Elytra
Placed 3rd at Battle in the Backwoods 7 (out of 29)
6-4 win/loss overall
Elytra is an extremely weight-efficient 3-lb combat robot designed around its large diameter weapon spinner. I determined ideal weapon MOI, tooth rake angle, wheelbase distance, counterweight clearance, and more to maximize energy and momentum transfer while remaining hyper-maneuverable.
Weapon Design
Elytra's weapon is primarily optimized for tooth engagement. The single-toothed design allows for higher weapon speeds without sacrificing bite, and the steep rake angle allows the tooth to dig-in to soft materials, further increasing tooth engagement.
The large diameter allows for high tip speed at lower RPM, which makes it easier to win weapon-on-weapon engagements. The small tooth thickness also reduces the likelihood of devastating out-of-plane hits.
The weight and moment of inertia of the weapon is also as low as possible. The low weight allows me allocate weight to other aspects of the robot, and the low MOI reduces the gyroscopic effect from turning.
Weapon Assembly
To save weight and reduce complexity, Elytra uses a supported direct drive system which transfers force through large bearings attached to the frame rather than through the motor. There are fillets and notches to prevent stress concentrations.
Frame and Drive
Elytra's extremely wide wheelbase reduces the overall gyroscopic effect on the driving of the robot. This improves maneuverability enough so that the robot can rapidly turn to face the weapon toward the opponent.
Additionally, the wheels are compliant and squeeze the shaft of a drone motor in leu of a gearbox. This reduces complexity, size, and weight drastically with the only sacrifice being a relatively limited center distance between the wheels.
The large size of the frame is enabled by liberal pocketing of the UHMW frame rails and clever geometry. The frame rails were lightened using a very mediocre CNC router with proprietary software, but a custom post-processor allows for use of external CAM programs. I also removed half the material on the sides of the robot. Why not, right?