First robotics competition is a high school program where teams around the world are given a brand new game the first weekend in January. Teams must design, build, and program a robot to play that game. Starting in March, they begin to compete. (These robots weigh up to 125 lbs)

As a mentor for a robotics team for the last 8 years, I've faced the same 2 challenges every year

• How to teach robotics
• How to keep students engaged when there's only one robot to work on

I feel like I've done something different every year to address these problems, but it's always been last minute. (this is probably a similar story for the mentors on most of the other 3600 teams) This year is going to be different though!

I'm going to write actual lesson plans, and have multiple robots for students to work on!

The multiple robots part is a challenge though, the drive base kit that's widely used costs $750 without any motors or other electronics. With motors and electronics the cost totals $2400

Item	cost	quantity	url
kitbot	$739	1	andymark
roborio	$485	1	andymark
Power distribution basics	$395	1	andymark
Radio bundle	$179	1	andymark
Cim motor	$46	4	andymark
Motor controller	$90	4	rev-robotics
Battery	$55	1
Total	$2397

The meat of this project is going to be around identifying, implementing, and testing replacements for each of the previous line items. The potential impact this project can have can be looked at in different levels depending how which line item a replacement is found for.

• Kit bot chassis
• (70%) Impacts teams that already have multiple sets of the control system electronics
• Lesson plan
• Could impact 100% of teams by giving the mentors a starting point for how to teach their students in the off season
• Roborio, power distribution, radio, cim motor, motor controller
• Each replacement should be compatible with the rest of the system, which would allow teams to put together their own training kits based on what they already have.
• In reality, many teams will hesitate to spend the money on electronic components that aren't competition legal. They would rather put that money towards back up parts due to thing frequently breaking.
• The impact of this project could be far greater if I'm able to show that these replacements are just as capable as the current standards and get the FRC design committee to allow their use at competition. 

For each line item, I'm going to outline requirements and list potential replacements

Kitbot chassis requirments

• 90-120 inch frame perimeter
• Can support ~80 lbs
• Can move at minimum of 5 ft/sec when at ~80 lbs
• Electronics mounting
• Battery holder
• Bumper mounts
• Can withstand side impacts from other robots
• Assembled in less than 3 hours by someone with no experience

The design of the chassis can be broken up into sections, I'm going to rate the options (1-3-5) with 5 being the best.

Frame

Option	Cost	robustness	complexity	Time for assembly	Reusability
Welded Steel tube	5	5	1	5	1
Steel tube gussets	5	3	3	3	3
Aluminum tube	3	3	3	3	3
T-slot aluminum extrusion	1	3	5	3	5
Wood	5	1	3	3	1

Gearbox

Option	Cost	robustness	complexity	Time for assembly	Reusability
Prebuilt gear box	1	5	5	5	5
Custom metal gearbox	1	5	1	3	1
Metal gear, 3d printed plate	3	3?	1	3	3
Entirely 3d printed	5	1?	1	3	1

Drive train

Option	Cost	complexity	maneuverability
4 wheel	5	5	1
6 wheel drop	4	4	3
Mecanum	3	5	4
Swerve	1	1	5

For the prototype I'm going to start with the following:

• T-slot frame - most expensive option, but the cost will still be significantly less that the custom machined plates used by the current standard. Also won't require me to drill any holes after they've been cut to length.
• Fully 3d printed gearbox - starting with the cheapest option, will progressively do upgrades until it stops breaking
• 6 wheel drop drivetrain - trying to match the standard kit
• Wheels - I'm need to do some exploring on how to make wheels cheaply

Roborio requirements

• Run off 12v
• Able to accept code
• Works with existing code libraries
• 10 pwm outputs
• 5 analog inputs
• 10 digital IO
• Can bus
• Not sure on the actual processing and memory requirements
• Able to interface with driver station
• Robot Signal light for safety

Options:

• Romi software running on RaspberryPi equivalent
•  compatible with existing WPI software
• Needs daughter board with microcontroller to handle IO
• ESP32 or other microcontroller
• A lot of software work needed to be compatible with existing system
• May not have enough processing power
• Pure radio control module
• Not compatible at all with existing system, doesn't provide programming training opportunity

Going to start looking at Romi software on raspberry pi. Pis are still hard to come by so need to look at the alternatives.

Power Distribution:

• Main power switch
• 12v input
• X10 outputs with up 40 amp auto reset breaker
• 10A 12V output for roboio
• 5V output

This part will likely be best done with a custom PCB, but I did find some possible components on amazon (which means I can probably find cheaper options else where)

Power switch:

• amazon

Fuses:

• amazon

Power distribution

• amazon

Radio Bundle:

I believe this can be gotten rid of completely since a Raspberry pi will have wifi built in.

Cim motor:

For DC motors at the 300W level, a cim is a pretty  low cost option, and most teams already have a bunch in their shops. For the design I want to keep it compatible with a cim, but an alternative would be to use power wheels motor and gearbox. Not even close to the same amount of power, but provides a very low cost alternative and can be used to teach the same concepts.

• amazon

Motor controllers:

BTS7960 is by far the cheapest option I've been able to find and use. The only problem is that it doesn't use the same control signal as the motor controllers used in FRC. I'm planning on using a rasperry pi pico to interpret the signal and control the BTS7960.

• amazon

Battery

I'm currently planning on using 3s lipo batteries as the alternative, but want to make sure everything would be fine using the 12v lead acid batteries that teams already have.