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Unread 01-30-2009, 09:57 AM
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LabVIEW - Analog inputs from driver station lag?

Hey guys!

We made our own controller box to control various motors on our robot. This is plugged into the analog and digital inputs on our driver station. The actual input seems to work fine but we have seen weird issues on the motor itself. We are using the analog inputs connected to potentiometers to control the motor speed and then a digital switch to turn them on or off. When one is turned on, all of the values going to the motor seem to be steady and good, however, the motor will reverse direction randomly every now and then when we try to adjust the motor speed using the analog pot. The values of this analog control seem to be good too and no negetive values are getting to the motor itself nor coming out of the pot. I thought maybe putting a saturation on the values going into the motor, just in case.

Any ideas?

Our thoughts was maybe some sort of lag from the LabVIEW to the actual control system since we are not deploying it and running it from the laptop which we have had different issues with already.

Thanks!
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Unread 01-30-2009, 10:39 AM
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Re: LabVIEW - Analog inputs from driver station lag?

You need to put a max/min limiter on the wire going to the motor. I have not tried this on the new control system, but if you tried to output a value higher than the old maximum on the IFI system, it would "flip" and become negative.

Use the limit and coerce function in labview with limits of -1 and 1 to see if this is your problem.
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