Bee-Roll is built by my teammate Peter Lombardo, and he put together a little intro for me to share! You may have seen it on YouTube recently.
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Combat robotics is a game won and lost at several distinct gates, the last of which is the actual combat. The first gate is the design and concept phase. If you start out designing a robot with jello armor, you aren’t going to make it far when 200mph of hardened steel is careening towards you. Likewise, even the perfect armor, weapon, and electronics will lose if the wheels don’t touch the ground. Having a CAD program like SolidWorks is immensely helpful in ensuring a well rounded design with the best possible chance of success.
For a robot like Bee-Roll, the process of designing is the most influential aspect of the final product. Small changes in this phase determine winning or losing fights months in the future. With three pounds of constantly spinning mass storing over 2 kilojoules of energy at full speed, the internals need to be balanced, and shock mounted to prevent damage. The choices here shape how the robot looks, drives, and fights.
The first step of any good design is to take all the components you want to use and to smash them as close together as you dare! In this case, the motors are 3536 sized drone motors, the battery is a generic 4s 850mah, and the speed controllers are 70A AM32 ESCs from NeutronRC. The shafts are 5mm ejector pins, and the wheel hubs are hand made from some aluminum cutoffs. The only power tools needed to make this robot were a 3d printer and a drill press.
From here, I add in some simple, cheap weapon impactors in the form of 7/16-20 screws, and some drilled and tapped strips of 1/4” aluminum. By joining multiple impactors together, the impact is spread out across the set. This prevents them from pulling out of the printed TPU tube.
This tube, to be exact! Just the tube and teeth weigh a whopping 600 grams!
Here’s a side view of the robot. Would you have thought a quarter inch of ground clearance was enough? Because the tube is printed from the tough but flexible TPU, it expanded enough at full speed to hit the ground, digging into the wooden floor and rocketing the robot backwards. The transparent grey outline represents an updated tooth profile, hopefully one that stretches out a little less and does a bit more damage!
Bee-Roll competed at the February 1st National Havoc Robotics League, earning a 3-2 record (check out the event report here) and learning a LOT of lessons. First, when the robot connects with an opponent it can hit like a ton of bricks, a great sign and motivator to keep working on it. Second, the 5mm wheel shafts aren’t enough. Eruption, the final opponent for the day, sheared one of my wheels clean off without doing too much damage to the hub itself. Lastly, I learned that replacing the motors was a pain, made more difficult by the attachment of the motors to the battery compartment. Those three lessons, as well as the expansion issue noted above, are the main goals for Bee-Roll version 2, and should be competing sometime later this year.
