliant link. Using the measured data, the end-displacement of the link is estimated using EKF and compared with the experimentally measured end-displacement. Significant qualitative agreement is observed. It is noted, that the convective heat transfer coefficient significantly affects the quantitative discrepancy. Thus the coefficient of convective heat transfer is determined, so as to minimize the gap between the two responses for a particular applied voltage. The coefficient is then used for different set of experiments, revealing the true potential of the EKF based approach to harness the self-sensing capability of SMA.

The Application of Shape Memory Alloy as Vortex Generators and Flow Control Devices for Enhanced Convective Heat Transfer

2007 ◽  
Author(s):  
Mohd. S. Aris ◽  
Ieuan Owen ◽  
Chris. J. Sutcliffe
Keyword(s):  
Heat Transfer ◽  
Flow Control ◽  
Shape Memory ◽  
Convective Heat Transfer ◽  
Heat Transfer Enhancement ◽  
Convective Heat ◽  
Vortex Generators ◽  
Transfer Enhancement ◽  
Flow Control Devices ◽  
Control Devices

This paper is concerned with convective heat transfer enhancement of heated surfaces through the use of vortex generators and flow control devices. A preliminary proof-of-concept investigation has been carried out into the use of active vortex generators and flow control elements, both manufactured from Shape Memory Alloys (SMAs) which are activated at set temperatures. The vortex generators change their shape to intrude further into the flow at high temperature to enhance heat transfer, while they maintain a low profile at low temperatures to minimise flow pressure losses. One set of vortex generators was made from pre-alloyed powders of SMA material in an advanced rapid prototyping process known as Selective Laser Melting (SLM). Another set of devices was also made from commercially available flat annealed thin SMA sheets for comparison purposes. The flow control elements are devices that preferentially guide the flow to heated parts of a surface, again using temperature-activated SMAs. Promising results were obtained for both the vortex generator and flow control device when their temperatures were varied from 20° to 85°C. The vortex generators responded by increasing their angle of attack from 20° to 35° while the wavy flow control elements straightened out at higher temperatures. As the designs were two-way trained, they regain their initial position and shape at a lower temperature. The surface temperature of the heated plate on which the active devices were positioned reduced between 8 to 51%, indicating heat transfer enhancement due to the generated vortices and changes in air flow rates.

Design of Extended Kalman Filter for a Shape Memory Alloy Manipulator

2003 ◽  
Author(s):  
Mohammad H. Elahinia ◽  
Hashem Ashrafiuon ◽  
Mehdi Ahmadian ◽  
William T. Baumann
Keyword(s):  
Kalman Filter ◽  
Shape Memory Alloy ◽  
Shape Memory ◽  
Extended Kalman Filter ◽  
State Space Model ◽  
Angular Position ◽  
The State ◽  
State Variables ◽  
Time Step ◽  
Noisy Measurements

This paper presents an Extended Kalman Filter (EKF) for estimation of the state variables of a single degree of freedom rotary manipulator actuated by Shape Memory Alloy (SMA). A state space model for the SMA manipulator is presented. The model includes nonlinear dynamics of the manipulator, constitutive model of Shape Memory Alloy, and the electrical and heat transfer behavior of SMA wire. In the experimental setup, angular position of the arm is the only state variable that is measured. The other state variables of the system are arm’s angular velocity, SMA wire’s stress, temperature and the Martensite factor, which are not available experimentally due to measurement difficulties. Hence, a model-based state estimator that works with noisy measurements is presented based on the Extended Kalman Filter. This estimator predicts the state vector at each time step and corrects its prediction based on the angular position of the arm which can be measured experimentally. The state variables collected through model simulations are also used to evaluate the performance of the EKF. Several EKF simulations are presented that show accurate, and robust performance of the estimator for different types of inputs.

Application of the Extended Kalman Filter to Control of a Shape Memory Alloy Arm

2003 ◽  
Author(s):  
Mohammad H. Elahinia ◽  
Hashem Ashrafiuon ◽  
Mehdi Ahmadian ◽  
Daniel J. Inman
Keyword(s):  
Kalman Filter ◽  
Shape Memory Alloy ◽  
Shape Memory ◽  
Extended Kalman Filter ◽  
State Vector ◽  
Angular Position ◽  
The State ◽  
State Variables ◽  
Time Step ◽  
State Variable

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 model-based state estimator that works with noisy measurements is presented based on the Extended Kalman Filter (EKF). This estimator predicts the state vector at each time step and corrects its prediction 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. The state vector estimates help reduce or avoid the undesirable and inefficient overshoot problem in SMA one-way actuation control.

A Heat Transfer System Identification Method for Shape Memory Alloy Wires

2017 ◽  
Author(s):  
Cody Wright ◽  
Onur Bilgen
Keyword(s):  
Heat Transfer ◽  
System Identification ◽  
Shape Memory Alloy ◽  
Shape Memory ◽  
Constitutive Models ◽  
Heat Transfer Model ◽  
System Response ◽  
Model Parameters ◽  
Transfer Model ◽  
Mechanical Coupling

The thermo-mechanical coupling of shape memory alloys has been modeled comprehensively using energy based constitutive models. These constitutive models describe the relationship of temperature, stress and strain in material and propose a solid methodology for system identification of model parameters. Equally important in the dynamics of shape memory alloy applications is the heat transfer model. Heat transfer models have been proposed but a complete resource for system identification of the model parameters is missing in the literature. Therefore, in this paper, the parameters for a low-order heat transfer model are identified experimentally. It is shown that for all parameters the measured parameters accurately model the system leading to the necessary values for use in predictive models. Furthermore, it is shown that using nominal values will produce inaccuracies in the predicted system response.

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