Team 190, WPI Robotics “Gompei and The H.E.R.D”, presents our 2023 offseason robot: Ember.
Ember will compete at the New England Robotics Derby, River Rage, and the FIRST Championship (the battery did).
Team 190 is sponsored by Worcester Polytechnic Institute, JABIL Healthcare, and Mass Academy of Math and Science.
can’t wait to see Ember light up the grid at NERD
Update: 3-cube Autonomous
I wonder if you could tell us a bit about the rotational motion between the MaxSpline and those two pieces of 2 x 1. Are you using some kind of bearing? We are looking for a more elegant way to make those kind of joints.
Looks like a bushing captive by shaft collars to me (thin profile). In this instance a bushing makes a lot of sense.
I would have liked to see a chain reduction for the last stage of the intake up/down due to shock loading and gear teeth, but that’s more of a robustness/hardening measure than a pure functionality one.
Pivot Gearing
The pivot is geared at approximately a 18:1 reduction off a single falcon motor through a custom machined gearbox built into the gusset that holds the support structure together. After a competition season struggling against the backlash caused by using a planetary gearbox in a similar application, we decided this custom gearbox would be a more robust solution.
We also talked about using a chain reduction as the final stage of the powertrain but, ultimately, decided against it. We had used a chain in our pivot on the competition robot this year and struggled keeping it tensioned. This led to numerous control problems, gearbox failures, and maintenance headaches as the chain would often become slack throughout the course of a match. For Ember, we decided to take the risk on shock loading to solve some of these other problems.
Pivot Bearing Stack
There are 2 bearings that support the length of MaxSpline that transfers torque from our gearbox to the collector.
We were able to find a low profile bearing from McMaster that fit the OD of the spline shaft (35mm) while still fitting within the envelope of the 2” side of the 2”x1” structure. We used a high infill 3D printed part (Markforged Onyx) to retain the bearing next to the 2” x 1” structure. Since there isn’t a flange on that bearing, we felt this was the easiest way to retain it. That bearing carrier is then bolted through the aluminum tube into a gusset plate on the inside of the assembly using 4x #10-32 bolts.
To make sure the left and right bearings were aligned to one another, we kept these bolts loose until the shaft was installed, then went back and tightened everything up. To keep the shaft (and collector) axially constrained, we utilized 2 MaxSpline shaft collars and a few spacers to clamp the shaft in place against the inner race of each bearing.
I only see two cubes haha, all jokes aside I love how you just fling the cone. Going to be my favorite bot to watch tomorrow.
any chance that CAD will be posted for this?
Yes. We plan on releasing our CAD and code for Ember sometime mid November after our last off-season competition.
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