Patent ID: 7225061
Filing Date: 2007-05-29
Classification: G05D

Abstract:
1. In an aircraft having: at least one tilting control that controls said aircraft about at least one of its axes of maneuver; and a means operated by a pilot for generating an electric command δ, representative of the amplitude of the tilting of said at least one tilting control, said electric command δ being able to adopt a maximum value δo, a method for detecting pilot induced oscillations in said electric command δ comprising: sampling said electric command δ at a sampling interval Δt to obtain a plurality of N successive samples X choosing the number of samples N and the sampling interval Δt so that the inverse of their product N.Δt is at least approximately equal to 0.3 Hz; breaking down said sampled command into a Fourier series in such a way that each sample x in which expression j is the symbol assigned to the imaginary part of a complex number, r is the number of harmonic components in the Fourier series and A r are the Fourier coefficients, each of the latter being equal to: determining the moduli |A1| and |A2| of the first two Fourier coefficients Al and A calculating the sum |A1|+|A2| of said moduli, said sum being representative of the energy of said signal samples X calculating an index I that is equal to the quotient of the sum |A1|+|A2| of said moduli divided by the number N of samples; comparing said index I with a fraction q.δo of said maximum value δo of said electric command δ, said coefficient q of said fraction q.δo being determined from a pre-established database grouping together a number of earlier flight scenarios in which such pilot induced oscillations occurred; and generating a signal that is: