Modelling of nonlinear helicopter model and loopshaping based controller synthesis
This paper deals with the problems of identification and control of nonlinear helicopter model. The helicopter model is achieved by closed loop identification based on grey-box structure through two steps. The first step considers experiment design to minimize the number of parameters to be estimated. It employs a genetic algorithm for parameter value estimation. In the second step, a criteria function was defined for evaluation of model fitness. After that, linearization of nonlinear model was performed and linear state-space model was obtained for use in controller synthesis. The main contribution of this paper is design of loop shaping controller which is capable to control a nonlinear helicopter model. Advantage of this controller is its simpler linear structure and simpler synthesis. The quality of obtained helicopter model and effectiveness of proposed controller are verified both in simulation and experimental modes.