A novel hybrid fuzzy PID controller for attitude stabilization of a remote operated quadrotor unmanned aerial vehicle
Zul Azfar, Ahmam
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This thesis presents a new attitude control development to be implemented in the flight control board (FCB) of quadrotor unmanned aerial vehicle (UAV). A simple structure of quadrotor was developed to test the attitude stabilization control. The cross “+” shaped structure of quadrotor make it is very easy to develop. A remote operated quadrotor consists of four brushless DC motors (BLDC) with fixed pitch propeller attached on it, the FCB equipped with an inertial measurement unit (IMU) sensors, four electronic speed controllers (ESC), a set of remote controller transmitter and receiver and a high discharge lithium polymer (Li-PO) battery. Quadrotor have six degree of freedom (DOF) of flight control. The quadrotor flight behavior is same as helicopter but can fly as fast as fixed wing aircraft. However, only four movements are produced from 6 DOF flight control which are take-off/landing, roll, pitch and yaw. These movements are performed by varying speed of four propellers to produce different amount of thrust. The differences of thrusts will produce different quadrotor flight direction. A mathematical modeling was done to analyze the effectiveness of a control system to the real quadrotor. This mathematical model is used to represent the real quadrotor which was simulated using Simulink in Matlab Software. The new attitude control involved a hybrid controller of proportional-integral-derivative (PID) and a fuzzy logic controller (FLC). This new hybrid Fuzzy-PID (FPID) controller is developed to improve the performance of traditional PID controller. The approach to hybrid both of these controllers is using the parallel technique. All hybrid Fuzzy-P, Fuzzy-I and Fuzzy-D structures are combined together to form a new FPID controller. The purpose of designing the hybrid system is to use FLC as an automatic tuner for PID controller. The well-tuned PID gain of PID controller is combined with FLC to get a better performance compared to using the PID controller alone. Both controllers are simulated in Matlab software and then implemented to the real quadrotor to compare the performance. A test flight is conducted to observe the differences in controlling the quadrotor in flight using the new FPID controller instead of using PID controller. The result showed that the new FPID controller is better than PID controller in term of response and stability. The FPID controller is very quick to achieve the desired target and produce less overshoot than the PID controller and thus proof that the FPID controller is more stable compared to the conventional PID controller.