Programming · Autonomous
Autonomous that lands reliably
Encoders, IMU turns, basic PID, and reliability practices for match-ready autonomous.
What this is
- Core motion building blocks: encoder drive and IMU turns.
- Lightweight PID concepts for driving straight and turning.
- Reliability habits to survive field variance.
When you need it
- Auto misses targets, drifts, or times out.
- Runs differently on carpet vs field tiles.
- Need consistent scores for judging and playoffs.
How it works
- Encoder drive: convert inches → ticks; run to position or open-loop with power cap and timeout.
- IMU turns: read heading, compute error, apply proportional (and optional integral/derivative) correction.
- PID basics: P corrects error, I handles bias (use small or zero), D damps oscillation.
- Reliability: clamp power, add timeouts, and re-zero heading at start; gate motions by both position and time.
Common mistakes
- No timeout → stuck robot burns whole auto.
- Too high P on turns → oscillation; too low → saggy turns.
- Ignoring battery level → distance overshoots when voltage is high.
- Not resetting encoders/heading before path start.
How to test it
- Bench: confirm encoder counts change with wheels raised.
- Drive straight 1–2 m at low, then medium power; log drift vs heading.
- Turn 90° both directions; measure average error; tune P (and small D) until settle is quick and stable.
- Run full path 5×; confirm variance stays within scoring tolerance.
Related problems
- Auto stops early → timeout too short or encoder not counting; check wiring.
- Inconsistent turns → recalibrate IMU; warm-start and wait for init.
- Slides sag during moves → add hold power or PID position control.