This paper studies the problem of designing adaptive observers for linear time-invariant systems with unknown inputs when the observer matching condition is not satisfied. The unknown inputs are divided into two parts: one is matched and the other is mismatched. Under the assumption that the mismatched unknown inputs are deterministic and can be expressed as the response of a fictitious autonomous system
an augmented system consisting of the original system and the mismatched unknown inputs dynamical system is constructed so that the observer matching condition can be satisfied. For the augmented system
the procedure to design this adaptive observer is given
and it is able to not only observe the state of original system but also reconstruct the matched unknown inputs. Such adaptive observer is applied to a kind of robot system and the simulation results demonstrate the effectiveness of the proposed approach.
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ASTROM K J, WITTENMARK B. Adaptive control [M]. [s.l.]: Pearson Education North Asia Limited, 2003.
YIN Shen, YANG Xuebo, KARIMI H R, et al. Data-driven adaptive observer for fault diagnosis [J]. Mathematical Problems in Engineering, 2012, 2012: 832836.
ZHANG K, JIANG B, COCQUEMPOT V. Adaptive observer-based fast fault estimation [J]. International Journal of Control, Automation, and Systems, 2008, 6(3): 320-326.
HAN Dong, LIANG Yueyong, YE Hao. Adaptive actuator fault estimation based on second-order sliding-mode differentiators [C/CD]∥The 25th Chinese Process Control Conference. Dalian, China: CPCC, 2014: 1-6.
CORLESS M, TU J. State and input estimation for a class of uncertain systems [J]. Automatica, 1998, 34(6): 757-764.
DRAZENOVIC B. The invariance conditions in variable structure systems [J]. Automatica, 1969, 5(3): 287-295.
FLOQUET T, EDWARDS C, SPURGEON 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.
KALSI K, LIAN J, HUI S, et al. Sliding-mode observers for systems with unknown inputs: a high-gain approach [J]. Automaitca, 2010, 46(2): 347-353.
HAN Dong, ZHU Fanglai. Simultaneous estimation of states and unknown inputs for linear systems based on auxiliary outputs [J]. Acta Automatica Sinica, 2012, 38(6): 932-943.
PARK T G. Designing fault detection observers for linear systems with mismatched unknown inputs [J]. Journal of Process Control, 2013, 23(8): 1185-1196.
TANG Chenglin, LIAN Lanxiang, LIU Jun. Sliding-mode observers design for uncertain systems based on an algebraic approach [J]. Journal of University of Electronic Science and Technology of China, 2015, 38(6): 932-943.
ALBERTOS P, SALA A. Multivariable control systems: an engineering approach [M]. Berlin, Germany: Springer, 2004.