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two observer-based fault detection designs are considered for detecting a fault in any inaccessible tank which forms part of a larger n-tank system. A subsystem of n – 2 tanks is situated in a hazardous environment and only control and measurements of the outer tanks is possible. Given a set of nonlinear differential equations, several transformations are derived to aid the design of the two problems of control and fault detection. Two nonlinear observer approaches are given and illustrated by an example. Stability and detectability are examined.

Firstly, a general nonlaminar model is considered for pipeline dynamics, including a treatment of faults caused by pipe restrictions. For three cases results are given for stability, robustness and fault detectability of a combined observer and residual (fault detection signal). An efficient numerical design algorithm is proposed. The method is applied to an actual experimental pipeline (rig system) which is set up to model a sub-sea umbilical. Results on modelling and on observer and residual (signal) design are given. The effectiveness of the design is tested by inducing two types of fault on the rig system.

This paper proposes a robust fault detection observer for a wide class of nonlinear models. Results are given for existence, error stability and detecability. Special choices of the gain matrices are chosen relating to the time-varying error dynamics. These enable algebraic conditions to be given for detectability of faults. An application example is given demonstrating the use of the theory.

This paper proposes a fault detection observer for classes of nonlinear models which consist of bilinear and polynomial nonlinearies up to degree three and are structured in continuous state space form. A design procedure is presented for calculating the observer matrices and is applied to an industrial application.

The linear parity space method is extended to bilinear systems in this paper. A recursive algorithm for calculating the matrices in the parity equation is developed. Fault isolation is achieved by transforming residual matrix such that the effects of different faults are decoupled. The proposed method is applied to an estimated model of a gas-fired high temperature furnace. Two component faults and two sensor faults are simulated and tested. The simulation results indicate the effectiveness of the method.

A fault detection method is proposed for a fairly wide class of nonlinear systems based on a nonlinear observer. Other methods proposed in the field are related to this method or are special cases of it. The observer is designed such that the error dynamics are independent ofstate, input, output and unknown disturbances. Conditions are given for the observer to exist and to be robust with respect to an unknown input. Applications are made to a hydraulic system.

A fault detection observer is considered for a class of continuous singular bilinear descriptor systems subject to unknown inputs and faults. A member system may be singular and possibly noncausal. Existence of solutions is considered and the initial system is is firstly transformed into a special (causal) form given certain assumptions hold true. The main observer design rests on the solution of a Riccati equation and the use of a quadratic Liapunov function. Two other designs are briefly outlined. A design algorithm is given and applied to the estimation of the states of a flexible joint robot.

A simulation study is undertaken on fault diagnosis for a gas-fired high-temperature furnace. A single-input multi-output bilinear model is found to be a suitable representation of the furnace. A recently proposed full-order bilinear state observer is used to generate the residual. Two actuator and two sensor faults are simulated and tested using this method.

A bilinear fault detection observer is proposed for a bilinear system with unknown inputs. The residual vector in the design of the observer is decoupled from the unknown inputs and, under certain conditions, is made sensitive to all the faults. Sufficient conditions are given for the existence of the observer and results are given for the explicit calculation of the observer design matrices. An application to a hydraulic drive system is given.

fault detection and isolation (FDI) of bilinear systems is considered. Two main quantitative methods are outlined. A bilinear fault detection observer is proposed which focuses on the problem of decoupling the unknown inputs from the residuals. Secondly, a parity space method is developed for bilinear systems. Robust issues are addressed throughout the paper. Related methods are briefly discussed and two applications are considered.

A bilinear fault detection observer is proposed for a bilinear system with an unknown input. Necessary and sufficient conditions are given for the existence of the observer. Robustness of the residual to the unknown input is achieved. The method is applied to a hydraulic test rig and some simulation results are displayed.