This season Team 122 built a 6-CIM Kiwi Drive. Why was this a bad idea?
Here's an opportunity to freely provide your feedback-- either
negative or positive.
As it turns out, "you should have just built the AM14U chassis" actually meets the criteria for an acceptable criticism here in this thread! But just barely. This assertion can be improved if you provide reasons: Would it have saved time, money, and energy? Would it have been more reliable? Would it have spared 2 CIMs which could have been more useful if they were powering a manipulator instead? Would it have resulted in a robot design that better met the specific game challenges? Would it have given us more learning opportunities and added more useful lessons-learned to our knowledge base, leading to a more-capable team in future seasons?
Both technical and nontechnical criticisms are acceptable here. Did this choice of drive system lead to less engineering inspiration that another option could have provided? If we (intentionally or unintentionally) chose to ignore the most-competitive robot design that we could have accomplished with our team's resources and built some less-competitive thing instead, did we fail to meet some key goal of FIRST? By not being as competitive as we could have been, we were acting as a bad citizen of the FRC community?
In the offseason, we started down the path to this design by building a small demonstration robot using all COTS parts. Intended as a programming test platform, this bot used 4 CIMS and 4 omnis arranged in a square:
In week 1 of the build season, we prototyped the proposed drive system using 3 CIMS and 3 omnis arranged in an equilateral triangle:
Here's the rolling chassis in week 3 of the build season:
And here's the final robot at our first event:
The system was designed for ~10 ft/s in the "cardinal" directions (the three directions parallel to the drive axles) and ~6 ft/s in the "ordinal" directions. It used AndyMark
6" dualie omnis and the absolutely bulletproof, excellent, single-speed
10.71:1 Toughboxes. To the driver, the system felt very smooth to drive and had more than enough acceleration to do complex maneuvers around opponents. It required an intermediate amount of maintenance; over 20 matches played across 2 competitions, the wheel-retaining screws that thread into the blind holes on the gearbox output shafts needed to be tightened or replaced 4 or 5 times-- even with mentor-supervised applications of Loctite.
Happy to provide more data upon request.