Organic Air Vehicle (OAV) Flight Control An Application of Multi-Application Control (MACH)

DE/kv 12/1/03AES Technology Centers of Excellence

Organic Air Vehicle (OAV) Flight ControlOrganic Air Vehicle (OAV) Flight ControlAn Application ofAn Application of

Multi-Application Control (MACH)Multi-Application Control (MACH)

Dale EnnsHoneywell

4 March 2005

SAE AEROSPACE CONTROL AND GUIDANCE SYSTEMS COMMITTEESalt Lake City, Utah


Introduction

Takeoff, ascend, hover, rotate, translate, descend, land autonomously and with pilot in the loop

MissionsVehicle


Design Theory

True Aircraft Model (TRAC)

Controlled Variable (CV)

Calculus and On-board Aircraft Model (OBAC)

Dynamic Inversion

Feedback Controls

u,xfx

xhy

uxbxaxxhy

yyKy cdes

xay xbu desinv

x = States incl. p, q, r, u, v, w, …u = Control Surfaces

y = p, q, r

x

x

xx

x

x

X TRAC OBAC

CC

K )x(binv

a(x)

f(x,u)s

1 h(x)

x x yucy desy


Basic Feedback Loop

Proportional Gain =

Integral Gain =

Command Gain =

Anti-Integral Windup Gain =

Closed Loop Transfer Function =

Loop Transfer Function (at y) =

bandwidth sets secrad4Kb

rejection edisturbanc and ationdesensitiz for needed 41fi

tailoring response loop closed for needed 21fc

limited are commands actuator whenneeded 3fa

2s

2KfsKs

2Ks

2K

sysy

2bib

2

bb

c

22

bib

s1s4

sKfsKsL

bi K f

cf

s 1

bKs 1

af

cy y_ _

_


HeadingCommand

PositionCommands Velocity

Commands

AttitudeCommands

AngularRate

Commands VaneCommands

sKpos

sKatt sKpqr

sKvel

ThrottleCommand

Inner loop pairOuter loop pair

Control Law Structure


Control Allocation Approach

Given B and d find u to minimize || Bu – d ||2

Subject to constraintsumin < u < umax

u1

u2

d1

d2

d = B u

Constraints include worst case of Position and rate limits

Solution involves finding the intersection of two ellipsoids

Desired d is unachievable so find

Closest approximation with axis prioritization


Unique Inverse

Montontonicity for scalars

Example for 2 dimensions

We require that the Jacobian not change sign over the region of interest

Jacobian =

Such that the solution to has a unique solution for a given d

uf det

duf

Solution 1 Solution 2

Jacobian > 0 Jacobian < 0

f (u)

du

f(u)


-3 -2 -1 0 1 2 3 4 5-4

-3

-2

-1

0

1

2

3

f1

f2

quadrant 1quadrant 2quadrant 3quadrant 4

2x2 Example of Non-Unique Inverse

In Quadrant 1

f1 = u1 + 3/2 u2

f2 = 1/3 u1 + u2

In Quadrant 2f1 = u1 + 3/2 u2 f2 = u1 + u2

In Quadrant 3f1 = u1 + 1/2 u2

f2 = u1 + u2

In Quadrant 4f1 = u1 + 1/2 u2

f2 = 1/3 u1 + u2

f(u) is piecewise linear, continuousSlopes of diagonal are equal to 1

Off-diagonal slopes change at the origin

Mapping of -2 < u1 < 2-2 < u2 < 2Jacobian = 1/2

Jacobian = -1/2

Jacobian = 1/2

Jacobian = 5/6


Closed Loop Poles = Open Loop Zeros

Open Loop

Dynamic Inversion

CxyBuAxx

BAsICsG

wheresG of zeros z for

00CBAzI

det

1

Closed Loop for 0yd

Theorem

CAxy CBu d1

CAxCBBAxx 1

0 ,zCACBBA then

sG of zeroz If1


OAV Integrated Avionics – AV2

FMU

WOW

Magnetometer

Altimeter

Air Data A/D

Engine Speed

Temperature

Battery State

x-axisy-axisz-axis

12

6

5

8

3

7

4

Servo 3

Servo 4

Servo 1

Servo 2

Engine Throttle

IMU

+5V

+5V

+V

GND

GND

GND

+5V

+5VGND

GPS Rcvr+3.3V

GND

+15V -15V+5V

Interim RadioReceiver

µHard Modem

Base Station

CMOS Camera

InfraRed Camera

Serial

FMU H/W

External H/W

Payload H/W

Comm. H/W

Seria

l

2.4GHz VideoTransmitter

Engine Temp

I2C

Ser

ial

PWM

Pulse Train

Seria

l


OAV Avionics

IMU

FMU

Flight Management Unit– MEMS IMU HG-1900– GPS– Blended GPS/Inertial Nav & Attitude information– Flight Control Laws– Actuation commands

Flight Control Surfaces Engine Throttle

– Payload selection– Payload pointing

Commonality of hardware leads to lower cost - common gun-launched IMU entering high volume production

Honeywell Intl. Proprietary


Flight Controls Adverse Weather Issues

Hover in steady wind– Vehicle will tilt into the wind– More tilt for more wind

Gusting winds– Vehicle will tilt back and forth to adjust to changing wind– Non-minimum phase response

Measurements of airspeed relative to vehicle lead to improved performance– Direct sensing– Estimation– 3 components of relative wind


Hover in Steady Wind

Tilt from Vertical Force BalanceForce Balance Moment BalanceMoment BalanceT

L

D

mg

0CGMDuct Nose Up

Vanes Nose Down

10 20 30 40

Pitch AxisRoll Axis

VaneDeflection

forTrim

(Degrees)

Horizontal Wind Speed (Knots)

LargeRoll Vane Deflection

Required for Trimat Intermediate Speeds

Wind

Wind Alonga

e


OAV Specifics

On-board Aircraft Model (OBAC)– 3 Forces and 3 Moments are Dependent Variables– – Combine table lookup and analytical expressions for forces and moments– Rigid body with propeller/engine momentum equations of motion

Wind Estimator

Variablest Independen are rpm , , , , , ,rea

V

EstimationGains S

1

OBAC MeasurementsModeled Accels

Accels Wind Estimate


Robust Stability Analysis

a

iGK

s

az aw

szsw

s

a

00

MSatisfactory

Negotiable

Unacceptablelog 10

0

10log

M log

bwlog

1

1log

IntroduceMultiplicativePerturbationsat all interfacesbetween Plant &Control Law

_

Control Law Plant

s

a

ww

s

a

zz


MOVIE OF OAV FLIGHT TEST

1 July 2004

Ft. Benning, Georgia


Conclusions

Multi-Application Control (MACH)– Reusable control law– Robust, versatile, modular, nonlinear,

multivariable design

Other Applications of Dynamic Inversion– X-35 Lockheed Martin Joint Strike Fighter– X-38 Prototype Crew Return Vehicle

Organic Air Vehicle (OAV) Flight Control An Application of Multi-Application Control (MACH)

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