Modeling, Simulation and Control of a Fly-by-wire Flight Control System Using Classical PID and Modified PI-D Controllers

摘要

The Fly-By-Wire (FBW) system is a computer-based flight control system that replaces the mechanical link between the pilot's cockpit controls and the moving surfaces by much lighter electrical wires. This concept is applied in the electro-hydraulic servo systems. In the present work, a detailed non-linear mathematical model of an aircraft integrated servo actuator (ISA) is developed and a computer simulation program is built using MATLAB/SIMULINK package. The ISA mainly consists of two separate active hydraulic power systems, used to supply the ISA with the required power. The studied ISA incorporates two electro-hydraulic servo-valves, a twin-symmetrical-hydraulic actuating cylinder, and a smart design of built-in directional control valves with a feedback system. The output linear motion of the actuating cylinder of the ISA is presented and its transient response is analyzed. A classical PID and modified PI-D controllers are designed and tuned by Zeigler-Nichols method according to the Integral Square Error (ISE) criteria to minimize the difference between the obtained system output feedback and the desired set input by adjusting the system control parameters. The comparative study between the two types of controllers show that the modified PI-D controller has better response than basic one and slower in the presence of disturbance.