Binari

Introduction

This robot had a name before a design. It born when Brian thought to himself, "Hey, it would be really funny if we named a robot Chonki and made it really, really big and really really loud..." Throughout the design process the robot lived up to its name. Chonkii is a 45lb shuffling shell spinner competing in the 30lb weight class that serves as an iteration on the original Chonki, which was never fully constructed. It was developed during 2021-2022. The drive system was iterated from that of Apachi and Chonki. The weapon system was a brand new concept for BattleBots. The goal of Chonki was to evaluate the viability of shell spinners while taking advantage of the 1.5 times weight multiplier afforded by using a mechanism other than wheels for movement. Competed at Motorama 2022 and finished with a 2-2 record.

Members:

• George 'Knute' Brady (Lead)
• Paul Matesevac
• Lucy Bricker
• James Peavy
• Joe Irwin
• Mannan Goel

Drive System

Chonki utilizes a shuffler system for drive. It consists of two shuffler modules, each with 4 UHMWPE feet. The feet sit on two parallel, keyed cam shafts. These allowed for the four feet to be positioned 90 degrees from each other, so feet would always be in contact with the ground through the cam shaft's rotation. To fit inside the feet get smaller as they move away from the chassis. The longer feet have fillets to clear the rollers and support which they sit under. The cams have offset keyed holes to accommodate the shafts and sit inside circular cutouts in the feet, which keep them parallel with the ground as it walks. The use of the shuffling system allowed Chonki a weight bonus, bringing the max weight to 45 lbs.

Weapon System

Design Considerations

Because we had 2 weapons, it was important to have them be light enough as to not surpass a combined weight of ~15 lbs. The extra weight bonus from the shuffler allowed for this to be much more feasible (also required because we have 2x the weapon motors).

Weapon Design

Overall Design: Made to resemble Valkyri's overall weapon stack, minor changes were made to the overall design, A roller bearing (in design) was not needed at the bottom because of the constraint on the shaft itself (enough distance to spin without touching the bottom plate). This did not work, therefore a needle roller bearing should always be strongly considered in future live-shaft designs despite clearance looking good enough.

Weapon: Our weapons were waterjet out of AR500 steel (made from sheets of gun target steel). Each weapon was 0.5 inches in thickness and 11 inches in diameter. The overall shape was intended to put as much mass at the hitting ends as possible, there was no need to save weight therefore we were able to have a solid weapon. There was added structural support around the location that met with our weapon shaft, this was to theoretically prevent any snapping of the weapon (fears due to Apachi's weapon failure). Additionally, the weapon's geometry was made in order to ensure that at the maximum distance, only 1 point has the possibility of hitting (in order to reduce the chance of us 'skimming' the other bot instead of properly hitting it).

Belt Protection: Carbon fiber reinforced nylon material called Onyx, printed on a Markforged 3D printer. The print was not the best, therefore our belt protection was pretty non-existent. Also, the material may not have been a good choice, as carbon fiber doesn't resist instantaneous hits very well.

Lessons:

• Do not use our classical belts, use industrial/automotive belts instead
• Look for better protection for belts/weapon stacks (testing materials/more research)
• AR500 is sorta hard to machine (we need to basically increase the waterjet thickness, machinability, and possibly do 2 passes)

Weapon Stack and Weapon Pictures

Chassis System

• The chassis mostly consisted of aluminum, featuring of a ¼” top and side plates and ⅛” bottom plate.
• The front and back plates were made of HDPE, which bent to form Chonkii’s robustly round shape.
• The chassis had multiple rollers spaced out along its top, giving additional support to the shell track above.
• The central dead axle was constrained by two blocks, mounted to both the top and bottom plates. However, it was later determined that a single longer block with a key would constrain the shaft better than the two block system.
  • While drilling through the blocks into the shaft, a drill bit melted inside, acting as a makeshift pin (that was instantly destroyed in competition).

Electronics

Drive Motors	Turnigy Aerodrive SK3 - 5055-280KV Brushless Outrunner Motor
Drive Motor Controllers	Flipsky Dual FSESC6.6 Based upon VESC6 with Aluminum Heatsink Mini Size (whatever apachi used)
Weapon Motor	Scorpion SII-4035-250KV
Weapon Motor Controllers	Tribunus 06-120A (6S) Brushless ESC
Receiver	Hobby King 2.4Ghz Receiver 6Ch V2
Remote Control	Hobby King 2.4Ghz 6Ch Tx and Rx V2
Battery	Turnigy Heavy Duty 5000mAh 6S 60C LiPo Pack w/XT90 Turnigy Graphene Panther 3000mAh 3S 75C Battery Pack w/XT90

Competitions

AVC 2022

• Results: 0-2
  • Bracket Style: Double Elimination
    • [Binari (loser) V.S. Crippling Depression (winner): YouTube Link]
      • Crippling Depression was a wedge and undercutter combination bot.
      • As an undercutter, the weapon went underneath ours, slightly sheared one of our bolts
      • After getting flipped, they absolutely destroyed the weapon guards and side armor and bent our shuffler system and front plate
      • Lost via tap-out
    • [Binari (loser) V.S. HUHMWPE DUHMWPE (winner): YouTube Link]
      • Ripped off sideplate, and the shuffler system slowly fell apart
      • Lost via tap-out
      • More Description

Issues

• Stuff
• Other Stuff

Changes to make

• Stuff
• Other Stuff

Trivia

• The Vectrax was rendered inoperable twice by Chonki members (mainly Brian) during its construction.