Pole Lifter - Winch

[AdamHeard]

For a system such as this, you really need to model and do the math for YOUR system.

The lever arms vary from team to team, the CG location varies, etc... For everything. To say team X had a ratio of 50:1 so we can use that is not going to work.

You need to look at your rotating joint, and figure out what torque the CG is causign around that. That number will vary throughout the rotation. For conservative gearing, through gearing have that equal 20% of the stall torque, that assures it'll be moving. If you gear it near stall, you'll just sit and pop breakers.

[rahilm]

Originally Posted by AdamHeard

For a system such as this, you really need to model and do the math for YOUR system.

The lever arms vary from team to team, the CG location varies, etc... For everything. To say team X had a ratio of 50:1 so we can use that is not going to work.

You need to look at your rotating joint, and figure out what torque the CG is causign around that. That number will vary throughout the rotation. For conservative gearing, through gearing have that equal 20% of the stall torque, that assures it'll be moving. If you gear it near stall, you'll just sit and pop breakers.

Very much agreed.

For example, we asked around a lot before plunging into design. We asked, IIRC, 33, 148, 254, and 1114, all of which use a wildly large range of reductions. The important part of asking around though, was understanding the underlying concepts involved between the different designs. IIRC, 33 had a fairly small arm they were rotating about, so they were able to use 1 CIM and hang fast. 254 was like us, using a PTO, because they had a much larger arm to rotate about, and so to hang in a short amount of time needed much more power. (Don't take my word for their systems. If you're curious, ask the teams who made them. This is my interpretation of their explanations) Using the information they gave us, we were able to determine what kind of ratios we needed to hang in the time we felt reasonable.

[NickE]

Another very significant consideration is ability to go under the tunnel. If you can go under the tunnel and would like to continue to have this feature, you will need to design some sort of two-stage mechanism so that you can get your lifter above the level of the platform to lift. This could either be a two-stage arm (like 254), an arm and an elevator (like 25), a telescoping arm (like 233) or something else. You will notice that the robots which hang in one motion (like 1114, 33, 27, 148/217, etc.) do so by starting the match with their hanger above the level of the platform and cannot go under the tunnel (Note: there may be an exception to this that I'm not aware of).