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1 Optimal Synthesis Inc. © Copyright 2007 by Optimal Synthesis Inc. All Rights Reserved Integrated Guidance-Control of Missiles Integrated Guidance-Control of Missiles By P. K. Menon, V. S. S. Vaddi, G. D. Sweriduk Optimal Synthesis Inc. 868 San Antonio Road Palo Alto, CA 94303-4622 (650) 213-8585, ext. 201 www.optisyn.com [email protected] Research Supported by NSWC-Dahlgren and MDA Technical Monitor: Ernest J. Ohlmeyer, NSWCDD

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Integrated Guidance-Control ofMissiles

Integrated Guidance-Control ofMissiles

ByP. K. Menon, V. S. S. Vaddi, G. D. Sweriduk

Optimal Synthesis Inc.868 San Antonio Road

Palo Alto, CA 94303-4622(650) 213-8585, ext. 201

[email protected]

Research Supported by NSWC-Dahlgren and MDATechnical Monitor: Ernest J. Ohlmeyer, NSWCDD

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Recursive Backstepping MethodObjective of Missile Guidance & ControlObjective of Missile Guidance & Control

Drive the Target Referenced Missile Position Components to Zero in Specified Time/RangeDrive the Target Referenced Missile Position Components to Zero in Specified Time/Range

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Recursive Backstepping MethodOutlineOutline

• Integrated Guidance-Control (IGC) Systems • Benefits and Difficulties• IGC Design Methods

- Linear and Nonlinear Techniques• IGC Design Examples

- Air-to-Air Missile- Internally Actuated Kinetic Warhead

• Summary and Conclusions

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Conventional Vs Integrated Guidance-Control Systems

Conventional Vs Integrated Guidance-Control Systems

Conventional Guidance and

Control SystemGuidance Law Autopilot

Target

MissileDynamics

RotationalRates

AccelerationComponents

Velocity and Position

Target States

ActuatorCommands

Integrated Guidance-Control

SystemIntegrated

Guidance-ControlSystem

Target

MissileDynamics

RotationalRates

AccelerationComponents

Velocity and Position

Target States

ActuatorCommands

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Recursive Backstepping MethodConventional Guidance & Control System

Conventional Guidance & Control System

• Partial Feedback of the Missile States to Guidance System, No Direct Feedback of the Target States to the Autopilot:

- Autopilot Time Constant has a Significant Influence on the Miss Distance.

• Potential for Instabilities in the G&C System Induced by the Integral Guidance Command Tracking Error Feedback in the Presence of Actuator Saturation.

• Iterative G&C System Design (Finite-Interval Guidance Law, Infinite Horizon Autopilot)

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• Simplifies the G&C Design Process• Can Takes Advantage of the Synergism Between Guidance and Autopilot Functions.

- Adjusts the Autopilot Response to Accommodate Guidance Demands,

- Avoids Autopilot Command Saturation Due to Agile Targets Maneuvers

- Provides Better Performance Margins.• Can Meet Enhanced Performance Requirements: E.G., Execute Terminal Maneuvers to Control Final Orientation of the Missile Velocity Vector W.R.T the Target.• Requires Substantial Onboard Computational Capability.

Benefits of Integrated Guidance-Control Systems

Benefits of Integrated Guidance-Control Systems

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Recursive Backstepping MethodDifficulties in the Design ofIntegrated Guidance-Control Systems

Difficulties in the Design ofIntegrated Guidance-Control Systems

• High-Order Nonlinear Dynamics• Finite-Interval Control Problem• High-Order Nonlinear Dynamics• Finite-Interval Control Problem

IGC Design using Taylor Series Linearized Dynamics(1992)Previous Work by the Authors:1. SDRE-Based IGC Formulation (1997, 1999)2. Infinite-Horizon IGC Formulations & Design with Feedback Linearized Dynamics (1998 - 2002).3. Finite-Horizon IGC Formulation (2003)4. Multi-Stepping Algorithm for Finite-Horizon IGC (2004)

IGC Design using Taylor Series Linearized Dynamics(1992)Previous Work by the Authors:1. SDRE-Based IGC Formulation (1997, 1999)2. Infinite-Horizon IGC Formulations & Design with Feedback Linearized Dynamics (1998 - 2002).3. Finite-Horizon IGC Formulation (2003)4. Multi-Stepping Algorithm for Finite-Horizon IGC (2004)

Most Recent Research (2006):Finite-Horizon Robust IGC Formulation and Solution Using Feedback Linearization

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Integrated Guidance-Control System Design Methods

• Nonlinear Design Methods:

- Proven Methods are Not Available.

