Climb Questions

  1. Our lift is mounted at the back of our robot out of necessity. When we lift the robot wants to tip forward. Is there any way to make the entire frame lift level while lifting from the rear?

  2. What’s the best method to prevent back-drive when the power is cut to the robot? We want to be able to extend and retract our wench motor, so a ratchet wrench is out.

  1. Unless you death-grip the bar (putting a large moment (torque) on it), the center of gravity will always want to be under the bar.

  2. There are a couple ways to do ratchets and trigger them on and off with pneumatics, servos, bike disk brakes (biased closed). You could also play with the gearing (ratio or type of gearbox that doesn’t back-drive, this will come with the penalty of climb time for high ratios, or inefficiencies inherent with commonly avalible worm-drives )

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  1. One option would be to have a second set of hooks that are attached directly to the frame of the robot that naturally hook onto the rungs after you’ve climbed (sort of like how zip ties work, if that makes any sense) so it doesn’t matter whether or not your climb arms extend/retract.
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Yup good point, and quite possibly the easiest to implement.

You could give yourself a “lock” by snapping onto the bar with other geometry once you complete your pullup.

If you are climbing with a brushless motor and it is in brake mode, you may be able to consistently stay off the ground for the requisite 5 seconds without any sort of anti back drive device, depending on ratio.

One option that could be carefully implemented is some kind of actuated latch or lock, such as with a pneumatic cylinder, which could freeze the mechanism. Many teams use disc brakes or friction brakes for this as well.

Much better way of saying it. I’ve also seen some hooks that have a latch on them that has to be manually released to take the hook off the bar. It acts as a safety measure. That is dependent on your team’s climb strategy though.

We finally got our 6 pt climber working today…it has a pair of 775 Pro motors, and 64:1 gearbox driving a 1" diameter spool. It falls back down, slowly (after setting brake mode on the speed controllers). We’re planning/hoping to take more than 5 seconds for it to reach the floor. It worked in 2018…

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We used pulleys on our 2020 robot to get the lifting ropes centered on each side of the robot. Is there any way you could do something like that?

also, posting a picture or two of your robot will really help folks be able to help you find solutions.

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