Motion Primitives for an Autorotating Helicopter

In this paper, we introduce a design criterion for motion primitives of a helicopter when engine failure occurs. A flight plan followed by such a helicopter after it has established autorotation consists of concatenation of such well-defined motion primitives. A library of primitives act as an useful finite action space for a motion planner to search over. Subject to the constrained flight dynamics, a set of useful trim or steady state motions are identified which either maximize glide slope or minimize descent speed. Incorporating these trim motions allows the system to coast along a trajectory for an arbitrary amount of time. To transition from one trim to another, a set of maneuvers or finite time trajectories are defined and solved for using optimal control.