Perpustakaan Digital ITB

Unmanned Aircraft Vehicle (UAV) are controlled remotely, hence the operator should rely on an autopilot system to maintain aircraft flight condition and attitude. In this study a design of longitudinal autopilot for Medium-Altitude Long- Endurance (MALE) UAV is discussed, specifically to control speed and altitude of the aircraft. The work starts by linearising a given nonlinear model of the aircraft. An autopilot controller based on linear quadratic regulator (LQR) is developed for the linear aircraft model. The selection of the weighting matrices in the controller design is performed automatically (randomise) to minimise Root Mean Square Error (RMSE) between the reference signal and aircraft response. Further, the controller is improved with the addition of integral action to remove the steady state error. The robustness of the controller is then evaluated for additional unmodelled actuator and sensor dynamics as well as dynamic changes for different trim speed. The design controller results without integral action; speed hold and altitude hold a RMSE of 25% and 32%. Meanwhile, final controller design with integral action; speed hold and altitude hold a RMSE of 16% and 11%. The controller can handle sensor delay better than actuator delay.