The helicopter or any twin rotor multi-input multi-output (MIMO) system (TRMS) experiences a critical time delay issue when it is in   the hovering state. In order to address this time delay problem, an appropriate model, and a fitting control algorithm needs to be developed. This review discusses the different methods of modeling, the procedure for identification of parameters of the considered model and the various methods of validating the estimated model. Also, this review discusses the implementation of various control strategies like PID control, adaptive control and sliding mode controller for the estimated model to ensure the basic requirements of any system like stability, robustness and sensitivity to control inputs.

twin rotor, multi-input multi-output system, modeling, linear, identification, control, adaptive control.