A rough CAD model of the Zoukeepers planned robot, the current plan is to go for the middle row of the grid, and potentially be able to give the extra push with a launch to get a cube onto the top row of the community.
Intake Prototype in the early stages, more on this in the day 1 update video. (when it comes out)
DAY 2
Today we built a majority of the actual robot components, originally we planned to run a sprocket system to drive the pivot arm, but due to a few items not being on hand for use and a bit of skepticism over chain stretch we scrapped that idea and moved on to plan B which was a direct drive system for the arm.
Our direct drive system is going to use 1 CIM as we don’t have easy access to a Falcon or Neo motor and will be geared 200:1 over the whole system. We do not predict to have the mechanism’s center of gravity to be extended over 40 inches from the point of rotation and estimate the end load to be about 20-30 lbs. Using the JVN calculator we confirmed this should work, but that does not mean we advise using it without some improvements to the system like better gear ratio or a way to hard lock with a product like the friction brake and ratchet mechanism from WestCoast Products.
We also tested the robot’s ability to reach the middle level before mounting the arm fully. We found that 1 stage from a spare set of Thriftybot Telescoping kits is a good way to get an extending arm, however, there is definitely a better and more reliable way to make a telescoping arm for this game.
The Robot is finished and Coded and works, well worked, at some point between testing we managed to turn a 775 pro into a paperweight pro, we think the motor was just bad and we plan to replace it and get out proper testing videos sometime relatively soon. For now, here is a link to a brief video of the arm functioning with the elevator.
Robot all wired, the concept works better than expected with the CIM only needing to be powered between 25-50% to move the arm, however, there is a lot of play in the shaft due to versa hubs and the gears having a bit of play on the shaft. It would be advised to have some form of friction brake or better gearing to hold the shaft if your team decides to use the idea, West Coast Products sells some form of shaft brake which could significantly improve the arm’s usability.
Currently the intake fits in the frame just barely if the arm starts at an angled upright around 70-80 degrees. We also designed the arm with a hinge to put in the intake if needed, however we don’t have it powered so the hinge has to passively let the intake, the good news is the hinge in is not necessary to make it legal.
I would caution against using Thrifty Bot telescopes for an arm like this without redesigning the telescoping block that goes inside. The Thrifty Bot blocks produce a lot of friction inside the tubes because they do not have roller bearings on the internal telescoping block, this produces a lot of friction inside leads to issues while trying to fully telescope out. I instead recommend using the West Coast Products style of telescoping block as they have rollers on the inside which will limit friction and be better overall for a horizontal telescoping design.
I was wondering if you could provide us with the Cad link. I was hoping to have a look at some of the measurements for the intake. I really like the idea of the wheels at the end to grip better.
The friction on the blocks is mostly due to side loading. If you keep a lot of overlap and keep your arm light it will help a lot. I am hoping someone will make up a 3d printable replacement for that block that has bearings on one side of it. If my team runs into problems, I will have to do that later in the season.
If the issue was side loading why not have the “loaded side” of the telescope facing the bearings (ie rotating the telescope arm 90 degrees). Why wouldn’t this work? Thanks!
One thing I’ve noticed: it looks like the telescoping gearbox peeks out of the frame perimeter when the arm rotates. That’s a fixable problem (I’d probably throw the REV 90-degree output on it), but worthy of caution for anyone looking to replicate.
Someone that has that robot now is going to have a lot of time to iterate on the gripper, fine-tune the telescoping action, and get more drive practice.
So the issue is that the weight of the intake forces the telescope to flex a bit and forces the corner of the block up no matter how it is orientated as long as it is being extended out in a more horizontal than vertical manner. We noticed the issue started happening 4-5 in from the end of the tube which limited the telescope in theory 4-5 in shorter than feasible with one stage, we think this is the difference between being able to top cube and mid cube as we narrowly missed our top cube in our reveal.
Yeah, it is a bit of an issue, it was originally designed with one motor and the extra motor was added to keep the telescope able to stall without the motor having to fight the springs. If that is what was caught as the issue at a comp I’d be more surprised as the chassis is actually illegal on frame perimeter, we ended up using last year’s chassis for this year’s Ri3D due to resource issues this year, and whoever designed that chassis last year thought 124in was legal frame perim. The design should still work though it just needs to be reconfigured to fit on a 26x34 vs a 28x34.
