Quote:
Originally Posted by mwsmith78
Thanks for all the great feedback. We tried out the example VI last night. We inserted it in the Timed-Tasks area with a 20ms wait loop.
We had to debug some other problems that ate up much of our time last night, but once we got past that it sort of worked. PID gains were VERY sensitive. We had lots of trouble getting a stable AND responsive control loop. Tried using a P-only loop, but responses ranged from 1) robot studdering to get to desired angle or 2) robot overshooting and wildly rotating back-forth. Had to keep P<0.02 in order for it to be stable (but not really responsive). Will try tweaking the gains more next week. Have others had this much trouble tuning a PID loop?
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Tell us a little more about your vehicle. What size and kind of mecanum wheels are you using; how are they mounted (can you post a close-up picture to go along with your words); are the rollers contoured and do they spin freely. And are you using direct-drive or chain drive, and how much free play is there at the wheels (ie if you lock the motor shaft, how much - what angle - can you rotate the wheels back and forth).