Add saltybot_safety_zone — ROS2 Python node that processes the RPLIDAR
A1M8 /scan into three concentric 360° safety zones, latches an e-stop
when DANGER is detected in the forward arc, and overrides /cmd_vel to
zero while the latch is active.
Zone thresholds (default):
DANGER < 0.30 m — latching e-stop in forward arc
WARN < 1.00 m — advisory (published in sector data)
CLEAR otherwise
Sector grid:
36 sectors of 10° each (sector 0 = robot forward, CCW positive).
Per-sector: angle_deg, zone, min_range_m, in_forward_arc flag.
E-stop behaviour:
- Latches after estop_debounce_frames (2) consecutive DANGER scans
in the forward arc (configurable ±30°, or all-arcs mode).
- While latched: zero Twist published to /cmd_vel every scan + every
incoming /cmd_vel_input message is blocked.
- Clear only via service (obstacle must be gone):
/saltybot/safety_zone/clear_estop (std_srvs/Trigger)
Published topics:
/saltybot/safety_zone String/JSON every scan
— per-sector {sector, angle_deg, zone, min_range_m, forward}
— estop_active, estop_reason, danger_sectors[], warn_sectors[]
/saltybot/safety_zone/status String/JSON 10 Hz
— forward_zone, closest_obstacle_m, danger/warn counts
/cmd_vel Twist zero when e-stopped
Subscribed topics:
/scan LaserScan — RPLIDAR A1M8
/cmd_vel_input Twist — upstream velocity (pass-through / block)
Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
