Virtual sensors design for active fault tolerant control system applied to a winding machine

This paper presents a method for designing a virtual sensor in the case of Fault Tolerant Control. The whole approach, described in the paper, is applied to a winding machine. The process is modelled by a Linear Time Varying (LTV) model. The control of the web tension is based on the estimated or virtual measurements as feedback variables. The main contribution concerns the design of an accurate bank of observers able to both isolate and estimate sensor faults while preserving the system’s integrity in terms of structure and performances. The objective of Active Fault Tolerant Control System, is to maintain current performances close to desirable ones and preserve stability conditions when faults occur. The presented method allows one to isolate and to estimate sensor faults. The effectiveness and performances of the strategy are illustrated on the winding machine in the case of a complete loss of sensor.