Flight Testing Air Data Sensor Failure Handling with Hybrid Nonlinear Dynamic Inversion

Kurzfassung

Loss of one or more air data signals to the flight control laws typically results in activation of backup modes. These reduce functionality and work solely with inertial sensors. Since the failure situation is already a significant stress for the flight crew, this reduction of supporting control functionality comes at an awkward moment. This work shows how a combination of classical and so-called sensory nonlinear dynamic inversion can be used to maintain more or less the same handling characteristics in case of partial or even complete loss of air data. Under nominal conditions, hybrid NDI uses a complementary filter to combine NDI and sensory NDI. In case of failure, it is possible to degrade to a control law based purely on sensory NDI, which is predominantly inertial sensor dependent. This paper describes the application of the proposed modification to a CS-25 class aircraft, as well as the validation of its intended features in flight tests.