Guidance and control for autonomous emergency landing of the rotorcraft using the incremental backstepping controller in 3-dimensional terrain environments

This paper treats the approach to safe emergency landing for an autonomous rotorcraft in 3-dimensional terrain environments. The autorotation flight that the rotorcraft flies without the power supply is dangerous and needs the high-skilled control ability of the pilot. Ordinary, this flight is divided into three phases: Entry, Steady-Descent, and Flare phase. The emergency landing trajectory is generated by imitating each phase. The Trajectory optimization method using the high-fidelity math model is applied to the entry and flare phase to consider the complex dynamics of the rotorcraft. To generate a steady-descent phase trajectory without obstacle collisions, one of the path planning methods, the improved Rapidly-exploring Random Tree algorithm is used. The Incremental Backstepping controller is adopted as the trajectory tracking controller. Simulation is conducted in the One Engine Inoperative condition. Through the simulation, it is shown that the method proposed in this paper guarantees the safe landing of the rotorcraft in an emergency like engine failure.