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.

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.

Observer-based sliding mode control of a robotic manipulator

Robotica ◽  
1994 ◽  
Vol 12 (5) ◽  
pp. 443-448 ◽  
Author(s):  
Karel Jezernik ◽  
Boris Curk ◽  
Jože Harnik
Keyword(s):  
Control Method ◽  
Sliding Mode ◽  
Variable Structure ◽  
Robust Performance ◽  
New Approach ◽  
Structure Control ◽  
Dynamic Motion ◽  
Parameter Variations ◽  
Joint Acceleration ◽  
Acceleration Signals

SUMMARYThis paper presents a new approach for the design of variable structure control (VSC) of nonlinear systems. The approach is based on estimation of joint acceleration signals with introduction of load estimation with the asymptotic observer. The control system is insensitive to parameter variations for a chosen switching hypersurface in conditions when it is reached by the dynamic motion with the required dynamics. The parameter insensitive response provided by this control method is demonstrated on the model of the SCARA robot. Simulation results confirm the validity of accurate tracking capability and the robust performance.

Sliding Mode Control of a Non-Collocated Flexible System

2003 ◽  
Author(s):  
Aimee M. Frame ◽  
Wayne J. Book
Keyword(s):  
Control Method ◽  
Sliding Mode ◽  
Variable Structure Control ◽  
Variable Structure ◽  
Flexible Beam ◽  
Actual System ◽  
Structure Control ◽  
Control Techniques ◽  
Flexible System ◽  
Position Tracking Control

A new control method is developed for position tracking control of a flexible, non-collocated system. The desired trajectory is specified for the free end of a flexible beam that moves along a horizontal track actuated by a linear motor. First, a system model is reformulated based on a pendulum with stiffness and dampening. Small angle approximations are used so that a linear model can be obtained. Next, variable structure control is chosen as the control method due to its seemingly robust nature. The sliding surface and feedback gains are designed using the developed model based on literature describing various variable structure control techniques. Simulations are then conducted to verify the control method and examine its robustness. Finally, the method is implemented on an actual system using a Kalman filter to estimate the states.

scholarly journals A Novel Sliding Mode Controller for Underactuated Vertical Takeoff and Landing Aircraft

2020 ◽  
Vol 14 ◽  
Keyword(s):  
Flight Control ◽  
Degrees Of Freedom ◽  
Control Method ◽  
Sliding Mode ◽  
Variable Structure Control ◽  
Variable Structure ◽  
Superior Performance ◽  
Sliding Mode Controller ◽  
Structure Control ◽  
Sliding Mode Variable Structure

Compared with other control methods, the biggest advantage of using sliding mode variable structure control method lies in its strong robustness which could be used to directly handle the strong nonlinear flight control system. However, this control method requires switching between different switching surfaces, which will inevitably cause buffeting problems, so that the energy consumption increases. Therefore, how to overcome this disadvantage to achieve the superior performance of sliding mode variable structure control method is the current research focus. This paper studies the trajectory tracking of under-actuated VTOL aircraft with three degrees of freedom and two control inputs under various coupling effects. By the input and coordinate transformation, the dynamic equation of the system is transformed into decoupled standard under-actuated form and the sliding mode controller is designed. Then Lyapunov stability theorem is used to derive sliding mode control law which could ensure that the system asymptotically converges to the given trajectory. The simulation has demonstrated the effectiveness of this method

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.

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