US 5,722,620 A · Aircraft pitch-axis stability and command augmentation

Abstract

Disclosed is a pitch-axis stability and command augmentation system (19) in which a pilot column input (.delta..sub.C) is provided to a pitch command processor (26), the output of which is a C*U feedforward command (C*U.sub.FFC) that is supplied as an additive input to a combining unit (20). The combining unit (20) receives a second additive input of an augmented feedback command signal (AFB.sub.COM). The resulting output is filtered and generates an elevator command signal (.delta..sub.e,FILT). The command processor (26) additionally supplies a corrected column position signal (.delta..sub.C,COR) to a pitch command C*U processor (26) that converts the corrected column position signal (.delta..sub.C,COR) into a C*U pitch command (C*U.sub.PilotCmd), representative of the pilot's requested elevator pitch which is generated by movement of the control cola. A computed C*U processor (32) forms a computed C*U signal (C*U.sub.Computed) that is based on the current state of the aircraft. The C*U processor (32) includes a speed stability processor (150) that computes the difference between a reference speed (V.sub.REF) and calibrated airspeed (V.sub.CAS). The speed stability processor (150) includes phugoid damping (400) in generating a speed error signal (E.sub.z), and providing a means by which the pilot may set a reference airspeed (V.sub.REF) by using a trim device. An underspeed protection signal (C*U.sub.Us) is supplied by a stall protection processor (416). A flare compensation signal (C*U.sub.FR) is supplied by a flare compensation processor (414). An overspeed protection processor (412) supplies an overspeed protection signal (C*U.sub.OS). A combining unit (424) is provided to combine the stall protection signal (C*U.sub.Us), flare compensation signal (C*U.sub.FR), and overspeed protection signal (C*U.sub.OS) to form a compensation and protection signal (C*U.sub.C&P). A combining unit (22) combines the pilot-requested C*U command (C*U.sub.PilotCmd), the computed C*U signal (C*U.sub.Computed), and the compensation and protection signal (C*U.sub.C&P). The resulting signal is an error signal (E.sub.C*U) which is supplied to an integrator (28) that outputs a C*U integral command signal (IC*U.sub.COM). Another combining unit (23) receives the C*U integral command signal (IC*U.sub.COM) and combines it with a pitch rate damping command signal (Q.sub.COM). The output of the combining unit (23) is the augmented feedback command signal (AFB.sub.COM).

Claims23

Dependent claims

An aircraft pitch control system having input signals representative of commanded elevator response, control column position, normal acceleration, and aircraft pitch rate;

the pitch control system for changes in aircraft pitch exhibiting stable speed response characteristics;
the pitch control system comprising:
(a) a computed elevator response processor comprising:
(i) a first combining unit for combining a signal representative of reference speed with a signal representative of aircraft speed to generate a speed error signal representative of their difference;
and
(ii) a second combining unit for combining the normal acceleration signal, the aircraft pitch rate signal, and the speed error signal to generate a signal representative of computed elevator response, the computed elevator response signal representing the anticipated aircraft response under current flight conditions;
(b) a first signal combiner having first and second inputs, the commanded elevator response signal being fed to the first input, the computed elevator response signal being fed to the second input, the first signal combiner generating a difference signal;
and
(c) mechanisms for controlling the aircraft in response to the difference signal.

6 more elements

An aircraft pitch control system for use with an aircraft having a movable control column, the aircraft further including a position sensor for generating a signal representative of the control column position, the system comprising:

(a) a first signal combiner having first and second inputs and an output;
(b) a pitch command processor connected for receiving the column position signal and for supplying a feed-forward elevator command signal to the first input of the first signal combiner;
(c) a commanded elevator response processor connected for receiving an input including the signal representative of the control column position and for generating an output including a signal representative of the commanded elevator response, the commanded elevator response signal embodying the desired flight characteristics;
(d) a computed elevator response processor for receiving inputs including signals representative of the aircraft normal acceleration, aircraft pitch rate, aircraft speed, and a reference speed;
the computed elevator response processor generating an output sisal representative of a computed elevator response according to current flight conditions;
the computed elevator response being based upon at least the aircraft normal acceleration signal, the aircraft pitch rate signal, the aircraft speed signal, and the reference speed signal;
(e) a second signal combiner connected for receiving the computed elevator response signal and the commanded elevator response signal and for generating an output signal representative of the difference between the computed elevator signal and the commanded elevator signal;
(f) an integrator connected for receiving the difference signal and for driving the difference signal to about zero, the integrator generating an output signal received by the second input to the first signal combiner.

5 more elements

Dependencies are inferred from the claim text.

Aircraft pitch-axis stability and command augmentation

Life of this patent

Aircraft pitch-axis stability and command augmentation

Life of this patent

Abstract

Claims23