Chief Delphi - Wheelless Robot?

OK, returning to this thread with an update following the Midwest Regional, where we were the only wheelless robot, as well as the tallest robot @ 72"
(PICs to follow). Making it to only one practice match on Thr., we had effectively no real practice by the time of our first qualifying match on Fri., so we did not perform very well until the final few matches.
Even so, we ended up being captains of the 8th seed alliance for eliminations.

Though our original design goal was to be an wheelless outside corner climber for a 30 point climb, the team could not handle the compound angle design requirements (no CAD) that the frame and mechanism mounting demanded.

After Losing a week to finals, a week to building a badly executed half-pyramid out of conduit, and a week to no real progress with the corner climber concept --- we finally bailed on the plan and switched to an inside face climber, going only for 20 points.

We already had built a lightweight, tiny 2 wheel linear rail shooter capable of hitting 3-point shots in autonomous, and working consistently enough that we expected to get our 18 points on auto shooting. So, with 20 more from the climb, we felt that with a reliable 38 points we could still make it into the elimination round,

Our climb concept was to have our bot sit in middle of far side of pyramid (from goals) with hooks on lower rail. We made dual vertical linear sliders with vertical 80/20 framing and window motors turning 5/8" OD shafts to wind high tech cord for lifting, Cords pulled down on crossbars, each with a pair of hooks pointing outward mounted to them, and the crossbars slid down between the two pairs of columns.

The the slider travel of the shorter column pair could get us up as high as 13 inches, and the longer column pair, ~11" closer to center of pyramid, could lift until the cross bar nearly hit the winder shaft mounted close to the base plate of our wheeless bot -- about 42" of travel

The short column pair was set near center of the the bot so as we came off the ground onto the lower hook pair we stayed balanced. Our shooter was mounted to the top ends of the shorter column pair on overlapping extension legs that extended the shooter up higher. The hook slider bar for the tall column pair was positioned so both its hooks would start out above and nearly engaged to the 2nd level rail, but not until the lower hooks got us an inch off the ground.

Once off the ground, the upper hooks were engaged with the second level rail and we planned to elevate with both hook crossbars pulling together, to keep us from tipping over much for the first foot or so.

Once the cross bar pulling down the lower hooks reached its lower travel limit, where it would start to capture the lower rail against the frame if it did not stop, the upper hooks took over. At this point our excess weight (battery, electronics, etc.) sticking out of the pyramid was meant to cause the robot to swing away from the lower rail as the upper hooks continued to lift and the lower hooks disengaged, allowing the upper hooks to drag the bot past the lower rail.

Getting the bumper frame, base plate, winders, columns, sliders, and shooter module built and in the bag by deadline was all we were able to do with the late start. We would have to complete the build in the pits, but we still planned to make a practice bot to verify functionality before competition.

We barely finished our practice bot in time to do the most rudimentary test and confirm that it looked like the balancing could work well enough for 20 points, but it was not a perfect mockup at all.

In the pits on Thr. we were able to complete our bag bot assembly rather efficiently, but our electronics were giving us fits, and we could only get one shooter shooter motor to run at a time, not both. We finally confirmed that a missing firmware update was needed, and it would have to be installed in Fri.
We really did not get to do any climb testing until our first practice match in late PM on Thr., and we found out that our upper hooks were swinging too far away from the 2nd level rail before we could clear the ground enough to engage.

So by the time of the 1st Fri. match we had only just got our shooter running with both motors, and had not practiced aiming at all. We also had modified our column angles to ensure upper hooks remained able to engage the 2nd level rail

There were several seconds of wild pendulum swing as the lower hooks disengaged and the unbalanced weight tipped the base of the robot down and toward the center of the pyramid. This always gave the crowd a thrill.

As we continued to pull the upper hooks toward the robot base, the robot kept tipping over more from the weight of the shooter above the 2nd rail going progressively further away from the 2nd rail as the heavier base got closer to the 2nd rail. With a couple increments of adding upper ballast (done in the pits), we finally tuned the the weight distribution so that we balanced with our initial vertical now oriented horizontal, and only 29" of our robot length hanging down below the 2nd level rail,

It took missing the twenty points by 2" then 1" then 1/2" over several matches before we finally got things tuned up enough to score our first 20 point climb. Meanwhile we were getting 10 point climbs every match and finally getting two 3-point autonomous scores in one match. Plus our human shooter was coming through with some amazing shots to even win one close match.

We steadily moved up in the standings until on Sat. at the end of qualifying we were in the low teens. As the alliance picking process started pairing up the top 8 seeds, we ended up heading the 8th seed alliance.

While our alliance with Team 1091, and Team 2704 was not quite enough to match the first seed's alliance in the quarter final, we thank our partners for working hard with us for a respectable performance in our two matches.

In hindsight, I still don't quite see how a wheelless bot that averaged only around 15 points per qualifying round could end up heading the 8th alliance, but this is how things turned out. Needless to say many of the team members who were grumpy about the no wheels design ( no wheels means no fun), quickly forgot all that when they saw how few bots could climb past 10 points, and how low the match scoring was in the qualifying rounds.

So, to address the concerns of the OP in this thread, the lesson our team learned is that, at least in this year's competition, a wheelless robot, that remains protected contacting the pyramid has a lot of things going for it. It takes on little damage. It is less complicated to maintain and troubleshoot. It is easier to produce consistent scores in every single match, which in the end is what allowed us to do so well. We weren't expecting to make it all the way to the final match, but we surprised ourselves at how well we ended up doing.

So in this fourth year of our FRC program, we managed for the first time make it to a practice match, to make it to every qualifying match, to score in autonomous, and to make it to the elimination round without having to be picked. Pretty amazing results for a wheelless robot.

Once again, thanks to our alliance partners, Team 1091 and Team 2704, for a strong effort at trying to upset the top dog alliance. Wish we could have offered more firepower and defense, but we still had a great time competing.

-Dick Ledford