- Tedious and Extensive Algebraic Manipulations may be Required.

- Complex to Design and Analyze.

- Computational Tools are Not Available.

- Proven Methods are Not Available.

- Tedious and Extensive Algebraic Manipulations may be Required.

- Complex to Design and Analyze.

- Computational Tools are Not Available.

• Recently Developed Numerical Methods and Design Software for Nonlinear Control Techniques can Ameliorate these Difficulties.

• This Software (Nonlinear Synthesis Tools) is used in IGC System Research.

• Can Automatically Generate Error-Free C Code for Real-Time Implementation of Nonlinear Control Systems

• Linear Design Techniques Require Gain Scheduling with respect to Dynamic and Kinematic States

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USER-DEFINEDSLIDING MODE

MIN MIN-MAX

POLE PLACEMENT

LINEAR QUADRATIC

DESIGN

SINGLE TIMESCALE

MULTIPLE TIME SCALE

STATE-DEPENDENT REGULATOR

QUICKEST DESCENT

3

TRANSFORMATION-BASED

NONLINEAR SYNTHESIS TOOLS

DIRECT

BACK STEPPING

4

PREDICTIVE CONTROL

5

STATE-DEPENDENT COEFFICIENT FORM

2 FEEDBACK LINEARIZATION

1

USER-DEFINEDDESCENT

QUADRATICDESCENT

MIN MIN-MAX

ROBUST DESIGN

FiniteInterval

LQ Design

FiniteInterval

LQ Design

Discrete OrContinuous Time

IGC System Design Using Nonlinear Synthesis Tools™IGC System Design Using Nonlinear Synthesis Tools™

IGC Design Methodologies

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Graphical User Interface for Nonlinear Control Design

Main GUI Panel GUI Panel for FeedbackLinearization Method

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Feedback Linearization of Dynamics

• Transform the Model to Brunovsky Canonical Form

• Given the Nonlinear Dynamic System: uxgxfx )()( +=&

SystemNonlinearities

SystemNonlinearitiesControls

TransformedStates

Outputs

∫∫∫

NonlinearDynamicSystem

NonlinearDynamicSystemControls

States

Outputs

Chains of Integrators

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• Solve State Dependent Riccati Equation:

SDRE Design Technique

• Transform the System Model to the SDC Form:uxgxxAx )()( +=&

• Compute State Dependent Control Law As:

Corresponding to the Performance Index

0)()()()()()( 1 =+−+ − xQPxgxRxgPxPAPxA TT

dtuxRuxxQx TT ])()([0

+∫∞

xxPxgxRu )()()(1−=

• Select Q(x) and R(x) Matrices to Satisfy:0)()()()( 1 <−− − PxgxRxgPxQP T&

• Given Nonlinear Dynamic System: uxgxfx )()( +=&

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Integrated Guidance-Control System Design Philosophies

• Zero-Effort-Miss Guidance-Control Law

• Pure-Pursuit Guidance-Control Law

• Proportional Navigation Guidance-Control Law

• Finite-Interval Terminal-Miss Minimizing IGC

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Missile and Target Models• Six Degree-of-Freedom Air to Air Missile Model, Fixed-Aim Warhead:

• Target Model:- Point-Mass Model (F-4 - Like Performance)

θφ

φ

θ

cosgcosaz

sinay

singm

DTx

nVT

nVT

VT

+=

=

−−

=

&&

&&

&&

⎥⎥⎥

⎢⎢⎢

=⎥⎥⎥

⎢⎢⎢

VT

VT

VT

V/IIT

IT

IT

zyx

Tzyx

&&

&&

&&

&&

&&

&&

• Straight and Level Flight Or 5g Weave Maneuver at 0.2 Hz.

XB

YB

ZB

Cone ofEffectiveness

XW

YWZWTarget

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Zero-Effort Miss IGCS

• Integrated Guidance-Control System Objective: Drive the Zero-Effort Miss Components Normal to the Missile Y and ZBody Axes to Zero.

