Analog input noise, best way to filter?

Hello

I use a cRIO (w / LV 8.5) to make a lever on an electric race car and the driver throttle control signals are 0 - 5V or 0-5kOhms.  Now, I work with a signal of 0 - 5V for some tests.  If this gas 0 - 5V input arrives, the cRIO resembles certain conditions, and if all goes well, just if he crosses this 0 - 5V located on the engine without changing it at all.  So I have a NI 9201 AI module and a module NI 9263 AO.  Our first hook this system up to a motor on our chassis dynamometer, however, we quickly realized that there too much noise in the signal of butterfly, and engine jerking around, kind of like he's possessed.  We thought that maybe we could live with that, sort of like the irregular Growl, you get a burly V8, thinking that this might be nostalgic for the former riders, but it is a bit difficult for our lab tests pending.

I had a look at a few examples of using a lowpass butterworth filter on the FPGA, and this seems to be a nice implementation.  My stumbling block comes from the fact that I use calibrated data, value engineering coming out of the modules and just passing the value of the voltage of my HAVE on area of OCCUPANCY.  Meanwhile, the Butterworth filter can operate with integer values.  I then tried affecting the entry and the exit of the modules of the raw data and not calibrated sends me data whole instead of FXP and then passing the entrance through the filter and then straight in the output module.  It seemed to work at first, but then I realized that my exit was not mapping to my entry, the voltage output was far from what I was before.  This is because the calibration of the raw data to engineering values is different for the two modules, and integer values, as I passed from one to the other do not match values of voltage.  Then I thought that I could take in the raw data from the input module, filter it and then pass it through a calibration unit which become values of voltage, and send data to the output module calibrated (reset the rear output of Raw to calibrated, but keep the entrance of raw data.)  That was when I realized the calibration of raw to engineering values, I've seen always happened in vi of the host, and that the calibration does not support the FPGA that blocks, I found in the examples.

I don't see how do now (maybe throw a gain to adjust the output data until my entry maps correctly to the output) but she think there must be a more legitimate way of filtering data from a module of HAVE and that passing on an AO module.  Thank you in advance for your help!

Jeff

Hybrid of McGill Racing Team

I've backed a LabVIEW 8.5 project that shows an example of what you're trying to do.  There is a test case of windows showing the result of the filter.  I think this can help.

The analog input is 12 bits and the output is 16-bit, I'm sure that is part of the issues you dealt with that.

Tags: NI Hardware

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