Real-time Path Planning for Time-Optimal Helicopter Shipboard Landing via Trajectory Parametrization

A real-time path planning algorithm is developed to generate time-optimal trajectory for helicopter shipboard landing.
The trajectory optimization problem is translated to the lower dimensional flat output space by exploiting the
differential flatness property of the simplified helicopter model. Then, the flat outputs are parameterized using piecewise
spline functions with adjustable coefficients, which are used to shape the trajectory and approximate the optimal
solution. Further, by allowing the flexible selection of each spline segment’s time-duration and enforcing additional
path constraints, the time-optimality of the planned trajectory is largely preserved without violation of state and input
bounds. Compared to pure temporal discretization methods, the proposed algorithm employs considerably less decision
variables and significantly reduces the computational time by 75%, which only leads to a 0:5% growth in the
optimal flight time as the trade-off. The improvement in computational efficiency enables the real-time recalculation
of the time-optimal trajectories on-the-fly if there are unforeseen deviations from the planned flight path.