Output feedback control synthesis for a helicopter using explicit nonlinear model predictive control, dynamic inversion and extended high gain observers

Control design for a helicopter is a challenging problem because of its non-affine inputs, complicated dynamics and it is an under-actuated system. To solve a control problem of the helicopter under model uncertainties and disturbance present environments, an Explicit Nonlinear Model Predictive Control (ENMPC), a dynamic inversion and an Extended High-Gain Observers (EHGO) are combined in a multi-time-scale fashion. The multi-time scaled structrue and the ENMPC provides the framework of the control design, the dynamic inversion deals with nonaffine control inputs, and the EHGO estimates the unmeasured states and uncertainties. In addition, a discretization scheme using the saturation and adding low pass filters to the control inputs is presented. Finally, the numerical simulation of a fixed sampling period has been carried out to demonstrate the validity of the proposed multi-time-scale control design and the discretization scheme.