How Steward OS monitors health

1. Components self-report their health

Every essential component, and most non-essential components regularly publish DiagnosticStatus messages. These statuses include the name of the component, its current health level, and a brief description.

2. The Health Monitor monitors all statuses

The Health Monitor, which is itself a ROS2 node, combines all statuses into a complete list. It inspects each status in the list with the help of a predefined list of checks. These are like unit tests, but they happen constantly during operation.

3. The Health Monitor makes a diagnosis and takes action

The Monitor has two jobs. First, it provides clear information to the user about Steward’s complete health. Think of this as the diagnostic panel on your car: Your car may display may warn you about low tire pressure or a faulty engine, but it doesn’t actually prevent you from trying to drive. It’s up to you, the user, to either operate the car or not.

Second, the Monitor disables operation if necessary. This makes it different from your car’s diagnostics. In serious failure conditions, the Health Monitor will actually block Steward from entering TELEOP or AUTO modes. See system-wide status levels

Example: Disabling TELEOP and AUTO

If the Monitor detects a motor failure, then it will disable both TELEOP and AUTO, as it is not safe to move the Warthog either autonomously or manually.

Example: Disabling AUTO but not TELEOP

If instead the Monitor detects a Map Manager error, then it will disable AUTO but not TELEOP, as it is still safe for a human to control the robot.

System-wide status levels

🟢 Healthy

All systems are operating normally.

🟡 Warn

Steward can operate autonomously, but some features may be disabled or limited. For example, ground speed may be limited.

🟠 Teleop Only

Steward’s autonomy is unavailable due to a significant fault in the planning or perception systems, in a sensor interface, or some other critical component.

🔴 Out of Service

Steward OS is completely unavailable.

Checks

Interfaces

Is Steward OS connected to the Warthog or EcoSim?

Code	BRIDGE_FAILURE
Inspects	bridge/steward or bridge/warthog
Period	0.2s (5 Hz)
Triggers	🔴 Out of Service
Message	Steward is unable to connect to the Warthog or the simulator and cannot operate.