ROS service adapter

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The ROS service call adapter allows you to map commands and buttons in Formant to ROS service calls. For example, using the adapter, you can map a button in your teleoperation interface called Check Robot to a ROS service called /robot_status_check. When the button Check Robot is pressed, it will internally call /robot_status_check. The result of the service call is then posted to a data stream.

This guide will teach you how to configure the ROS service adapter for your Formant organization.

Step 1: Install rosgraph

Install rosgraph to your device via the following command:

Ubuntu 20.04

apt-get install python3-rosgraph

Ubuntu 18.04

apt-get install python-rosgraph

Step 2: Download and install the ROS service adapter

  1. On our GitHub page, download the latest ROS service adapter from our Adapters repository: GitHub: Adapters releases.
  2. Follow the instructions in Add an adapter to install the adapter to your Formant organization and your device.

Step 3: Configure command mapping

By default, Formant will send commands, and the adapter will listen for them, under the name rosservice.

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It is highly recommended that you do not change this mapping.

Step 4: Configure button mapping

You can configure a button either as a ROS button (in which case other sources can also request the adapter call a services by sending a boolean message) and also as an API button.

To map a button press to a specified ROS service, go into the config.json file. Under either ros-button-mapping or api-button-mapping, we need to add a dictionary entry. The key of this entry will be the name of either the ROS topic or the API button. The value of this entry will be a dictionary which holds the service call parameters, and this dictionary can be automatically generated via the create_call.py script. The usage of the
script is show in the section below.

This is a sample of a ROS button mapped to a call to the /random service looks like in the config.json:

{
    "service-commands": [
        "rosservice"
    ],
    "api-button-mapping": {},
    "ros-button-mapping": {
        "/ros_button": {
            "/random": {
                "string": "sample-string",
                "int64_arr": [
                    1.0,
                    2.0
                ],
                "float32": 3.0,
                "float64_arr": [
                    4.0
                ],
                "twist": {
                    "twist.linear": {
                        "twist.linear.x": 5.0,
                        "twist.linear.y": 6.0,
                        "twist.linear.z": 7.0
                    },
                    "twist.angular": {
                        "twist.angular.x": 8.0,
                        "twist.angular.y": 9.0,
                        "twist.angular.z": 10.0
                    }
                }
            }
        }
    }
}

That's it. Now a button press to the i_am_a_button button will map to the service call!

Step 5: Generate the service call using create_call.py

To generate the service call using create_call.py (which is highly recommended), first ensure that roscore and the service are both running. Further, ensure that the proper catkin_ws has been sourced. Once that is done, run python3 create_call.py.

This will first output all the current running services. You will be prompted to type the service you would like to generate the call json for. In our example case, we input /random. Once we input the service name, the script will ask for an input for each parameter in the service. Simply type the wanted value for each parameter. Once complete, the script will print out the service call json. Copy this value and paste it into the config.json, specifically, it is should be the value of the key we added for the button which we would like to call the specified service.

Here is an example of using the create_call.py script:

$ python3 create_call.py

INFO: Agent communication established.
Current services: 

        /rosout/get_loggers
        /rosout/set_logger_level
        /formant_tf2_lookup_transform_node/get_loggers
        /formant_tf2_lookup_transform_node/set_logger_level
        /formant_tf2_lookup_transform_node/tf2_frames
        /formant_bridge_node/get_loggers
        /formant_bridge_node/set_logger_level
        /random_server/get_loggers
        /random_server/set_logger_level
        /random


Please enter service: /random
Please enter a value for parameter 'string': sample-string
Please enter a comma separated array of numbers for parameter 'int64_arr':
        1,2
Please enter a number for parameter 'float32': 3
Please enter a comma separated array of numbers for parameter 'float64_arr':
        4
Please enter a number for parameter 'twist.linear.x': 5
Please enter a number for parameter 'twist.linear.y': 6
Please enter a number for parameter 'twist.linear.z': 7
Please enter a number for parameter 'twist.angular.x': 8
Please enter a number for parameter 'twist.angular.y': 9
Please enter a number for parameter 'twist.angular.z': 10
Successfully Generated service call...


{'/random': {'string': 'sample-string', 'int64_arr': [1.0, 2.0], 'float32': 3.0, 'float64_arr': [4.0], 'twist': {'twist.linear': {'twist.linear.x': 5.0, 'twist.linear.y': 6.0, 'twist.linear.z': 7.0}, 'twist.angular': {'twist.angular.x': 8.0, 'twist.angular.y': 9.0, 'twist.angular.z': 10.0}}}}

Step 6: Updating current services in Formant.io

It is possible to get this adapter to send back all the currently active services along with their argument names and types. To do this, simply add the command ros.services.update-services to Formant. Issuing this Command will cause the adapter to send back all currently active services to the stream ros.services.json.

Troubleshooting

You may attempt to run the service call adapter and notice that one of the service's that is running on your machine is not showing up on the stream ros.services.json. The most common reason that this occurs is that the export CATKIN_WS=<catkin_ws dir> is not located in /var/lib/formant/.bashrc. You can check by running cat /var/lib/formant/.bashrc and checking if the export CATKIN_WS=<catkin_ws dir> is located in the file. If not, then simply add a new line in the bashrc file, and replace <catkin_ws dir> with the directory of your machines catkin workspace such that setup.bash may be found at <catkin_ws dir>/devel/setup.bash.

Updated 3 months ago