Thread: Discussion G sensor not reading correctly
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Old Jan 19, 2013, 10:39 PM
BobW99 is offline
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Joined Jan 2013
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I just received the system about two weeks ago.

The first time I plugged the unit in it did a firmware update and there was a gforce expander calibration that popped up as well. I didn't do anything with the g force calibration as I was told the unit was factory calibrated and it was not possible to calibrate it anyway.

I also opened a support ticket and received a response Friday suggesting I return it to be recalibrated. I won't be doing that as it will be faster and cheaper to buy a new unit if I decide to worry about the accuracy of the z axis.

I am also having problems with both the brushless motor RPM sensor and the optical sensor. The Brushless RPM sensor gets huge spikes when the motor is running. This is a car application so there is a lot of RPM change. Peak RPM on the motor should be 14 kRPM and I get spikes to 50-60 kRPM when throttle changes. Hard to make sense of the data with all the spikes.

After that experience I figured I'd just use the optical sensor I bought as well. I can't get it to read properly at all. I roughed up the black plastic surface of a drive cup to remove the shine and painted 1/2 of it white. It's about 10mm diameter. I get an output but the RPM and speed calculation is wrong. It doesn't matter where I say the sensor is located, motor, spur gear or axle the output RPM and speed in live or logged mode never changes. The gear box ratio is 2.5:1 with a 75T spur and 48T pinion. The motor RPM should read around 13.5kRPM but it always reads 5.4kRPM. And I mean always. Even when I change the gearbox ratio to 1 and the pinion/spur to 1 it reads the same. I could understand if that was the drive shaft RPM but it isn't. Drive shaft RPM at full throttle is around 9kRPM.

Yours truly very frustrated.
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Last edited by BobW99; Jan 19, 2013 at 10:41 PM. Reason: typo
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