Approved for Public Release, Distribution Unlimited

Micro-Technology forPositioning, Navigation and Timing

(µPNT)

Dr. Andrei M. ShkelProgram Manager

DARPA/MTO

Approved for Public Release, Distribution Unlimited

Andrei M. ShkelAggregation

Overall goal:Enable self-contained chip-scale inertial navigationReduce SWaP of existing Inertial Measurement Units (IMU)

What we have now: CSAC, IMPACT, NGIMG, PINS (DSO) - ComponentsMINT, TUNS (DSO), SoOP (STO) – System Integration

Unaddressed need:Limited dynamic rangeUnacceptable long-term driftSize, Weight, Power and Cost (no path for chip-scale IMU)

New approaches:Exploit inertia of elastic waves for increase in dynamic range Self-calibration on-a-chip for compensation of long-term bias driftIntegration of time and inertial measurement units for cross-calibration and SWaP&C

Why now?Recently emerged precision manufacturing of 3D structuresLab demonstration of bias stability improvement via mimicking inertial forces and persistent excitationAccumulated knowledge in heterogeneous integration and algorithms

2

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Andrei M. ShkelDurations of DOD Missions

3

Enable self-contained inertial navigation with micro systems

Range of Mission (km)

Spe

ed o

f Pla

tform

(km

/hr)

1

10,000

1 1,000

24 hr

1,000

100

10

10 100

Missile 2

M-16

Grenade Launcher

Missile 1

Missile 11

Missile 7

Missile 5

Missile 3Missile 10

Missile 6

Missile 8

Missile 4

Soldier Walking in Open Field

HMMWV

SEALs Underwater Mission

Soldier Walking in

Cave

MicroUAV

Precision Engagement with GPS-assisted guidance

Ballistic

Personal navigation GPS-assisted

Curre

ntly

Fund

ed

New

Star

ts

Missile 9

Over 70% of missile missions are less than 3 min

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µPNT Technology Drivers

Driving Operation Characteristics

Technical Focus Area

High Dynamic Range Low Power Consumption

Components1 1

System Calibration

Device Integration

NGIMG: Navigation Grade Integrated Micro Gyroscopes

MRIG: Micro Rate Integrating Gyroscopes

MINT: Micro Inertial Navigation Technology

CSAC: Chip Scale Atomic ClockIMPACT: Integrated Micro Primary Atomic Clock Technology

- New Starts

Guidance Navigation

PASCAL: Primary and Secondary Calibration on Active Layer

TIMU: Deep Integration of Time and Inertial Measurement Unit

IT-MARS: Information Tethered Micro Automated Rotary Stages

Gyros, clocks, accels, velocity sensors

ZUPting, persistent excitation with micro stages,algorithms

Fabrication approaches,architectures

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Andrei M. ShkelPrecision Engagement

DEFINE ORIENTATION DEFINE TARGET

ACTIVE GUIDANCE

Today: GPS, magnetic compass, and range finderVision: eliminate magnetic compass with ultra-small gyro compassing solutions

Today: GPS-assistedVision: self-contained guidance (no GPS) in fast precision engagement

Today: large & expensive sensors on static platformsVision: small SWaPsensors extended to mobile platforms

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Approved for Public Release, Distribution Unlimited

Andrei M. Shkel

Deep integration of clocks & IMUSoA clocks and sensors are incompatible, and implemented separately Multiple non-synchronized frequency sources are used in Navigation system routinely (power consumption, grows in uncertainty of time-position-orientation)

µPNT Challenges

Sensors for dynamic environmentFrequency miss-match grows proportionally to input rotation rate. Linearity of response is affected by rotation rate

Challenging dynamic environment, bias drift, ultra miniaturization on system-level

Long-term bias driftIncreased surface- to-volume ratio makes micro devices sensitive to surface effects: charging, contamination, out-gassing, trapping This results in long-term fluctuation of physical parameters, reflected in long-term sensor drift

2 m

m

6

Fabrication processesDissimilar and incompatible with wafer-level parallel fabrication →SWaP & CCan build small, but cannot build precise (~10-2 relative tolerance) → performanceSoA micro-structures are fundamentally flat, non-ideal for high-g environment and fast-agile sensor concepts

Approved for Public Release, Distribution Unlimited

Andrei M. Shkel

Deep integration of clocks & IMUDevelop clocks and sensors around a compatible combination of materials (Si, SiO2, Rb, Cs)Use a single master clock for time, sync, and signal processing

