feat(#169): emergency behavior system — obstacle stop, fall prevention, stuck detection, recovery FSM
Two new packages:
- saltybot_emergency_msgs: EmergencyEvent.msg, RecoveryAction.msg
- saltybot_emergency: threat_detector, alert_manager, recovery_sequencer, emergency_fsm, emergency_node
Implements:
- ObstacleDetector: MAJOR <30cm, CRITICAL <10cm; suppressed when not moving
- FallDetector: MINOR/MAJOR/CRITICAL tilt thresholds; floor-drop edge detection
- StuckDetector: MAJOR after 3s wheel stall (cmd>threshold, actual~0)
- BumpDetector: jerk = |Δ|a||/dt with gravity removal; MAJOR/CRITICAL thresholds
- AlertManager: per-(type,level) suppression; MAJOR×N within window → CRITICAL escalation
- RecoverySequencer: REVERSING→TURNING→RETRYING FSM; max_retries before GAVE_UP
- EmergencyFSM: NOMINAL→STOPPING→RECOVERING→ESCALATED; acknowledge to clear
- EmergencyNode: 20Hz ROS2 node; /saltybot/emergency, /saltybot/e_stop, cmd_vel mux
59/59 tests passing.
Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
sl-controls
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