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Motor[x].DesPos keeps 'drifting'
I am currently attempting to control a piezo-driver using the Powerbrick Controller. Now, since the piezo-driver accepts an analog signal of -2==> +10V, and also outputs an analog feedback signal between 0=> +10V I decided to use the following configuration:
- Powerbrick output: True DAC (single ended) with modified DacBias and MaxDac to keep within the -2 => +10V voltage range (same config as in page 145 of the Powerbrick Controller Manual)
- Powerbrick input: ADC (single ended) via X10 connector (same config as in page 76 of the Powerbrick Controller Manual)

After having set the configuration, I can freely output anything open loop (ex. #2out100), of which the ADC input shows a corresponding value holding constant while my command remains unchanged.

Sometimes (roughly 50% of the time) when I close the loop, I will have a drifting Motor[x].DesPos, despite not having commanded a movement. And since the motor is in closed loop, it will follow this 'drifting' trajectory indefinitely. I have included a screenshot of the 'drifting', here during a step move.
If Motor[x].DesPos is driftin, there could be three possible causes to this:
- Motor[x].Desired.Pos ==> NOT the source, holds constant
- Motor[x].ActiveMasterPos ==> NOT the source, holds constant
- Motor[x].CompDesPos ==> NOT the source, holds constant

Therefore this little problem leaves me abit stumped. Has anyone else encountered a similar problem?

Thanks in advance,

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Motor[x].DesPos keeps 'drifting' - christerron - 04-15-2019, 07:14 AM

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