Ok sorry if I’m bad at wording this, but we’re having an issue with our design. Basically we are building a gripper on a multi-staged elevator, and the elevator is going to be near the front of the robot. Our issue is that we just assumed we’d be able to put the gripper on wrist of some sort, have it start upwards and outside the frame perimeter, but then when the match starts have it fall down to be usable and pick up game pieces. We cannot figure out an effective way to have the gripper start either up or down in a way that it will be within the frame perimeter, but I saw many teams last year used “wristed” intakes or something like that. We don’t need it to be too in depth, but I was just wondering what sort of stuff you guys used to do that? Thanks for the help! Let me know if you have any questions.
Do you plan on having a need for the “wrist” to move other then starting config?
If you need it for a game play application then you can use motors or pneumatics to make it move.
If it is only for starting config you can use a hinge and prop it up and as the robot moves it falls down.
There are a lot of design choices that you can look at. I would take a look at robots from last year to see how they store their grippers at the start of matches.
We just need it to fall down at the start of a match, we were just worried that if we have our 10ish pound claw fall repeatedly into place with just a hinge and not much support over anywhere from 24 to 50+ matches then eventually it would cause irreparable damage to our frame. Is this something we should be worried about or nah?
We had a “wrist” on our robot last year. The intake at the end of our arm moved down after the start of a match. Never had any issues. It weighed a little over 8lbs. We used pneumatics.
May help to visually see it: video
Last year we used a door hinge, and made a hook out of some steel wire that would let us attach the intake to the outside of the elevator. To get it down, the first step of the auto routine was to just put the elevator up a little bit.
Our intake “fell” into position each match last year and weighed about 10 pounds and we didn’t have any issues with it dropping/rotating into place. Our high tech solution was to hold the wrist in place with painter’s tape until the elevator started up.
You can cushion the fall with rubber attached to the frame. in the kop you should have received some rubber “buttons” for lack of a better term lol. there are two sizes and the larger ones have holes in the middle that you could probably put a bolt through because the original adhesive does not stick very well to aluminum
figure out how to cut the weight of the gripper thingy to less than 5 lbs, first
then think about if you ever want to play defense in a match, and whether it is wise in this game to have a device that you cannot retract back into the frame perimeter.
But yeah, also investigate the “four bar linkage” thing.
If falling into place can damage your intake then you have not built it tough enough. Yes some rubber stoppers will help. Those buttons are called “feet” and are normally used for the bottoms of computers and such. You can also put a 1/4 in bolt through some fuel line and let it hit that.
If you want to retract it then I suggest a versaplanetary light with a hex output and two versa hubs installed face to face makes an off the shelf winch. Use some kevlar paracord for firm action. Regular nylon paracord if you want some spring.
Our intake last year was held in place by hooking it’s elbows on some bolts on the frame. When we lifted the elevator a bit it fell and landed on a stop with one of those rubber buttons. To retract it we used the above described winch.
Here is the cord we used. https://paracordgalaxy.com/solid-colors/1074-kevlar-1050-lb-paracord-red-made-in-usa.html#/1-length-10_feet
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Use this as your starting point. It will make your ultimate solution simpler and easier to implement.
The team I am mentoring now had a similar arrangement on last year’s robot. They used a piece of surgical tubing tied to a higher point to give their intake mechanism a “soft landing”. They adjusted the length and number of pieces of surgical tubing so that it started stretching with the intake part way down. Since this is a program to encourage STEM education, you may get some benefit from reading about Hooke’s Law to understand how and why their solution worked.