Anxieti

Chonki
Year Of Creation	2020-2021
Versions
Current Version	V 2.0
Update Year	2021-2022
Wins/Losses	2/2 Moto 1/2 AVC
Information and Statistics
Weight Class	Featherweight
Weapon Class	Shell Spinner
Combined Wins/Losses	3/4
Weapon Speed	1200 RPM (67 MPH)
Other	Chonk!!!

Introduction

Anxieti is a classic undercutter with a modern twist. A heavy emphasis was placed upon serviceability and reliability, resulting in a design with easily swappable armor plates, drive modules, and a removable weapon block. Most of Anxieti’s design is relatively straightforward, with the main unique aspect being the slanted armor, meant to deflect direct hits to the robot and mitigate some of the absorbed energy. Anxieti competed at NHRL's March Qualifier, winning 3 matches and losing 1. The team qualified for the NHRL World Championship.

Members:

• Lucas McCarty (Lead)
• Todd Hayes (Mentor)
• Keaton Sadoski (Weapon Lead)
• Paul Matesevac (Chassis Lead)
• Evan Strakes
• Daniel Johnson
• Xiang Li
• Lucy Bricker

Chassis System

Anxieti has a rectangular footprint measuring roughly 12x18 inches at its widest. Side Plating in vertical planes was avoided, instead opting for smooth slanted sheets of Titanium (0.125 inches thick in all directions except for the front plate which is 0.25 inches). These smooth angled plates were meant to help deflect the energy from hits to the robot during combat and prevent Anxieti from absorbing the full force of other weapons. Furthermore, the chassis features a “skirt”, metal plating covering some of the distance between the bottom plate and the ground, helping to defend against Vertical Spinners or Beater Bars by preventing their access to a biteable ledge on the bottom of the robot.

Weapon System

For the weapon assembly, a 1:1 pulley driven system was selected to help protect the drive motor from feedback from weapon impacts. The weapon is a 11.5 inch diameter disk with approximately 3 inches of extension from the front of the robot. This subassembly is asymmetrical and single tooth to maximize weapon bite. The entire weapon assembly is housed in a solid Aluminum 6061 weapon block that can be removed from the robot entirely.

Drive System

The drive system features four inch Coulson wheels directly mounted to 1:16 gearboxes which are mounted to the chassis. Given the ½ inch shaft diameter for the gearboxes, concerns about lack of dual sided wheel support were minimal. Furthermore, the gearboxes are driven by two Turnigy Aerodrive SK3 - 4240-740KV Brushless Outrunner Motors. These gearbox+wheel+motor modules are easily swappable between rounds. In terms of electronics, two 5500 mAh 3s batteries were selected to run in series to get 6S voltage in a divided form factor.

Electronics

Overall, the drive and weapon were both undervotled and over capacity. The drive performed fine, but was a bit on the slower side. The weapon did not reach a high enough top speed (~1200 RPM max) to deal enough damage. Drive battery was approximately 60% depleted after each fight, and weapon battery was approximately 5% depleted.

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 (was too big)
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

NHRL_2023

Over the course of the March 2023 NHRL Competition, Anxieti competed in 4 matches and was forced to forefit 1. Here is a recap of Anxieti’s Perormance at its inaugural tournament.

Anxieti’s first fight was against a beater bar named Vacca Tank. Their left side drive was dysfunctional, but their right could move and their weapon was functional.

The footage from the match can be viewed here: https://youtu.be/xQTbCkwBmD4?t=3100

The Fight was a quick and decisive victory for Anxieti, with the titanium armor taking 0 damage, and dealing a significant amount of carnate to the vertical spinner. Anxieti ended up ripping off the robot’s rear armour as well as numerous fasteners and other mounting hardware. After this match, no repairs or replacements were necessary with the exception of some tuning and retightening.

Anxieti’s second match was against a flipper named Sake Shrovin. This was also a quick fight with no damage being supplied by the opponent.

Here is the footage: https://youtu.be/xQTbCkwBmD4?t=14851

Ultimately, the opposing robot almost managed to flip Anxieti once. This was, however, not a danger to Anxieit as the robot is flippable. The fight was ended by Anxieti when the horizontal weapon destroyed Sake Shrovin’s drivetrain, wheels, belts, and protective hdpe armor.

Anxieti’s third match was against a midcutter named Floor Letter Word. This was a challenging fight, but the victory here, ultimately qualified Anxieti for the NHRL world championships in November 2023.

Here is the fight footage: https://youtu.be/xQTbCkwBmD4?t=21213

A number of issues presented themselves during this fight. Mainly, that the weapon assembly went offline due to an ESC issue for a majority of the fight, and because Floor Letter Word was able to dislodge one of Anxieti’s armor plates by hitting the robot at its vulnerable corners. This was a close fight, and came down to judging. Between this fight and the next 2 corner blocks had to be replaced as well as a plate. Between the 3rd and 4th Fights, an ESC caught fire in the Pits. This set Anxieti behind schedule severely and caused the team to have to forfeit a match. At this point the team had already qualified for the world championship, so the robot’s performance was still a success. Ultimately, this explosion as likely the result of having BEC turned on on multiple ESCs.

Anxieti performed in one final round for NHRL (3rd vs. 4th place). Unfortunately, this match resulted in a total destruction of the robot.

Here is the footage:https://youtu.be/xQTbCkwBmD4?t=31000

STF (being 50 lbs with weight bonuses) was able to shear off Anxieti’s plates exposing its internals. From there on, it was game over. The robot looked like this in the end:

Issues

The main failure point for the robot was the plate mounting. If hit at the corners, the plates would shear off, leaving Anxieti exposed. Because Anxieti qualified for the NHRL world championship, work began immediately after competition to analyze this failure and prepare an enhanced rebuilding of the robot for the November 2023 competition.

Ultimately, a good balance between number of fasteners and fastener size was determined, as demonstrated in the table above. This along with many design conversations resulted in a design for Anxiei 1.5.

Changes to make

Anxieti 1.5’s corner blocks will feature 4 upgraded fasteners as well as steel inserts, interfacing between the armor and the bottom plate. The corner blocks will also be made from AL 7075 and not 6061. Furthemore, Anxieti’s bitable edges will be chamfered down and smoothed. All these design details will help eliminate any cases where Anxieti’s plates may shear off.

On the electronics side, the robot will upgrade to 8s, and switch to censored motors in order to ensure greater consistency in drive. 

Ultimately, we hope that these changes will improve Anxeiti’s effectiveness at its next competition and make it a strong competitor for the World Championship.