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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
Approved for Public Release, Distribution Unlimited
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
Approved for Public Release, Distribution Unlimited
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
4
Approved for Public Release, Distribution Unlimited
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
5
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
Approved for Public Release, Distribution Unlimited
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
Approved for Public Release, Distribution Unlimited
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
9
Motivation Approach
Approved for Public Release, Distribution Unlimited
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
10
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
Approved for Public Release, Distribution Unlimited
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
11