Design of hovering altitude holding control system for helicopter

Effected by sea wave and other noises, altitude holding becomes difficult when helicopter is hovering or rescuing near the sea face. In this paper, according to the integrated height system of radio altimeter and vertical accelerometer, a Kalman filter is designed to get the accurate altitude signals of the helicopter hovering over the sea. Then, two altitude holding control structures are developed based on helicopter explicit model following control system (EMFCS), which has excellent operation characteristics. In order to simulate the real situation and to design the filter, sea wave model is established by using the rational spectrum modeling method. Simulation results show that the two control systems designed both can realize helicopter hovering altitude holding efficiently, and have good resistance to vertical wind disturbance or parametric perturbations.