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I am making a robot for my college project. For now, the robot simply has to move forward, reverse, right and left. While the forward and reverse thing is very smooth but while taking a turn it wobbles continuously. I tried to add weight and slow down the speed but the vibration is still there. I need to know what I am doing wrong. Attaching the youtube links of the wobbling robot.

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  • $\begingroup$ Is it a fair assumption that you are managing the speed of the wheel to make the turn. $\endgroup$ – user8055 Oct 1 '19 at 17:32
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    $\begingroup$ Yes. The problem was in the frame as pointed by the answers. I have updated the frame with a wider body and now it works fine. $\endgroup$ – Nitesh Singh Oct 8 '19 at 18:20
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Your connection of the wheels to the robot enclosure (suspension) is flimsy and has too much free play. It starts to jerk and gives enough kick energy to the flimsy box to keep it dancing. And the skidding of the wheels resonates with the vibration of the robot.

To improve the stability without having to use electronics self balancing chips:

  • Use an integrated frame separate from the box, with wider distance between the wheels, wider track, more like a square footprint. It is essential that the wheels axels are substantial and have long extension, may be all the way to the opposite end.

  • Put diagonal bracing inside the box and use self locking screws to make it more a rigid frame, as it is it is too rickety, and side panels act like the pendulum to excite the vibration.

  • Try different size and material on wheels and may be a bit of toe out angle in the in the wheels because it seems the wheels' skidding is resonating with the box vibration natural frequency.

  • Use a small flywheel on the motors to keep the torque output steady.

  • If practical change the geometry of robot to make it less narrow.

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  • $\begingroup$ Thank you for your response. I have divided the model in two frames keeping the base frame wider than the top frame and it works like a charm now. Thank you for your help. Much appreciated. $\endgroup$ – Nitesh Singh Oct 8 '19 at 18:19
  • $\begingroup$ @NiteshSingh, I am glad you got you robot to behave and follow commands. $\endgroup$ – kamran Oct 9 '19 at 3:56
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You have a tall skinny skid-steer vehicle, and you're trying to run it on a surface with a high friction coefficient. So the wheels are constantly grabbing and letting go, grabbing and letting go.

Try making either the front or rear pair of wheels castoring.

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