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Tracking Sound and Vibration Levels Using RFID

Dr. Ravi N. Margasahayam

Safety and Mission Assurance Engineer

NASA Kennedy Space Center

Florida, USA 2

Active RFID Application Highlights

• Goal: Record launch-induced Sound and Vibration

• Existing: Extensive Wired systems/ no Wireless

• Microstrain: Embedded sensors showed promise

• RFID type: Active - signals over extended range

• Wireless : Monitors large area/complex situations

• Issues: RFI affecting People, Systems, Mission

• Deployment: Battery, Line-of-Sight, Large Data

• Environmental: Weather, Power, Far-field

• Inception to data: 3-6 months; Shuttle launch

• Phase II: Near-field data, High Sample Rate

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Space Shuttle Discovery Lift-off

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Why measure Rocket Noise?

• KSC’s role as a premier rocket launch site, dictates reliability of ground equipment and structures

• Structural vibration is a consequence of launch-induced acoustics, both air- and structure-borne

• Launch of Shuttle generates in excess of 188 decibels, largest man-made continuous sound

• Sound affects Astronauts, payload, wildlife, community, and helps define explosive blast zones

• Resonance primarily attributable to the generated sound; study of sound and vibration is vital to structural design, safety and mission assurance

• Sound or unwanted Noise - leads to Structural Vibration, which results in partial or full Resonance

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Natural Frequencies & Modes

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Structures : Natural Frequencies

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Eyeball, Intraocular Structure (20-90 Hz) Head (axial mode) (20-30 Hz) Shoulder Girdle (4-5 Hz) Chest wall (50-100 Hz) Arm (5-10 Hz) Hand (30-50 Hz) Abdominal Mass (4-8 Hz) Spinal column (axial mode) (10-12 Hz) Abdominal mass mode (around 5 Hz) Space Shuttle Astronauts – 3-4 G’s

Astronauts: Natural Frequencies

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Eyeball, Intraocular Structure (20-90 Hz) Head (axial mode) (20-30 Hz) Shoulder Girdle (4-5 Hz) Chest wall (50-100 Hz) Arm (5-10 Hz) Hand (30-50 Hz) Abdominal Mass (4-8 Hz) Spinal column (axial mode) (10-12 Hz) Abdominal mass mode (around 5 Hz) Space Shuttle Astronauts – 3-4 G’s

Resonance: Due To High Pitch Noise

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Resonance: Due to Gear Vibration

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Resonance: Caused By Wind Loads

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Resonance: Due to Ocean Waves

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Noise: Deforms Rocket Structures

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Noise: Leads To Structural Vibration

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Noise: Affects KSC Wild Life

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Noise +Vibration =Vibroacoustics

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Input Forces

+ System

Response (Mobility)

= Vibration

Forces caused by Imbalance Shock Friction Noise

Structural Parameters: Mass Stiffness Damping

Vibration Parameters: Acceleration Velocity Displacement

Frequency

Noise: Max Q - Aerodynamics

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Noise: Measurement Challenges

• Sensors affected by noise levels – over 180 dB

• Excessive Vibration – over 100 g’s for 6-8 seconds

• Thermal environment in excess of 4000 degree F and plume heat rate of over 5000 BTU/Ft2-sec

• Total Shuttle Thrust - 6.5 Million pounds

• Daily environment - moist salt air, UV radiation

• System Dynamics – sensors must be designed to withstand resonant effects

• Near-field Sensors typically cooled, shielded, wires have thermal tape, terminated inside Pad

• Traditionally – sensors – are limited by cabling, cannot measure all locations, cannot instrument critical locations due to access issues

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RF Controls: Manned Space Flight

• The Radio Frequency (RF) environment is managed to avoid RFI issues that could harm People, Systems or the expensive and critical Mission.

• RF emitter evaluation is based on device frequency, power and distance relative to RF sensitive systems –pyrotechnics, communications and control systems.

• Direct and harmonic frequencies as well as the potential to swamp the receive circuits of existing devices using a close frequency.

• NASA frequency manager reviews frequency utilization for license requirements from the FCC

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900 MHz: Wing Leading Edge

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900 MHz: Orbiter Stinger Issue

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2400 MHz: Holding Pond Water Level

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Microstrain – Active RFID Sensors • Founded in 1987 in Vermont ; wireless sensors since 1996

• Has COTS systems for strain, pressure, load, displacement,

acceleration, tilt, etc

• Developing the next generation of cutting-edge wireless systems

for Navy and Army helicopters and fixed wing aircraft

• Used in automotive, aerospace, industrial manufacturing,

semiconductor, alternative energy, environmental monitoring, oil

& gas, power generation, civil structures and defense markets.

