How much did you struggle with getting the balls to settle into the serializer? We also did top load for 2020 and realized one of the biggest struggles was to quickly get balls from
Intake to there and settled.
You guys also show a picture pointed towards goal where you have what looks to be two balls still pinched by intake and some balls in serializer too. Anything special in programming sequence to stops jams and/or get fast feeding in that scenario?
Any video of how that bar off back of intake works for feeding/intaking?
I sort of remember you talking about solving controls problems in hardware instead of software in one of your Citrus Circuits Fall Workshops, but I’ve never been able to find the specific one again since watching it originally. Wish I could, it was really well done IIRC.
In your strategy decisions, you say that you decided a buddy climb mechanism would be beneficial, but you don’t have any mention of it elsewhere. Did y’all choose to not go through with a buddy climb, or was it something that you planned to implement later?
Great job on the documentation, btw! Super helpful and easy to follow!
Seconding getting more details and/or any available CAD screenshots of the buddy climb. A quick motor count leaves a single remaining PDP slot that could have been allocated to the mechanism, and a on the drivetrain page of the technical binder we can see two pancake cylinders, presumably for deploying it:
Since their 2020 FRC Season page has their weight listed at the 125 lbs limit, I assume they just didn’t have the weight for it.
On a different note, and since I wasn’t able to type all of this out earlier since I was in class, thanks for doing this Q&A. Your technical binder threads are probably my favorite threads aside from the 254 Robot thread, less so because of the binder itself (although it is certainly a great resource) but more as a result of the information that can be garnered from your responses about the reasoning behind design choices and the specific detail from your CAD screenshots. Just a lot of great stuff in general, and a pleasure to read through after the fact.
We ran about 21 FPS free speed a few years ago, had a ton of fun with it, But also found it a bit uncontrollable. Can you go into more detail about gearing that high, and how you address controllability issues?
Allows the operator to select between the outer port and the inner port
This is such an underrated, under-discussed bullet point, and I’m really looking forward to the public code release! Just attempting to figure out if the robot could hit the inner goal exposed my programming team to a number of things like strategic CAD sketches, multilateration and imaginary point projections.
Great work as always! I love the details that y’all put into these tech binders. I’m curious about how the shooter hood articulates, the back of the shooter seems to be obstructed in the pictures.
It looks like it’s just a printed Markforged Onyx sector gear, integrated directly into the back of the hood. 2910 used a similar hood design in 2021, think it might have been based off of 254’s, but I can’t remember my source on that.
Looks like those pancake cylinders are in the bumper zone, and the drivetrain has a matching set of holes on the front rail. Some kind of quick-change bumper mounting scheme?
Considering the contents of this post, I personally doubt it.
^ Circa October, 2020
Also, you can see the 3/8”-16 thumb screws in one shot of their 2020 Season Recap (pictured and linked to above), in roughly the same position as the outermost set of holes in the back rail of their drivetrain pictured in my original screenshot of the binder. (IMO the cost-benefit analysis for that doesn’t really work out either [costs: weight, complexity, use of a manifold slot, loss of robustness; benefits: slightly faster, easier bumper attachment?])
CHOCK
The Chock was a late addition that helps the Serializer. While intaking, the Serializer is contantly running counter-clockwise (when viewer from above). As the first few balls come in, they will get swept around and back to be under the shooter, making space in the front half of the serializer for the next 2-3 balls to fall in. When we are ready to shoot, the chock gets lifted and the serializer spins up while the shooter spins up.
The Chock itself is just a fixed plate and a moving plate. A cylinder pulls the moving plate down. Pivot is a shoulder bolt and a bushing.
"Skatepark Ramp"
Normally while the Serializer is spinning, the balls barely contact the 2 Feeder rollers. When we want to shoot, we needed some way to slightly elevate the balls above the normal serializer floor they were rolling on, so they would contact the Feeder and get taken up into the Shooter.
The Skatepart Ramp is our nickname for this little pancake cylinder that just pushes up a flap of 1/16" polycarb to create a little ramp that guides the balls up to the Feeder. Nothing more than a cylinder whose rod pushes directly on a piece of polycarb is thin and fixed on one end.
Our primary trick to getting balls to settle fast is having the Serializer always be running, with the balls getting swept under the Shooter and held there by the Chock, as I explained in above post. So when the new balls come in, there is a guaranteed open space for them and they aren’t acting like popcorn bouncing over balls in the Serializer getting swept around.
Additionally, if we are seeing jams or balls not falling down, we have a driver command to quickly alternate the Serializer rotation direction to try to unjam / unstick and balls.
The bar on the top/rear of the intake is a rod with spacers over that act as little rollers. It is there so that balls getting intaken from the Human Player Feeder station can roll across it and into the Serializer, even with the intake retracted.
The intake deploys via a non-parallel 4-bar linkage composed of 1/4" polycarbonate plates, actuated by a pair of 3/4" bore pneumatic cylinders. The non-parallel linkage lets us position the 3 intake rollers in either an deployed, angled, position for getting balls from the ground or a nearly vertical position for fitting in starting configuration frame perimeter whilst maximizing the amount of space above the Serializer for balls to roll in from the Human Player station.
The intake pivot points are comprised of 3/8" shafts or shoulder bolts with bushings.
When fully retracted or deployed, the plates of the linkage hardstop into each other. This slightly improves robustness. When an impact occurs, all forces will just be going into the plates and into their pivots, with none of the impact energy going into the more fragile pneumatic cylinder.