)yy(x MT −= )yy(x MT &&& −=

gotxxz &+=

goMT t)aa(z −=&

• Zero-Effort Miss (ZEM):

Where:

Relative Position and Velocity Vectors

• Zero-Effort Miss Rate:

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Zero-Effort Miss IGCS

Control Chain:

ZEMr

ZEMq

p

yr

zq

p

→→→

→→→

→→

βδ

αδ

φδ

Integrated Guidance-Control System Objectives:1. Use Roll Fin Deflection to Regulate the Roll Rate and Roll Attitude Near Zero.

2. Use Pitch Fin Deflection to Generate Pitch Rate, and Consequently the Angle of Attack to Drive the Pitch Component of the ZEM to Zero (While Stabilizing the Pitch Axis Dynamics).

3. Use Yaw Fin Deflection to Generate Yaw Rate and Consequently the Angle of Sideslip to Drive the Yaw Component of the ZEM to Zero (While Stabilizing the Yaw Axis Dynamics).

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Recursive Backstepping MethodFinite-Interval IGCSDesign Using Feedback Linearization

Finite-Interval IGCSDesign Using Feedback Linearization6-DOF Nonlinear Missile Dynamics: (In the Form of a Computer Program)

States: y, z, α, β, φ, P, Q, RControls: δp, δq, δr

Point-Mass Target Dynamics (Open-Loop Maneuvers):States: x, y, zControls: ay, az

Feedback Linearize the System Dynamics In Terms Of Target Relative Missile Position Components and Their Derivatives (Numerically Carried Out Using theNonlinear Synthesis Tools™ Software)

Feedback Linearize the System Dynamics In Terms Of Target Relative Missile Position Components and Their Derivatives (Numerically Carried Out Using theNonlinear Synthesis Tools™ Software)

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Recursive Backstepping MethodFinite-Interval IGC SystemDesign Using Feedback Linearization

Finite-Interval IGC SystemDesign Using Feedback Linearization

( ) ( ) ( ) ( )( ) ( ) ( ) ( )

( ) ( ) ( ) ( ) 3r23q22p213

2r23q22p212c

1r13q12p111c

v.g.g.g.f

v.g.g.g.fy

v.g.g.g.fz

≡+++=

≡+++=

≡+++=

δδδφ

δδδ

δδδ

&&

&&&

&&&

• Feedback Linearized Missile-Target Dynamics:

uBxAx +=&

• Can be Placed in the LTI Form in terms of Transformed States and Controls:

• Formulate a Finite-Interval Optimal Control in terms of Transformed States and Controls:

( ) τdRuuQxxxSxJ tfto

TT21

ffTf2

1 ∫ ++=

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Recursive Backstepping MethodFinite-Interval IGC SystemDesign Using Feedback Linearization

Finite-Interval IGC SystemDesign Using Feedback Linearization

• Solution to the Transformed Optimal Control Problem:

( )[ ]ψ1T1T1 VTxTVTSBRu −−− +−−=

Where: ( ) ffT1T StS,SBSBRQSASAS =+−−−= −&

( ) ( ) [ ] ⎥⎦

⎤⎢⎣

⎡=−=

×−

q)qn(

qf

TT10

ItT,TABSBRT&

( ) [ ] qqfT1T 0tV,TBBRTV ×

− ==&

Jerk, Acceleration, Velocity, Position Optimizing Control

Pseudo Control Vector can be Inverse Transformed to Obtain Fin Deflections

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Recursive Backstepping MethodEngagement ScenarioEngagement Scenario

Vertical Plane TrajectoriesHorizontal Plane Trajectories

Miss Distance: 0.035 ft

- Missile at 11,640 ft & Target at 10,000 ft Altitude.- Target Speed 1,037 ft/s, Heading 198.4 degrees,

Maneuver Acceleration 3g.

