A shape memory alloy spring-based actuator with stiffness and position controllability

2011 ◽  
Vol 225 (7) ◽  
pp. 902-917 ◽  
Author(s):  
A Hadi ◽  
A Yousefi-Koma ◽  
M Elahinia ◽  
M M Moghaddam ◽  
A Ghazavi
Keyword(s):  
Boundary Layer ◽  
Shape Memory Alloy ◽  
Shape Memory ◽  
Environmental Changes ◽  
Control Method ◽  
Variable Structure ◽  
External Loading ◽  
Positioning Accuracy ◽  
Structure Control ◽  
Stiffness Control

In this paper, a one-degree-of-freedom actuator that is based on shape memory alloy (SMA) springs is developed and tested. The use of SMA springs allows a larger actuation workspace and controllable stiffness than SMA wires. It is shown that the actuator demonstrates a good positioning accuracy in addition to a higher level of stiffness control. A strategy based on the variable structure control method is implemented for simultaneous displacement and stiffness control. It is shown that the actuator’s position is always kept within a boundary layer defined around the desired position while a preferred stiffness is also obtained in the actuator. Such an actuator could be used to develop flexible mechanical systems which need to adapt to environmental changes in the form of external loading variation.

Model Reference Adaptive Control Based on KP Model for Magnetically Controlled Shape Memory Alloy Actuators

2017 ◽  
Vol 15 (1_suppl) ◽  
pp. 31-37 ◽  
Author(s):  
Miaolei Zhou ◽  
Yannan Zhang ◽  
Kun Ji ◽  
Dong Zhu
Keyword(s):  
Adaptive Control ◽  
Shape Memory Alloy ◽  
Shape Memory ◽  
Control Method ◽  
Model Reference Adaptive Control ◽  
Positioning Accuracy ◽  
Model Reference ◽  
Hysteresis Nonlinearity ◽  
Adopted Model ◽  
Model Reference Adaptive

Introduction Magnetically controlled shape memory alloy (MSMA) actuators take advantages of their large deformation and high controllability. However, the intricate hysteresis nonlinearity often results in low positioning accuracy and slow actuator response. Methods In this paper, a modified Krasnosel'skii-Pokrovskii model was adopted to describe the complicated hysteresis phenomenon in the MSMA actuators. Adaptive recursive algorithm was employed to identify the density parameters of the adopted model. Subsequently, to further eliminate the hysteresis nonlinearity and improve the positioning accuracy, the model reference adaptive control method was proposed to optimize the model and inverse model compensation. Results The simulation experiments show that the model reference adaptive control adopted in the paper significantly improves the control precision of the actuators, with a maximum tracking error of 0.0072 mm. Conclusions The results prove that the model reference adaptive control method is efficient to eliminate hysteresis nonlinearity and achieves a higher positioning accuracy of the MSMA actuators.

Indirect Intelligent Sliding Mode Control Using Hysteretic Recurrent Neural Networks With Application to a Shape Memory Alloy Actuated Beam

2012 ◽  
Author(s):  
Jennifer C. Hannen ◽  
Gregory D. Buckner
Keyword(s):  
Shape Memory Alloy ◽  
Shape Memory ◽  
Sliding Mode ◽  
Variable Structure ◽  
Superior Performance ◽  
Flexible Beam ◽  
Single Input Single Output ◽  
Structure Control ◽  
Single Output ◽  
Parameter Variations

This paper presents the development of an indirect intelligent sliding mode controller (IISMC) for shape memory alloy (SMA) actuators. The controller manipulates applied voltage, enabling temperature control in one or more SMA tendons, which are offset to produce bending in a flexible beam tip. Hysteresis compensation is achieved using a hysteretic recurrent neural network (HRNN), which maps the nonlinear, hysteretic relationships between SMA temperatures and bending angle. Incorporating this HRNN into a variable structure control architecture provides robustness to model uncertainties and parameter variations. Single input, single output and multivariable implementations of this control strategy are presented. Controller performance is evaluated using a flexible beam deflected by single and antagonistic SMA tendons. Experimental results demonstrate precise tracking of a variety of reference trajectories for both configurations, with superior performance compared to an optimized PI controller for each system. Additionally, the IISMC demonstrates robustness to parameter variations and disturbances.

SHAPE MEMORY ALLOY ACTUATED MICRO-FLOW EFFECTORS FOR VORTEX MANIPULATION

2007 ◽  
Vol 31 (1) ◽  
pp. 19-38
Author(s):  
F.C. Wong ◽  
C.A. Rabbath ◽  
N. Hamel ◽  
D. Corriveau ◽  
N. Léchevin ◽  
...  
Keyword(s):  
Shape Memory Alloy ◽  
Shape Memory ◽  
Dynamic Performance ◽  
Variable Structure ◽  
Control Law ◽  
Supersonic Wind Tunnel ◽  
Structure Control ◽  
Micro Flow ◽  
Actuation Systems ◽  
Force Displacement

Smart structures are seen as an enabling technology for designing innovative control actuation systems for future missiles. In this study, the feasibility of employing shape memory alloy (SMA)-actuated micro-flow effectors to control the vortex shedding behaviour that produces side forces on slender body missiles is examined. Supersonic wind tunnel tests were performed on a slender finless missile equipped with static micro-flow effectors on a conical nose to determine suitable configurations that could generate significant side forces. Shape memory alloy actuators for the flow effector were developed using numerical techniques and validated experimentally. Matching the force-displacement characteristics of the SMA actuator to the micro-flow effector force-displacement requirement was accomplished by a compliant transmission mechanism. The dynamic performance of the micro-flow effector was assured with a two-step variable structure control law. Closed-loop test results showed that the control law was capable of providing effective displacement control up to 1.0 Hz.

