Helicopter flight control with variable rotor speed and torque limiting

A helicopter flight control system is designed to incorporate variable rotor speed while handling torque limits and other constraints. The vertical axis controller uses a fixed non-linear mapping to find the combination of collective pitch and rotor speed to optimize performance in level flight, climbing/descending flight, and steady turns. In this scheme, the controller is open-loop, making it an inexpensive and reliable solution. The mapping is designed to produce a desired power level for a given pilot input. Thus the mapping can take into account the performance limits associated with the vertical axis such as power limits, torque limits, and maximum rate of descent. A model following controller is implemented for the pitch, roll, and yaw axes. The control system is demonstrated using the GENHEL simulation of a UH-60A helicopter.