Welding Application

This is a GL Hub Application for Welding Operations. The interface, built using Flask, is designed to be run on reTerminal DM devices that come with a Raspberry Pi CM4 + Touchscreen. The application also control one of the GPIO pins to lock/unlock the solenoid when performing welding operations.

Getting Started

The device (reTerminal DM) will need to be flash with a custom balenaOS image with the necessarily custom device tree so that the OS can see the touchscreen (See Google Docs runbook for more details). Additionally, the touchscreen would also require a special branch of GL Hub that allows the custom kernal modules to be loaded in before initializing the browser container.

Configuring the Application

The app requires the following environment variables:

• WELD_APP_CONFIG: This is the application config for the app and it follows the following JSON format which can be copied/pasted to the balena dashboard's device variables section:

{
    "edge_endpoint": "EDGE_ENDPOINT_URL_OR_NONE_TO_USE_CLOUD",
    "ml_detector_id": "WELD_DETECTOR_ID", 
    "printer": {
        "printer_ip": "TAG_PRINTER_IP", 
        "printer_port": 9100, 
        "printer_timeout": 5, 
        "printer_paper_width": 2.25, 
        "printer_paper_length": 4.0,
        "printer_dpi": 203 
    }
}

• WELD_CAMERA_CONFIG: This is the camera config for each Jig Stations and it follows the following JSON format which can also be copied/pasted to the balena dashboard's device variables section:

{
    "jig_stations": {
        "1": {
            "camera_config": {
                "name": "Jig Station 1 Camera",
                "input_type": "rtsp",
                "id": {
                    "rtsp_url": "RTSP_URL_HERE"
                },
                "options": {
                    "keep_connection_open": true,
                    "crop": {
                        "relative": {
                            "left": 0.0,
                            "right": 1.0
                        }
                    }
                }
            }
        }, 
        "2": {
            "camera_config": {
                "name": "Jig Station 2 Camera",
                "input_type": "rtsp",
                "id": {
                    "rtsp_url": "RTSP_URL_HERE"
                },
                "options": {
                    "keep_connection_open": true,
                    "crop": {
                        "relative": {
                            "left": 0.0,
                            "right": 1.0
                        }
                    }
                }
            }
        }
    }
}

Each camera_config entries will need to match the configuration settings for FrameGrab so the cameras can be intiialized correctly.

• WELD_APP_DATABASE_CONFIG: This is the database config for fetching data from Google API Service.

{
    "enabled": true,
    "service_account": {
        "type": "service_account",
        "project_id": "PROJECT_ID_HERE",
        "private_key_id": "PRIVATE_KEY_ID_HERE",
        "private_key": "PRIVATE_KEY_HERE",
        "client_email": "CLIENT_EMAIL_HERE",
        "client_id": "CLIENT_ID_HERE",
        "auth_uri": "https://accounts.google.com/o/oauth2/auth",
        "token_uri": "https://oauth2.googleapis.com/token",
        "auth_provider_x509_cert_url": "https://www.googleapis.com/oauth2/v1/certs",
        "client_x509_cert_url": "CLIENT_CERT_URL_HERE",
        "universe_domain": "googleapis.com"
    },
    "database_id": "YOUR_DATABASE_ID_HERE",
    "database_range": "Sheet1!A2:C"
}

The service_account section should match the credential JSON file downloaded from Google Cloud.

• WELD_APP_SUPERVISOR_PASSWORD: The supervisor password to lock/unlock the Jig Lock, default to None if not set

• WELD_APP_DEVICE_ID: Set the device ID for this particular device, should set this unique for each device for easier debugging

• GROUNDLIGHT_API_TOKEN: Groundlight API Token

• LAUNCH_URL: Set this to http://router/hub/launch/1 to ensure that the device automatically redirects to the application main page when it is ready

Setting up Database

The app can communciate with Google Sheets to get the weld count of a particular part number if the WELD_APP_DATABASE_CONFIG is properly configured. The sheet should follow the following format:

Part Number	Left Weld Count	Right Weld Count
Part1	5	2
Part2	2	0
Part3	0	10

Creating Supervisor Password

If the you would like to only allow supervisors to lock/unlock the Jig Lock, you need to set the environment variable WELD_APP_SUPERVISOR_PASSWORD with the hashed password.

The hashed password can be created with the generate_hash.py script by running the following command:

poetry run python generate_hash.py PASSWORD

Copy the hashed password generated from the script to the environment variable:

export WELD_APP_SUPERVISOR_PASSWORD="HASHED_PASSWORD"

For balena deployment just copy the hashed password into the Device Variables tab.

Local Testing

To run the app on your local machine just run this command:

poetry run python run.py

Note that the GPIO function will not work and the app will shows a warning about this.

For testing your own RTSP streams you can use VLC's command to start a RTSP server on your local machine.

brew install vlc

vlc -vvv YOUR_VIDEO_HERE --loop --sout '#transcode{vcodec=h264,acodec=mpga,ab=128,channels=2,samplerate=44100,scodec=none}:rtp{sdp=rtsp://:8554/feed}' --sout-all --sout-keep

The video should be broadcasting on rtsp://127.0.0.1:8554/feed or on your machine assigned IP address.