Hey everyone Team 5104 is due for a build update so we’ll give you a brief rundown of each day of the past week and @kieler_troy will be available to answer any questions on Chief or on the Open Alliance discord. Here we go:
Day 1: Kickoff (8 AM - 6 PM)
After the game was released we spent most of the morning creating rule presentations, testing each other, and taking a mandatory rule quiz. A score of 80% or higher was required to participate in design discussions. After lunch, the afternoon was spent listing all possible abilities/attributes of our robot in this game and ranking them according to value and difficulty (programming or mechanically).
We finished off the day with a brief simulation of the game using taped power cells as cargo and humans as robots.
The major takeaway from this activity is that, despite lag time between getting cargo back after they’ve been scored (3-7s according to manual), we’ll be unlikely to have ball scarcity (power cells would often pool on sides of the field in 2020). Especially with 11 balls per alliance and a maximum of 6 that can be held by all 3 robots at a given time it seems that there will always be cargo available.
Day 2: Design (9 AM - 6 PM)
In a concerted effort to bust out design discussions we follow kickoff with another longer meeting. The primary focus was to identify which abilities/attributes we identified the day prior were must-haves for our robot.
*A note on this section: We have inferred that the field of this game will be crowded with cycles that can range dramatically in length due to the bounciness of cargo and how they get distributed after scoring. As such, the mentions of pushability (or in other words ability to resist getting pushed) are a measure against a game where we are expecting a lot of robot to robot contact. Equally, climb has been selected here, because value estimates are hard to make, it is a reliable source of points earned fairly quickly compared to cycles which we estimate will be between 15-30s each.
- Fine Control
- Intake/store two cargo
- Climb the mid-bar
Further Investigation needed:
- High or low shooting
- Traversal bar climb?
- What kind of drive?
After we narrowed down components we broke off into groups to draw quick sketches of each main subsystem. This activity helps us hear from people who aren’t as active in the full group discussions and have a variety of ideas to choose from.
- Over the bumper
- Cut Chassis
- Compliant wheels
- Piston deployed intake
- 4 Hooks
- Telescoping tubes
- Dual wheel
- Adjustable hood
- Fixed shooter
- Low angle?
Having so many members with so little experience made a drive a full team discussion
- 6 inch vs 4 inch wheels
- Omnis or all colsons
- Gear shifting?
Put together a drive chassis and started wiring:
Day 3: Prototyping begins (3 PM - 6 PM)
After we finalized preliminary design components and identified the decisions that had to be made later we broke off into groups.
Nearly all of our sketched designs up to that point had featured a full length over the bumper intake so we began to make an adjustable wood over the bumper roller to see what passed the eye test.
Started with a wooden 1:2 scale system of wood sliders similar to this: 2022 FRC traversal climb prototype 01
Used a rolling wood scrap box created a single wheel shooter with a ramp
Day 4: First prototypes (3 PM - 7 PM)
Several wheel and roller types are tested by rolling or bouncing cargo into the bumper run by a drill. We then added 2 more rollers at a diagonal from the chassis to help capture and push down bouncing cargo, belted them together, and added a 775 motor.
Shooter prototype run by a hand drill comes to fruition. *Red tape on the wall is the height of the upper hub
Ideas floated about going from the mid bar directly to the traversal prompted the construction of a similar wooden 1:2 model of the geometry.
Day 5: No back to back (3 PM - 7 PM)
First day off on wednesday and we definitely needed it. We continued to work on prototypes and started on to develop our drivetrain. Now, team 5104 tries to follow a 3 robot build model with the purpose of improving on each one. Alpha bot is a simple drivetrain weighed down for testing autos, gearboxes, and code. Next, Beta bot is our MVP (minimum viable product) and is the unpainted, unrefined, least functional robot we’d be willing to take to competition. Finally, Charlie bot is ideally our completely tested final competition robot where we’ve improved the components we’ve tested. Our general schedule for this season looks like this:
With our model in mind, alpha bot is normally built in season, however, because we did not change the size of the chassis in CAD (28x32) for our 2022 robot we decided to use the pre-built drive base we had in house instead. We installed WCP 3 stage flipped gearboxes (WCP Flipped Gearbox (Single Speed, 3 Stages) – WestCoast Products) so that we could test 4 vs 6 falcons and several combinations of gear ratios. We started with a far cry from frc standards at 28:1 and 3ft/s and later switched to 6.3:1 and 15ft/s. We hooked each up to a scale for pushing power and to an amp meter to see the draw on turning in place.
We attached our intake prototype to a dolly cart and got more testing of intaking balls on carpet and while bouncing. The diagonal set of 2 compliant wheels (gray) picks up bouncing balls really well. Ideal spacing seemed to be 8 inches from bumper to wheel and from ground to wheel.
Developed our idea of climbing with 4 hooks
After some more careful analysis of arc height (Shooting Profile (FRC 2022)) we started a 2nd shooter prototype. We added two flywheels and made it bottom fed. The second wheel gives us more control over the ball arc and the option of a lower arching shot to also get into the lower hub.
Day 6: Friday baby (3 PM - 9 PM)
Continued testing of amp readings and pulling power. We also changed between 4 colsons, two omnis and 6 colsons to see how it affected turning. Omnis reduce power draw substantially on turning and all colsons increased pulling power.
Added 775 motors to both flywheels and controlled them with an RC remote.
Day 7: 45 hours down (9 AM - 6 PM)
Finally got a set up for the upper hub. Up against the fender seems to require an angle about 5˚ and from the launchpad seems to require around 25˚. The cargo have begun to deflate after about 4 days worth of testing. Feeding the balls into the shooter by hand seems inconsistent so we are working to make a rolling system that leads to the shooting mechanism.
Finally we prototyped a sorting mechanism with sets of vertical rollers feeding from our full length intake into a single file. While we would need more rollers to guarantee that the ball makes it from the intake to the sorter, the sorter worked remarkably well in getting two balls single file. One technique that involved spinning one set of rollers slightly slower and that seemed to force the cargo through quickly.
Ordered more gears for drive aiming for around 11.7 ft/s. We continued to test amps and saw the per falcon power draw was higher than we expected even on 6.3:1 drive with 6 falcons.
We explored different climb mechanisms including telescoping, winch, and elevator. We are building a single stage elevator to test out mid-bar pull up on a weighted chassis.
Our CAD lead will post an update sometime soon. I’m sure I’ve left some things out, so please ask any questions or provide any feedback you have for us! Love the stuff I’ve already seen out of the Open Alliance teams this season.