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Recorder Service Overview

The Recorder App/Service is the backbone of the Amiga's data logging and playback functionality. It is designed to capture and store raw data from various robot services, facilitating later analysis, debugging, and model training.

Beginning with AmigaOS 2.3 Elderberry, the Recorder service is a sub-service included as part of the Amiga Service.

Purpose​

The primary objective of the Recorder sub-service is to provide a robust mechanism for recording data streams from different services. This is invaluable for tasks such as training computer vision/AI models, where capturing field imagery is essential. For instance, when developing a precision sprayer application for weeds, one would first traverse the field, recording data to train a model to detect weeds.

Subscriptions​

The Recorder Service is a subscriber to the following services:

  • Canbus
  • Filter
  • GPS
  • Oak (Multiple Oak topics may be available, depending on the number of Oak cameras connected, e.g., oak/0, oak/1, ...)
  • System Monitor
  • Track Follower

Available Topics for Recording​

The Recorder Service offers a variety of topics that can be recorded. Each topic provides specific data streams from the robot's various services. Here's a breakdown of each topic:

tip

Check out the protobuf messages streamed on these topics at:
farm-ng-amiga/protos/.

Some of which may inherit from the protobuf messages found at:
farm-ng-core/protos/

  • Canbus Topics

  • Filter Topics

  • GPS Topics

  • Oak Topics

  • System Monitor Topics

    • system_monitor/health: Delivers health metrics for the system_monitor service, including publishing frequency.
    • system_monitor/cpu_usage: Streams the percent of CPU currently being consumed on the brain.
    • system_monitor/filter_state: Streams the filter service state.
    • system_monitor/wifi_state: Streams auto mode state (either true or false).
    • system_monitor/virtual_memory_usage: Streams athe percent of virtual memory being consumed by the brain.

  • Track Follower Topics

These topics ensure that users have a comprehensive set of data streams to choose from, depending on their specific needs and analysis requirements.

Recording Profile​

To initiate recording, a "Recording profile" must be provided as an argument. This profile is a EventServiceConfig protobuf, detailing the subscriptions or topics to be recorded.

{
    "name": "my_profile",
    "subscriptions": [
        {
        "uri": {
            "path": "*",
            "query": "service_name=canbus"
        },
        "every_n": 1
        },
        {
        "uri": {
            "path": "*",
            "query": "service_name=gps"
        },
        "every_n": 1
        },
        {
        "uri": {
            "path": "/imu",
            "query": "service_name=oak/0"
        },
        "every_n": 1
        },
        {
        "uri": {
            "path": "*",
            "query": "service_name=filter"
        },
        "every_n": 1
        }
    ]
}
INFO

The * symbol in the path field indicates that all available topics of that specific subscription (service) should be recorded.

The every_n field indicates the ratio of recording frequency. For example, if the publishing rate of oak/0/imu is 50 ms, an every_n of "2" will yield in data being recording every 100 ms (2 * 50 ms).

API​

Users can interact with the Recorder Service using the following commands:

  • recorder/start: Initiates data recording. A valid "Recording profile" must be provided as an argument.
  • recorder/stop: Halts the data recording process.

Data Storage​

All recorded data is saved as binary files on the disk at /mnt/data. The naming convention for these files captures the precise timestamp (to the microsecond) at the recording's start, the robot's name, and the file number in the sequence:

<yyyy>_<mm>_<dd>_<hh>_<mn>_<ss>_<msmsms>_<robot_name>.0000.bin

For example:

2024_06_01_12_00_00_134845_element-vegetable.0000.bin

How to Use​

Data can be recorded through the AppBar, the Camera App, or using the EventsClient class as in the Events Recorder example.