I need help with my catapult jerking

We build a catapult, but when it hits where it stops, it jerks around and bounces like crazy. Is this normal and fine to happen? What can I do to fix this issue?

I’m not sure how to attach a video so I will show some pictures instead.

Well the short answer is Physics - inertia is not your friend here… If you want less jerk as you transfer energy from one system to another, you might need more mass on your robot (which is super light weight with aluminum and will want to follow the motion)… This is true for so many systems - car crashes, cannon recoils, …


Thanks a lot for your reply! The brain and battery are both not attached to the robot right now, so that might be why it’s jerking so much. It is just so light. Is it a big issue to have it jerk or is it fine? If it is a big issue (which I hope it is not), what should I do to change it?

  • heavier base (use steel)
  • tilt prevention mechanism - think about when you are pushed from behind you put a leg forward to prevent losing balance (your robot is going to want to rotate about the front wheels and rear wheels lift up)
  • for brain - you might want some shock absorbent material - just like it is not great to get whacked in the back of your head, robot brains sometimes lose power for microsecond when high energy impact happens… best not to mount battery or brain on catapult structure…)

As for fine or not fine, unsure until you put it in competition environment (scrimmages are great way to test designs…).