scholarly journals Fractional-Order Sensing and Control: Embedding the Nonlinear Dynamics of Robot Manipulators into the Multidimensional Scaling Method

Sensors ◽  
2021 ◽  
Vol 21 (22) ◽  
pp. 7736
Author(s):  
António Lopes ◽  
José Machado
Keyword(s):  
Multidimensional Scaling ◽  
Fractional Order ◽  
Sliding Mode ◽  
Variable Structure ◽  
Design Parameters ◽  
Time Signal ◽  
Fractional Dynamics ◽  
Test Bed ◽  
System States ◽  
And Control

This paper studies the use of multidimensional scaling (MDS) to assess the performance of fractional-order variable structure controllers (VSCs). The test bed consisted of a revolute planar robotic manipulator. The fractional derivatives required by the VSC can be obtained either by adopting numerical real-time signal processing or by using adequate sensors exhibiting fractional dynamics. Integer (fractional) VCS and fractional (integer) sliding mode combinations with different design parameters were tested. Two performance indices based in the time and frequency domains were adopted to compare the system states. The MDS generated the loci of objects corresponding to the tested cases, and the patterns were interpreted as signatures of the system behavior. Numerical experiments illustrated the feasibility and effectiveness of the approach for assessing and visualizing VSC systems.

Fractional Variable Structure Control

2011 ◽  
Author(s):  
J. A. Tenreiro Machado
Keyword(s):  
Fractional Order ◽  
Sliding Mode ◽  
Variable Structure Control ◽  
Variable Structure ◽  
Control Algorithms ◽  
System Response ◽  
Test Bed ◽  
Control Effort ◽  
Structure Control ◽  
Order Variable

This paper studies fractional order variable structure control algorithms. For that purpose the fractional order of the sliding mode is varied and its effect upon the system performance is evaluated. The test bed is constituted by a simple mechanical manipulator. Both the system response and the control effort are analysed. The results show that the fractional order provides an extra method for adjusting the closed loop system response.

Enhanced Fractional Order Sliding Mode Approach for Maximum Power Tracking of Five-phase PMSG based WECS

2021 ◽  
Vol 12 (5) ◽  
pp. 918-929
Author(s):  
Salah Eddine Rhaili Et. al.
Keyword(s):  
Power Systems ◽  
Fractional Order ◽  
Sliding Mode ◽  
Control Function ◽  
Dynamic Performance ◽  
Electrical Power ◽  
Variable Structure ◽  
Synchronous Generator ◽  
Lyapunov Theory ◽  
Static Performance

Variable structure strategies have shown an efficient performance in controlling nonlinear electrical power systems by reason of its strength to handle perfectly the unmodeled system dynamics. In this study, with the exponent reaching law, a robust enhancement method of sliding mode controller (SMC) based on a nonlinear fractional order sliding surface that consists of both fractional differentiation and integration is proposed and applied to control a high-power multiphase permanent magnet synchronous generator based direct-driven Wind Energy Conversion System (WECS), in order to improve the energy efficiency and reduce the produced chattering phenomenon of conventional SMC . Moreover, a new smooth and derivable nonlinear switching control function is applied to replace the traditional non-derivable nonlinear control law, to improve dynamic performance, static performance, and robustness of the system. The proposed strategy stability is investigated under Lyapunov theory. A comparative simulation of the new proposed approach with the conventional SMC and PI controller display the excellent performance, stability and high robustness of FOSMC, by improving the system efficiency up to 98.66%, compared to conventional SMC with 91,14%, while the PI control achieves 86, 2%.

Study on Active Suspension with Variable Structure Control Based on the Fractional Order Exponential Reaching Law

2017 ◽  
Vol 872 ◽  
pp. 337-345
Author(s):  
Yan Dong Chen
Keyword(s):  
Fractional Order ◽  
Reference Model ◽  
Sliding Mode ◽  
Variable Structure Control ◽  
Variable Structure ◽  
Active Suspension ◽  
Mode Switching ◽  
Structure Control ◽  
Reaching Law ◽  
Exponential Reaching Law

Based on the dynamic model of 1/4 vehicle suspension, an active control system is designed using the fractional order exponential reaching law of model following variable structure control strategy. An active suspension with linear quadratic optimal control is used as the reference model. The sliding mode switching surface parameters is designed by pole placement method to ensure the stability of the system. At the same time, combined with the index reaching law proposed by Professor Gao Wei Bing and the definition and properties of fractional index, constructs a similar fractional order exponent reaching law to improve the dynamic quality of sliding mode motion. And in MATLAB, system modeling and controller design are implemented. By setting up experiments, the different suspensions are compared. The results show that compared with the passive suspension, the performance of the vehicle can be improved better, and the performance of the tracking reference model has good tracking performance. Moreover, compared with the integral exponential reaching law, the chattering can be more effectively weakened. Finally, before and after the change of vehicle parameters in the simulation, the results show that the system has good robustness.

scholarly journals Robust Output Feedback Passivity-Based Variable Structure Controller Design for Nonlinear Systems

2019 ◽  
Vol 2019 ◽  
pp. 1-10
Author(s):  
Jeang-Lin Chang ◽  
Tsui-Chou Wu
Keyword(s):  
Nonlinear Systems ◽  
Output Feedback ◽  
Controller Design ◽  
Sliding Mode ◽  
Damping Ratio ◽  
Variable Structure ◽  
Sliding Surface ◽  
Estimation Errors ◽  
System States ◽  
Approach Zero

This paper examines the use of an output feedback variable structure controller with a nonlinear sliding surface for a class of SISO nonlinear systems in the presence of matched disturbances. With only the measurable system output, the discontinuous observer reconstructs the system states and ensures that the estimation errors exponentially approach zero. Using the estimation states, the proposed nonlinear sliding surface with variable damping ratio can simultaneously achieve low overshoot and short settling time. Then the passivity-based controller including a discontinuous term can guarantee that the closed-loop system asymptotically converges to the sliding surface. Compared with other sliding mode controllers, the proposed passivity-based control scheme has better transient performance and effectively reduces the control gain. Finally, simulation results demonstrate the validity of the proposed method.

