397 research outputs found
The design of quasi-sliding mode control for a permanent magnet synchronous motor with unmatched uncertainties
AbstractIn this study, the concept of a quasi-sliding mode control (QSMC) is introduced for the robust control of a permanent magnet synchronous motor (PMSM) system subjected to unmatched uncertainties, and even with input nonlinearity. On the basis of the new concept of QSMC, continuous control is obtained, to avoid the chattering phenomenon. As expected, the system state can be stabilized and driven into a predictable neighborhood of zero. Also, this approach only uses a single controller to achieve chaos control, which reduces the cost and complexity of implementation. The results of numerical simulations demonstrate the validity of the proposed QSMC design method
Synchronization of Fractional-order Chaotic Systems with Gaussian fluctuation by Sliding Mode Control
This paper is devoted to the problem of synchronization between
fractional-order chaotic systems with Gaussian fluctuation by the method of
fractional-order sliding mode control. A fractional integral (FI) sliding
surface is proposed for synchronizing the uncertain fractional-order system,
and then the sliding mode control technique is carried out to realize the
synchronization of the given systems. One theorem about sliding mode controller
is presented to prove the proposed controller can make the system synchronize.
As a case study, the presented method is applied to the fractional-order
Chen-L\"u system as the drive-response dynamical system. Simulation results
show a good performance of the proposed control approach in synchronizing the
chaotic systems in presence of Gaussian noise
Output Feedback Fractional-Order Nonsingular Terminal Sliding Mode Control of Underwater Remotely Operated Vehicles
For the 4-DOF (degrees of freedom) trajectory tracking control problem of underwater remotely operated vehicles (ROVs) in the presence of model uncertainties and external disturbances, a novel output feedback fractional-order nonsingular terminal sliding mode control (FO-NTSMC) technique is introduced in light of the equivalent output injection sliding mode observer (SMO) and TSMC principle and fractional calculus technology. The equivalent output injection SMO is applied to reconstruct the full states in finite time. Meanwhile, the FO-NTSMC algorithm, based on a new proposed fractional-order switching manifold, is designed to stabilize the tracking error to equilibrium points in finite time. The corresponding stability analysis of the closed-loop system is presented using the fractional-order version of the Lyapunov stability theory. Comparative numerical simulation results are presented and analyzed to demonstrate the effectiveness of the proposed method. Finally, it is noteworthy that the proposed output feedback FO-NTSMC technique can be used to control a broad range of nonlinear second-order dynamical systems in finite time
An investigation of techniques for nonlinear state observation
A dissertation submitted to the Faculty of Engineering and the Built Environment,
University of the Witwatersrand, in fulfilment of the requirements for the degree of
Master of Science in Engineering.
Johannesburg, 2016An investigation and analysis of a collection of different techniques, for estimating the states of
nonlinear systems, was undertaken. It was found that most of the existing literature on the topic
could be organized into several groups of nonlinear observer design techniques, of which each
group follows a specific concept and slight variations thereof.
From out of this investigation it was discovered that a variation of the adaptive observer could be
successfully applied to numerous nonlinear systems, given only limited output information. This
particular technique formed the foundation on which a design procedure was developed in order to
asymptotically estimate the states of nonlinear systems of a certain form, using only partial state
information available. Lyapunov stability theory was used to prove the validity of this technique,
given that certain conditions and assumptions are satisfied. A heuristic procedure was then
developed to get a linearized model of the error transient behaviour that could form the upper
bounds of the transient times of the observer.
The technique above, characterized by a design algorithm, was then applied to three well-known
nonlinear systems; namely the Lorenz attractor, the Rössler attractor, and the Van Der Pol
oscillator. The results, illustrated through numerical simulation, clearly indicate that the technique
developed is successful, provided all assumptions and conditions are satisfied.MT201
Projective synchronization analysis for BAM neural networks with time-varying delay via novel control
In this paper, the projective synchronization of BAM neural networks with time-varying delays is studied. Firstly, a type of novel adaptive controller is introduced for the considered neural networks, which can achieve projective synchronization. Then, based on the adaptive controller, some novel and useful conditions are obtained to ensure the projective synchronization of considered neural networks. To our knowledge, different from other forms of synchronization, projective synchronization is more suitable to clearly represent the nonlinear systems’ fragile nature. Besides, we solve the projective synchronization problem between two different chaotic BAM neural networks, while most of the existing works only concerned with the projective synchronization chaotic systems with the same topologies. Compared with the controllers in previous papers, the designed controllers in this paper do not require any activation functions during the application process. Finally, an example is provided to show the effectiveness of the theoretical results
Finite-time reliable nonfragile control for fractionalorder nonlinear systems with asymmetrical saturation and structured uncertainties
This paper investigates the finite-time stabilization problem of fractional-order nonlinear differential systems via an asymmetrically saturated reliable control in the sense of Caputo’s fractional derivative. In particular, an asymmetrical saturation control problem is converted to a symmetrical saturation control problem by using a linear matrix inequality framework criterion to achieve the essential results. Specifically, in this paper, we obtain two sets of sufficient conditions under different scenarios of structured uncertainty, namely, norm-bounded parametric uncertainty and linear fractional transformation uncertainty. The uncertainty considered in this paper is a combination of polytopic form and structured form. With the help of control theories of fractional-order system and linear matrix inequality technique, some sufficient criteria to ensure reliable finite-time stability of fractional-order differential systems by using the indirect Lyapunov approach are derived. As a final point, the derived criteria are numerically validated by means of examples based on financial fractional-order differential system and permanent magnet synchronous motor chaotic fractional-order differential system
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