Rotorcraft Flight Envelope Protection by Model Predictive Control

摘要

A novel flight envelope protection method is presented in this paper. The approach is based on a model predictive receding horizon formulation, which computes at each instant in time the future extremal control inputs that would lead the vehicle to ride the flight envelope boundary without ever exceeding it. The actual control inputs fed to the vehicle are then bounded, through pilot cueing, by the extremal ones. The calculation of the extremal inputs is based on the constrained optimization of a quadratic figure of merit for a linear parameter varying reduced model of the vehicle. The model accounts for the cross-couplings among the inputs that characterize the flight mechanics of rotorcraft vehicles, and spans the entire flight envelope of interest by piecewise linear interpolation of given trim points. The approach leads to a convex optimization problem, which can be computed very efficiently in real-time using a deterministic number of operations. A heuristic modification of the limit parameter allowables, driven by a non-linear reduced model of the vehicle, is used for on-line solution adaption against possible model mismatch. The new approach is demonstrated by the numerical simulation of a number of complex pilot-in-the-loop aggressive maneuvers.