Sliding Mode Control of Mechanical Systems Actuated by Shape Memory Alloy

Author(s):  
Hashem Ashrafiuon ◽  
Vijay Reddy Jala

This paper presents a model-based sliding mode control law for mechanical systems, which use shape memory alloys (SMAs) as actuators. The systems under consideration are assumed to be fully actuated and represented by unconstrained equations of motion. A system model is developed by combining the equations of motion with SMA heat convection, constitutive law, and phase transformation equations, which account for hysteresis. The control law is introduced using asymptotically stable second-order sliding surfaces. Robustness is guaranteed through the inclusion of modeling uncertainties in the controller development. The control law is developed assuming only positions are available for measurement. The unmeasured states, which include velocities and SMA temperatures and stresses, are estimated using an extended Kalman filter based on the nonlinear system model. The control law is applied to a three-link planar robot for position control problem. Simulation and experimental results show good agreement and verify the robustness of the control law despite significant modeling uncertainty.

Author(s):  
Hashem Ashrafiuon ◽  
Jala Vijay Reddy

This paper presents a model-based sliding mode control law for a planar three-degree-of-freedom robot arm actuated by two rotary Shape Memory Alloy (SMA) actuators and a servomotor. The SMA actuators use a combination of SMA wires and pulleys to produce rotational motion. A model of the robot is developed which combines robot equations of motion with the SMA wire heat convection, constitutive law, and phase transformation equations. Two second-order sliding surfaces are defined leading to derivation of asymptotically stable control laws within the actuation region of the SMA wires. Outside the actuation region, constant inputs are used based on the one-way nature of the SMA actuators. The control law is shown to be effective in several simulations for both set point and trajectory tracking of the robot.


Author(s):  
Ayman A. Nada ◽  
Abdullateef H. Bashiri

Trajectory tracking robotic systems require complex control procedures that occupy less space and need less energy. For these reasons, the development of computerized and integrated control systems is crucial. Recently, developing reconfigurable Field Programmable Gate Arrays (FPGAs) give a prominence of the complete robotic control systems. Furthermore, it has been found in the literature that the model-based control methods are most efficient and cost-effective. This model must interpret how multiple moving parts interact with each other and with their environment. On the other hand, MultiBody Dynamic (MBD) approach is considered to solve these difficulties to attain the models accurately. However, the obtained equations of motion do not match the well-developed forms of control theory. In this paper, the MBD model of a mobile robot is established; and the equations of motion are reshaped into their control canonical form. Additionally, the Sliding Mode Control (SMC) theory is used to design the control law. The constraints’ manifold, which is available in the equations of the MBD system, are imposed systematically as the switching surface. SMC is applied because of its ability to address multiple-input/multiple-output nonlinear systems without resorting any approximations. Eventually, the experimental verification of the proposed algorithm is carried out using DaNI mobile robot in which, a Reconfigurable Input/Output (RIO) board is used to reorient the control design, so that can fit the required trajectory. The control law is implemented using LabVIEW software and NI-sbRIO-9631 with acceptable performance. It is obvious that the integration of MBD/SMC/FPGA can be used successfully to develop embedded systems for the applications of trajectory tracking robotics.


2014 ◽  
Vol 971-973 ◽  
pp. 714-717 ◽  
Author(s):  
Xiang Shi ◽  
Zhe Xu ◽  
Qing Yi He ◽  
Ka Tian

To control wheeled inverted pendulum is a good way to test all kinds of theories of control. The control law is designed, and it based on the collaborative simulation of MATLAB and ADAMS is used to control wheeled inverted pendulum. Then, with own design of hardware and software of control system, sliding mode control is used to wheeled inverted pendulum, and the experimental results of it indicate short adjusting time, the small overshoot and high performance.


Author(s):  
Yohan Díaz-Méndez ◽  
Leandro Diniz de Jesus ◽  
Marcelo Santiago de Sousa ◽  
Sebastião Simões Cunha ◽  
Alexandre Brandão Ramos

Sliding mode control (SMC) is a widely used control law for quadrotor regulation and tracking control problems. The purpose of this article is to solve the tracking problem of quadrotors using a relatively novel nonlinear control law based on SMC that makes use of a conditional integrator. It is demonstrated by a motivation example that the proposed control law can improve the transient response and chattering shortcomings of the previous approaches of similar SMC based controllers. The adopted Newton–Euler model of quadrotor dynamics and controller design is treated separately in two subsystems: attitude and position control loops. The stability of the control technique is demonstrated by Lyapunov’s analysis and the effectiveness and performance of the proposed method are compared with a similar integral law, also based on SMC, and validated by tracking control problems using numerical simulations. Simulations were developed in the presence of external disturbances in order to evaluate the controller robustness. The effectiveness of the proposed controller was verified by performance indexes, demonstrating less accumulated tracking errors and control activity and improvement in the transient response and disturbance rejection when compared to a conventional integrator sliding mode controller.


2012 ◽  
Vol 2012 ◽  
pp. 1-7 ◽  
Author(s):  
Jeang-Lin Chang

For a class of linear MIMO uncertain systems, a dynamic sliding mode control algorithm that avoids the chattering problem is proposed in this paper. Without using any differentiator, we develop a modified asymptotically stable second-order sliding mode control law in which the proposed controller can guarantee the finite time convergence to the sliding mode and can show that the system states asymptotically approach to zero. Finally, a numerical example is explained for demonstrating the applicability of the proposed scheme.


10.5772/15994 ◽  
2011 ◽  
Author(s):  
Rogelio Hernandez ◽  
America Morales ◽  
Norberto Flores ◽  
Eliseo Hernandez ◽  
Hector Puebl

Author(s):  
Hafedh Abid ◽  
Mohamed Chtourou ◽  
Ahmed Toumi

In this work we are interested to discrete robust fuzzy sliding mode control. The discrete SISO nonlinear uncertain system is presented by the Takgi- Sugeno type fuzzy model state. We recall the principle of the sliding mode control theory then we combine the fuzzy systems with the sliding mode control technique to compute at each sampling time the control law. The control law comports two terms: equivalent control law and switching control law which has a high frequency. The uncertainty is replaced by its upper bound. Inverted pendulum and mass spring dumper are used to check performance of the proposed fuzzy robust sliding mode control scheme.


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