Abstract:
An aircraft contains three rotational motions like pitch, yaw and roll. The pitch motion is controlled by the elevators that are present on the part of the tail, at the rear of an aircraft. An autopilot is a software or tool that can only manage the aircraft under certain conditions using the vehicle’s hydraulic, mechanical and electronic systems. This system, which can follow the flight plan, can stabilize speed and height as well as the location of the front of the aircraft (heading). Pilots mostly lead the aircraft in a controlled manner by autopilot except for departure and landing. Autopilot is mostly used on passenger aircrafts. In this research, elevators are considered as plant and its transfer function is used in modeling of the controller. The proportional integral derivative (PID) controller was used in the modeling of the control system to find the best performance for the aircraft (pitch motion). The comparison was made before and after adding the PID controller and the performance parameters are as follows. Before adding the controller, the rise time was 0.285s, the peak time was 0.143s, the settling time was 0.914s, the overshoot was 137 and the steady state error was. 0.065. After adding the PID controller it was found that at the selected point (-3.7915-0.0466i), from the geometric locus of the roots, achieves the best performance of the aircraft (pitch motion). The rise time is 0.0021s, the peak time is 0.0045s, the settling time is 0.0124s, the overshoot is 8.6561 and the steady state error is zero. It’s noted from comparison that adding the PID controller led to better performance for the aircraft in terms of the stability which the required in flight until we reach safe and comfortable flight and fewer accidents
