Advanced Training Module for Mech Students & Mentors

[alecmuller]

I did a modular Octocanum design in the off-season and documented it as a tutorial. I know teams are starting pre-season training soon, so I wanted to share it with the community:

https://docs.google.com/spreadsheets...it?usp=sharing

It currently covers:

• Researching robot drivetrains and deciding which one to buy or design for a particular team and game.
• Setting design requirements and targets.
• Making a series of concept sketches and checking them against the requirements.
• Preliminary calculations to predict what gear ratios and wheel sizes will help you hit your design requirements.
• Preliminary cost estimate.
• Finding CAD models for all the off-the-shelf parts and importing them into SolidWorks.
• Links to the most up-to-date CAD models shared on GrabCAD.

In the last month I've focused more on testing and iterating the design. I have robot test videos on Youtube:

• Forward / Sideways drive test in Mecanum mode. https://www.youtube.com/watch?v=0n9aZLCCd8E
• Shifting from Mecanum to Traction with pneumatics. https://www.youtube.com/watch?v=5FDd_2kI52s
• 1/8 speed slow motion driveby in Traction mode. https://www.youtube.com/watch?v=nBcZnm7hvIQ
• Traction Force test. https://www.youtube.com/watch?v=2PZiDumPYUs

I still need to document the remainder of the CAD development steps, as well as a bunch of things I learned while building and testing this.

Still, I think it will be useful for students who already have a basic understanding of robot mechanical design to help them continue learning.

I'd like to continue to refine this tutorial to make it easier for students to use, so please email me at alecmuller@gmail.com with feedback.

Sincerely,
Alec Muller
Mechanical Engineering Mentor
Team 2342

p.s. Thank you to the folks who provided feedback in my earlier CD thread on this topic.

[Gregor]

I'd be concerned about the thickness of the angle on the cylinder, the thickness of the module plates, and the diameter and unsupported length of the axle on the mecanum wheel.

[asid61]

The way your cylinder is mounted is not good- it's pushing against a bend. Your plates could be thicker too, although your axle seems fine to me.
I remember seeing this tutorial a while back, and as we are starting training in a couple weeks I will be using it for sure. Octocanums cover a lot of good topics.

[adammiller3122]

Thanks for posting this! I will have to read through it and give it to my team for the new students!

[alecmuller]

The original photo doesn't show it well, but the pneumatic cylinder bracket has more support than just the side (the real bracket design has 3 flanges: 1 screwed to the front, one to the side, and 1 floating).

I definitely need to do some robustness testing to see what minimum wall thicknesses will work (it's all currently 0.125"), particularly against side impacts from other robots.