A scheme to design observer with unknown input and unknown input reconstruction for Lipschitz nonlinear systems is proposed when the observer matching condition is not satisfied. An auxiliary output vector is constructed to satisfy the observer matching condition
and a high-order sliding mode differentiator with high-gain is designed to exactly estimate the auxiliary output vector and its derivative. Then
an adaptive robust sliding mode observer which complies with a robust sliding mode control law and an adaptation law is developed based on the estimations of the auxiliary output vector and its derivative
and an unknown input reconstruction method is derived without using the derivative information of system's output vector. The Lipschitz constant does not need to be known and is adjusted using the adaptive law. The method of unknown input reconstruction avoids the direct use of the derivative information of system's output. Simulation results show that states and unknown inputs can be gradually estimated by the proposed unknown input observer when the observer matching condition is not satisfied
and that the Lipschitz constant can be adjusted within 5 seconds by the proposed adaptation law.
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WANG S H, DAVISON E J, DORATO P. Observing the states of systems unmeasurable disturbances [J]. IEEE Transactions on Automatic Control, 1975,20(5):716-717.
PANUSKA V. A new form of the extended Kalman filter for parameter estimation in linear systems with correlated noise [J]. IEEE Transactions on Automatic Control, 1980,25(2):229-235.
BENALLOUCH M, BOUTAYEB M, OUTBIB R, et al. Nonlinear estimation of states and unknown inputs for communication systems [C]∥Proceedings of IEEE International Conference on Signal Processing and Communications. Piscataway,NJ,USA: IEEE, 2007: 696-699.
BAR-SHALOM Y. Optimal simultaneous state estimation and parameter identification in linear discrete-time system [J]. IEEE Transactions on Automatic Control, 1972,17(3):308-319.
YAN Xinggang, EDWARDS C. Adaptive sliding-mode observer-based fault reconstruction for nonlinear systems with parametric uncertainties [J]. IEEE Transactions on Industrial Electronics, 2008,35(11):4029-4036.
RAO S, BUSS M, UTKIN V. Simultaneous state and parameter estimation in induction motors using first-and-second-order sliding modes [J]. IEEE Transactions on Industrial Electronics, 2009,56(9):3369-3376.
DING Zhengtao. Differential stability and design of reduced-order observers for non-linear systems [J]. IET Control Theory Applications, 2011,5(2):315-322.
LI Jianmin, ZHENG Yunfeng, SHEN Zhipeng. Nonlinear observer design for a class of nonlinear systems with non-Lipschitz nonlinearities of the unmeasured states [C]∥Proceeding of the 29th Chinese Control Conference. Beijing, China: Chinese Association of Automation, 2010:3531-3533.
SHEN Zhongyu, ZHAO Jin, XU Jie, et al. Nonlinear unknown input observer design by LMI for Lipschitz nonlinear systems [C]∥Proceeding of the 8th World Congress on Intelligent Control and Automation. Beijing, China: Chinese Association for Artificial Intelligence, 2010:3450-3453.
KALSI K, LIAN J M,HUI S, et al. Sliding-mode observers for systems with unknown inputs: a high-gain approach [J]. Automatica, 2010,46(2):347-353.
CORLESS M, TU M. State and input estimation for a class of uncertain systems [J]. Automatica, 1998,34(6):757-764
KHALIL K H. Nonlinear systems [M]. 3rd ed. Beijing:Publishing House of Electronics Industry, 2007.
FlOQUET T, EDWARDS C, SPRUGEON S K. On sliding mode observers for systems with unknown inputs [J]. International Journal of Adaptive Control and Signal Processing, 2007,21(8/9):638-656.
LEVANT A. High-order sliding modes: differentiation and output-feedback control [J]. International Journal of Control, 2003,76(9/10):924-941.