jetson/config/RECOVERY_BEHAVIORS.md

@@ -4,7 +4,12 @@
 
 ## Overview
 
-Recovery behaviors are triggered when Nav2 encounters navigation failures (path following failures, stuck detection, etc.). The recovery system attempts multiple strategies before giving up.
+Recovery behaviors are triggered when Nav2 encounters navigation failures (path following failures, stuck detection, etc.). The recovery system attempts multiple strategies before giving up:
+
+1. **Clear costmaps** — Reset perception obstacles
+2. **Spin recovery** — In-place 90° rotation to detect surroundings
+3. **Wait recovery** — 5-second pause for dynamic obstacles to move
+4. **Backup recovery** — Reverse 0.3m to escape deadlocks
 
 ## Configuration Details
 
@@ -32,13 +37,29 @@ Recovery behaviors are triggered when Nav2 encounters navigation failures (path
 
 ## Safety: E-Stop Priority (Issue #459)
 
-The emergency stop system (Issue #459, `saltybot_emergency` package) runs independently of Nav2 and takes absolute priority.
+The emergency stop system (Issue #459, `saltybot_emergency` package) runs independently of Nav2 and takes absolute priority:
+
+- **Trigger**: Obstacles within 0.3m (configurable)
+- **Action**: Immediate zero velocity command, overrides all recovery behaviors
+- **Integration**: Publishes directly to `/cmd_vel`, pre-empting Nav2 output
 
 Recovery behaviors cannot interfere with E-stop because the emergency system operates at the motor driver level on the STM32 firmware.
 
 ## Behavior Tree Sequence
 
-Recovery runs in a round-robin fashion with up to 6 retry cycles.
+Recovery runs in a round-robin fashion with up to 6 retry cycles:
+
+```
+NavigateRecovery (6 retries)
+├── Normal navigation (compute path → follow path)
+└── Recovery fallback:
+    ├── Clear costmaps
+    ├── Spin 90°
+    ├── Wait 5s
+    └── Back up 0.3m @ 0.1 m/s
+```
+
+Each cycle, the next recovery action is attempted (round-robin). If navigation succeeds, recovery stops. If all retries exhaust, goal fails.
 
 ## Constraints for FC + Hoverboard ESC
 
@@ -49,3 +70,31 @@ This configuration is specifically tuned for:
 - **Recovery velocity constraints**: 50% of normal for stability
 
 The conservative recovery speeds ensure smooth deceleration profiles on the self-balancing drivetrain without tipping or oscillation.
+
+## Configuration Files
+
+- **nav2_params.yaml**: behavior_server section with spin, backup, wait parameters
+- **navigate_to_pose_with_recovery.xml**: Behavior tree defining recovery sequence
+- **emergency.launch.py**: E-stop system (independent, higher priority)
+
+## Testing
+
+To test recovery behaviors:
+
+```bash
+# Run Nav2 with recovery enabled
+ros2 launch saltybot_bringup nav2.launch.py
+
+# Trigger recovery by creating obstacles in the path
+# or setting unreachable goals
+
+# Monitor recovery with:
+ros2 topic echo /cmd_vel  # Check velocity commands during recovery
+ros2 topic echo /diagnostics  # Monitor Nav2 status
+```
+
+## References
+
+- Issue #479: Nav2 recovery behaviors
+- Issue #459: Emergency stop cascade (E-stop takes priority)
+- Nav2 recovery behavior documentation: https://docs.nav2.org/