A nonlinear observer with disturbance attenuation and its application to fault detection

One difficulty in the problem of fault detection is robustness w.r.t. disturbances which are not faults, and one approach to this problem is observer-based residual generation. In this paper, it is first shown how a so-called high-gain observer, designed for a class of nonlinear systems, can also guarantee "arbitrary" attenuation of unknown disturbances on some penalty variable. The use of such an observer in robust fault detection purposes is then discussed, and finally illustrated by a small example.