Autonomus Helicopter Landing on a Mobile Platform.

Abstract: In this thesis we investigate the problem of landing a helicopter autonomously on a mobile platform by designing controllers for the attitude- and translational dynamics in parallel. A mathematical model of the helicopter, in form of general 6-degrees-of-freedom rigid-body dynamics with application-specific actuations, is developed. A linearized model is used in order to make a landing problem more tractable, which is also rather reasonable under landing constraints, where small angle- and velocity approximations are valid. The inputs used for the attitude controller are the tail rotor thrust and the tip-path-plane angles. Then, a form of cascaded control is adopted for the translational dynamics, in which the inputs are the Euler angles together with the main rotor thrust. The resulting control system is tested by MATLAB simulations against a smooth position reference path, with satisfying results. For the landing scenario, a trajectory planning strategy based on linear model predictive control (MPC) is adopted. The cascaded control system is then used to track the translational reference trajectory. The translational reference trajectory is chosen such that the attitude dynamics is adapted to the attitude of the platform at touch-down.