µPNT Technical Approaches

Sensors for dynamic environmentUtilize inertia of elastic waves. Precession of standing waves preserves linearity and extends the dynamic range. Explore new materialswith large Young Modulus

Inertia of elastic waves, self-calibration/cross-calibration algorithms, 3D fabrication

Long-term bias driftCompensate by applying persistent excitation via calibration stage integrated along side with sensors

Fabrication processesUtilize under-explored process: post-release assembly, chip-level welding, stacking Explore precision fabrication based on surface tension (~10-6

projected tolerance)3D processes: blow, stretch, stamp, roll

2 m

m

7

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Andrei M. Shkel

New Approach for Solving Dynamic Range Limitations

HRG on micro scaleExploits inertial properties of elastic waves in solidsRelies on wafer-scale fabrication of isotropic 3D solidsResults in unprecedented increase in dynamic range

Hemispherical Resonance Gyro (HRG)

Highly successful“Boutique” process

Northrop Grumman HRG

dtφ = − Ω∫

]50

]4][deg0006.0

]deg01.0

3cm

Wattshour

hour

[ :Size

[ :Power :(ARW) WalkRandom Angle

[ :Stability Bias

≈

Price Range per axis: $50,000-$100,000

Classical Rate Gyroscope

New approach Rate Integrating Gyroscope

40 Hz

3%

separationfrequency -factorquality resonator -Q

raterotation measured -frequency natural edrive/sens -

Δ

ΩnωR

ate

Res

pons

e

Input Angular Rate

20 Hz

Classical Rate Gyroscope

Axis of RotationElastic wave

New ApproachRate Integrating Gyroscope

8

xyyQ

y

yxxQ

x

nn

nn

&&&&

&&&&

Ω−=++

Ω=++

2

2

2

2

ωω

ωω

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Andrei M. Shkel

Calibration Stage

Gyroscope

Self-Calibration On-a-Chip

Input(Rotation)

Output(Voltage)

Ideal responseDrifted responseB

ias

Drif

t (ill

ustr

atio

n)

New Approach:1. Fabricate sensor directly on

calibration stage2. Periodically apply reference

stimulus (e.g. oscillatory)3. Extract reference stimulus

and sensor response4. Recover new I/O

relationship and reset bias

Why Now?:Previously, technology pushedtowards the “perfect” sensor

community now realizes the challenges of this approach

Phenomenon of drift not well understoodRe-calibration circumvents knowledge about the cause of driftNew emerging technological advances permit the miniaturization of rate tables for on-chip calibration

Current options when sensor drifts:Use inaccurate dataRemove sensor from system

re-calibrate in lab & re-insert in systemdiscard & replace

1. Co-fabricate

sensor reference

2. Excite 3. Extract 4. Reset

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Motivation Approach

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Andrei M. ShkelµPNT Objective

Parameters Units SOA SOA MEMS µPNTSize mm3 1.6*107 6.5*104 8Weight gm 4.5*103 2*102 ~2Power W 25 5 ~1Gyro Range deg/sec (Hz) 1,000 (3) 3,600 (10) 15,000 (40)Gyro Bias deg/hr 0.02 4 0.05Gyro ARW deg/√hr 0.01 0.12 0.01Gyro Drift ppm, 3σ 1 400 1Accel. Range g 25 70 1,000Accel. Bias mg 0.1 4 0.1Misalignment µ-radians, 3σ 200 1,000 100

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The program addresses the emerging DOD need to

Decrease reliance on GPSIncrease system accuracyReduce co-lateral damageIncrease effective rangeReduce SWAP&C

HG9900 Nav grade IMU HG1930 MEMS IMU This program

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Components

µPNT Organization

Nav-Grade Integrated Micro Gyro (NGIMG)

Micro Rate IntegratingGyroscopes (MRIG)

=BAA =End of Phase

FY10 FY11 FY12 FY13 FY14

Demo 3D isotropicmanufacturing

Demo Rate Integrating Gyro

SWaP and Performancedemonstrated

BAA

Device Integration

Integrated Micro Primary Atomic Clock Technology (IMPACT)

Timing and IMU Integration (TIMU)

Chip-Scale Atomic Clock (CSAC)

Demo functional T+IMU unit

Demo tactical grade performance

Demo Nav. grade performanceBAA

System CalibrationMicro Inertial Navigation Technology (MINT)

Information Tethered Micro Automated Rotary Stages (ITMARS)

Prim. and Sec. Calibration on Active Layer (PASCAL)

Demo Sensors onCalibration Stages

Demo Improvement in drift characteristicsBAA Completely

Integrated System

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