Add saltybot_head_tracking — ROS2 Python node for automatic person-
following using dual-axis PID control targeting the pan/tilt camera head.
Pipeline:
1. Subscribe to /saltybot/objects (DetectedObjectArray from YOLOv8n)
2. Filter for class_id==0 (person); select best target by score:
score = 0.6 * 1/(1+dist_m) + 0.4 * confidence
(falls back to confidence-only when distance_m==0 / unknown)
3. Compute pixel error of bbox centre from image centre
4. Apply dead-zone (10 px default) to suppress micro-jitter
5. Convert pixel error to angle error via camera FOV
6. Independent PID controllers for pan and tilt axes
7. Accumulate PID output into absolute angle setpoint
8. Publish geometry_msgs/Point to /saltybot/gimbal/cmd:
x = pan_angle_deg, y = tilt_angle_deg, z = confidence
State machine:
IDLE -> waiting for first detection
TRACKING -> active PID
LOST -> hold last angle for hold_duration_s (3 s)
CENTERING -> return to (0, 0) at 20 deg/s -> IDLE
Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
