Raccoon WikiDeep Dives — Algorithms and Sensor Methods
This section explains the sensor processing, control theory, and geometry behind raccoon’s key built-in algorithms. You do not need to read this to use the SDK — the high-level steps handle everything — but this material helps when:
- tuning PID gains or thresholds and you want to understand why a parameter exists
- debugging unexpected behavior (oscillation, false triggers, drift)
- implementing a custom step that reuses the same ideas
Mental model
Every algorithm here follows the same three-phase pattern:
Sense → Compute → Act
| Phase | What happens |
|---|---|
| Sense | Read one or two calibrated IR sensors, an IMU, or a light sensor |
| Compute | Apply a control law (PID, geometry, Kalman filter) to produce a correction |
| Act | Apply a velocity override to the drive, or signal a stop |
The pages in this section go from beginner-relevant (line following, lineup, wait-for-light) to more diagnostic (IR calibration internals, wall alignment parameters).
Pages in this section
| Page | Core idea | When you need it |
|---|---|---|
| Line Following | PID error from sensor difference → angular or lateral velocity correction | Any surface-tracking mission |
| Lineup | Single-pass stagger geometry → exact turn angle, no iteration | Squaring up before a pickup or delivery |
| Wait for Light | Kalman baseline + relative-drop trigger for the start lamp | Every competition run |
| Wall Alignment | IMU linear-acceleration spike → settle-then-stop, heading reset | Re-localization after odometry drift |
| IR Sensor Calibration (K-Means) | K-Means clustering separates black/white readings robustly | Understanding calibration quality or debugging mis-triggers |
Reading order
If you are new: read Line Following first (it explains the PID error signal used everywhere), then Lineup (pure geometry, no tuning), then Wait for Light (competition workflow). Come back to Wall Alignment and IR Calibration when you need to tune or debug.
Cross-links:
- IR calibration produces the
probabilityOfBlack()values that line following and lineup consume — see IR Sensor Calibration - After wall alignment, call
mark_heading_reference()to lock in the corrected heading for subsequent turns — see Wall Alignment - Multiple calibration sets (for different floor surfaces) are covered in Calibration