auto tuning

Questions about using encoders with the Roboclaw product line
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SouthernAtHeart
Posts: 32
Joined: Fri Jan 29, 2016 4:00 pm
auto tuning

Post by SouthernAtHeart »

When I manually set the PID values to P = 3; I = 1; D = .25; my motor runs quite well. It will turn nicely at slow speeds and fast speeds, though, if I hold it back it will kinda get sluggish, then speed up in excess for a bit before it runs at the speed I'm asking it to run.
I tried the auto tuning feature several times on my motor, but it gave me very odd values. I forget exactly, but something like P= 300, I= .03 and D = 0; And when I use those values, the motor is quite jerky at low speeds. They seems rather extreme. During the auto tune phase, it turned the motor very nicely, a slow speed forward, a slow speed backward, then stopped. Is there a trick to using auto tune? with the values of 3, 1, & .25 it works fairly well, but I think it could be better.
thanks.
ps. in the ion motion utility, when I click on help/manual it always just give me an error. I have the manual for my roboclaw 2x7, but is there a manual for the ion motion utility, or is that link obsolete?
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Basicmicro Support
Posts: 1594
Joined: Thu Feb 26, 2015 9:45 pm
Re: auto tuning

Post by Basicmicro Support »

The autotuner is trying to set the optimum values which also will tend to be somewhat jerky. After running the autotuner you can use the sliders under the buttons to adjust how hard/soft the tuning is. Autotune, then slide the slider all the way to the left to set it to very soft. If that is still not soft enough then you can manually adjust the values in P and I. Leave D at 0. Is almost never required in a Velocity only tune. P and I should be reduced evenly(eg if you half P then hald I as well).

You description of how the motors acts when you use your valeus and apply load indicates the P is way too low and the I is being used to compensate for it(eg the delay when speeding back up and the large speed overshoot indicates its almost all integral).

The help/manual menu item just tries to open the pdf Manual. Its possible there is somethign wrong with your default pdf viewer. if you dont have a default pdf viewer that could also explain the error.

The link on the website should be up to date.
SouthernAtHeart
Posts: 32
Joined: Fri Jan 29, 2016 4:00 pm
Re: auto tuning

Post by SouthernAtHeart »

GREAT! That is the problem-I didn't have a pdf viewer on the machine I was using for roboclaw. The manual will hopefully answer many questions for me.

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