Quote:
Originally Posted by JamesCH95
That's not a bad way to do it, and it certainly is better than doing nothing, but force != stored energy when the spring rate is changing.
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You are correct, and I should have been more clear. There was a potentiometer on the system in addition to the strain gauges, which gives enough information to calculate the spring rate at any given time. We found that the surgical tubing was fairly consistent enough in the spring rate that it would have to deteriorate very far before the assumption stopped being accurate enough to make a difference, so I don't think we actually had this particular feature coded. We were using the black thick-walled stuff available from McMaster, very hardy.
As mentioned before, our measure of accuracy wasn't anywhere close to the degree necessary for this year's challenge, so your mileage may vary. I do believe you will be able to be more accurate with a measurement of force/spring rate, but it still might not be enough to have the kind of "drop in replacement" capability we envisioned for 2010.