Helicopter Modeling and Optimal Control in Autorotation

An optimal control method was developed for helicopter control after power failure. A seven degrees of freedom model of single rotor helicopter was developed (6 DOF of rigid body and angular velocity of the main rotor). Helicopter engine dynamic was modeled as the system of the first-order. The helicopter control vector was composed of the main rotor collective and cyclic pitch and collective pitch of the tail rotor. Induced velocity was modeled using Glauert formula including ground effect. In the optimal control method the quadratic cost function was used with selected constrains. In the method applied both cost function and constrains may vary during the helicopter flight. The helicopter model was validated using flight tests data. The simulations confirmed the proper behavior of the model and effectiveness of control algorithm.