A formal structure for advanced automatic flight-control systems

[Pages:42]FORMAL $ 1

3

STRUCTURE FOR ADVANCED

AUTOMATIC FLIGHT-CONTROL SYSTEMS(

George Meyer and Lzligi Cicolani Ames Research Center

Moffett Field, Gal$ 94035

FATIONAL 3AERONAUTICS AND SPACE ADMIN.---

1

WASHINGTON, D. C.

3,"%.I@

GAY w)75

I

__1. Report No.

TN D-7940

2. Government Accession No.

7. Author(s)

George Meyer and Luigi Cicblani

9. Performing Organization Name and Address

Ames Research Center Moffett Field, Calif., 94035

12. Sponsoring Agency Name and Address

National Aeronautics and Space Administration Washington, D. C. 20546

15. Supplementary Notes

TECH LIBRARY KAFB, N M

IIlil1111/1l1/1l11l1111111I1l1Il 0333435

5. Report Date

May 1975

6. Performing Organization Code

8. Performing Organization Report No.

A-5710

10. work Unit No.

501-03-11

11. Contract or Grant No.

13. Type o f Report and Period Covered

Technical Note

14. Sponsoring Agency Code

__

16. Abstract

An effort is underway at Ames Research Center to develop techniques for the unified design of multimode, variable authority automatic flight-control systems for powered-lift STOL and VTOL aircraft. This report describes a structure for such systems which has been developed to deal with the strong nonlinearities inherent in this class of aircraft, to admit automatic coupling with advanced air traffic control requiring accurate execution of complex trajectories, and to admit a variety of active control tasks. The specific case being considered is the augmentor wing jet STOL research aircraft.

~

7. Key Words (Suggested by Author(sJ)

Handling qualities Flight controls Autopilot

18. Distribution Statement

- Unclassified unlimited

.- .

19. Security Classif. (of this report)

Unclassified

1 20; Security Classif. (of this page)

Unclassified

~~~

21. No. o f Pages

39

~~~~

*For sale by the National Technical Information Service, Springfield, Virginia 22151

22. Price'

$3.75

TABLE OF CONTENTS

Page

SYMBOLS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . v

SUMMARY . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1

. INTRODUCTION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1

BASIC COMMANDS TO AUTOMATIC FLIGHT-CONTROL SYSTEM . . . . . . . . . . . . 4

TRACKING ACCURACY . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7

EQUATIONSOFMOTION . . . . . . . . . . . . . . . . . . . . . . . . . . .

8

. . AUGMENTOR WING JET STOL RESEARCH AIRCRAFT . . . . . . . . . . . . . . 13

. TheTrimmap . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16

Perturbation . Controller . . . . . . . . . . . . . . . . . . . . . . 18

Angular Acceleration . Controller . . . . . . . . . . . . . . . . . . 23

Trajectory Command Generator . . . . . . . . . . . . . . . . . . . . 27

. . . . . PROPOSED STRUCTURE FOR ADVANCED AUTOMATIC FLIGHT-CONTROL SYSTEMS

31

CONCLUSIONS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32

. REFERENCES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33

iii I-

SYMBOLS

direction cosine matrix, actual attitude of the aircraft with respect to inertial space

direction cosine matrix, commanded attitude of the aircraft with respect to inertial space

direction cosine matrix, commanded velocity axes with respect to inertial space

wing span

wing chord

drag coefficient

commanded drag coefficient

cold thrust coefficient

lift coefficient

commanded lift coefficient

moment coefficient vector with respect to body axes

commanded moment coefficient with respect to body axes

total force vector coefficient

drag

elementary rotation about axis i through angle $

total aerodynamic and propulsive force in inertial coordinates

right-hand side of system state equation

acceleration of gravity

trimmap

body coordinates of total angular momentum

right-hand side of transition dynamics

feedback gain schedule

L

lift

m

aircraft mass

M a

body coordinates of aerodynamic and propulsive moment

Q

dynamic pressure

inertial coordinates of position vector

RS

R*

inertial coordinates of position vector commanded by air traffic

S

control

R

inertial coordinates of position given by command generator

SC

sw

wing area

t

time variable

6T

thrott1e

'e

cold thrust

'h

hot thrust

U

control vector

U a

body coordinates of unit vector along relative velocity vector

U

inertial coordinates of unit vector along relative velocity vector

S

V

airspeed (true airspeed)

V a

body coordinates of relative velocity vector

van measured body coordinates of relative velocity vector

inertial coordinates of relative velocity vector

vS

inertial coordinates of aircraft velocity vector

*S

v"

inertial coordinates of velocity commanded by air traffic control

S

inertial coordinates of velocity commanded by command generator

vSC

inertial coordinates of aircraft acceleration vector

v

inertial coordinates of acceleration commanded by air traffic control

S

tse

inertial coordinates of acceleration commanded by command generator

%I

inertial coordinates of acceleration input to trimmap

vi

L7

W

S

h

wS

X

6

yV

6ec 6F

6i

6rc 6T

6wc rl

e

V P

w a w n

inertial coordinates of acceleration modifications due to perturbation controller

inertial coordinates of wind inertial coordinates of estimated wind system state angle of attack angle of sideslip glide-slope angle of relative velocity vector elevator command flap angle column matrix with 1 in ith row and 0 in the other two rows rudder command throttle command wheel command variables of unsteady aerodynamics pitch angle nozzle angle density of air side-force angle roll angle yaw angle body coordinates of aircraft angular velocity bandwidth

vi i I

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