PI-D controller with optimized parameters of a scaled-model helicopter

Scaled-model helicopters are highly nonlinear, coupled, and unstable machines. They have fast response and controlling them is very complicated and need high degree of precision. In this paper, a detailed nonlinear model is derived. The derived nonlinear model is linearized around a nominal point in the hovering state and a linear classical controller is designed. Then, an optimization algorithm is applied where the linear controller's parameters are adjusted offline so that the Integral Time-multiplied Square Error (ITSE), the error between the output response of the nonlinear system and the reference signal, is minimal. Both the linear and the optimized controllers are augmented with the nonlinear model and the simulation results are compared.