Control and simulation of arbitrary flight trajectory-tracking

A detailed description of a six-degree-of-freedom nonlinear flight simulation is presented and a method of generating the guidance commands for controlling the aircraft trajectory in three-dimensional space is proposed. Tracking errors are expressed in terms of zero effort miss vector, which is the expected miss distance at the future time between two flight vehicles, that is, one on the desired trajectory and the other on the actual trajectory. This zero effort miss vector is used to form a Lyapunov function. Then a set of guidance commands for the speed and flight direction control loops are selected in such a way that they will strictly decrease the Lyapunov function. Thus obtained guidance commands are incorporated into the existing flight control systems and tested with representative flight scenarios where the performance of trajectory tracking is considered to be important.