ROS-Aseba: examples

Setup

To reproduce a multi-robot network (two Thymios with id 14031 and 21181, and two e-pucks with id 1 and 2), launch Aseba Playground

asebaplayground

and open the world at ros-aseba/asebaros_examples/launch/simulation/multirobot.playground

<!DOCTYPE aseba-playground>
<aseba-playground>
     <author name="Jerome Guzzi" email="jerome at idsia dot ch" />
     <description lang="en">A simple multi-robot playground to experiment with asebaros without physical robots.</description>
     <color name="wall" r="0.9" g="0.9" b="0.9" />
     <world w="100" h="100" color="wall"/>
     <robot type="thymio2" x="45" y="15" port="33334" name="Thymio A" nodeId="1" />
     <robot type="thymio2" x="45" y="45" port="33335" name="Thymio B" nodeId="1"/>
     <robot type="e-puck" x="15" y="15" port="33336" name="E-Puck A" nodeId="1" />
     <robot type="e-puck" x="15" y="45" port="33337" name="E-Puck B" nodeId="1" />
</aseba-playground>

Use Aseba Switch to make the robots join the same network at port 33333.

asebaswitch "tcp:host=localhost\;port=33334\;remapLocal=21181\;remapTarget=1" "tcp:host=localhost\;port=33335\;remapLocal=14031\;remapTarget=1" "tcp:host=localhost\;port=33336\;remapLocal=1\;remapTarget=1" "tcp:host=localhost\;port=33337\;remapLocal=2\;remapTarget=1" -p 33333

With this setup DEVICE="tcp:host=localhost;port=33333".

To execute any ROS command, you have first to source the ROS setup script

source <WORKSPACE>/install/setup.bash

Note

The examples below works with any other Aseba network, and in particular with real robots too. In this case, just change the ids and add device:=<DEVICE> to the ROS launch arguments (e.g., device:="ser:name=Thymio" to connect a Thymio).

All nodes

The following launch files configure asebaros to connect to all nodes at Dashel target device. Each node will receive a ROS namespace "node_{id}". No script will be automatically loaded into the nodes.

<launch>

  <arg name="device" default="tcp:host=localhost;port=33333"/>
  <arg name="port" value="44444"/>

  <node name="asebaros" pkg="asebaros" type="asebaros" output="screen">
    <param name="port" value="$(arg port)"/>
    <param name="shutdown_on_unconnect" value="false"/>
    <param name="highest_acceptable_protocol_version" value="20"/>
    <rosparam param="targets" subst_value="true">
      ["$(arg device)",]
    </rosparam>
    <rosparam param="nodes">
      any:
        accept: true
        prefix: node_
    </rosparam>
  </node>
</launch>

Launch it with

roslaunch asebaros_examples all_nodes.launch

Inspect the system using services:

  1. Get the list of nodes

rosservice call /aseba/get_nodes asebaros_msgs/GetNodeList '{}'

  1. Get the description of one of the nodes

rosservice call /node_14031/aseba/get_description asebaros_msgs/GetDescription '{}'

  1. Get the value of a variable

rosservice call /node_14031/aseba/get_variable asebaros_msgs/GetVariable "{variable: prox.horizontal}"

  1. Set the value of a variable

rosservice call /node_14031/aseba/set_variable asebaros_msgs/SetVariable "{variable: motor.left.target, data: [100]}"

A single node

The following launch files configure asebaros to connect to just the first Thymio (i.e., the first Aseba node with name=="thymio-II")

<launch>

  <arg name="device" default="tcp:host=localhost;port=33333"/>
  <arg name="port" value="44444"/>

  <node name="asebaros" pkg="asebaros" type="asebaros" output="screen">
    <param name="port" value="$(arg port)"/>
    <param name="reload_script_on_reconnect" value="true"/>
    <param name="set_id_variable" value="false"/>
    <param name="shutdown_on_unconnect" value="false"/>
    <param name="highest_acceptable_protocol_version" value="20"/>
    <rosparam param="targets" subst_value="true">
      ["$(arg device)",]
    </rosparam>
    <rosparam param="nodes">
      others:
        accept: false
      thymio:
        name: thymio-II
        id_variable: _id
        accept: true
        include_id_in_events: false
        maximal_number: 1
    </rosparam>
    <rosparam param="script" subst_value="true">
      path: $(find asebaros_examples)/launch/single_node.aesl
      constants:
        MY_CONSTANT: 3
    </rosparam>
  </node>
</launch>

The node will receive an empty ROS namespace and a script will be automatically loaded into the node. The script has a single constant MY_CONSTANT, which the launch file sets to 3, and two events: ping and pong.

