Aircraft adaptive control system

Claim 1

A control system for providing automatic compensation of variations in the gain of the controlled member, applicable for actuating an aircraft control surface having a control surface actuator and drift sensing circuits, comprising a closed-loop circuit which operates in obedience to a law relating the value of the actuation quantity to the difference between the actual output quantity and the commanded quantity, in which said closed loop includes multiplier means for multiplying the signal proportional to said difference, inverting amplifiers of said signal and of the output signal from said multiplier, summing means for summing the signals issuing from said amplifiers, integrator means for integrating the output signal from said summing means, a differentiating circuit for delivering the derivative of said output signal with respect to time, a circuit driven by said derivative and delivering an output signal y such that : Ty'' + y T Beta ''c, where Beta ''c is said derivative and T is a constant, and a circuit for delivering the absolute value y of said signal y to said multiplier means, the output from said integrator means controlling said actuator the deflection angle imparted by which is related to the pitch angle of the aircraft, the general law taking the form : Beta ''c K1 y F (x) - K2G (x) where x is the difference between the actual position of the control surface and its commanded position, F(x) is a function of x G(x) is a second function of x and K1 and K2 are predetermined positive coefficients of said amplifiers, K2 being smaller than K1.