Abstract:
In this paper, a time-optimal trajectory generation algorithm is proposed for helicopter shipboard landing. The algorithm utilizes a simplified model of the helicopter's dynamics and exploits the differential flatness of the model to formulate a nonlinear programming problem, whose solution provides time-optimal reference approach/landing trajectories. The trajectories are then tracked by an inner-loop linear dynamic inversion (LDI) controller to generate the actual inputs that steer the full-state nonlinear helicopter model. The proposed algorithm reduces approach/landing flight time and enables a higher degree of maneuverability in comparison to typical state of the art methods of trajectory generation. Because of its computational efficiency, the path planner can also be used in real-time, i.e., through iterative recalculation of the remaining trajectory to account for deviations from the planned flight path. High fidelity simulations have been conducted on a verified UH-60A Black Hawk model, which show the effectiveness of the proposed method.