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Recursive Backstepping MethodEngagement ScenarioEngagement Scenario

P, Q, R Historiesα, β Histories

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Recursive Backstepping MethodEngagement ScenarioEngagement Scenario

Fin Deflection Time Histories

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Recursive Backstepping MethodKKV Guidance-ControlKKV Guidance-Control

• Agile Guidance and Control System Necessary for Hit-to-kill• Must Exploit System Nonlinearities to Enhance Performance • Integrated Design of Guidance-Control Systems Using Feedback Linearized Dynamics and,

- LOS Rate Regulation

Background Work:• Software for Nonlinear Control System Design: Nonlinear Synthesis Tools™ (1997-2000).• Missile Integrated Guidance-Control System Design Methodologies (1999 - 2002)

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Recursive Backstepping MethodKKV IGCS - Actuation OptionsKKV IGCS - Actuation Options

Moments Forces

KKVKKV

SensorsSensors

ActuatorsActuatorsGuidance

&Control Systems

Guidance&

Control Systems

Endo-AtmosphericEndo-Atmospheric Exo-AtmosphericExo-Atmospheric

AerodynamicSurfaces (External)

AerodynamicSurfaces (External)

Reaction JetThrusters/TVC

(Interal/External)

Reaction JetThrusters/TVC

(Interal/External)

Divert ThrustersDivert Thrusters

Moving Mass Actuator(Internal)

Moving Mass Actuator(Internal)

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Recursive Backstepping MethodMoving-Mass Actuators for KKVMoving-Mass Actuators for KKV

Principle of Operation: Moving Masses Alter the CG Location of the KW, thereby Creating Control Moments from External Forces

Principle of Operation: Moving Masses Alter the CG Location of the KW, thereby Creating Control Moments from External Forces

MovingMasses

NominalCenter

ofMass (C.M)

C.MAfter Moving

the Masses

Thrust

XB

YB

ZB

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Recursive Backstepping MethodCharacteristics of Internal ActuatorsCharacteristics of Internal Actuators

Advantages:1. Effective in any Speed Range (Endo and Exo-Atmospheric Flight)2. Contained within the KKV Geometric Envelope.3. No Mass Expulsion

Disadvantages:Complex, Nonlinear System Dynamics

- Potential Non-minimum Phase Behavior- Variable Speed of Response- Atmospheric Performance can be Sensitive to Center of Pressure Uncertainty.

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Recursive Backstepping MethodEngagement GeometryEngagement Geometry

λz

λy

xV

yVzV

Vehicle-carried�inertial frame

Line Of Sight

xN

yNzN

Earth-fixed�(North-East-Down)�inertial frame

⎟⎟⎠

⎞⎜⎜⎝

⎛= −

x

y1y r

rtanλ ⎟⎟

⎞⎜⎜⎝

⎛= −

x

z1z r

rtanλ

2yxyx

y2

x

yxyy r

rrrrsecr

tanrr &&&&&

−=

−=

λλ

λ 2zxzx

z2

x

zxzz r

rrrrsecr

tanrr &&&&& −=

−=

λλ

λ

( ) 212

z2y

2x rrrr ++=[ ]Tzyx rrrr =

r

tsinAzORgz,0y,0x 2 ωω==== &&&&&&&&Target Model:

Line-of-Sight Angles:

Line-of-Sight Rates:

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Recursive Backstepping MethodKKV DynamicsKKV Dynamics

Free-body Diagram of the Moving-Mass KW

xB

yB

y x�

z�

B

zB�

O

T

+

+

my

mx

mB

rC.P.

rT

v

u

w

q

p

r

Fmz

yoffset

xoffset

ag

δx,δx

δy,δy

δz,δz•

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Recursive Backstepping MethodKKV DynamicsKKV Dynamics

First-Order Moving-Mass Positioning Actuator Dynamics

0

5

10

15

20

0

10

20

30

40

500

0.1

0.2

0.3

0.4

0.5

0.6

0.7

MachAOA (deg)

Axi

al F

orce

Coe

ffici

ent C

A

0

5

10

15

20

0

10

20

30

40

500

0.5

1

1.5

2

2.5

3

3.5

4

MachAOA (deg)

Nor

mal

For

ce C

oeffi

cien

t CN

AC NC

KW Mass: 55 lbsKW Diameter: 1 ft.Actuator Masses: 5 lbs Each

Aerodynamic Coefficients (Neutrally Stable):

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Integrated Guidance-Control by LOS Rate Regulation

Integrated Guidance-Control by LOS Rate Regulation

IGC Philosophy:1. Apply Force uz on the Pitch Moving Mass to Position it at δz along the z-body axis, so as to Generate Pitch Rate qand Consequently a Lateral Velocity w to Drive the Pitch Component of the LOS Rate to Zero (While Stabilizing the Pitch Axis Dynamics).

