VVS Ballers: RoboCupJunior Soccer

Autonomous RoboCupJunior Soccer robots by Team VVS Ballers, designed and iterated across multiple seasons, from EV3 regional robots to a custom Teensy-based international platform.
Firmware (C++) · multi-board electronics (KiCad) · mechanical design (Fusion 360).

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Results

• RoboCup 2026, Incheon, South Korea (International): 9th place, RoboCupJunior Soccer (IR League). Two self-built robots, designed, wired, and programmed by a team of two.
• RoboCupJunior India, 2025-26 season: came up through the Indian regional and national rounds to qualify for RoboCup 2026. The trophy and finals footage from the national event are in the Nationals gallery.

Press and media

• Two Students, Two Self-Built Robots, And A 9th-Place Finish At The Robot "World Cup" (Republic World, July 2026)
• Team Instagram - Robot builds, competition footage, and event coverage

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Seasons

Season	What's inside
RoboCup Internationals 2025-26 ⭐ current	Two autonomous Soccer-Infrared robots (attacker + defender): a Teensy 4.1 multi-board stack with an IR ball ring, line ring, ultrasonic, OpenMV goal camera, and 48 V solenoid kicker. Firmware + KiCad PCBs + Fusion CAD.
RoboCup Nationals 2025-26	Nationals build: EV3 robot program (HiTechnic IR seeker and compass), an Arduino relay-driven solenoid kicker, 3D-printed chassis parts, the season poster, and the trophy and finals gallery.
RoboCup Regionals 2025-26	EV3 holonomic robot (diamond omni drive, dual underside colour sensors, side IR distance, IR seeker, compass heading hold) + an Arduino ultrasonic-triggered kicker + printable parts + poster.
RoboCup 2024-25	Prior season: international Team Description Paper, posters, and earlier EV3 reference designs.

The Internationals 2025-26 robots are the current flagship, and the rest of this page focuses on them. The full detail lives in that folder's detailed README and a complete technical deep-dive. Competition media: TDP · poster · TDP video · photo gallery.

Code-span paths below (e.g. Firmware/Attacker) are relative to RoboCup Internationals 2025-26/.

Earlier-season highlights

• Regionals 2025-26 (EV3): EV3 motors driving omni wheels in a diamond layout; underside colour sensors for white-line and goal-area avoidance; side IR sensors for walls; an IR seeker for ball tracking; and a compass for heading correction. An external Arduino kicker (TB6612FNG H-bridge + gearmotor, ultrasonic ball detect) steps through kick, hold, retract, and cooldown phases.
• Nationals 2025-26 (EV3): the same EV3 sensing platform, upgraded with a relay-driven solenoid kicker triggered by an ultrasonic capture sensor. The custom Teensy and KiCad electronics stack was developed next, for the Internationals robots.

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Internationals 2025-26: the robots at a glance

Both robots share one electronics stack and one chassis; only the role firmware on the main board differs.

	Attacker	Defender (goalkeeper)
Job	Win the ball, aim, and shoot the open corner	Hold the goal mouth and clear the ball
Main firmware	Firmware/Attacker/Attacker_Chase_Aim_Kick_Line	Firmware/Defender/Defender_Full
Ball	IR ring (16 sensors)	IR ring
Staying in bounds	Line ring + ultrasonic fused boundary escape	Line keeps it on the goal-area ("D") line; ultrasonic cross-check
Goal / aim	OpenMV camera to open-corner bearing	(camera optional)
Kicker	48 V solenoid, camera-gated	Short clearing kick

Electronics: the boards

A multi-board design: each subsystem has its own microcontroller, and the boards talk to the main board over compact UART links (CRC-8-framed, bar the plain-ASCII IR link), keeping the fast sensor loops off the main control CPU.

Board	MCU	Does	KiCad	Firmware
Main	Teensy 4.1	Drive (4x DRV8263H), BNO055 IMU, capture sensor, kicker relay, all links	PCB/Main	Firmware/Attacker, Firmware/Defender
IR ring	Teensy 4.1	16x TSSP58038 for ball bearing and distance	PCB/IR	Firmware/IR_Ball_Sensor
Line ring	Teensy 4.1	4x QTR-MD-05A (18 ch) for white-line detection	PCB/Line	Firmware/Line_Sensor
Ultrasonic	Arduino Nano Every	4x HC-SR04 for wall distances	PCB/Ultrasonic	Firmware/Ultrasonic
Camera	OpenMV H7	Goal / keeper / open-corner vision	-	Firmware/Camera
Power	-	12 V / 5 V / 3.3 V rails + 48 V solenoid boost	PCB/Power	-
Motor-current (optional)	Arduino Nano Every	DRV8263H stall / over-current watchdog	-	Firmware/Motor_Current

Human-readable wiring PDFs for the Main, Power, IR, and Line boards are in PCB/Wiring/.

How it plays: design choices vs. the game

Everything is built around what actually wins (and loses) a RoboCupJunior Soccer match. (A goal counts when the ball touches the back wall of the goal; touching a wall or driving fully into the marked penalty area is an out-of-bounds penalty.)

• Score in the goal. The IR ring gives the ball's bearing; the main board chases it with an omni-wheel drive held straight by a BNO055 heading PID. Once the ball is captured, the OpenMV camera finds the goal, picks the open corner (dodging the keeper), and the chassis turns in place until that corner is dead ahead before the solenoid fires. Aiming for the open corner instead of the goal centre is how you beat a keeper.

• Never cross the line (the expensive mistake). The attacker treats a side as the field boundary only when the line ring and the ultrasonics agree (white line seen and wall within 300 mm), then flees away from it. Two independent sensors must concur, so one noisy reading can't make the robot dart out of bounds.

• Keep the keeper on its line, not inside the box. No robot may be fully inside the penalty area, so the defender uses the line ring to ride the edge of the goal area ("the D") while tracking the ball laterally and clearing it on contact.

• Stay legal in the Infrared league. IR-emitting rangefinders (ToF, LiDAR, IR distance sensors) are banned because they'd swamp other robots' IR ball sensors. That is why walls are ranged with ultrasonic HC-SR04s here, not IR.

• Power within the rules. The rules cap robot power at 48 V DC; the solenoid kicker runs from a 48 V boost converter (right at the legal ceiling, for the hardest legal kick) while logic and motors run from 3.3 V / 5 V / 12 V rails.

• Referee start/stop. The main board pins out the RoboCupJunior Communication Module GO/STOP inputs, with firmware support toggled via USE_COMMS in the defender build.

The binary inter-board links (ultrasonic, line, camera to main) are short frames, each guarded by an identical CRC-8 (poly 0x07); the IR link is plain delimited ASCII. Full byte-level layouts are in the technical deep-dive.

Team

Member	Roles
Kushal Sachdeva (Team Leader)	Electrical, Software & CAD
Darsh Goel	Mechanical & CAD

Region: India · League: RoboCupJunior Soccer Infrared

Sponsors

Our thanks to Amazon · DLF · Havells · OpenMV · Magnum Ventures · Budtree Management, and to our mentors, school, and the RoboCup Junior community for their support.

Related projects

• K.A.D-Ballers-Genius-Olympiad: our mecanum-drive robot for the GENIUS Olympiad robotics competition
• More at github.com/Kushal-Sachdeva78

License

Released under the MIT License; see LICENSE. © 2026 VVS Ballers (Kushal Sachdeva, Darsh Goel). You're welcome to learn from and build on this work; please keep the attribution.