Nonlinear MPC (model predictive control) for minature coaxial helicopters

This paper introduces an optimization based control scheme for stabilizing and controlling coaxial helicopters. The scheme consists of a nonlinear MPC (NMPC) and an inner-loop linear feedback controller. The proposed MPC works in a piecewise constant fashion to reduce the computation burden and to extend the predictive horizon, which is available for engineering implementation. The linear matrix inequality based (LMI-based) inner-loop feedback controller responds to fast dynamics of the helicopter and compensates for the low bandwidth of the high-level controller in the presence of disturbances and uncertainties. The stability issues of the NMPC and the overall control scheme are discussed. Simulations are carried out to verify the proposed control scheme.