Military aircraft research opportunities for the future are briefly surveyed. Aircraft control theory, design analysis, systems integration and flight characteristics are discussed

Schwanz, R. C.

English

NASA Technical Reports Server

MILITARY AIRCKAFT KESEARCH OPPORTUNITIES FOR THE FUTURE 
Robert C. Schwanz 
Air Force Wright Aeronautical Laboratories 
Wright-Patterson Air Force Base, Ohio 
First Annual NASA Aircraft Controls Workshop 
NASA Langley Research Center 
Hampton, Virginia 
October 25-27, 1983 
559 
https://ntrs.nasa.gov/search.jsp?R=19840012530 2020-03-22T08:18:32+00:00Z
DESIGN OF DECENTRALIZED CONTROL SYSTEMS: 
"INTEGRATED CONTROL" 
The objective is to develop a methodology for the design of control systems for 
interacting dynamical systems which employ only local measurements and control 
devices. 
TRAJECTORY OPTIMIZATION 
OPTIMAL WEAPON DELIVERY 
ENVIRONMENTAL 
CONTROL 
MINIMUM TIME CLIMB 
MINIMUM FUEL 
MINIMUM TIME INTERCEPT 
DIFFERENTIAL GAMES 
ELECTRONICS 
LIFE SUPPORT 
FLYING QUALITIES 
NOZZLE CONTROL REDUCED STATIC STABILITY 
SIX DEGREES OF FREEDOM 
ALTITUDE HOLD 
ALPHA-G LIMITING 
HEADING HOLD 
MODE RECONFIGURATION 
. POWER CONTROL 
STEADY STATE OPERATION 
TRANSIENT CONTROL 
CONTROL CONFIGURE0 WEAPON 
.THROAT EXIT PRESSURE GUIOANCE 
THREAT IDENTIFICATION SHOCK POSITION RIDE CONTROL AN0 CONTROL 
THREAT AVOIDANCE STRUCTURAL FATIGUE REDUCTION 
MANEUVER LOAD CONTROL MINIMIZE MISS (;- 
STORE MANAGEMENT . FLUTTER MODE CONTROL 
DISTANCE 
. 
AND INITIATION CAMBER CONTROL 
SEEKER POINTING 
ENGINE CONTROL 
STEADY STATE OPERATION 
TRANSIENT CONTROL 
MODE RECONFIGURATION 
. 
. 
. 
. 
560 
- 
HISTORICAL PERSPECTIVE 
Relative to the design of decentralized control systems, recent publications 
by the IEEE (e.g., ref. 1) and results of military development programs indicate 
that serious engineering problems prevent reliable control of interacting dynamical 
systems. 
“LARGE-SCALE SYSTEMS AND DECENTRALiZED CONTROL" 
l .(SPECIAL ISSUE, iEEE TRANS. AUTO. CONTROL, APRIL 1978) 
l iNEFFICIENT OPERATION OF LARGE SCALE INTERCONNECTED SYSTEMS 
l , LACK OF FUNOAMENTAL UNOERSTANOING OF PHYSICS MOOELS 
l LACK OF COORDINATED CONTRZL STRATEGIES 
. USE OF DETERMINISTIC STATIC STRATEGIES ON STOCHASTIC OYNAMIC SYSTENlS 
l EXISTING TOOLS FOR CENTRALlZED CONTROL ARE INAPPROPRIATE 
l SERVOMECHANISM THECRY 
l RECENT THEORY 
- MAXIMUM T?RINClPLE 
. LYAPUNOV STABILITY 
- ESTIMATION 
- DYNAMIC PROGRAMMiNG 
l IMPLEMENTATICN REIIUIREMENTS UNKNOWN 
. NEEO FOR AN0 COST OF COMMUNICATION CHANNELS 
l FIOELITY AND RELIABILITY OF INFORMATiON 
l ALLOWABLE TIME OELAYS IN INFORMATION 
561 
. . . _ . 
AVAILABLE DECENTRALIZED CONTROL DESIGN METHODS 
The current practice is to employ both hierarchical and heterarchical design 
procedures. They are evolutions of the centralized control theory design methods 
of the last 30 years. Current development applications depend heavily upon insight 
gained from centralized design of large-scale systems. Research activity seeks to 
understand relationships among the decentralized control theories. 
CENTRALIZED CONTROL (DEVELOPMENT) DECENTRALIZED CONTROL (RESEARCH) 
CLASSICAL SERVO-MECHANISM a 
- BOOE l 
- RrJOT LOCUS e 
NON-CLASSICAL DEVELOPMENT . 
- EIGENVALUE I IGNEVECTOR 
ASS!GNMENT 
- LYAPUNOV STABILITY 
- SEPARATION THEOREM 
- LINEAR GUADRAT:C REGULATOR 
- KA’LMAN FILTER 
STABiLITY METHODS 
\ 
MODEL APPRDXlMATION I \ RESEARCH 
LINEAR GUADRATIC ‘2 
- l\!ASH STRATEGY 
- STACKELBERG STRATEGY 
I? 
RESEARCH 
OPTIMAL DECENTRALIZED FEEDBACK 
- CONSTRAINED OUTPUT FEEOEACK 
- FiXEO CONTROL STRUCTURE 
OPTiMAL DECENTRALIZED FILTERING 
562 
- 
t 
RESEARCH AND DEVELOPMENT NEEDS IN 
DESIGN OF DECENTRALIZED CONTROL SYSTEMS 
Research needs include the development of (1) clearer mathematical relation- 
ships among the various existing methods and (2) the practical significance of the 
Witsenhauser nonlinear counter-example for linear Gaussian design. Development 
needs include the definition of (1) suitable dynamics problems of varying complexity 
