Computer Automation of a Computer Automation of a TribometerTribometer

Michael Eng, TJHSSTMichael Eng, TJHSST

With Nimel Theodore, Kathy Wahl With Nimel Theodore, Kathy Wahl

NRL Code 6176NRL Code 6176

ObjectiveObjective Main goal- integrate positional data Main goal- integrate positional data

w/ friction collectionw/ friction collection Using LabVIEW programUsing LabVIEW program

Can be applied to microscopic or Can be applied to microscopic or spectroscopic analysis of frictional spectroscopic analysis of frictional eventsevents

http://www.rpi.edu/dept/materials/COURSES/NANO/oja/nanocrys.gif

OutlineOutline

Reciprocating stageReciprocating stage TribometerTribometer Circuit boardCircuit board Program structureProgram structure Sample outputSample output ApplicationsApplications

Stage and ControllerStage and Controller

Aerotech ALS Aerotech ALS 130-150 stage130-150 stageMoves tribo armMoves tribo arm

Soloist motion Soloist motion controllercontrollerProcesses Processes

stage’s digital stage’s digital voltage signal voltage signal into positioninto position

Stage sends voltagesignal to controller

Controller transformssignal into position

value

Computer receivesposition value via USB

TribometerTribometer Arm + probeArm + probe 4 strain gauges4 strain gauges Moving stage/platform- 1-D motionMoving stage/platform- 1-D motion

Motion controller sends position to computer as Motion controller sends position to computer as ++VV

M

Signal Conditioning BoardSignal Conditioning Board Powers strain Powers strain

gauges, gauges, receives strain receives strain signal from signal from strain gaugesstrain gauges

Excitation Excitation voltage (Vvoltage (Vinin) ) controlled via controlled via potentiometers potentiometers (1.25-2.5 V)(1.25-2.5 V)

Output voltage Output voltage (V(Vgg) nulled via ) nulled via potentiometerspotentiometers

Figure 2-1. SC-2043-SG Parts Locator Diagram- NI manual

+Vin

+Vg

Cable to PCI

Vg Potentiometer

Vin potentiometer

Int/ext excitation jumpers

Bending ΔR

Signal board- Wheatstone

bridge

ΔR ΔV

Computer- LabVIEW program

ΔV Ff

Ff / FN = μ

Microsoft ClipArt

F f

M

http://sine.ni.com/images/products/us/1sc567a1m.jpg

LabVIEWLabVIEW Programming environmentProgramming environment Data acquisition/analysis focusData acquisition/analysis focus

Logging, graphing, etc.Logging, graphing, etc. Graphical programming languageGraphical programming language Human-Machine InterfaceHuman-Machine Interface

http://www.mathworks.com/company/newsletters/news_notes/dec04/images/mlint_srccode_wl.gif

http://www.mezintel.com/LVCode01.png

Data structureInput voltage signals

stage and signal conditioning board

Position data Friction data

Convert w/ calibrationConverted by

motion controller

Program StructureRun

Stage/controller:Oscillate

DAQ card:Collect

Receive, convertfriction data

Calculate position dataw/ # data points collected, start point

Record as (x, y) pts, graph

Re-sync every half-cycle

CalibrationCalibration

Arm turned on Arm turned on sideside

Multiple loads Multiple loads appliedapplied

Linear regressionLinear regression Y-intercept, Y-intercept,

slope convert slope convert voltage to voltage to frictionfriction

Calibration 8/7/08

y = 0.0169x + 0.2866

R2 = 0.999

0.0001.0002.0003.0004.0005.0006.0007.0008.0009.000

10.000

0.000 100.000 200.000 300.000 400.000 500.000 600.000

Load (g)

Vol

tage

(mV

)

Friction vs. cycleFriction vs. cycle

Friction (y) vs. Friction (y) vs. cycle (x)cycle (x)

Allows analysis Allows analysis over many cyclesover many cycles

Account for Account for debris, reactions, debris, reactions, etc.etc.

Friction vs. positionFriction vs. position

Friction (y) vs. Friction (y) vs. position (x)position (x)

Updates real-Updates real-timetime

Provides Provides coordinates of coordinates of friction friction anomaliesanomalies

Intensity plotIntensity plot

Pseudo-3DPseudo-3D Friction (color) Friction (color)

vs. position (y) vs. position (y) vs. cycle (x)vs. cycle (x)

Combines Combines previous two previous two graphsgraphs

ConclusionConclusion

LabVIEW programLabVIEW program Integrates positional and frictional Integrates positional and frictional

datadata Extracts data as CSV and TXT filesExtracts data as CSV and TXT files Graphs friction vs. cycle, friction vs. Graphs friction vs. cycle, friction vs.

position, friction vs. position vs. cycleposition, friction vs. position vs. cycle

Future ApplicationsFuture Applications

Integrate with microscopy or Integrate with microscopy or spectroscopyspectroscopy Use coordinates of frictional event in Use coordinates of frictional event in

other analysis instrumentother analysis instrument Example- FTIR of nanocrystalline Example- FTIR of nanocrystalline

diamond filmsdiamond films

AcknowledgementsAcknowledgements

Nimel TheodoreNimel Theodore Kathy WahlKathy Wahl Irwin SingerIrwin Singer Jeffrey WeimerJeffrey Weimer SEAPSEAP ONRONR