Co-axial Rotation and Power with Differential Gears

Hello everyone,

I wanted to share two projects of mine, a six-wheeled Co-axial swerve robot based off of NASA’s Chariot robot, and a tank with an infinite rotation turret with pitch control.

I apologize that all I have are the snapCAD models, as I do not have the parts to build these at the moment.

Chariot was my first major project in snapCAD. It was aimed at finding a way to create a co-axial swerve drive in vex IQ without modifying parts and with a minimal size. The coaxial motion is achieved by using a differential gear pinned by a ring of 12 tooth gears to absorb the radial loads, and a 1x5 beam working with a 4x6 plate to absorb the axial loads. (Apalrd touched on a similar mechanism a while ago, but I did not see it until a few minutes ago) The robot is controlled using a variable rotation point.

Features of Chariot [LIST=1]

  • Infinite rotation drive pods
  • Omni-directional control with rotation about a point
  • Completely electronic differential wheel pod control
  • Independent suspension
  • 2.67 ft/s calculated top speed [/LIST] Chariot LDR Download Robot Code Download (my Virtual Worlds licence expired before I could test the logic for wheel direction inversion, but the angle and differential wheel speed calculations were working)

    The second project was to build a model which would get more kids excited in Vex IQ, so I decided on a tank. To make it look more interesting than a brick, I tried to implement angled parts wherever possible. The turret uses the same mechanism as the Chariot pod for infinite rotation, only the 12 tooth gears could be replaced with the large turntable.

    Some design goals: [LIST=1]

  • Infinite rotation turret. So no wire wrap for the kids to be restricted by (Rotates at 48 deg/s, which is a similar traverse speed to real tanks)
  • Independent suspension
  • X and Y gyro-stabilized cannon (Operates at 24 deg/s)
  • The robot must be fast (Currently calculated to be 3 ft/s driven by four motors per side, will be slowed down if the drive train pulls too much power) [/LIST] Tank LDR Download Tank Code Download (Untested)