Model-Following Control and Actuators Limits Analysis to Transform Helicopters into Personal Aerial Vehicles

The paper shows the design of a control augmentation system to transform helicopters into Personal Aerial Vehicles, accounting for handling qualities and actuator constraints. In this paper, PAVs are conceived as augmented rotorcraft that can be safely flown by minimal-trained pilots with a training comparable in length to that necessary to learn how to drive a car. The goal of the paper is to evaluate if existing actuators allow current helicopters to achieve PAV's characteristics without incurring into prolonged rate or position saturation due to abrupt or large control inputs given by minimal-expert pilots. The goal is achieved in two steps: in the first step, a model-following control approach is implemented to follow PAV's reference dynamics used as command models. The controller is designed and tested by considering the state-space model of a Sikorsky UH-60 and by including actuator dynamics. An optimization routine is created to achieve a trade-off between handling qualities, disturbance rejection properties and stability margins. In the second step, pilot in-the-loop simulations are conducted with one expert and one non-expert pilot to evaluate the feasibility of the controller implemented in the first step. Results show that PAV requirements can be achieved with the available technology but the current helicopter handling qualities requirements should be relaxed in order to reduce the risk for actuators saturation, especially in presence of disturbances.