• Customers: Bell Helicopter, Sikorsky, Boeing, Caterpillar,

Motorola, Johnson & Johnson, general Electric, Pratt & Whitney,

Rolls Royce, Lockheed Martin, Ford, Intel, IBM, NASA, US Navy,

US Army

• These are Active RFID sensors, with internal battery power and ability to transmit data during rocket launches

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What is a Wireless Node?

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low power,

microcontroller

Radio Frequency

(RF) transceiver

Flash EEPROM for

sensor logging

12, 16 or 24 bit

A/D converter

Lithium thionyl

chloride battery

Sensor Inputs

Sensor signal

conditioning

multiplexer, PG

instrumentation

amplifier

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Microstrain -Wireless System

Sensor Nodes

Base Station

Node Commander - GUI

Cloud Computing

Deployed Wireless Technology

• 2.4 GHz active RFID tags with built-in sensors and signal conditioning for external sensors

• Easy to configure/deploy using Node Commander GUI

• Scalable network support hundreds of synchronized wireless nodes

• Comprised of G-Link accelerometer nodes, a SG-Link strain node, a Wireless Sensor Data Aggregator base Station(WSDA-Base), and SensorCloud, a web data management platform

• SensorCloud -Tool to remotely visualize and manage data and to isolate and interpret launch event data - key for test analysis correlation.

• Qualifies and meets requirements for use at NASA

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Active RFID: Health Monitoring

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Active RFID: Aerospace Applications

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Plume-induced Vibroacoustics

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Test Article and Test Design Issues

• Pad 39B location – far-field, historical data exists,

linear acoustics laws, SVETA (test article)

• Accessibility of test site 24 hours prior to launch

• Plate dynamics - easy to model and build

• Plate weight – does not affect modal behavior

• Wireless systems would not affect sensitive Shuttle

communications during pad clear to launch

• Sensor installation – access, support, environment

• Base station – inside building, line-of-sight issues

• Computer – location, Ethernet, remote access

• Launch issues – access, pad closeout, safety

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FE, Modal for Launch Validation

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KSC

SVETA: Laboratory Calibration

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SVETA: Pad 39B Camera Mount

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Space Shuttles on Pads 39 A & B

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SVETA on Pad B (Launch from A)

SVETA– Line of Sight - WSDA

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SVETA- Field Setup -WSDA

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Endeavour Final and Historic Lift-off

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Space Shuttle Lift-off Sequence

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Test Analysis Correlation Method

• TOA, Shape, Frequency, Magnitude (PSI Load)

• Time of Arrival (TOA) – tells us when the Rocket lifted off at Pad 39A; how and when SVETA experiences the sound load (magnitude and speed of sound)

• Shape – Acoustics and Vibration signature be similar in shape (less in magnitude – distance effect)

• Frequency– Modal (Static test), FE computer Analysis, Shuttle Lift-off – should be same from all 3 methods

• Magnitude of Vibration – actually measured g’s and then backtracked PSI and dB load (it would have been easier to measure acoustics)

• Pressure load (PSI) is converted to dB and compared with historical data from NASA Master Planning

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Shuttle Acoustic and Vibration

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LaunchVibration: TOA and Shape

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SVETA :Modal Test Frequencies

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SVETA: Launch Frequencies

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SVETA : Frequency and Modes

• Modal Test and FE Analysis (Hz) Lift-off (Hz)and Mode Shape

• 8.0 8.29 8.03 BENDING

• 31 34.1 31.1 TORSION

• 51 53.4 51.2 TORSION

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SVETA : Lift-off G’s and dB Levels

• G loads on lift-off at SVETA Equivalent PSI and dB level

• 0.5 g’s ………………………………….. 0.0075 psi (128.2 dB)

• 0.6 g’s ………………………………….. 0.0090 psi (129.5 dB)

• 0.7 g’s ………………………………….. 0.0108 psi (130.8 dB)

• 0.8 g’s ………………………………….. 0.0120 psi (132.2 dB)

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Shuttle Acoustics- Analysis & Test

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Acoustic Levels – Historical Data

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Future Wireless Application- Hypers

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Future Wireless Application- GUCP

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Future Wireless Application - COPV

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Conclusions & Observations

• 2.4 GHz RFID tags with built-in sensors from Microstrain were used to measure launch vibrations – First use of ACTIVE RFID in the Space Shuttle program and rocket launches

• Verified time of arrival of rocket noise data and Vibroacoustics implications of a rocket launch

• Launch Vibration data is used to assess loads/stresses imposed by rocket noise on structures/useful life

• Test data is vital to study safety and operational readiness and to predict impending failures of GSE

• Helps monitor pressurized, hazardous systems operating at high temperatures with access issues

• Developed a tool to evaluate Safety, Reliability, and Maintainability of structures via condition/health monitoring

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Time for Questions?

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