Add System Monitor Configuration Guide

docs/how-to-guides/configuring-system-error-monitor.md

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+# Configuring System Error Monitor
+
+## Overview
+
+Although Autoware repository has CI tests to do integration testing, there are always unkown error causing function failure.
+This may include:
+
+- Nodes terminates abnormally
+- Nodes freezes without crashing and stops publishing message or causes drop in publish rate of message.
+- Nodes functioning beyond it's designed state (e.g., losing its localization pose, large deviation from planned trajectory, etc)
+
+In order to detect such failure and trigger minimum risk manuever, we have system monitoring module.
+This page explains how users can configure `system_error_monitor` for Autoware for their use case.
+
+## Configuring Parameters
+
+### Turning on Emergency Handler function
+
+By default, Contorl module will ignore any emergency control sent from System Monitor Module.
+This is because it is not always safe to make a sudden stop at node failure, and we would like the user to be aware of the function when it is turned on.
+
+In order to turn on its function, modify `use_emergency_handling` parameter to true in [vehicle_cmd_gate](https://github.com/autowarefoundation/autoware.universe/tree/main/control/vehicle_cmd_gate) package.
+For example, if you are using autoware.launch.xml to launch Autoware, modify the parameter in this [file](https://github.com/autowarefoundation/autoware_launch/blob/main/autoware_launch/config/control/vehicle_cmd_gate/vehicle_cmd_gate.param.yaml).
+
+### Adding new topic monitoring
+
+By default, only few of the topics are monitored as default.
+You can add new topic monitor by modifying `topics.yaml` file passed to [component_state_monitor](https://github.com/autowarefoundation/autoware.universe/tree/main/system/component_state_monitor) launch file.
+
+For example, if you are using autoware.launch.xml to launch Autoware, modify the parameter in this [file](https://github.com/autowarefoundation/autoware_launch/blob/main/autoware_launch/config/system/component_state_monitor/topics.yaml) to add the new topic `/planning/scenario_planning/lane_driving/behavior_planning/path` as monitoring target:
+
+```
+- module: planning
+  mode: [online, planning_simulation]
+  type: autonomous
+  args:
+    node_name_suffix: scenario_planning_path
+    topic: /planning/scenario_planning/lane_driving/behavior_planning/path
+    topic_type: autoware_auto_planning_msgs/msg/Path
+    best_effort: false
+    transient_local: false
+    warn_rate: 5.0
+    error_rate: 1.0
+    timeout: 1.0
+```