  This paper proposes a novel and practical framework for safe flight envelope
estimation and protection, in order to prevent loss-of-control-related
accidents. Conventional analytical envelope estimation methods fail to function
efficiently for systems with high dimensionality and complex dynamics, which is
often the case for high-fidelity aircraft models. In this way, this paper
develops a probabilistic envelope estimation method based on Monte Carlo
simulation. This method generates a probabilistic estimation of the flight
envelope by simulating flight trajectories with extreme control effectiveness.
It is shown that this method can significantly reduce the computational load
compared with previous optimization-based methods and guarantee feasible and
conservative envelope estimation of no less than seven dimensions. This method
was applied to the Innovative Control Effectors aircraft, an overactuated
tailless fighter aircraft with complex aerodynamic coupling between control
effectors. The estimated probabilistic flight envelope is used for online
envelope protection by a database approach. Both conventional
state-constraint-based and novel predictive probabilistic flight envelope
protection systems were implemented on a multiloop nonlinear dynamic inversion
controller. Real-time simulation results demonstrate that the proposed
framework can protect the aircraft within the estimated envelope and save the
aircraft from maneuvers that otherwise would result in loss of control.
