Polar Bear: 3D-printed combat robot

May 2023 to Present

Ranked 1st out of 772 competitors nationwide in March 2025. Combat Robotics 2025 National Championship Qualifier (1 of 3 high schoolers). Winner of Bot'Geddon (2024), Summer Meltdown (2024), NorCal Knockout (2025).

400+ hours of design, assembly, and testing over 2+ years.

1. Polar Bear V1-V2

I was introduced to Combat Robotics in mid-2023 by older students who mentored me through the first iteration (left) of “Polar Bear”, my 1-lb combat robot. Inspired by the Battlebot “Tombstone”, Polar Bear is a horizontal spinner that uses a rotating impactor to damage opponents. The material opposite the blade tooth is a counterweight.V1 was one of my first experiences with Onshape. After I designed V1, I realized I wanted to make some major changes. I spent the next months designing V2 (right), which featured a 7” blade, wheelguards, and an improved shape. I discovered the Grid Extrude custom featurescript, which helped me create cool polygon patterns. I added ridges at the back to prevent Polar Bear from being beached on its back, and kept the motor clamping retention system from V1. I asked my parents for a 3D printer so I could build and test V2 (next slide).
~August to September 2023 (V1); October 2023 to January 2024 (V2)

2. Polar Bear V2-V3

V2 got wrecked at its first competition. Top left is the disassembled robot, with the weapon and support breaking completely. I was happy with the rest of the chassis and the drive system, which proved reliable even after some big hits. I needed to do something about the weapon system.I shrunk the diameter of the weapon from 7” to 5”, which shortened the supports as well. This lessened the impact forces considerably (less torque). I created a more cheesecake-y looking weapon that was thicker all around. These changes proved helpful, and Polar Bear V3 performed well during spars with peers in my school’s Combat Robotics Club.
~February to August 2024 (V3)

3. Polar Bear V3-V4

I took V3 to another competition, securing 2nd/16 (bottom left). I was proud of Polar Bear’s improvements, but I had problems with driving.I started applying multiple layers of liquid latex to my foam wheels, which offered better grip. I pocketed the inside of the chassis and added a few more ribs. I removed material from the side walls, making them 3mm instead of 4mm.I now had lots of extra weight to experiment with. Guided by mechanical engineers in the Society of Combat Attack Robotics Discord server, I designed two attachments for my front end: a ground-scraping fork to get under other bots, and an extra shoulder/weapon support protector. V4 (colored red here; green in CAD) went on to win 18/21 matches.
~August 2024 to April 2025 (V4)

4. Polar Bear V4 Battles

The first video was the final of Bot’Geddon and the second was a semifinal at the NorCal Robotics Expo. I won both matches, the first by judges’ decision (points awarded on damage, control, and aggression after 3 minutes) and the second by tap-out (opponent surrenders). I used the blocky armor attachment in both matches. It proved key, especially in the first match where my opponent was an undercutter. I liked Polar Bear’s stability and durability. V4 was a definite improvement over V3 and V2, which were prone to malfunctioning and flipping over.
~October 2024 (Bot’Geddon), December 2024 (NorCal Robotics Expo)

5. Polar Bear V4-V5

At the May 2025 National Championships in LA, Polar Bear would square up against the best robots from across the country. Even though V4 was doing well, I wanted to improve.I made V5 wide and squat (right). I added a recessed shaft collar to help constrain the weapon and a plate to hold it in. I tilted the walls to give vertical spinners less lip to hit. There would be no undercutters at the competition, so I removed the front attachment and thickened the chassis. I switched from brushed drive to brushless, adding power at the cost of complexity.However, at the competition, the brushless motors weren’t tuned properly. Polar Bear started spinning uncontrollably, resulting in an early loss. I was disappointed, and learned my lesson to test new features more thoroughly. Nonetheless, I’m proud of the work I’ve put in on Polar Bear over the last 2+ years. Combat Robotics is about trying new things and constantly developing. I hope to start work on V6 soon!
~May 2025 to Present