Stanford PNT Symposium 2017web.stanford.edu/group/scpnt/pnt/PNT17/presentation_files/I07... ·...

Recent Innovations in MEMS Sensors for PNT Applications

Stanford PNT Symposium 2017Alissa M. Fitzgerald, Ph.D. Founder & CEO | [email protected]

Overview

• Navigation• Developments in MEMS gyroscope technology• Other MEMS sensors for navigation• About AMFitzgerald

Stanford PNT Symposium 2017 © AMFitzgerald 2017

Navigation has always depended on sensor fusion


Synthesis of information from multiple imperfect sources

Today, GNSS provides highly accurate navigation information



A proliferation of vehicles now depend on satellite navigation

On land, GNSS-denied environments are everywhere


How to operate safely in complex environments (without a $100K+ IMU)?


MEMS: a powerful miniaturization technology

Navigation unit (1995) Navigation unit (2015)


Approx:150 mm x 150 mm x 150mm

MEMS inside

MEMS are widely used in consumer and automotive applications


> 10 MEMS 1-2 MEMS > 100 MEMS!

Micro Electro Mechanical Systems

© AMFitzgerald 2017

Silicon dioxide (a.k.a. sand, dirt)

Ingot Wafers

Made by silicon (semiconductor) process technology

Stanford PNT Symposium 2017

Fabrication

Wafer dicing Chip packaging Circuit board mount


MEMS sensors useful for navigation

AccelerometersGyroscopes

MicrophonesPressure sensors IMUs(Accel+Gyro+Mag)

GE

Magnetometers

MEMS sensor qualities

• What’s great about MEMS:– Tiny size and mass– Low(er) cost and power– High sensitivity– Compact electronics integration

• What’s not:– Tricky to package– Small signals, custom ASICs often

needed– Stability over long duration or

extreme environments


Gyroscope

Grade Bias stability

Main Application Est. MEMS Price (in volume)

Example Maturity

Consumer 10 deg/sec Human motion $1 ST Micro CommercialAutomotive (safety) 1 deg/sec Stability control $5 Bosch CommercialIndustrial 10 deg/hr Munitions $20 ADI, Qualtre CommercialTactical; Assisted Nav 1 deg/hr Vehicle Nav $300 SSS CommercialShort-term Nav 0.1 deg/hr Missile Nav - UMich: Najafi R&D (TRL 6)Navigation 0.01 deg/hr Aeronautics Nav - UCI: Shkel R&D (TRL 4)Strategic 0.001 deg/hr Submarine Nav - DARPA

C-SCANR&D (TRL 2)

MEMS gyroscope application grade and bias stability


Performance needed for navigation in GNSS-denied environments

MEMS comb-drive tuning fork gyro (consumer-automotive grade)

• Rotation of component exerts perpendicular Coriolis force on resonating proof mass

• Sealed in vacuum environment to maximize Q• Capacitive comb-drives to drive/sense mass


MEMS comb-drive tuning fork gyro (consumer-automotive grade)


Source: ST, Chipworks iPhone 4 Teardown

2-axis gyro (infrared photo) 2-axis gyro (SEM image)

Source: ST, Chipworks iPhone 4 Teardown

Bigger chips can span etch

zones

Edge of wafer etches faster

Manufacturing tolerances limit performance of comb-drive gyros

• Nearly all current gyro designs inherently limited by silicon etch accuracy– Non-uniform etching causes quadrature error and cross-axis coupling– Lower Q = higher power consumption

• Work-arounds to maximize gyro performance:– “Cherry-picking” a.k.a. binning– Mode-matching designs– Signal processing and compensation


Source: Intellisense

Top heavy etch Bottom heavy etch

Bulk acoustic wave gyro (industrial grade)


Precision single-axis with inductive drive/sense (tactical grade)

Source: Silicon Sensing Systems


Micro-scale rate integrating gyros (navigation grade)


• 3D MEMS structures– Symmetric, atomically-smooth, high Q resonators

Source: UC Irvine, Shkel LabSource: U Michigan, Najafi Lab

Blown ultra low expansion silicate glass

Molded fused silica

Atomic gyroscopes (strategic grade)


• DARPA Chip-Scale Combinatorial Atomic Navigator (C-SCAN)– Program Manager: R. Lutwak– Two architectures being explored:

Nuclear Magnetic Resonance Gyroscopes Atom-Interferometric Gyroscopes

• The ultimate gyroscope, which could one day enable Secretary Ash Carter’s vision of making GPS obsolete

• “MEMS-ish” components useful in physics package

Other potentially useful MEMS for navigation and sensor fusion


Infrared Imager Ultrasonic RangingChirp Microsystems

SensirionGas Sensors

FLIR

MaradinMicro-mirrors: LIDAR

Conclusions

• Navigation continues to be the practice of sensor fusion– MEMS sensors offer lightweight, low power (low CSWaP) measurements

• MEMS gyroscopes useful for navigation in GNSS-denied environments still in development, at least 5 years away

• Non-inertial sensors could augment navigation in specific applications

• GNSS will continue to be an essential navigation technology for at least 20 more years...while MEMS R&D grinds away on better gyros


About AMFitzgerald

AMFitzgerald creates MEMS and sensor solutions for specialty applications


MEMS Innovation MEMS Solutions Technology Strategy

Paths to manufacturing and

market

Creation of novel devices and IP

Key insights from MEMS experts


• Custom MEMS development for commercial production• Rapid prototyping on state-of-the-art tools • Supply chain creation and management• Focus on high-performance, specialty silicon devices


Strategic partners

Development services from concept to production


Fab operations at 1500m2 UCB Marvell Nanolab

Headquarters in Burlingame, CA

AMFitzgerald in-house


Our work is at the leading edge in many markets


AMFitzgerald typical annual revenue, by market

Cardiology guidewires,

pacemakers, pumps; diagnostic chips

Fiber optic networking, laser

system components,

infrared detectors

Atomic sensors, commercial print heads, quantum

computers

Microphones, pollution detectors

Aircraft, spacecraft sensors


Company contact information

700 Airport Blvd. Suite 210Burlingame, CA 94010, USAPhone: +1 (650) 347 MEMSFax: +1 (650) 347 6366

www.amfitzgerald.com

General Inquiries: [email protected]


http://www.amfitzgerald.com/

mailto:[email protected]

Stanford PNT Symposium 2017web.stanford.edu/group/scpnt/pnt/PNT17/presentation_files/I07... ·...

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