My GoPiGo3 turnes left without permission even though I instruct "Go Straight"

Hello, I have used two GoPiGo3s in my research, and there have been cases in which one of the robots turned left without permission even though I instructed “Go Straight”.
Since we can’t do correct experiment anymore with this robot, I changed the robot to the another one and I was doing a turning experiment with it, and the another robot also started turning left on its own. In such a case, what kind of correction should I do to make it go straight again?
(Postscript: Another GoPiGo3 can go straight after I changed the battery.)


How old are the robots?

You might have a defective GoPiGo controller board, especially since it seems that the problem follows the board when it is moved to another robot.  (I’d suspect the “H-bridge” driver chip based on what you’re experiencing, but it could be other things as well.)

If the robot is new, (or relatively new), contact Modular Robotics support e-mail, (, and see if they can send you a replacement.


One thing to check when straight command results in turning behavior: the encoder sensor spacing/positioning.

If the gopigo board is not receiving encoder signal from a side, it will increase the power to that side trying to make that wheel go faster. This makes that wheel turn faster than the “good encoder” wheel, resulting in uncommanded turning behavior.