How did you scale?

[frcguy]

Originally Posted by KohKohPuffs

I recall talking to 254 about potential climber designs at SVR. They did talk about using two gas springs, which would be retracted and held like that using pancake cylinders. When the pistons were activated, the gas springs would extend, and a winch gearbox would be used to retract the gas springs to pull the robot up. However, looking at their technical binder, it seems they used surgical tubing instead, I guess since it's more cost-efficient than gas springs.

Here is the explanation of why 254 didn't use gas springs if anyone is interested.

Originally Posted by Ashwin Adulla (from 254 Technical Binder thread)

Initially, the idea of utilizing gas shocks as the means to scale the tower after time had ended seemed like a feasible idea in CAD. When it came to assembling them on the hanger however, we encountered the issue of both gas shocks releasing at different times as was evident in a test which consequently bent the hanger weldment. This problem could have either been attributed to a difference in the force exerted by each gas shock or a difference in force exerted by the pistons with a spring coiled around the rod that were used to compress the gas shocks. We knew that a winch gearbox was both a proven and feasible option, and thus we decided to implement it following SVR.

[Zac]

On the topic of a spring powered climb, I am convinced that there is potential for a constant torque spring solution. Vuclan calls this a contorque motor. It can be seen at the bottom of this page

I had toyed around with this idea for the 1768 climber. Given that the system was already driven by just a single motor, there was already a single shaft in existence that could be used for the contorque motor. The trouble was really that the system needed to both extend and retract, which meant that implementing this would have just meant extending would take longer.

Had we initially started designing with this in mind I think the idea would be to use pancake cylinders as brakes to hold the contorque motor locked until it was time to release it and climb. Another pancake cylinder could be used to hold the entire system down in the stowed position, upon releasing this cylinder the mechanism would rotate up and the elevator could extend.

In this implementation there was no synchronization to worry about as it was a single driven shaft.

~Zac

[C.Lesco]

We didnt, although if you dig around cheif delphi there was a cool magnet graple design in the photos a while back. Kinda wish i was on BREAD sometimes, you guys always seem to be doing something cool. Good luck with the climber!

[BrendanB]

Our climber was a little "Rube Goldberg" this year.

The main system was two 30" pieces of box tubing that with two gas shocks creating an over center linkage so the climber could be "locked" down. A 2" throw piston pushed up on one end of the stowed climber to get it started. The other side the base of the box tube assembly was attached to an 8020 slide. This got us up close to the bar and we used a torsion spring attached to another short piece of box tube to deploy our hook onto the bar which was released with a spring loaded piston.

A video of it deploying can be found here.

The cable ran from the hook down through a delrin block in the top of the first box tube stage. To put tension on the arm and keep it from being destroyed as the robot lifted up we used a cord running from the top of that first stage down to the middle of the robot. You can see the cable here.

The winch was a 27:1 banebots with a CIM motor with a 1/2" wrench on the output shaft to keep it from back driving. The hook us just held in with velcro so it comes loose when we start winching in.

During our first few events we had to add a lot to get this system to work just right. Pre-Reading we added some surgical tubing to assist the 8020 sliding across the back.

After a few successful climbs at Reading the hook started missing the bar as it rotated around. We adjust the curvature of the hook but the big change was adding a long piston that pushed the assembly towards the bar and put pressure on the support cord. This kept the assembly upright while we deployed our hook and prevented it from swaying.

Going into Rhode Island we added a small piston that kept the climber from deploying early. During our first match of the year the climber wasn't locked down all the way so it popped up as we crossed a defense in autonomous. We survived Reading by placing a tiny strip of painters tape between the two stages to keep them from moving and the piston would rip it during the extension.

Before Boston we had a few failed climbs because our wrench flipped directions during the match even with some tape holding it. We decided to get rid of convenience and put a wrench on without the switch. Our consistency peaked during Boston with only one or two failed climbs from a bad lineup on the side.

The rest of the year we saw some wear and tear on few parts but it still works well.

[nuclearnerd]

The attached picture doesn't show much detail unfortunately, but our climber was about as simple as you could make: We had a single stage elevator we called the "ladder" with about 30" of travel (built very similar to last year's robot). the ladder, which held the hooks, used constant force springs to extend, and a strap winch to retract. At the bottom of the ladder, we installed a "push to close latch" which held the ladder once it was fully retracted.

The great things about this design were:

• we didn't need to engineer any kind of custom clutch (we don't have much in the way of machining resources)
• the ladder could be reset if the first attempt didn't hook (something you can't do with a ratchet)
• the rigid elevator held the hooks steady when driving up the batter, something a lot of flimsier designs had trouble with.

The result was that we scaled something like 25 times in 26 attempts, something I'm very proud of.

As an aside, we really wanted to use two big 1.5" diameter, 30" travel air cylinders (and about 9 clippard tanks) instead of the winch and latch. The advantage would have been that it was mechanically simpler, and we could climb after the buzzer. Unfortunately the pneumatic version would have been about five pounds heavier than we had allowance for.