Relic Recovery Strategy Part 1

By Austin

Task: Determine building strategy for Relic Recovery

Any well-versed team understands that, depending on the competition for the year, a robot will either be modified to compete or be built from the ground up. In any case, however, a robot often starts at its chassis, and teams have multiple companies that provide solutions to the common robot chassis’ needs and specifications. To name a few: AndyMark® has its standard kits that include all the parts and electronics needed to build a very basic frame that includes a few mounting points for the rest of the robot’s components, Tetrix has its standard kit that provides all the parts for an entire robot if used properly (however, we’ve discovered drawbacks to be mentioned later), and even REV has thrown its hat in the ring with new motor and battery types to add to the highly adjustable REV rail chassis kits. For rookie teams there is no lack of options for starting your robot chassis. However, as a team gains experience they find the flaws that come with each kit and move towards creating robots that harness equal amounts of parts from all companies. Here’s what we’ve learned about each company:

AndyMark: overall, AndyMark is a great supplier for all the standard parts you’ll need, however we wouldn’t recommend buying their overall chassis kits because they can be on the pricier side and come with few replacement parts and too many unnecessary parts. Most of our gears, wheels, pulleys, motors, and batteries come from AndyMark in batches of parts that we keep on hand to prototype with or replace failing parts. This keeps us from paying for parts we don’t need and having what we do need on hand. The overall quality of their parts is high, but they do decay quicker with use, especially when running the robot at multiple competitions without proper repair time.

Tetrix: Tetrix is highly standardized in all dimensions, making the connections between parts easy to grasp for basic builders who haven’t developed a mental 3D idea of what they’re working towards. Tetrix kits don’t include electronics. However, their brackets, channels, and joints are very useful for making connections between various components of your robot, so keep plenty on hand for quick fixes and prototyping. Our biggest concern with tetrix are their designated nuts; we find that they often are shaken completely off respective bolts, which can lead to mechanical failure and penalties. To combat the issue of robots quite literally shaking themselves apart, we recommend using nyloc nuts. They have a small amount of nylon in them that grips the threads of bolts making them almost immovable without a pair of pliers.

Rev: Iron reign loves our Rev rails. The ability to have a mounting point at any incident on a bar is amazing, and often allows us to pull off the crazy designs we create. Rev has created a system that is beyond flexible, meaning that the limits of your designs have expanded. For those who want a chassis that is easily maneuverable, Rev rail is extremely light as well. While Rev is expanding into providing parts like AndyMark, we find that they are still in development but we eagerly await upgrades.

Overall, Iron Reign wanted a robot chassis that was stable, maneuverable, and modular to our needs, so this is our compromise that we’ve applied to all aspects of our robot;

- AndyMark FRC Standard Omni-Wheels: we chose these because of their dependability and maneuverability. They provide standard motion as well as strafing for fine-tuning movements in front of cryptoboxes. While we had to print custom mounts, and modify tetrix channels for the necessary axels, the wheels pared nicely with the rest of our components once mounted.
- Rev Rail: our entire upper chassis is made from interconnected Rev Rails that serve as a smooth, easily adjustable, and light support for the massive omni wheels that rest below it. The rails provide plenty of room for future expansion, and can take quite a beating (we learned this the hard way by dropping our robot off a table).
- Tetrix Channels and Brackets: these are the middle men, the parts we change to fit those awkward angles and fittings, such as the axels for our wheels. Overall never a bad idea to have extras on hand.
- Hardware: we always use standard hardware sizes, but we make sure that the corresponding components are snug fitting and streamlined to minimize unnecessary snags and sharp edges.

While these are the typical components that make an Iron Reign base, we have seen other teams get extremely creative with raw material, although this usually requires heavy machinery such as laser cutters and lathes. Overall, we are a team that uses what companies provide and modify it to fit our needs (which has worked well for the past years of competition.) For smaller start up teams we recommend a similar approach of learning each system and its advantages over the course of multiple years, and finding what you feel works best for your needs.