Thanks to not being able to do any typical robotics activities amidst this pandemic, I’ve been working on fleshing out some concepts that I’ve had kicking around in my head for some time now. After seeing all the advancements that teams are making in the wheel department, I was inspired to come up with a concept that would solve some of the issues that we faced with our drivetrain wheel selection.
For some background 1923 has traditionally built 8 or 6 wheel tank drivetrains. Starting in 2019 (probably should have done this sooner) we made the switch from parallel plate to WCD. After making this switch we immediately loved the ease with which we could swap wheels, both for testing new wheel configurations, and for routine maintenance. One thing that we did not love as much is that when swapping wheels it was relatively easy to lose spacers, or have a belt slip off it’s pulley, etc, which made wheel change over times longer. Also we had a tendency to choose wheels that gave us good traction, but would wear easily leading to the need for more frequent swaps.
Based on these concerns I came up with the concept for a two part wheel where the robot side half is permanently attached to the drivetrain and the outside half is held in place by 6 bolts. The tread in this setup would be an injection molded part which has a circular t-slot profile interrupted by blocks which transfer torque from the wheel to the tread. The wheel can be opened up with the 6 bolts and a new tread can be effortlessly swapped in. With some practice and an torque limited electric screwdriver, tread swaps should be quick and easy.
Here are some images of the front and back of the wheel, a cross section showing the method for retaining the tread, as well as some other views to help visualize the concept. Note that the tread pattern is for illustration only and likely not optimal in anyway.
Currently this is drawn as 1 inch wide, but theoretically, using a different molded tread and some shim plates you could make this as wide as needed. I do not have any plans to currently make this other than perhaps printing a prototype on the Markforged I have access too.