Proposed Control Approach Quasi-Sliding Mode Control
Lodhi Sadam Sadiq Khan, Du Bao Zhu, Naveed Ahmed Qureshi, Ibrajimov Shokhzod "Proposed Control Approach Quasi-Sliding Mode Control". International Journal of Computer Trends and Technology (IJCTT) V55(1):7-16, January 2018. ISSN:2231-2803. www.ijcttjournal.org. Published by Seventh Sense Research Group.
Time delays and external disturbances are unavoidable in many practical control applications, e.g., in robotics, manufacturing, and process control and it is often a source of instability or oscillations, see, e.g., [1,2] and the references therein. Therefore, the design of control and observation schemes has been an interesting problem for dynamical systems to compensate for time delays  and to estimate external disturbances . To enhance robustness, the sliding mode control methodology has been recognised as an effective strategy for uncertain systems, see, e.g., and references therein. In this context, there have been considerable efforts devoted to the problem of sliding mode control design for uncertain systems with matched disturbances, see, e.g., [5,6] and references therein. However, when the matching conditions for disturbances are not satisfied, their effects can be only partially rejected in the sliding mode. Therefore, the control design for this case remains a challenging problem. For a class of linear systems with time-varying delay and unmatched disturbances, a sliding-mode control strategy was developed in and sufficient conditions were derived in terms of linear matrix inequalities (LMIs) to guarantee that the state trajectories of the system converge towards a ball with a pre-specified convergence rate. By using the invariant ellipsoid method, another sliding mode control design algorithm was proposed for a class of linear quasi-Lipschitz disturbed system to minimise the effects of unmatched disturbances to system motions in the sliding mode . Later, by combining the predictor-based sliding mode control with the invariant ellipsoid method, an improved result was reported to take into account also time delay in the control input . Recently, a disturbance observer-based sliding mode control was presented in where mismatched uncertainties were considered.
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Quasi-Sliding, Model Control, Time-Delay Systems, Lyapunov Functionals.