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Article Citation - WoS: 4Citation - Scopus: 4Multiloop State-Dependent Nonlinear Time-Varying Sliding Mode Control of Unmanned Small-Scale Helicopter(Sage Publications Ltd, 2020) Ozcan, Sinan; Salamci, Metin U.; Nalbantoglu, VolkanTime delays, parameter uncertainties, and disturbances are the fundamental problems that hinder the stability and reduce dramatically the tracking performance of dynamical systems. In this paper, a new state-dependent nonlinear time-varying sliding mode control autopilot structure is proposed to cope with these dynamical and environmental complexities for an unmanned helicopter. The presented technique is based on freezing the nonlinear system equations on each time step and designing a controller using the frozen system model at this time step. The proposed method offers an improved performance in the presence of major disturbances and parameter uncertainties by adapting itself to possible dynamical varieties without a need of trimming the system on different operating conditions. Unlike the existing linear cascade autopilot structure, this study also proposes a nonlinear cascade state-dependent coefficient helicopter autopilot structure consisting of four separate nonlinear sub-systems. The proposed method is tested through the real time and PC-based simulations. To show the performance of the proposed robust method, it is also bench-marked against a linear sliding control control in PC-based simulations.Article Citation - WoS: 1Citation - Scopus: 3Multivariable Nonlinear Model Reference Control of Cement Mills(Arnold, Hodder Headline Plc, 2003) Efe, MÖ; Department of Electrical & Electronics EngineeringThis paper presents a method for model reference control of a cement milling circuit that has previously been studied several times. The approach presented is based on an experimentally justified model of a cement milling circuit. We derive the form of the control vector with the goal of driving the response of the system to that of a desired model in a noisy operating environment. The paper demonstrates the selection of the reference dynamics and the derivation of the control laws. The approach is based on the Lyapunov theory, and the results observed justify the tracking and stability claims of the paper.Article Citation - WoS: 2Citation - Scopus: 2Discrete Time Neuro Sliding Mode Control With a Task-Specific Output Error(Springer, 2004) Efe, MO; Department of Electrical & Electronics EngineeringThe problem of obtaining the error at the output of a neuro sliding mode controller is analyzed in this paper. The controller operates in discrete time and the method presented describes an error measure that can be used if the task to be achieved is to drive the system under control to a predefined sliding regime. Once the task-specific output error is calculated, the neurocontroller parameters can be tuned so that the task is achieved. The paper postulates the strategy for discrete time representation of uncertain nonlinear systems belonging to a particular class. The performance of the proposed technique has been clarified on a third order nonlinear system, and the parameters of the controller are adjusted by using the error backpropagation algorithm. It is observed that the prescribed behavior can be achieved with a simple network configuration.
