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Article
Publication date: 25 January 2008

Jia‐hui Luan and Ting‐di Zhao

This paper aims to present a novel fault estimator design scheme, in order to improve the practicability of the fault estimation.

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Abstract

Purpose

This paper aims to present a novel fault estimator design scheme, in order to improve the practicability of the fault estimation.

Design/methodology/approach

The paper first transforms the system state into three parts. Then a reduced‐observer is designed for an unknown input and fault‐free system, and the observer can get no bias error in the state estimation. So the estimator can get the exact estimation for the unknown input and fault of the actuator.

Findings

By using this approach it is found that the condition of the estimator is weaker than other observers. It is a qualified and simple and straightforward approach to be applied in wide domains.

Research limitations/implications

It should be noted that the sensors should be perfectly reliable. The maximum number of disturbances which can be decoupled cannot be larger than the number of independent actuators.

Practical implications

It is a very useful approach to solve the problem that the actuator is contaminated by disturbances.

Originality/value

The paper uses a transformation to divide the state into three parts. By estimating the part that is not affected by the disturbance and fault, it gets the exact estimation for the unknown input and fault of the actuator. The design condition of the reduced‐order observer which is proposed is weaker than others.

Details

Aircraft Engineering and Aerospace Technology, vol. 80 no. 1
Type: Research Article
ISSN: 0002-2667

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Article
Publication date: 1 August 2005

Jia‐hui Luan, Xing‐wei Jiang and Zheng‐ji Song

In order to improve the practicability of the design in state estimation, the paper aims to present a novel disturbance decoupled reduced‐order observer (DDRO) design scheme.

501

Abstract

Purpose

In order to improve the practicability of the design in state estimation, the paper aims to present a novel disturbance decoupled reduced‐order observer (DDRO) design scheme.

Design/methodology/approach

The paper first uses equivalence transformation to eliminate unknown input appearing in measurement. Then based on Luenberger observer and using two non‐singular coordinate transformation, the design observer can get no bias error in the state estimation.

Findings

By using this approach we find that the conditions of DDRO depend on the system itself that is weaker than other observers. It is a qualified and simple and straightforward approach to be applied in wide domains.

Research limitations/implications

We should note that the number of independent rows of the matrix C must not be less than the number of the independent columns of the matrix E to satisfy condition rank(CE)=rank(E)=q. In other words, the maximum number of disturbances which can be decoupled cannot be larger than the number of independent measurements.

Practical implications

It is a very useful approach to solve the problem that the measurement is contaminated by disturbances.

Originality/value

The paper proposed an equivalence transformation. It is used to eliminate unknown input appearing in measurement. At the same time the algebraic transformation guaranteed that it would lose no information of the unknown inputs. And compared with other known results, the design condition of the reduced‐order observer which proposed in this paper depends on system itself, especially, which is weaker than others.

Details

Aircraft Engineering and Aerospace Technology, vol. 77 no. 4
Type: Research Article
ISSN: 0002-2667

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