Controller design for a 3-DOF helicopter using multiple models with second level adaptation

In this article, an adaptive model following control of a nonlinear multi-input multi-output (MIMO) coupled system with unknown parameters is considered. The decoupling matrix of the system is assumed to be singular, so that the system can not be decoupled by static state feedback. A dynamic state feedback with nonlinear structure algorithm is applied to design the controller. An observer is used to estimate the unknown parameters of the system. A multiple model with second level adaptation is introduced for the nonlinear MIMO coupled system. A 3-DOF (degree-of-freedom) helicopter model is simulated to validate the theoretical establishments. The advantage of using second level adaptation is established by conducting simulation studies.