for testing of new methods and (2) an efficient computerized methodology that 
minimizes mathematical complexity and presents the physics essentials of both 
problem and solution. This method should store user experience in a data base. 
563 
FLYING QUALITIES OF ADVANCED VEHICLES 
The objective is to manually employ the decentralized control of many on-board 
systems to achieve full dynamics control in highly maneuverable vehicles. 
HEAD-UP l-77+ 
HEAD-DOWN 
DISPLAYS 
NAVIGATION 
SYSTEM fNTEGRATlON EMlPHASlZES CONTROL 
USING LARGER MEASUREMENT SETS 
564 
HISTORICAL PERSPECTIVE; 
FLYING QUALITIES/CONTROL SYSTEM DYNAMICS 
Recent development programs have experienced manual control problems as the 
flight control system increases in complexity. If increasing complexity occurs in 
many control systems, can the manual control problem become easier? 
PROBLEM AREA PROBLEM SOURCE PROBLEM SOLUTION 
TAKE OFF AND BLENDEO AOA I
LANDING LOAD FACTOR 
COMMAND SYSTEM, 
AOA SIGNAL FADE 
OUT TIME = .Ol SEC 
ROLL RACHETING TOO SENSITIVE TO 
SMALL INPUTS 
Pi0 PRONE AT TIME DELAY 
TOUCHDOWN IN PITCH 
PITCH PROBLEMS EXCESSIVE INITIAL 
AT TOUCHDOWN RESPONSE DELAY 
Pi0 PITCH PROBLEMS 
AT TOUCHDOWN ,I ? 
MANUAL TERRAIN URGE AMPLITUDE 
FOLLOWING PITCH DAMPING 
LANDING APPROACH PI0 ? 
INSTALL PITCH RATE 
COMMAND SYSTEM, 
INCREASE SIGNAL FADE 
OUT TIME TO 1.1 SEC 
CAS MODIFICATION 
FCS PITCH TIME DELAY 
ADJUSTED 
? 
? 
RESIDUAL OSCILLATION 
FROM PILOT INPUTS 
ELIMINATED 
? 
565 
HISTORICAL PEPSPECTIVE; 
FLYING QUALITIES/DISPLAY DYNAMICS 
Recent develoiment programs have also been characterized by displays designed 
with inattention to d-isplay/computer dynamics. Displaying additional information 
from many decentralized systems may decrease manual flight safety. 
FLYING QUALITIES - LEVEL 1 . . PilOT INPUT 
TO AIRPLANE RESPONSE400 MS 
0 TYPICAL PILOT TRACKING TIME DELAY, c= 300 MS 
. EFFECT OF C.25 CM QUANTIZATION FERROR DISPLAY =sa c = 34% = 100 MS 
0 TYPICAL DISPLAY TIME DELAYS 
AIRCRAFT DISPLAY 
a FLIGHT PATH MARKER, 30 MS; AOA INDICATOR, 50 MS 
0 TARGET PREDICTOR, 70 rv~s 
0 PITCH LADDER, 50 MS CALCULATION, 20 MS REFRESH 
NAV MAP CHANGE, 1 SEC 
CD DATE UPDATE, 40 MS; REFRESH, 1 SEC 
566 
HISTORICAL PERSPECTIVE: 
FLYING QUALITIES/VEHICLE DYNAMICS 
Much of the nonlinear dynamics information in the MIL SPEC/MIL STD 8785C (ref. 
2) must be made more quantitative to manually control many dynamical.processes in 
highly maneuverable tasks. What does a pilot require to utilize nonlinear dynamic 
phenomena? What is too much of a good thing? What does he want if some system 
failure occurs? 
LINEAR + NCNLINEAR 
567 
HISTORICAL PERSPECTIVE: 
FLYING QUALITIES/VEHICLE DYNAMICS (CONCLUDED) 
The MIL SPEC/MIL STD 8785C (ref. 2) describes many design objectives as 
eigenvalue/eigenvector relationships. Typical of these are the n/cc versus wn 
charts describing manual control requirements at "moderate frequencies." 
13.8 
568 
10 
n/0 g’s/RAD 
100 
RESEARCH AND DEVELOPMENT NEEDS IN 
FLYING QUALITIES OF ADVANCED VEHICLES 
Research needs include the parametric characterization of nonlinear systems: 
Volterra series 
Least-squares errors projection 
Least-squares error/orthonormal projection 
Energy concepts 
Development needs include the evaluation of experimental procedures and data 
used to characterize flying qualities boundaries for centralized/decentraliied 
control; the definition of metrics to identify manual/automatic system interface 
boundaries; and the creation of a generic, nonlinear dynamics, manned flight 
simulator. 
REFERENCES 
1. Athans, M.: Guest Editorial on Large-Scale Systems and Decentralized Control, 
IEEE Transactions on Automatic Control, vol. AC-23, no. 2, April 1978, 
pp. 105-106. 
2. Military Specifications, Flying Qualities of Piloted Airplanes, MIL-F-8785C, 
5 November 1980. 
569 


Military aircraft research opportunities for the future

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