Steady maneuver envelope evaluation for aircraft with control surface failures

A critical prerequisite of researches in the field of fault-tolerant flight control and planning is flight envelope evaluation. In order to be in compliance with path planning or trajectory generation under abnormal conditions, steady maneuver envelope is defined and evaluated. This envelope provides a complete set of equilibrium flight states under a given set of control and state limits awkward. We propose a numerical procedure using continuation technique to directly compute the boundary of the envelope, instead of trimming every flight on a grid of state and maneuver parameter points. The advantage of this approach is that it eliminates the time spent in the calculation of disequilibrium points and thus save the overall cost of evaluation. We present its application to several situations involving stuck aileron and rudder in this paper. In comparison with nominal condition, the size of the envelope decreases and the shape changes, owing to the saturation of corresponding key control variables. The open-loop stable region also shrinks as a consequence.