Scissor bot issues

Our team has built a new scissor bot, but when testing it, the left and right sides go up unevenly. We tried adding a counter weight on the left side because it was going up faster than the right, but when it goes down the right side is faster. We have rubber bands to help the lift lift, but there are the same number of bands on each side. On top of the lift, we have one motor and one potentiometer on one side only, but I don’t think it would be the cause. Any ideas how to fid this?

Adding extra weight to one side is a very bad solution… Check for friction in your joints, and make sure the gear ratios on the motors on both sides are the same. It’s hard to say more without seeing the lift.

Be sure to add many cross-bars to connect the two sides of the lift. Having sufficient mechanical restraints is my #1 way to fix things.

There are a number of reasons your scissor lift could be uneven. Are the motors geared the same on both sides? It’s easy to make the mistake of having speed motors mixed in with torque motors. Also, not all rubber bands are created equal, some of the rubber bands could be worn out and not providing the same power as newer fresh-out-of-the-package rubber bands. However, The most likely cause of the unevenness is friction. Make sure all your bearing flats line up and none of your shafts are bent. You can also add more cross bracing to the two sides of the lift to increase stability. If you’re up for it, programming a PID controller for the two sides of the lift could solve your issue but I would recommend stabilizing the two sides more before attempting any complex programming solutions.