Patent ID: 9216830
Filing Date: 2015-12-22
Classification: B64F,G05B

Abstract:
1. A method for detecting at least one oscillatory fault in at least one positional servocontrol arrangement of at least one control surface of an aircraft, said servocontrol arrangement forming part of a system of electric flight controls of the aircraft, the system including said control surface which is mobile, and whose position with respect to the aircraft is adjusted by at least one actuator, said actuator which adjusts the position of said control surface, as a function of at least one actuation order received, at least one sensor which measures the actual position of said control surface, and a computer which calculates a control surface control order, which receives said measured actual position and which deduces therefrom an actuation order which is transmitted to said actuator, and the method comprising: coupling, to the control surface, at least one actuator configured to adjust the position of the control surface with respect to the aircraft in response to at least one actuation order; coupling, to the control surface, at least one sensor configured to measure the actual position of the control surface; communicatively coupling a computer to the at least one actuator and the at least one sensor, the computer configured to calculate a control surface control order, receive the measured actual position, determine the actuation order, transmit the actuation order to the at least one actuator, and detect the at least one oscillatory fault by performing the steps of: a) estimating a theoretical position corresponding to a reference position of said control surface in the absence of any fault with the aid of said control surface control order which feeds a model of said actuator; b) computing the difference between said theoretical position estimated in step a) and the actual position measured by said sensor so as to form a residual value; and c) comparing the residual value with at least one predetermined threshold value; and counting all the successive and alternate oversteppings of said predetermined threshold value by said residual value, and, as soon as the number resulting from said counting becomes greater than a predetermined number, an oscillatory fault is detected which represents a periodic signal of sinusoidal type, whose frequency, amplitude and phase follow a uniform law, wherein in step a), at each iteration, said theoretical position is estimated with the aid of at least one auxiliary value corresponding to the residual value formed in step b) of the previous iteration, that has been multiplied by a dynamic gain, and wherein said dynamic gain is computed with the aid of an H-infinity synthesis procedure, and a corrector is used for carrying out a correction in step a) making it possible to obtain an amplification gain in a passband corresponding to the frequency band in which a fault may occur, and an attenuation outside of this passband.