Variable Structure Control of a Three-Link SMA-Actuated Robot

2004 ◽  
Author(s):  
Hashem Ashrafiuon ◽  
Mojtaba Eshraghi ◽  
Mohammad H. Elahinia
Keyword(s):  
Shape Memory Alloy ◽  
Shape Memory ◽  
Sliding Mode ◽  
Variable Structure Control ◽  
Variable Structure ◽  
Constitutive Law ◽  
Robot Kinematics ◽  
Robot Arm ◽  
Parameter Uncertainties ◽  
Structure Control

A fast, accurate and robust position controller is proposed for a planar three degree of freedom robot arm actuated by rotary Shape Memory Alloy actuators and servomotors. Servomotors are used to actuate the first link and the gripper, while the remaining two links are actuated by a combination of shape memory alloy wires and pulleys. Initially, a model of the robot arm is developed for theoretical controller development. The model combines robot kinematics and dynamics with the SMA wire heat convection, constitutive law, and phase transformation equations. The model is then used to develop several nonlinear position controllers based on the Variable Structure Control, also called sliding mode control. The controller development is of an evolutionary nature starting from a simple switching control based only on position feedback and then adding velocity and integral feedbacks, respectively. Several simulations of the proposed controllers are presented. Several experiments have been performed with a desktop prototype of the robot arm. The experimental results verify the effective and accurate performance of the controllers despite significant modeling inaccuracies and parameter uncertainties.

Design, Modeling and Control of a New Robotic Module Actuated by Shape Memory Alloy Springs

2009 ◽  
Author(s):  
Alireza Hadi ◽  
Mohammad Elahinia ◽  
Asadollah Ghazavi ◽  
Majid M. Moghadam
Keyword(s):  
Shape Memory Alloy ◽  
Shape Memory ◽  
Variable Structure ◽  
Robotic Systems ◽  
Modeling And Control ◽  
Modular Systems ◽  
Structure Control ◽  
Spring Type ◽  
Sma Spring ◽  
And Control

Modular robotic systems provide attractive benefits in the form of re-configurable robots that can change and adapt for special tasks. Self-reconfigurable is re-configurable robot with the ability to change their framework for different missions. One way to increase robots capabilities and to achieve self-configurable robots is to develop small, powerful and dexterous modules. In this paper, a new mechanism which uses Shape Memory Alloy (SMA) spring actuators is applied to develop a robotic module. Among the proposed modular systems until now, shape memory alloys especially the spring type are rarely used as actuators. The proposed mechanism is based on antagonistic application of SMA springs which provide faster actuation response. It is shown that the module mechanism is suitable for developing modular robotic systems, such as mobile robots, snake robots, and legged robots. The design of mechanical and electrical hardware of the module in addition to the sensing and actuating system is done talented in an optimum space. The same extendable modules communicate through a common bus in order to develop a distributed system. Consequently a proper module is presented to be applied in different robotic systems. Moreover, an effective non-linear control strategy which is variable structure control is applied for controlling the position of the module. Benefits and suitability of this controller for the module different configurations is verified using simulations and experiments.

scholarly journals Disturbance compensation-based output feedback adaptive control for shape memory alloy actuator system

2021 ◽  
Vol 18 (1) ◽  
pp. 172988142199399
Author(s):  
Xiaoguang Li ◽  
Bi Zhang ◽  
Daohui Zhang ◽  
Xingang Zhao ◽  
Jianda Han
Keyword(s):  
Adaptive Control ◽  
Shape Memory Alloy ◽  
Shape Memory ◽  
Control Method ◽  
Control Law ◽  
Reference Trajectory ◽  
Disturbance Compensation ◽  
Comparison Results ◽  
Control Scheme ◽  
Actuator System

Shape memory alloy (SMA) has been utilized as the material of smart actuators due to the miniaturization and lightweight. However, the nonlinearity and hysteresis of SMA material seriously affect the precise control. In this article, a novel disturbance compensation-based adaptive control scheme is developed to improve the control performance of SMA actuator system. Firstly, the nominal model is constructed based on the physical process. Next, an estimator is developed to online update not only the unmeasured system states but also the total disturbance. Then, the novel adaptive controller, which is composed of the nominal control law and the compensation control law, is designed. Finally, the proposed scheme is evaluated in the SMA experimental setup. The comparison results have demonstrated that the proposed control method can track reference trajectory accurately, reject load variations and stochastic disturbances timely, and exhibit satisfactory robust stability. The proposed control scheme is system independent and has some potential in other types of SMA-actuated systems.

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