How to collect data from a 5 wire force sensor using an arduino?

hello,

this first post here, please excuse me if i'm doing wrong. i'd hello community! disclaimer, first experience programming , first time using arduino, i'm struggling bit.

here problem. have force sensor strain gauges connected in wheatstone bridge (4 wires) additional shielding (5th wire). precise, i'm using km102 k 0-100n sensor rated stretching company mofo name megatron. board arduino uno. need measure force, , i'd love if save measurements in file , process them in matlab. i'd grateful if me out couple of basic issues jig.

it has excitation voltage of 10-15v, , rated output of 1,0629mv/v. wires come out of sensor are: excitation+, excitation-, signal+, signal-, , shield.

so i'm guessing have use external source of power excitation (because arduino provides 5v), , here comes question 1. thinking usng 9v battery connected in series a 1,5v battery power source. idea , work? have 9v power adapter, below recommended value.

once have proper supply excitation voltage, question 2 arises: how should connect signal pins? guess signal- ground in analog section of arduino, , a0 signal+. shield connected ground on arduino board. right?

question 3, , biggest mystery me this: arduinos resolution/sensitivity enough nicely measure single milivolts, or need amplifier? i'm not sure how rated output thing works... rated output of 1,0629mv/v mean, of changes in voltage in whole 0-100n spectrum within 1 milivolt per every volt of excitation voltage? i.e., if feed excitation wire 10v, difference between no load , 100n 10*1,0629mv? arduino able notice suble difference in voltage?

and lastly, question 4: best way data text file on computer? arduino board can plugged in usb whole time.


huge in advance of help!

hi washington,
my first post yesterday, so, new arduino well.   
however, have background in scientific measurement , in lab equipment.

a primer strain measurements can found in: http://www.ni.com/white-paper/3642/en/#toc3. maybe have seen already.

the term wheatstone bridge bit distorted these days. bridge invented when voltmeters had no sufficiently high input impedance , there no stable laboratory power supplies around. beauty of circuit if tune 2 resistors (one sensor, , 1 tuning rheostat) in adjacent branches of circuit until voltage reading zero, can calculate resistance in question according simple rule of proportions. voltage instabilities of power supply don't matter (since balance voltage zero). likewise input impedance of voltmeter not matter (since balance voltage zero). days...

now sensors use unbalanced wheatstone bridges, , of above starts matter.

since want use matlab, presume interested in higher level of precision, accuracy , repeatability.

re question 1: generally, batteries not enough since voltage differs lot "full" "empty" , dependent on temperature. since sensor km-102 not cheap one, presume 1 of megatron's external amplifiers in budget. use ima2r24v10v. solve power supply problem too. if happen have quality sensor , *very* budget circuit, think in different direction.

re question 2: yes. i'd prefer external amplifier.

re question 3: value returned analogread() defaults 10 bits (returns values between 0-1023) backward compatibility avr based boards. due has 12-bit adc capabilities can accessed changing resolution 12. enough? have tell...
also raise point: need match output voltage of sensor input voltage of measurement device. pin reads 5 v, based on 10 bit resolution can measure in 5 mv increments. so, if sensor sensitivity 1,0629mv/v , feeding voltage 10v, have 10,629 mv @ 100n. means ardunio can tell between cases of "no load", "half load" , "full load". not good...

re question 4: write serial port. (see serial.println)

all best!
jürgen

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