Are We Building A Submarine?
Well, unfortunately water game doesn’t have much in the way of water. As an aside, it’s technically also promoting harmful practices: algae and coral reefs actually typically have a beneficial symbiotic relationship and removing algae technically contributes to coral bleaching. Wonder if that’s why the coral gamepiece is white…
Prototypes
This year, we’re using a mix of Protopipe, Hypeblocks, and laser-cut wood pieces for rapid prototyping. This week, we mainly tested two concepts: a roller claw for picking up coral, and an OTB intake.
Roller claw was more of a proof of concept, and showed that we can design a claw to pick up both coral and algae if needed. Algae intake was also pretty simple, and after prototyping we’re fairly sure we can just add a slap-down roller that could work as an OTB algae intake and outtake. However, OTB intake for coral was less than consistent, and it raised some concerns about its viability, especially when aligning the coral for the handoff into the gripper will need to be done so many times.
We are also busy testing ramps/funnels for coral station intake and passive alignment methods for reef scoring.
A Menagerie of KrayonCAD Animals
With a combination of designs from kickoff weekend, RI3D inspiration, and random shower thoughts that people shared throughout the week, we put together a library of design archetype ideas that we sketched and then KrayonCADded. When the list was compiled, we pitched each idea to the team on Saturday. As is a budding tradition, each design idea got an animal name — this year they’re all aquatic themed.
I won’t bother talking through all of them, but here’s an overview of a few notable ones:
Anemone
Telescoping arm on a pivot with a wrist for dropping off coral; gripper can be used as an intake or for scoring. Decent arm geometry would allow for ground intaking (the gripper would cup the circular base of the coral).
Main cons: TOO MANY DOFS. Also, it’s generally harder to adjust the position of the end effector with precision when the arm is so long.
Loch Ness Monster
The idea of this is a side intake (originally planned as OTB, but switched to station intake after prototyping wasn’t very OTB-favorable) could feed horizontally aligned coral into the center of the robot, but with an intake offset 90 degrees from the elevator, it would eliminate the need for coral realignment since the gripper could just grab the coral at the right angle straight away. It also theoretically leaves more space in the center of the bot if we want to try incorporating a climb.
Main cons: May slow down autos since it would require turning the robot 90 degrees in between the coral station and the reef. There are also lingering questions about if it it would be easier for coral to get stuck in the robot with this design. It’s also harder to design a gripper that can do both algae and coral if the gripper is doing this style of handoff.
Manatee/Whale
(Pictured is Manatee, please excuse the questionable KrayonCAD)
These are essentially the same thing, the only difference being whether or not there is a wrist joint. The primary consideration of this design takes inspiration from the Penn State RI3D, which has an asymmetric end effector with the coral outtake offset to one side so that the robot is capable of removing algae and scoring coral all in one go. We like the idea of being able to parallelize tasks like this, but this led us to wondering if we could make the offset side adjustable. Manatee theoretically would use some sort of linear drive, whether worm drive or rack and pinion, to shift a coral outtake left or right. This could also provide finer control when scoring coral, since just the coral outtake could be lined up as opposed to having to adjust the entire robot.
Main cons: A moveable coral outtake adds a ton of complexity and likely weight to the end effector, as well as another degree of freedom. We’re not sure if the advantage of being able to remove algae and score coral at the same time is worth all this added trouble.
Beluga/Sea Snapper/Orca
Pictured: Orca
These are all derivatives of the same archetype, which is somewhere between the Rusthounds and Cranberry Alarm Ri3D. All of them have a station intake that passes into an elevator, with an end effector on the end capable of scoring/removing either coral or algae. Beluga is the simplest, with a fixed-angle end effector. Sea Snapper adds in a passive align feature, hopefully to speed up scoring in-game. Orca has the end effector on a wrist. An OTB algae intake/scorer similar to that of the Rusthounds is only listed for Orca, but we’re fairly sure we can fit that onto the robot.
On Saturday team meeting, we managed to narrow down the archetype list to Sea Snapper, Loch Ness Monster, and Whale. These designs actually aren’t that different, and once we’re done deciding some of the finer details we’ll essentially have made our final choice.
Decisions
Features we have solidly decided on including are:
- An elevator
- A station intake (probably going to be a ramp/funnel-style thing)
- Some form of aligning to the scoring target (passive: Sea Snapper, active: Whale, or moving the drivebase side-to-side)
- Algae intake on the elevator end effector
We have yet to decide:
- Wrist or fixed angle outtake
- Active or passive align mechanism
- Location of ramp and intake in robot
- Whether to combine algae gripper with coral gripper
To help along the rest of the decisions, this week we plan to work on prototyping:
- Passive align mechanisms
- Active align motion (worm drive and alternatives)
- Algae intake/gripper with offset coral gripper (Whale)
- Algae intake/gripper that is combined with a coral gripper
- Coral intake ramps and handoffs
- Fixed angle outtakes
Thankfully, with some major decisions made, we can now start the actual robot CAD as far as the mechanisms we know we’re going to have.
Lobster photo of the week is this crocheted one I made a while back, where I somehow managed to take a day to make the pieces and a week to sew them all together…though honestly, that’s probably average for weirdly shaped amigurumi.
-Kendree
