I am working on observer based active fault tolerant control( Fault detection and isolation (FDI) scheme) for handling sensor faults in a system. The system has also a dynamic disturbance component also which is difficult to have a proper observer design to design the FDI of the FTC scheme. I would like to know the effective methods to handle such situations with observer based FTC schemes. How to handle the issues of disturbance modelling and threshold selection in such schemes? Also what could be the limitations for such schemes?