CogniTao ROS2 Examples

• Make sure cognitao plugins for ROS2 are installed
• For cognitao library general examples see https://git.cogni.io/cognitao/cognitao_examples .

WorldModel Monitor

• cognitao_wmm is a program installed by default along cognitao_server
• Using cognitao_wmm it is possible to create a local synchronized world model through a ros2 datasource

$ export COGNITAO_DATASOURCE="ros2"
$ cognitao_wmm

• This will make available a topic /wme/in
• Through this topic it is possible to listen and publish world model key/value events
• These events will be synchronized among wolrd models

Wait example

• In this example we are going to create a server for one or more wait action requests.
• To do so we extend RosActionServer RosActionServer header and implement it's execute method RosActionServer cpp

void RosActionWaitServer::execute(RosActionContext action) {

    // get parameters
    for(auto param : action.getParameters())
    {
        cout << param.first <<  << endl;
    }
    
    while( /* check condition*/)
    {
        // do some work
        std::this_thread::sleep_for(std::chrono::milliseconds(1000));

        // check if should stop
        // cancel goal
        if (ros2ActionContext.isPreemptRequested() ) {             
            ros2ActionContext.cancelGoal();            
            return;
        }      
 
    }

    // return when done
    action.setResult(true);
}

• In the execute method
  • we can use action.getParameters() to get the actions parameters from the XML
  • we can use action.isPreemptRequested() to query if this remote goal needs to be stopped
  • we can use action.setResult(true/false) to set the return value
• Now we will define an XML that will invoke this action on the server XML

<machine name="testBT" type="bt">
	<task name="wait" runner="ros2" action="wait" param_time="10.0"/>
</machine>

• Now you can compile this project using catkin and should be able to run

$ rosrun cognitao_ros action_wait_server 

• This server will connet to your ros_master and wait for a goal
• From another terminal run

export COGNITAO_DATASOURCE="ros2"
$ cognitao_server assets/wait_example.xml

• This will load a plan that will invoke an action in the wait server
• Actions can run in parrallel, are remotely monitored and preempted if needed

Build status

master

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