High-Speed Line Follower Robot (STM32)
Competition-grade line follower with 24-IR sensor array, custom PID (gain scheduling), and PWM motor control on STM32. Focus on stability at speed and repeatable lap times.
Objective
Achieve stable, high-speed tracking on varied surfaces with minimal overshoot and low lap-time variance. Emphasis on robust signal processing for a 24-channel IR array and tight, deterministic control loops on STM32.
System Architecture
- MCU: STM32 (C, HAL) with timer-driven control loop.
- Sensing: 24-IR reflectance array, outlier rejection, smoothing.
- Actuation: Dual DC motors via PWM, dead-zone compensation.
- Control: PID + gain scheduling by speed and curvature.
- Hardware: Rapid PCB iterations to improve SNR and reduce latency.
Control Design & Tuning
- Position error computed from weighted sensor centroid; clamped derivative to reduce noise amplification.
- Anti-windup via integral clamping; conditional integral at high error.
- Gain scheduling: higher Kd at speed; lower Ki on sharp curvature to prevent oscillation.
Results
- Overshoot events reduced significantly after derivative clamp and gain schedule.
- Lap-time variance tightened across surfaces (glossy/matte/painted).
- Repeatable performance through deterministic timing and debounced sensor reads.
