Abstract:

As the most basic control mode of the aircraft longitudinal motion, it is difficult to control the aircraft pitch angle. A two-degree-of-freedom PID control algorithm was proposed for the first-order integrating system with time delay, which was simplified by a fourth-order system. The fourth-order system was composed of the increment of pitching angle and the offset of rudder surface. The main idea of the algorithm was to design the set-point filter and controller separately based on the multiple dominant pole placement method and the direct synthesis method. The tuning rules were given in form of analytical equation. Simulation results showed that the proposed method could be well applied to the fourth-order system of aircraft pitch angle, and also had excellent disturbance rejection performance and better servo performance and robustness.

Key words: aircraft pitch angle, fourth-ordersystems, first order integrating system with time delay, two-degree-of-freedom PID controller, multiple dominant pole placement method, direct synthesis method