Stabilization of Fractional-Order Systems Subject to Saturation Element Using Fractional Dynamic Output Feedback Sliding Mode Control

2016 ◽  
Vol 12 (3) ◽  
Author(s):  
Esmat Sadat Alaviyan Shahri ◽  
Alireza Alfi ◽  
J. A. Tenreiro Machado
Keyword(s):  
Fractional Order ◽  
Output Feedback ◽  
Sliding Mode ◽  
Linear Matrix ◽  
Linear Component ◽  
Dynamic Output Feedback ◽  
Closed Loop System ◽  
Fractional Systems ◽  
Dynamic Output ◽  
System States

This paper addresses the design of a robust fractional-order dynamic output feedback sliding mode controller (FDOF-SMC) for a general class of uncertain fractional systems subject to saturation element. The control law is composed of two components, one linear and one nonlinear. The linear component corresponds to the fractional-order dynamics of the FDOF-SMC, while the nonlinear component is associated with the switching control algorithm. The closed-loop system exhibits asymptotical stability and the system states approach the sliding surface in a finite time. In order to design the controller, a linear matrix inequality (LMI)-based procedure is also derived. Simulation results demonstrate the feasibility of the FDOF-SMC strategy.

Adaptive Control of Systems with Time Varying Delay: A Sliding Mode Approach

2014 ◽  
Vol 668-669 ◽  
pp. 428-436
Author(s):  
Fa Xiang Xie ◽  
Bo Hai Ji
Keyword(s):  
Sliding Mode ◽  
Adaptive Sliding Mode Control ◽  
Linear Matrix ◽  
Multiple Delays ◽  
Time Varying ◽  
Adaptive Sliding Mode ◽  
Time Varying Delay ◽  
Adaptive Sliding Mode Controller ◽  
System States ◽  
And Control

This paper concerns the design of robust controller for a linear system with time-varying state and input delay. The new adaptive sliding mode control algorithm of the system with multiple delays in system states and control inputs are proposed. The delay dependent conditions of the closed loop system are formulated and the equivalent gain of the adaptive sliding mode controller is obtained in the form of linear matrix inequalities (LMI). Finally, simulation results of a numerical example based on a practical inverted pendulum shows both the feasibility and efficiency of the proposed controller.

Adaptive constrained sliding mode control of uncertain nonlinear fractional-order input affine systems

2019 ◽  
Vol 26 (5-6) ◽  
pp. 318-330
Author(s):  
Tahmine V Moghaddam ◽  
Seyyed K Yadavar Nikravesh ◽  
Mohammad A Khosravi
Keyword(s):  
Sliding Mode Control ◽  
Fractional Order ◽  
Sliding Mode ◽  
Nonlinear Function ◽  
Lyapunov Theory ◽  
Adaptive Sliding Mode Control ◽  
Mode Control ◽  
Adaptive Laws ◽  
Chattering Free ◽  
System States

This paper addresses asymptotic stabilization of uncertain nonlinear fractional-order systems with bounded inputs in the presence of model uncertainties and external disturbances. To develop the idea, it is assumed that the upper bound of perturbations is a nonlinear function of the pseudostates norm in which its coefficients are unknown and are obtained via proposed adaptive laws. The main contribution of this paper is to develop a new bounded fractional-order chattering free adaptive sliding mode control in which the system states converge to the sliding surface at a predefined finite time. The stability of the closed-loop system with the proposed control scheme is guaranteed by the Lyapunov theory. Furthermore, for more clarification, a comparison with the classical integer-order case is also presented; finally, some practical simulation results are provided to show the effectiveness of the proposed control algorithm.

Duffing Chaotic System Stability Control Based on Sliding Mode Control

2012 ◽  
Vol 605-607 ◽  
pp. 1639-1642
Author(s):  
Ding Ma
Keyword(s):  
Chaotic System ◽  
Control Method ◽  
Sliding Mode ◽  
Variable Structure ◽  
Stability Control ◽  
System Stability ◽  
Terminal Sliding Mode ◽  
Sliding Mode Variable Structure ◽  
The Stability ◽  
And Control

Considering the Duffing chaotic system, the problem of stability control based on the terminal sliding mode variable structure is studied. A new terminal sliding mode surface and control law are designed. On this basis, the stability of closed-loop system is analyzed. Simulation results show the effectiveness of the control method.

scholarly journals Adaptive Variable Structure Control for Mismatched Uncertain Systems

2016 ◽  
Vol 3 (1) ◽  
pp. 81
Author(s):  
Bach Hoang Dinh ◽  
Van Van Huynh
Keyword(s):  
Uncertain Systems ◽  
Sliding Mode ◽  
Variable Structure Control ◽  
Variable Structure ◽  
Linear Matrix ◽  
Matrix Inequalities ◽  
Structure Control ◽  
Unknown Disturbances ◽  
System States ◽  
Necessary And Sufficient

This paper proposes an adaptive variable structure control (VSC) for a class of mismatched uncertain systems with unknown disturbances. First, a necessary and sufficient condition in terms of linear matrix inequalities is proposed to guarantee the system in sliding mode is asymptotically stable. Second, an adaptive output feedback variable structure controller is designed to force the system states reach the sliding surface and stay on it thereafter. Finally, the advantages and effectiveness of the proposed approaches are demonstrated via a numerical example.

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