On Quadrotor Navigation Using Fuzzy Logic Regulators

In this paper the cascaded fuzzy controller system for quadrotor steering and stabilizing was deliberated. The mathematical model of quadrotor and its cascaded fuzzy controller were simulated using Matlab Simulink software. The fuzzy system was divided into three subsystems for controlling position and speed of the quadrotor and for steering rotation speed of propellers. In the article the square trajectory of quadrotor flight was presented as a system test. 1 Mathematical model of the quadrotor Several small UAVs, like small planes, triand quadrotors, balloons, etc. have been constructed recently. Most of them utilize the classical control theory, so they are controlled by proportional integral derivative (PID) feedback controller [1, 2, 4, 5, 8]. The other very promising method is based on the foundation of fuzzy logic [3, 10–12]. The main advantage of fuzzy logic, in compare to classical method, is the ability to develop controller using simple transformation of rules expressed in natural language. The good example of this methodology was demonstrated in our prior publications [6, 7, 9, 14]. PID controllers are well described in vast literature and the knowledge about PID is approved by numerous working systems. But there is a disadvantage PID controller uses an assumption about linear characteristics of the controlled system which is not always true. It means that such controllers usually need calibration procedure. Therefore, if the point of work changes (for example on account of weight change) then PID controller can have some problems with proper working. The controller using fuzzy rules should cope in such situation. Quadrotor, called in some publications “quadrocopter“ [4, 13], is a flying object with four fixed-pitch propellers in cross configuration. Driving the two pairs of propellers in the opposite directions removes the need for a tail rotor. Usually all engines and propellers are identical, so the quadrotor is a fully symmetrical flying object.