Feedback Control Structures, Embedded Residual Signals, and Feedback Control Schemes With an Integrated Residual Access

Driven by the increasing needs for the integration of model-based fault diagnosis into the electronic control units (ECUs) with limited computation capacity and motivated by the recent study on the fault tolerant controller architecture, we investigate feedback controller structures aiming at accessing the residuals embedded in the control loops. For this purpose, we first develop an observer-based realization of the Youla parameterization. This result reveals a new interpretation of control signals as a composite of the residual and reference signals. From this viewpoint, different control schemes are studied and useful relationships between the controller structures and embedded residual signals are established. It leads to the development of two kinds of schemes: 1) extracting residual signals from an existing control loop and 2) configuring control loops with an integrated residual access. The achieved results are demonstrated by two examples of the feedback control loops in engine management systems.