We received a grant from Columbia University to fund this build. The grant program has its flaws, but I think it’s a great step towards moving college education closer towards practical, applicable skills (how could one graduate as an EE without knowing how to solder?).
- What is the linear slide on the bottom for? It appears to have low ground clearance.
EDIT: Is that for articulate the turret up and down?
Right on. The window motor drives an XL belt using a 3D-printed pulley. The linear slide runs on linear bearings and articulates the shooter:
- Why rack and pinion instead of just a pneumatic cylinder? More speed? In any case I like your carriage a lot, but I can’t see the side bearing supports- is there a plastic bearing surface on the sides there?
We wanted to run everything via electricity - if we had a pneumatic system onboard, we would’ve gone down the more traditional (and likely longer-range) compressed air cannon road. An HS645MG servo drives the entire mechanism. The rack rides on 3D-printed bushings. The dark plastic surface you see is a 1/4" acrylic plate - the material was chosen just for appearance.
- Your corners are held together with just a single plate on the swerve modules. Can you add a 2x1 or something there as support?
Absolutely - we’ll be adding additional gussets to reinforce those rails. The rear corner of the robot (as a triangular chassis) is supported by a section of liberally riveted 2x1, so we’re not concerned about the rigidity of that end.
- Love the dual battery mounts, very well packaged. You make good use of the way the swerve drive elevates the chassis.
Thanks! As someone who usually spends more time in an IDE than SolidWorks, that means a lot to me.
- Your swerve drive might have a couple extra gears, but apart from that it looks very cheap and easy to make. Why not use timing belts for the first stage instead of a long chain of gears?
We were looking to source as many parts as possible from extras, bits, and pieces people were willing to donate. Those gears were far more common than timing belts and pulleys - so this boils down to just a monetary cost decision.
- Love the two sizes of motors and wheels for the shooter.
Thank you. We may choose to remove the first ‘stage’ (1:3 BAG motors) to conserve weight, depending on whether the linear actuator can handle it.
- The placement of the of Victors is neat!
Thank you. Here’s an image of the shooter from about a month ago, just to prove we’re serious about realizing this concept.
- Are your sensors in CAD yet?
We’ve got a rotary encoder and limit switch to provide feedback for the linear actuator - those sensors are in CAD (and real life). The indexing mechanism for the shooter is actuated by a hefty quarter-scale servo, which has builtin feedback. We may choose to add an extra hall effect sensor onto the rotating shirt cylinder, just to make sure those shirts line up properly.
(…) After looking at the swerve module however, are you sure it’s safe to use a window motor to rotate the module at >160rpm without stalling or overheating?
We’ve got one of the swerve modules built, and we’re testing it to see what kind of conditions it can withstand. Hope I can provide a concrete answer soon.