Sensor fault detection and isolation for aircraft control systems by kinematic relations

• A new approach to model-based aircraft sensor FDI is proposed using kinematic models.
• Kinematic models are known exactly even in case of constant wind.
• The approach is valid for the whole flight envelope and insensitive to actuator faults.
• Simultaneous input or output faults can be detected and isolated.
• Two practical applications are presented to demonstrate the advantages.

This paper presents a new approach to Fault Detection and Isolation (FDI) for sensors of aircraft. In the most general case, fault detection of these sensors on modern aircraft is performed by a logic that selects one of, or combines, the three redundant measurements. Such a method is compliant with current airworthiness regulations. However, in the framework of the global aircraft optimization for future and upcoming aircraft, it could be required, e.g., to extend the availability of sensor measurements. Introducing a form of analytical redundancy of these measurements can increase the fault detection performance and result in a weight saving of the aircraft. This can be achieved by exploiting the knowledge of the kinematic relations between the measured variables. These relations are exactly known giving the advantage that no model-mismatches need to be accounted for. Furthermore these relations are valid over the whole flight envelope and general for any type of aircraft. Two example applications will be presented, showing the applicability of the method for the FDI of air data sensors and measurements of the inertial reference unit.