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Time‐varying input delay compensation for nonlinear systems with additive disturbance: An output feedback approach
Author(s) -
Deng Wenxiang,
Yao Jianyong,
Ma Dawei
Publication year - 2017
Publication title -
international journal of robust and nonlinear control
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.361
H-Index - 106
eISSN - 1099-1239
pISSN - 1049-8923
DOI - 10.1002/rnc.3853
Subject(s) - control theory (sociology) , feed forward , backstepping , nonlinear system , controller (irrigation) , computer science , bounded function , compensation (psychology) , lyapunov function , observer (physics) , trajectory , robust control , state observer , lyapunov stability , control engineering , adaptive control , mathematics , control (management) , engineering , psychology , physics , quantum mechanics , artificial intelligence , psychoanalysis , biology , mathematical analysis , agronomy , astronomy
Summary This paper addresses the output feedback tracking control of a class of multiple‐input and multiple‐output nonlinear systems subject to time‐varying input delay and additive bounded disturbances. Based on the backstepping design approach, an output feedback robust controller is proposed by integrating an extended state observer and a novel robust controller, which uses a desired trajectory‐based feedforward term to achieve an improved model compensation and a robust delay compensation feedback term based on the finite integral of the past control values to compensate for the time‐varying input delay. The extended state observer can simultaneously estimate the unmeasurable system states and the additive disturbances only with the output measurement and delayed control input. The proposed controller theoretically guarantees prescribed transient performance and steady‐state tracking accuracy in spite of the presence of time‐varying input delay and additive bounded disturbances based on Lyapunov stability analysis by using a Lyapunov‐Krasovskii functional. A specific study on a 2‐link robot manipulator is performed; based on the system model and the proposed design procedure, a suitable controller is developed, and comparative simulation results are obtained to demonstrate the effectiveness of the developed control scheme.