Robust Generalized Fault Diagnosis Observer Design for Nonlinear Systems with External Disturbances
This study focuses on the robust generalized fault diagnosis observer design for a nonlinear system with external disturbances and an actuator fault. The robust generalized fault diagnosis observer (RGFDO) with the defined performance index, which can est
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Abstract This study focuses on the robust generalized fault diagnosis observer design for a nonlinear system with external disturbances and an actuator fault. The robust generalized fault diagnosis observer (RGFDO) with the defined performance index, which can estimate system states and fault signal simultaneously, is designed. Finally, simulations are performed on flexible joint robotic systems to illustrate the effectiveness and applicability of the algorithm proposed. Keywords Nonlinear system
Fault estimation Robust
1 Introduction Reliability and security of practical control systems are as crucial as performance defined. However, enhancing the dependability of systems has become a challenging task as a result of increasing complexity of automatic systems at present. Fault diagnosis (FD) and fault tolerant control (FTC) technologies are effective strategies designed with a certain degree of fault tolerant performance by means of the fault estimation information from fault estimation observer to guarantee reliable and desired performance of control systems not only under the fault free case but also the fault case. Fruitful FD and FTC approaches for linear systems have been proposed in both frequency and time domains [1–6]. However, because of the complexity and associated difficulties in nonlinear systems, much less work has Z.-D. Fu (&) R. Wang D.-X. Jiang Y. Song Beijing Institute of Mechanical Equipment, Beijing 100854, China e-mail: [email protected] R. Wang e-mail: [email protected] D.-X. Jiang e-mail: [email protected] Y. Song e-mail: [email protected] © Springer Science+Business Media Singapore 2016 A. Hussain (ed.), Electronics, Communications and Networks V, Lecture Notes in Electrical Engineering 382, DOI 10.1007/978-981-10-0740-8_38
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been done. In this paper, we focus on the design of RGFDO in nonlinear systems with external disturbances and actuator fault. Various approaches have been used for the design of FTC systems. Generally speaking, they can be broadly classified into: passive fault tolerant control systems (PFTCS) [7–9] and active fault tolerant control systems (AFTCS) [10–18]. The PFTCS apply unchangeable controllers throughout the systems and have the drawback of being reliable only for the class of faults expected and taken into account in the design. By contrast with the PFTCS, the AFTCS are designed on-line which the methods involve the fault information from the fault diagnosis observer so that the reliability and desired performance of the systems can be maintained [19–22].
2 Preliminaries and Problem Statement Consider the following nonlinear system with the external disturbances and actuator fault _ ¼ AxðtÞ þ BuðtÞ þ DdðtÞ þ Ef ðtÞ þ gðxðtÞÞ xðtÞ
ð1Þ
yðtÞ ¼ CxðtÞ
ð2Þ
where, x(t) is the state vector, u(t) is the control input vector, y(t) is the measured output vector, d(t) is the external disturbances which can also represent modeling errors and uncertainties. f(t) is actuator fault to be estimated. g(u(t)) is a continuous vector function. A,
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