Hey y'all, I was wondering if there was a way to make multiple PID loops without using the Array method in the PID VI. My issue is that I have 2 axes that I thought I'd try to control with a PID loop. I was going to take turns, first moving the X axis, then I'd use a different loop for the y axis. However, I don't think it'll work with the array, as both axes use the same processing parameter and setpoint, and since it's only actually moving/correcting 1 axes half the time, I feel like the Integral will get polluted with bad data, or at the very least data that wasn't actually directly changed. So is there any way to make 2 completely separate PID loops that don't need to be run at the same time, since each axis will have a different affect on the processing parameter? Just for completeness, the processing parameter is the difference between 4 diodes that are equidistant from each other, and it's trying to center the light between all 4 of them

Hi Ethan, @EthanHenry wrote: But the PID VI uses shift registers. I'd like to be able to just use the already built PID VI, but if that's not possible I guess I could always write my own. Just didn't want to have to reinvent the wheel if at all possible Each PID will have it's own internal shift registers - but what's the matter when you place them in their own independent loops??? @EthanHenry wrote: as if they both share the same processing parameter and setpoint, then I'm just going to have 2 loops that are the exact same, which isn't what I want. Instead, I could make each loops processing parameter the difference of 2 diodes + difference of the other 2 diodes. The groups of these diodes would be the 2 that change when that axis moved. then I'll have 2 different loops each trying to correct and, hopefully, drive all the differences to 0 How can you drive two independent motors, moving independent axes, using the very same set of setpoints and process values??? Each axis should have their own set of process value, motor (driver) and PID gains…

LabVIEW

Multi-axis PID Loop

Solved!

Hi EthanHenry,

To echo what ZYOng said, the PID.vi can actually support multiple channels in the same loop. You can right click on the PID.vi to accept an array input. Your 1st number in array will be setpoint for channel 1, 2nd number in array will be setpoint 2, etc. Same for output. Internal to the PID.vi, it keeps separate shift registers to remember the data for each channel. You can also set different PID parameters for each channel.

Check out this shipping example: <LabVIEW folder>\examples\control\PID\Multi Channel PID.vi

John

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