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Old 03-08-2010, 02:28 PM   #44 (permalink)
jfitzpat
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Quote:
Originally Posted by kubark42 View Post
1) I have to check to be absolutely sure, but I believe I left at least 4 analog inputs free.
If you are using the 10 bit ADC in the Atmel, then you need to keep in mind that the inputs are part of a mux. That is, the inputs are being sequentially sampled by the same internal ADC. So, more channels can mean lower sample rates for other sensors.

Quote:
Originally Posted by kubark42 View Post
Unfortunately, we cannot directly measure the difference between rough roads and smooth ones. This is within the capability of the observer, but in order to have that level of precision you would have to have much more accurate sensors. Specifically, you'd need a danged good elevation profile for your road. Also, a throttle position sensor would help.
If you trace back from your references, you should find a paper on this specific problem - basically seperating operational vibration out of a 3 axis accel measurment.

However, it is a difficult path. You might do better to look at the more recent work out of UC Riverside. One of the research projects there on emissions uses a very clever way of directly measuring torque in real time. With torque, their hurdle to efficiency precision was energy content of the fuel, which varies quite a bit depending on blend (how much alcohol, etc.) That's were we came in.

Even if you don't go that far, it should represent a significant improvment in precision.

-jjf
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