This is a two-parter post, the first part is our programming release, then the second is our CAD release, written by Ethan Scime.
My name is Grady, I’m the lead programmer for MARS, and this is our off-season code release! As a precursor to the 2022 season, and functioning as a concrete goal for the team after returning to in-person meetings after over a year and a half, MARS has created SwerveBot (name pending). This robot features an amalgamation of Marvin 14 parts from the 2021 at-home season combined with a new swerve drive train and magazine to create a functional robot for driver practice. It is a 28” x 28” drive base with 4 SDS MK3 swerve modules powered by 8 Falcon 500 motors. The central sensor directly reads the steering angle, allowing for immediate knowledge of the angle of the swerves, a vast improvement over our 2019 swerve design.
The code for the robot had to be done in a short period of time and with comparatively little programming experience compared to other years, so in an effort to get the swerve drive functional before this build season, much of our swerve code is an adaptation of 4265’s swerve code into our code architecture. This is so the code can be reused for future MARS robots. 4265’s code release can be used as reference for much of our swerve code: https://www.chiefdelphi.com/t/4265-code-release-2021/398314
Full autonomous play planning is implemented with this robot through the MARS text-based autonomous architecture. The architecture allows for concurrent commands from multiple subsystems that can be used to save the precious seconds we have in auto. 4265’s path planner is also used to create smooth complex paths that allow for custom headings, velocities, etc., which is used in a DrivePath command to utilize both feed forward and feedback error correction to follow the path as accurately as possible.
Other than the swerve drive, we also have a full intake, magazine, and turret with auto-targetting, which allowed our drivers to continue practicing Infinite Recharge with the new and improved swerve base. The code for these other subsystems is mostly the same as MARVIN XIII (2020) or MARVIN XIV (2021) code (due to the fact that some structures are directly from MARVIN XIV), which can be found here:
And here’s our SwerveBot repo: https://github.com/MARSProgramming/2021-MARS-Swerve
Feel free to ask any questions, and have a great season!
I wanted to make sure I included a little bit here about what’s actually contained in the CAD release for this year. The folder we’re putting out actually contains two robots: MARVIN XIV and its unnamed sibling. Both are robots developed between 2020 & 2022, and have several common elements including the intake and turret/shooter. Basically, this is the meat of what we’ve worked on since the cancellation of the 2020 season.
MARVIN XIV started development in Summer 2020 following the announcement that if events were to occur in 2021, we would be playing Infinite Recharge again. Since MARVIN XIII only made it to one event (and the version in the reveal video never actually got to see competition until 2021’s CHSy Champs) we took this as an opportunity to rebuild for 2021 with the knowledge of what some of the best 2020 robots looked like. I want to make it clear that this robot was not developed for IR@Home, and represents an evolution of our 2020 design instead. The design was completed ahead of the 2021 “Kickoff” entirely remotely and construction began that January when the team was finally able to have some in-person meetings. The robot was completed in time to be used for IR@Home, though never reached a state we would necessarily call “competition ready.”
Some neat changes with MARVIN XIV include the pivot from a “belly-pan” structure for our electronics to a more efficient “brain-pan” which opens up the top surface of the robot for more complex structural elements, the team’s first attempt at a telescoping climber system heavily inspired by 610’s work, a new intake more in line with common FRC designs, and modifications to the turret design to integrate a sliding hood.
Here’s some video of MARVIN XIV completing skills challenges for IR@Home.
In Summer 2021, we made the decision to restart development on a swerve system. 2614 has attempted swerve in the past to moderate success, but with the advent of the new REV control system, the SDS Mk.3 and Mk.4 modules, and internal changes in the team, we wanted to focus directly on integrating swerve into our current design language. In 2017, the team pivoted to manufacturing robot frames entirely out of sheet metal, to great success. The switch sped up our design and implementation process significantly and fits extremely well with the tools and sponsorships we have access to. The last time the team had a swerve season was 2019, but we moved away from our sheet metal design process to do it. Overall, we weren’t happy moving away from sheet metal, and went back to it the following year with a more standard six wheel drive system. Wanting to do swerve this coming season drove us to develop a bit of a hybrid system, where 1x1 tubes are packaged inside a more standard sheet metal frame. The frame generally remains light and structurally sound, and we tested it by disassembling MARVIN XIV and moving key subsystems like the turret upper structure and intake to the new swerve robot. Some issues cropped up with the integration of the 1x1 tubing, but nothing that reduced performance or caused clear damage; fixes for these are being implemented for the future, and we’re reasonably confident that a frame like this will last as long as any of our other robots.
Here’s some video from the last few weeks of the new robot running during driver trials (note that the shooter wasn’t tuned at all, so shots on goal kind of just go anywhere they want) and from yesterday (gosh, I’m still excited that it actually works) running its first autonomous routines.
And here are our CAD resources for MARVIN XIV and our swerve bot:
Hope everyone reading has a great kickoff, and MARS will see you at New York Tech Valley, Greater Pittsburgh, Smoky Mountains, and World Championships later this year.