Study on dual-loop controller of helicopter based on the robust H-infinite loop shaping and mixed sensitivity

Helicopter is a typical static instability, strong coupling, MIMO system. The controller is designed based on the dual-loop method. The internal loop ACAH controller is designed with the robust H-infinite loop shaping method, which can ensure the Robust decoupling of each channel. The external loop is designed to control the forward, sideward velocity and the height, with the H-infinite mixed sensitivity method on the base of decoupling internal loop. The simulation results demonstrate that the performance of the controller meets the design requirement in both time and frequency domain, which achieves LEVEL1 of ADS-33E-PRF, and the controller has some effect against to the model perturbation.