Robust LQR controller for landing unmanned helicopters on a slope

It has been a challenging task to land an unmanned helicopter on a slope for the fact that helicopters are apt to topple over when touching the slope. It is crucial that the bottom plane of the unmanned helicopter should be parallel to the slope with zero relative velocity when they get touching. In this paper, a robust finite-time LQR method is applied to drive a real unmanned helicopter to an expected state at specified time, with nonlinearities, couplings, parameter uncertainties and external disturbances considered. Experiment results are provided to demonstrate the effectiveness of the proposed control method.