· · · Institutional Repository

Nonlinear Dynamic Inversion (NDI) is a promising method for Fault Tolerant Flight Control. The NDI algorithm cancels out the aircraft dynamics based on a dynamic aircraft model such that the closed loop system behaves linearly. The aircraft model is estimated online, which allows it to accommodate changes in the aircraft configurations and failures. It is important that an accurate dynamic aircraft model is provided in order to minimise the parasitic dynamics of imperfect dynamic inversion. Sliding Mode Control (SMC) feedback is applied to increase the robustness of the NDI algorithm especially in the case of a failure. SMC is well known for its strong robustness properties and controls the system using brute force. 1st order SMC is a discontinuous control algorithm and the chattering behaviour is highly undesired in practical applications. Therefore 2nd order SMC is applied on the critical rate control loop. This algorithm is less sensitive to noise and the control signals are continuous. It is shown that SMC can accommodate large uncertainties originating from control allocation error. Constraining the control solution minimises the parasitic dynamics and reduces the load on the feedback controllers. The Control Allocation problem is written as a low complexity linear program. For load balancing purposes the control solution is shaped with the Pseudo-Inverse.