Design of PID Control strategy for Forward Flight of Quadrotor in the Ground Effect Condition

In unmanned aerial vehicle (UAV) classes, the control of quadrotor has attracted many researchers from around the world in recent years. In this type of rotary wing, it is attempted to achieve stability in hover and motion flight modes using the forces, produced by propellers. Quadrotor has nonlinear and time-varying behavior and the aerodynamic forces almost always disturb it. In near the ground, the wake of quadrotor interacting with the ground surface causes perturbation to the flow near the blades and frame. These perturbations have significant effect on quality and stability of flight. Most of the related researches were only studied hover and landing operation and the ground effect was considered as constant coefficient in dynamic equations. In this paper, a comprehensive nonlinear model is developed for variety modes of quadrotor flight in near the ground in space state, and the ground effect is as function of state variables in equation. Then, according to the proposed model, the PID controller is designed and the effect of the ground effect on controller performance is investigated. The results of simulation indicate that, the flight stability and trajectory tracking have improved significantly by using of the model and designed controller.