When should I use diagnostic_aggregator?
Please help in writing up a ROS best practice.
ROS Resources: Documentation | Support | Discussion Forum | Index | Service Status | ros @ Robotics Stack Exchange |
Please help in writing up a ROS best practice.
Executive Summary
Use /diagnostics
to publish hardware diagnostics data from every device driver.
Use diagnostics_aggregator
to collect and group diagnostics data on any significant system.
Background: /diagnostics
To begin with, it is best practice to set up diagnostics on all robot hardware at a minimum. Most of the drivers included with ROS include some form of diagnostics messages. The ROS diagnostics toolchain is not a computation graph level concept (like parameters, nodes, or topics), but is instead built on top of the /diagnostics
topic.
Hardware drivers publish to the /diagnostics
topic a diagnostic_msgs/DiagnosticArray message, which contains a header (sequence number, timestamp, and frame_id) and an array of diagnostic_msgs/DiagnosticStatus messages.
The DiagnosticStatus
contains:
byte level
- One of three states (OK, WARN, ERROR), which represents the overall hardware health.string name
- The name of the device this DiagnosticStatus
representsstring hardware_id
- A unique hardware identifier, possibly a serial number or UUIDAny node subscribing to this /diagnostics
topic will receive the raw diagnostics messages (which can be overwhelming on a large system like the PR2).
To visualize raw diagnostics messages in ROS, you can currently use the runtime_monitor by simply running:
rosrun runtime_monitor montior
More Background: The diagnostic_updater
The diagnostic_updater is not quite relevant to the aggregator, but is an often-overlooked tool. It provides convenience functions for working with the DiagnosticArray
messages with your hardware drivers in C++.
With the diagnostic_updater
libraries, you can create an object for interacting with DiagnosticArray
messgaes, as well as monitoring frequency status, and over/under monitoring for critical values in your hardware device (temperature, voltage, etc).
This was mainly included in this write-up so that no one tries to reinvent what is already written.
The Diagnostic Aggregator
diagnostic_aggregator is a package for aggregating and analyzing diagnostics data.
Assuming that you have a working robotic system publishing raw diagnostic data to /diagnostics
, you will see that the raw data accumulates quickly, and becomes cumbersome to actually sort through. For this reason, we use the diagnostic_aggregator
. It allows us to group and sort data into namespaces (much like the ROS computational graph). It will also rate-limit the aggregated diagnostics output to ~pub_rate
(typically 1 Hz).
From the wiki page, this can transform something like:
Left Wheel
Right Wheel
SICK Frequency
SICK Temperature
SICK Connection Status
Stereo Left Camera
Stereo Right Camera
Stereo Analysis
Stereo Connection Status
Battery 1 Level
Battery 2 Level
Battery 3 Level
Battery 4 Level
Voltage Status
Into something that is more readable, like:
My Robot/Wheels/Left
My Robot/Wheels/Right
My Robot/SICK/Frequency
My Robot/SICK/Temperature
My Robot/SICK/Connection Status
My Robot/Stereo/Left Camera
My Robot/Stereo/Right Camera
My Robot/Stereo/Analysis
My Robot/Stereo/Connection Status
My Robot/Power System/Battery 1 Level
My Robot/Power System/Battery 2 Level
My Robot/Power System/Battery 3 Level
My Robot ...
(more)RFP 107 might be worth being added to the ref to get an overview of ROS' diagnostics concept: http://www.ros.org/reps/rep-0107.html
This has been added to ROS/Patterns here: http://www.ros.org/wiki/ROS/Patterns/RobotModelling#Runtime_Diagnostics
Asked: 2011-11-07 11:45:35 -0500
Seen: 2,164 times
Last updated: Mar 14 '12
Publishing diagnostics info with python on fuerte?
diagnostics aggregator: discard_stale with no effect
Diagnostic aggregator not reading messages from new publishers on /diagnostics topic [closed]
How to update diagnostics on Groovy built from source (into Odroid)?
Diagnostic aggregator not resetting between runs
How can two nodelets in one process publish diagnostics?
add diagnostics at runtime not working (tutorial)
Removing a prefix from a Diagnostics Aggregator Group
DiagnosticAggregator Analyzer: report() does not report every analyzed message