weevil/templates/localization/docs/LOCALIZATION_GUIDE.md

Robot Localization Guide

What is Localization?

Answering: "Where is my robot on the field?"

The Grid System

12ft x 12ft field → 12x12 grid of 12" cells

Cell (0,0) = Red backstage
Cell (11,11) = Blue backstage
Cell (6,6) = Center

Sensor Fusion

Combine three sensors:

1. Odometry (Encoders) - Track wheel rotation

   • Accuracy: ±1" per foot (cumulative drift)
   • Always available

2. IMU (Gyroscope) - Measure heading

   • Accuracy: ±2° (non-cumulative)
   • Corrects heading drift

3. Vision (AprilTags) - Detect position markers

   • Accuracy: ±2" (when visible)
   • Ground truth - resets drift

Fusion Strategy

if vision available:
    position = vision (most accurate)
    correct odometry
elif IMU available:
    position = odometry
    heading = IMU
else:
    position = odometry only (dead reckoning)

Fault Tolerance

Sensors	Accuracy	Confidence
All 3	±2"	100%
Odometry + IMU	±4"	70%
Odometry only	±12"	40%

System keeps working when sensors fail!

Usage

RobotLocalizer localizer = new RobotLocalizer(odometry, imu, vision);
localizer.setInitialPose(new Pose2D(12, 12, 0));

while (opModeIsActive()) {
    localizer.update();
    
    GridCell cell = localizer.getCurrentCell();
    double confidence = localizer.getConfidence();
    
    // Make decisions based on position
}

See README.md for full examples.