2. Apply Force uy on the Yaw Moving Mass to Position it at δz along the z-body axis, so as to Generate Yaw Rate rand Consequently a Lateral Velocity v to Drive the Yaw Component of the LOS Rate to Zero (While Stabilizing the Yaw Axis Dynamics).

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•Define the Control Chain:

Integrated Guidance-Control by LOS Rate Regulation

Integrated Guidance-Control by LOS Rate Regulation

yyyy

zzzz

vru

wqu

λδδ

λδδ&&

&&

→→→→→

→→→→→Design Methodology:

• Specify Pole Locations or LQR Design Weights:- Pole Locations : {-51, -50, -35, -30, -20}

• Evaluated in Several Engagement Scenarios (Single Nonlinear Design):

- Endo-Exo Atmospheric Interception- Spiraling Target

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Recursive Backstepping MethodEngagement Scenario 1Engagement Scenario 1

Miss Distance: 0.17 ft

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Recursive Backstepping Method

0 0.5 1 1.5 2 2.5 3 3.5 4 4.5 5

x 104

0.6

0.7

0.8

0.9

1

1.1

1.2

1.3

1.4

1.5

1.6x 10

5

North Position (ft)

Alti

tude

(ft)

warheadtarget

Vertical Plane Trajectories Horizontal Plane Trajectories

0 0.5 1 1.5 2 2.5 3 3.5 4 4.5 5

x 104

0

500

1000

1500

2000

2500

North Position (ft)

Eas

t Pos

ition

(ft)

warheadtarget

Engagement Scenario 1Engagement Scenario 1

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Recursive Backstepping Method

0 1 2 3 4 5 6 7 8 9 10−50

−40

−30

−20

−10

0

10

20

Time (sec)A

ngle

(de

g)

aero angles α,β

βα

Body Rate Histories α, β Histories

0 1 2 3 4 5 6 7 8 9 10−3

−2

−1

0

1

2

3

Time (sec)

Ang

ular

Vel

ocity

(ra

d/se

c)

vehicle angular rates p,q,r

pqr

Engagement Scenario 1Engagement Scenario 1

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Recursive Backstepping Method

60 70 80 90 100 110 120−400

−200

0

200

400

600

800

1000

1200

1400

Altitude(Kft)

Nor

mal

Aer

odyn

amic

For

ce(lb

f)

Normal Force History

Engagement Scenario 1Engagement Scenario 1

60 70 80 90 100 110 1200

100

200

300

400

500

600

For

ce(lb

f)Altitude(Kft)

Rocket Motor Thrust

Axial Aerodynamic Force

Axial Force History

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Recursive Backstepping Method

Body Acceleration Histories

Engagement Scenario 1Engagement Scenario 1

60 70 80 90 100 110 120−20

−15

−10

−5

0

5

10

Altitude(Kft)

Acc

eler

atio

n(G

s)

Body Frame Acceleration Components

ay

az

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Recursive Backstepping MethodInterception of a Spiraling TargetInterception of a Spiraling TargetKKV: 45 Kft Altitude , 50 deg Flight Path AngleTarget: 90 Kft Altitude, 50Kft North, -35 deg Flight Path Angle, 1g Lateral Acceleration, 3 Rad/s Frequency, Reciprocal Heading

Miss Distance: 0.25 ft

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Recursive Backstepping Method

0 0.5 1 1.5 2 2.5 3 3.5 4 4.5 5

x 104

4.5

5

5.5

6

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Interception of a Spiraling TargetInterception of a Spiraling Target

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x 104

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Trajectories in the Horizontal and Vertical Plane

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Target Trajectory After Removing the Secular Component

Pitch-Yaw Acceleration Histories

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Recursive Backstepping MethodSummarySummary

• Discussed Integrated Guidance-Control System Design Methods

- Eliminates Iterative Design Process- Eliminates Spurious Effects Induced by more Traditional Design Methods

- Better Satisfaction of Design Objectives- Synergistic Design

• Illustrated IGC Design for Air-to-Air Missile and an Internally Actuated KKV.

- Nonlinear Control Techniques- Computer-Aided Nonlinear System Design- ZEM, LOS Rate, Terminal-Miss Design Strategies

• Being Investigated for Designing Flight Control Systems of other Vehicles.