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This is funny if you are at all interested in databases, plus ive got a question :-) — Parallax Forums

This is funny if you are at all interested in databases, plus ive got a question :-)

mickalmickal Posts: 75
edited 2011-04-30 07:29 in General Discussion
heck it out -> http://www.xtranormal.com/watch/6995033/mongo-db-is-web-scale

The question.
I have very limited idea on what a strain guage can do. Can I use it in conjustion with my car or bycicle along with a GPS ?

nother question
Are there any plans to have the prop IDE on the ipad ?

Comments

  • LeonLeon Posts: 7,620
    edited 2011-04-28 01:42
    No.

    It's very unlikely.
  • Heater.Heater. Posts: 21,230
    edited 2011-04-28 02:34
    mickal,

    Yes.

    Please God no. Android would be better. Especially when I get hold of an ASUS Transformer Tablet.

    A strain guage measures strain. Strain is to do with how much things are stretched. If you pull a wire tight and measure it's length L1 and then pull it tighter it stretches out to L2. The strain due to the extra pull is (L2 - L1) / L1

    Now if you know something about the modulus of elasticity of the wire you can calculate the extra force that you applied to cause that much strain. And hence use this as a weighing scale.

    The only strain gauges I have seen are thin resistive elements that you can glue to the side of metal bars and such. Bend the rod and the side under the strain gauge stretches. That changes it's resistance. Measure the change in resistance and you know the stain on that side of the bar under the gauge. Hence you can determine the load applied to the bar to bend it.

    So, on a bicycle, say, stick a strain gauge to each peddle crank. Half way along. Measure the strain you apply in real time as you peddle. From that you have the amount of force applied to the peddles. From that and with the RPM you can work out how much power you are applying as you peddle. From that you can work out how many calories you have burned and how much less you are going to weigh:)

    Combining with GPS is an exercise for the reader...
  • SRLMSRLM Posts: 5,045
    edited 2011-04-29 09:21
    You can also use strain gauges on the frame of your bicycle or car to measure the fatigue over time, and determine when it would likely fail (break). Modern planes each use thousands of strain gauges throughout the body of the aircraft to do just that. Putting some gauges on the peddles might be difficult because you'll need to run at least two wires to the gauge, possibly more depending on where you put the Whetstone bridge. But it would be informative... You could also put some on the shaft to measure the torque.
  • Phil Pilgrim (PhiPi)Phil Pilgrim (PhiPi) Posts: 23,514
    edited 2011-04-29 10:29
    SRLM wrote:
    Putting some gauges on the peddles might be difficult because you'll need to run at least two wires to the gauge, ...
    What you do is put everything on the crank, including the microcontroller and battery power. Then, either store the data on EEPROM or Flash, or send it via RF to a receiver on the frame.

    -Phil
  • mickalmickal Posts: 75
    edited 2011-04-30 07:29
    How about connecting a usb stick to the microcontroller. Is there a circuit that could do that? be easy to pull it out and log data to pc after a ride. Maybe im just making it more difficult! Even thought of using a smart card :)
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