Sumo Robot Build: Competition Rules & Electronics India 2026

Building a sumo robot for competition in India is one of the most exciting and accessible robotics challenges available to students and hobbyists. Sumo robotics competitions are organised at IITs, NITs, engineering colleges, and events like TechFest, Pragyan, and Shaastra across India. This guide covers the rules, electronics selection, chassis design, strategy programming, and where to compete in 2026.

Table of Contents

• Competition Rules: Indian Standard Classes
• Sumo Robot Strategy & Sensor Layout
• Chassis Design Principles
• Electronics Selection & BOM
• Arduino Control Code
• Where to Compete in India 2026
• Frequently Asked Questions

Competition Rules: Indian Standard Classes

Most Indian sumo robotics competitions follow rules adapted from the international standard. Know your category before building:

Mini Sumo (most common in India):

• Weight: Maximum 500g
• Size: 10cm × 10cm footprint (height unlimited)
• Dohyo (ring): 77cm diameter, black surface with white border line
• Autonomous operation: No remote control during match
• Match: 3 rounds, 2 minutes each
• Win condition: Push opponent off the ring (all contact with floor outside ring)

Standard Sumo:

• Weight: Maximum 3kg
• Size: 20cm × 20cm footprint
• Dohyo: 154cm diameter
• Same win condition

Mega Sumo:

• Weight: Maximum 13kg
• Larger ring and robot dimensions
• Much higher risk — high-current motors, structural requirements are extreme

Remote Controlled (RC) Sumo: Some Indian events also allow RC-controlled sumo, which is simpler to build but less intellectually interesting. The autonomous category is where the real engineering challenge lies.

Sumo Robot Strategy & Sensor Layout

A successful sumo robot needs two sensor systems: enemy detection (to find and attack the opponent) and ring-edge detection (to avoid falling off the dohyo).

Ring-Edge Sensors (mandatory):
QRE1113 or TCRT5000 reflective IR sensors mounted on the front corners and rear corners of the robot, facing the floor. The dohyo has a black surface with a 2.5cm white border line. When a sensor detects white (high reflectance), the robot knows it is at the edge and must reverse immediately.

Enemy Detection Sensors:
For mini sumo, the most common and effective sensor is the Sharp GP2Y0A21 (10-80cm range) infrared distance sensor. Mount 2-3 around the robot’s perimeter:

• 2 forward-facing sensors for attack direction
• 1 rear-facing sensor to detect flanking attacks
• Optional: 2 diagonal sensors for wider detection field

Strategy State Machine:

• SEARCH: No enemy detected — rotate slowly to scan, or use pre-programmed search spiral
• ATTACK: Enemy detected in front — full speed forward to push opponent off ring
• TURN: Enemy detected on side — turn to face enemy
• ESCAPE: Edge sensor triggered — reverse at full speed, turn, re-enter search

Chassis Design Principles

The sumo robot’s chassis design is as important as its electronics. Every gram of weight and every millimetre of traction matters.

Key Design Principles:

• Low centre of gravity: Keep the battery and heaviest components as low as possible. High CG makes the robot tippy and easier for opponents to flip.
• Maximum traction: Use soft rubber or polyurethane wheels for maximum grip on the smooth dohyo surface. Anti-skid rubber bands wrapped around plastic wheels work surprisingly well.
• Front shovel/blade: A thin metal or 3D-printed wedge at the front helps the robot get under the opponent. Even a 5mm height advantage at the front can win a match.
• Wide stance: Wider wheel track improves stability against lateral pushes. Push opponent sideways (tangentially) rather than directly head-on when possible.
• Weight distribution: More weight toward the front wheel axle improves traction at the drive wheels. Rear-heavy robots spin wheels.

Popular Indian Mini Sumo Chassis Options:

• 3D-printed PETG chassis (custom designed) — ₹200-₹400 in filament
• Aluminium sheet cut with hand jigsaw — available from hardware stores for ₹100-₹200
• PCB chassis — milled PCB serves as both structural member and circuit board

Electronics Selection & BOM

Bill of Materials for a competitive mini sumo robot (500g class):

Arduino Control Code

// Mini Sumo Robot - Autonomous Control
#include <Arduino.h>

// Motor pins (TB6612FNG)
#define LEFT_IN1   4
#define LEFT_IN2   5
#define LEFT_PWM   6
#define RIGHT_IN1  7
#define RIGHT_IN2  8
#define RIGHT_PWM  9

// Sensor pins
#define EDGE_FL   A0  // Front-left edge sensor
#define EDGE_FR   A1  // Front-right edge sensor
#define EDGE_RL   A2  // Rear-left edge sensor
#define EDGE_RR   A3  // Rear-right edge sensor
#define ENEMY_F1  A4  // Front enemy sensor 1
#define ENEMY_F2  A5  // Front enemy sensor 2

#define EDGE_THRESHOLD  600  // Higher = white (edge)
#define ENEMY_THRESHOLD 300  // Lower = close enemy
#define MAX_SPEED       255
#define SEARCH_SPEED    180

void motor(int left, int right) {
  // Left motor
  if (left >= 0) { digitalWrite(LEFT_IN1, HIGH); digitalWrite(LEFT_IN2, LOW); }
  else { digitalWrite(LEFT_IN1, LOW); digitalWrite(LEFT_IN2, HIGH); left = -left; }
  analogWrite(LEFT_PWM, constrain(left, 0, 255));
  
  // Right motor
  if (right >= 0) { digitalWrite(RIGHT_IN1, HIGH); digitalWrite(RIGHT_IN2, LOW); }
  else { digitalWrite(RIGHT_IN1, LOW); digitalWrite(RIGHT_IN2, HIGH); right = -right; }
  analogWrite(RIGHT_PWM, constrain(right, 0, 255));
}

void setup() {
  pinMode(LEFT_IN1, OUTPUT); pinMode(LEFT_IN2, OUTPUT);
  pinMode(RIGHT_IN1, OUTPUT); pinMode(RIGHT_IN2, OUTPUT);
  
  // 5-second delay at start (competition rule: robot must wait)
  delay(5000);
}

void loop() {
  // Read edge sensors (HIGH analog value = white = edge)
  bool edgeFL = analogRead(EDGE_FL) > EDGE_THRESHOLD;
  bool edgeFR = analogRead(EDGE_FR) > EDGE_THRESHOLD;
  bool edgeRL = analogRead(EDGE_RL) > EDGE_THRESHOLD;
  bool edgeRR = analogRead(EDGE_RR) > EDGE_THRESHOLD;
  
  // Read enemy sensors (LOW value = close = enemy detected)
  bool enemyF1 = analogRead(ENEMY_F1) < ENEMY_THRESHOLD;
  bool enemyF2 = analogRead(ENEMY_F2) < ENEMY_THRESHOLD;
  
  // PRIORITY 1: Edge avoidance
  if (edgeFL || edgeFR) {
    // Edge detected at front - reverse!
    motor(-MAX_SPEED, -MAX_SPEED);
    delay(200);
    motor(-MAX_SPEED, MAX_SPEED);  // Spin turn
    delay(300);
  } else if (edgeRL || edgeRR) {
    // Edge at rear - go forward fast
    motor(MAX_SPEED, MAX_SPEED);
    delay(200);
  }
  // PRIORITY 2: Attack enemy
  else if (enemyF1 && enemyF2) {
    // Enemy directly in front - FULL ATTACK!
    motor(MAX_SPEED, MAX_SPEED);
  } else if (enemyF1) {
    // Enemy on left-front - turn left slightly
    motor(SEARCH_SPEED, MAX_SPEED);
  } else if (enemyF2) {
    // Enemy on right-front - turn right slightly  
    motor(MAX_SPEED, SEARCH_SPEED);
  }
  // PRIORITY 3: Search for enemy
  else {
    // Rotate to search
    motor(SEARCH_SPEED, -SEARCH_SPEED);
  }
}

Where to Compete in India 2026

• IIT Bombay TechFest — One of Asia’s largest student techfests, held annually in December. Strong robotics competition lineup including sumo.
• IIT Madras Shaastra — January/February. Excellent technical robotics events with significant prize money.
• NIT Trichy Pragyan — February/March. Popular among southern Indian robotics teams.
• Robocon India — ABU Robocon qualifier; while not sumo, builds the same robotics skill set.
• BITS Pilani Oasis — Cultural and technical festival with robotics events.
• Local engineering college techfests — Virtually every engineering college in India runs annual techfests with sumo robotics as a standard event. Entry fees typically ₹200-500 per team.

Frequently Asked Questions

How do I make my sumo robot faster without exceeding the weight limit?

Use N20 gear motors with higher RPM ratings (600-1000 RPM at 6V) rather than TT motors. Reduce non-essential weight — use lighter battery (smaller mAh LiPo is fine for a 2-minute match). Use a lighter microcontroller (Arduino Nano vs Mega). Carbon fibre or thin aluminium sheet chassis weighs much less than 3D-printed plastic. Remember that battery weight IS weight — a 400mAh 2S LiPo weighs only 25g vs a 9V battery at 45g.

What is the best motor for a 500g mini sumo robot?

N20 gear motors (6V, 300-600RPM) are the gold standard for mini sumo. They are small, light, efficient, and available in a wide range of gear ratios. For pure pushing power, choose 100-200 RPM (more torque). For speed-based strategies, choose 500-600 RPM. Pair with matching rubber wheels (48-50mm diameter) for optimal performance.

Can I use ultrasonic sensors instead of IR for enemy detection?

Ultrasonic sensors (HC-SR04) are slower (50ms cycle time vs Sharp IR’s <5ms) which is a significant disadvantage in fast sumo matches. They also cannot detect small targets well at close range. IR sensors (Sharp GP2Y series) are strongly preferred for enemy detection. However, ultrasonic sensors are adequate for basic learning builds where speed is not critical.

My robot keeps driving off the ring — how do I fix edge detection?

First check sensor mounting angle — TCRT5000 sensors need to face directly down at the floor. Calibrate the threshold — read analogRead values over the black ring and white border with a Serial print, then set your threshold between these values. Ensure the edge detection and avoidance code runs BEFORE enemy attack code (higher priority). Test with a mockup dohyo before the competition.

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