Browsing by Author "Engelbrecht, J. J. K."

Now showing 1 - 1 of 1
  • Thumbnail Image
    Item
    Optimal attitude and flight vector recovery for large transport aircraft
    (Stellenbosch : Stellenbosch University, 2017-12) Engelbrecht, J. J. K.; Engelbrecht, J. A. A.; Stellenbosch University. Faculty of Engineering. Dept. of Electrical and Electronic Engineering.
    ENGLISH ABSTRACT: Loss of control (LOC) is the largest contributor to commercial jet aircraft fatal accidents worldwide. Aircraft upset conditions are a primary cause leading to LOC situations. Despite flight envelope protection systems, a need exists for an automatic system to assist the pilot in recovering from a flight envelope upset condition. This thesis presents the design and implementation of an attitude and flight vector recovery system for large transport aircraft. The upset recovery system consists of two major components, namely an optimal trajectory planning component and a practical trajectory execution component. For the optimal trajectory planning, the upset recovery problem is formulated as an optimal control problem and is solved using two different optimal control algorithms, namely dynamic programming (DP) and sequential quadratic programming (SQP). For the trajectory execution, four different control schemes are investigated that use a conventional fly-by-wire flight control system in different configurations to control the aircraft to practically execute the planned optimal trajectory. The attitude and flight vector recovery system was verified in simulation on the NASA Generic Transport Model (GTM), a wide-envelope aircraft model that is able to model the flight mechanics of large transport aircraft in out-of-envelope conditions. The simulation results show that the trajectory planning component generates kinematically feasible optimal upset recovery trajectories, and that the trajectory execution component successfully controls the aircraft to follow the planned trajectories using a representative flight control system. The SQP trajectory optimisation algorithm proposed in this thesis also improves on the dynamic programming algorithm used in previous research, because it is able to use a more representative model of the aircraft dynamics that includes the inner-loop controller dynamics and the engine lag dynamics.