Identification and control of RTAF aerial target

This paper presents the theoretical and experimental development of an autopilot for the Royal Thai Air Force (RTAF) aerial target. Since there was no prior information about the aerodynamic coefficients and propulsion model, an equation-error method was used to estimate aerodynamic and propulsion coefficients from flight data in order to develop a six-degree-of-freedom (6-DOF) nonlinear mathematical model of the aerial target. In addition, this flight data was an ordinary piloted manoeuvre and off-trim condition (racetrack maneuvers) which is different from the flight data of usually used. Moreover, based on the identified nonlinear model, the gains in each loop of a proportional, integral and derivative (PID) autopilot were determined. The PID autopilot was validated through both hardware-in-the-loop (HIL) simulation and real flight test over one particular flight envelope. As a result of the flight test, this PID autopilot successfully performed its functions without any need to adjust the controller gains.