Flight Autopilot Design using LQ and feedback controller theories

In the last years, several control theories have been widely developed. They are generally applied to control task such as trajectory tracking and mission optimization. In this paper, we consider a remotely piloted vehicle (RPV airplane), where the linear quadratic (LQ) and feedback methods are used to perform the control law of the autopilot. The equations of the complete airplane motion are first linearized and the flight variables decoupled. In this linear model, the total motion is equivalent to a superposed longitudinal and lateral motions. Each of these is decomposed to several modes. The LQ design of the autopilot consists in the minimization of a cost function. The corresponding results are obtained by the solution of the Riccati equation. When using the feedback theory, the adjustment of the autopilot gains is based on the pole placement or the root locus procedure. The response of the complete system (non linear RPV airplane with autopilot) is finally simulated. The two methods has proved to be well adapted for this design. The results show that th