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--- pid_tuning_guide [2016/12/07 10:49]
ian446
+++ pid_tuning_guide [2016/12/07 21:48] (current)
ian446
@@ Line 69: / Line 69: @@
 The I term is adjusted by lowering it until you see the quad having difficulty holding a set attitude both in hover or while travelling forwards on a set course, it will start to drift around. Then bump I up just enough so the quad will hold its attitude (say in 10% increments). If you start tuning with too much I, it will foil your tuning attempts. Any value of P, I or D that is too high for the quad will make tuning very difficult. It is always best to start low and work up, and do not increase any of the values any more than is needed.
-Also, you don't have to tune a quad and that's it (in one go). If you keep notes, you can keep tweaking it when you are in the mood to try some changes. Some quads I almost gave up on turned out to be great flyers in the end, given a bit of time and persistence, but not all at the same time, (or on the same day), sometimes it's weeks later until I get it flying right. Others quads, they are tolerant of many tuning values and fly well right from the start.
+It is difficult to know where to start with the I term. Usually it ends up being 1/3 to 1/2 of the P term once tuned (on my quads). Also I find it doesn't need to vary much when P and D are changing, it is almost an independent setting from P and D. Start as low as you are comfortable with. Before you fly a newly-built quad, it is almost impossible to know where to start, unless you have built a similar one before, or someone gives you some starting values. In the case where there is nothing to start with, you have to put some numbers in there and just see what happens.
+Some more comments by silverxxx regarding where to start with I from this post: [[https://www.rcgroups.com/forums/showpost.php?p=36368724&postcount=6881|https]][[https://www.rcgroups.com/forums/showpost.php?p=36368724&postcount=6881|://www.rcgroups.com/forums/showpost.php?p=36368724&postcount=6881]]
+"I sometimes start at zero to see how balanced the quad is. Otherwise if I can't balance the quad or I just don't feel like havig drifts, I just put 1 in there, that stops the drifts.\\
+However, low I seems good in gentle flights, but will be bad as soon as heavy maneuvering starts. Generally the quad tends to want to come back after a rate change with I too low."
+Also, you don't have to tune a quad and that's it (in one go). If you keep notes, you can keep tweaking it when you are in the mood to try some changes. Some quads I almost gave up on turned out to be great flyers in the end, given a bit of time and persistence, but not all at the same time, (or on the same day), sometimes it's weeks later until I get it flying right. Others quads, they are tolerant of many tuning values and fly well right from the start.\\
+\\
+Something else to add is that in general, higher kv motors need less PID because in effect they add gain to the PID's compared to the same size motor with lower kv rating. A similar thing can happen by changing prop pitch/diameter or number of cells, again the tuning is affected because for the same change in motor speed command from the FC, a different thrust change occurs compared to before the props or number of cells was changed. Unfortunately the FC does not know anything about the motors/props/batteries fitted, so it has to be tuned for whatever combination of parts are being used. Sometimes hardware changes do not require a retune, but usually they do.

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