Team 1640 Summer 2009 Drive Base Project

Technical Technical Discussion
1

For the FRC Team 1640 - 2009 Summer Program they build a swerve drive base using VEX parts and the cRio controller. The software has four modes:

  1. Tank drive - standard tank / skid drive
  2. Automobile drive - 4 driven wheels, the front two pivot the back two remain stationary
  3. Crab drive - all four wheels pivot in the same direction
  4. Snake drive - all four wheels pivot, front two turn in the opposite way from the back

As expected, the tank drive and the automobile drive are less effective than the crab and snake modes.

If you look at the pictures you can see the reinforcements to allow an axle to be used as the shaft and to reduce the wheel assembly wobble.

The cRio controller was used to give the FRC programming team practice and to serve as the base code for this winter’s robot. All of the project details are on the page, if anyone wants the cRio code let me know and I’ll get it to you.

Fall projects are to:

  • Replace the rubber wheels with omni wheels to see if we can improve tank and automobile modes
    **]Omni wheels will also allow a holonomic mode that we can try out.
  • Program the base with the VEX controller and RobotC
  • Program the base with the new VEX controller as a proof of concept

We will also be using the base for our robot demo’s this fall.

2

Very neat. We built a very similar vex swerve chassis with the Crio last fall when we took early delivery on the Crio. Here’s a youtube:

3

I’d love to have the code, if you’d like to share it.
It looks like you are driving the VEX motors straight from the cRio. Are you using the standard PWM outputs and drivers or did you have to do some programming to control the VEX parts?

4

[Contacted to send code via email]

The motors were driven by the cRio via the digital sidecar directly. You need to make a cable to adapt the pins, but the Vex motors work well with the cRio.

5

Very impressive - especially the documentation! In just a few minutes I was able to understand exactly the goal and how the robot systems were implemented.
Any thoughts about scaling that up to FRC size?