This paper aims to present a novel fault estimator design scheme, in order to improve the practicability of the fault estimation.
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.
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.
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.
It is a very useful approach to solve the problem that the actuator is contaminated by disturbances.
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.
