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PID for a modified B-Robot
04-26-2020, 04:57 PM
Post: #1
PID for a modified B-Robot
My B-Robot is now working properly, since changing to a large LiFe battery. However, this has left me with a problem - the thing is a bit heavier, and the centre of mass is higher (I had to make spacers to add about 12 - 14mm between the electronics shelf and the motors). This has messed up the PID, as you can see in this video:
YouTube
I have tried playing with the PID values in the Android app, but nothing seems to resolve the problem.

Any bright ideas?
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04-26-2020, 10:19 PM
Post: #2
RE: PID for a modified B-Robot
It is a tough challenge for even the best setup robot to balance complete still on a carpet, but still try adjusting your #define ANGLE_OFFSET in the BROBOT_EVO2_23_M0.ino
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04-27-2020, 09:10 AM
Post: #3
RE: PID for a modified B-Robot
(04-26-2020 10:19 PM)justjason Wrote:  It is a tough challenge for even the best setup robot to balance complete still on a carpet, but still try adjusting your #define ANGLE_OFFSET in the BROBOT_EVO2_23_M0.ino

I'll try that - but it also wobbles on a hard surface! Smile
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04-30-2020, 02:11 PM
Post: #4
RE: PID for a modified B-Robot
As a matter of interest, can anyone give guidance for changing this value, or is it trial-and-error to see what happens? I'd be interested to know the range of valid values, for a start.
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04-30-2020, 02:16 PM
Post: #5
RE: PID for a modified B-Robot
(04-30-2020 02:11 PM)David_J Wrote:  As a matter of interest, can anyone give guidance for changing this value, or is it trial-and-error to see what happens? I'd be interested to know the range of valid values, for a start.
Try to not "overshot" first. That means: reduce the Proportional value as much as you can (you will be below a valid value when the robot can not respond and fall). Then go for the D value, that will prevent the robot to wobble too much but at the same time, it will limit its response. So, it is a "finding the balance" with a set of values. The I will prevent the robot to move by itself, keep moving fordward without any input from your control APP.

This is just a general idea, there are some minor "interferences" among the PID values not easy to isolate by themselves, but it may help.
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06-08-2020, 11:25 AM
Post: #6
RE: PID for a modified B-Robot
Late update: It looks like this was due to a problem with my DEVIA board (one set of motor connector pins fell off the board!) - jjRobots promptly sent me a replacement and the B-Robot now only shows what I would call "acceptable wobble" (normal correction movement). Smile
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