Variable-Pitch Control of a Quadrotor Using Feedback Linearization Controller and Direct Adaptive Feedback Linearization Controller

In this paper, the dynamic structure of variable pitch quadrotor and the design of a suitable controller based on mathematical modeling have been studied. The fixed pitch quadrotor because of having a simpler dynamic structure than other models has been the focus of scientific studies. This kind of quadrotors, despite their relative simplicity, creates limitations such as shortening the flight time and various maneuvers. In this paper, at first, the characteristics of variable pitch propeller are studied and compared with the fixed pitch propeller for a quadrotor. In continue, a Feedback Linearization Controllerand a Direct Adaptive Feedback Linearization Controller are used to control the Variable-Pitch quadrotor. Ultimately, the results of the proposed control are investigated via MATLAB software simulation. To better evaluate the performance of the designed controllers, the simulation results are compared with PID and Nonlinear Inverse Dynamics (NID) and Sliding Mode and Adaptive Sliding Mode controllers in the mass change condition of the quadrotor.The simulation results show that this adaptive strategy allows the quadrotor to follow variable time attitude and altitude commands more accurately, in the presence of disturbances or parameter uncertainties, compared to non-adaptive feedback linearization controllers. And also it shows that adaptive feedback linearization and adaptive sliding mode controllers have more accurate tracking with less error compared to feedback linearization, sliding mode, PID and NID controllers, respectively.