<!DOCTYPE aesl-source>
<network>

  <!--list of global events-->
  <event size="3" name="ping"/>
  <event size="3" name="pong"/>

  <!--list of constants-->
  <constant value="0" name="MY_CONSTANT"/>

  <!--show keywords state-->
  <keywords flag="true"/>

  <!--node thymio-II-->
  <node name="thymio-II">
    var value[3] = [MY_CONSTANT, MY_CONSTANT, MY_CONSTANT]
    emit pong value
    onevent ping
    value = event.args[0:2]
    emit pong value
  </node>

</network>

The events are used to make the robot “pong” back the values (an array of length 3) sent with the ping. Launch it with

roslaunch asebaros_examples single_node.launch

In a new tab send a ping each second

rostopic pub -r 1 /aseba/events/ping asebaros_msgs/Event '{data:  [1, 2, 3]}'

and in another one, listen for pongs

rostopic echo /aseba/events/pong

Twin nodes

In this case, we want to connect to all nodes and load the same script. Each node will receive a namespace "node_{id}".

<launch>

  <arg name="device" default="tcp:host=localhost;port=33333"/>
  <arg name="port" value="44444"/>

  <node name="asebaros" pkg="asebaros" type="asebaros" output="screen">
    <param name="port" value="$(arg port)"/>
    <param name="reload_script_on_reconnect" value="true"/>
    <param name="set_id_variable" value="true"/>
    <param name="shutdown_on_unconnect" value="false"/>
    <param name="highest_acceptable_protocol_version" value="20"/>
    <rosparam param="targets" subst_value="true">
      ["$(arg device)",]
    </rosparam>
    <rosparam param="nodes">
      any:
        prefix: node_
        accept: true
        include_id_in_events: true
      thymio:
        name: thymio-II
        id_variable: _id
      epuck:
        name: e-puck0
        id_variable: id
    </rosparam>
    <rosparam param="script" subst_value="true">
      path: $(find asebaros_examples)/launch/twin_nodes.aesl
      constants:
        MY_CONSTANT: 3
    </rosparam>
  </node>
</launch>

Because the id of the target node is included in the event ping (include_id_in_events=true), the script can check if the event is addressed at the current node, and only in this case “pong” back.

<!DOCTYPE aesl-source>
<network>

  <!--list of global events-->
  <event size="4" name="ping"/>
  <event size="3" name="pong"/>

  <!--list of constants-->
  <constant value="0" name="MY_CONSTANT"/>

  <!--show keywords state-->
  <keywords flag="true"/>

  <!--node thymio-II-->
  <node name="thymio-II">
    var value[3] = [MY_CONSTANT, MY_CONSTANT, MY_CONSTANT]
    emit pong value
    onevent ping
    if (event.args[0] == _id) then
      value = event.args[1:3]
      emit pong value
    end
  </node>

</network>

Launch ROS with

roslaunch asebaros_examples twin_nodes.launch

In a new tab send pings each second to a specific robot

rostopic pub -r 1 /node_14031/aseba/events/ping asebaros_msgs/Event '{data:  [1, 2, 3]}'

and in another one, listen for pongs from different robots

ros2 topic echo /node_14031/aseba/events/pong
ros2 topic echo /node_21181/aseba/events/pong

Two nodes

In this case, we want to connect to two nodes of different types. As the different nodes uses different [incoming] events, we don’t need to include the node id in the event.

<launch>

  <arg name="device" default="tcp:host=localhost;port=33333"/>
  <arg name="port" value="44444"/>

  <node name="asebaros" pkg="asebaros" type="asebaros" output="screen">
    <param name="port" value="$(arg port)"/>
    <param name="reload_script_on_reconnect" value="true"/>
    <param name="set_id_variable" value="false"/>
    <param name="shutdown_on_unconnect" value="false"/>
    <param name="highest_acceptable_protocol_version" value="20"/>
    <rosparam param="targets" subst_value="true">
      ["$(arg device)",]
    </rosparam>
    <rosparam param="nodes">
      others:
        accept: false
      thymio:
        name: thymio-II
        id_variable: _id
        accept: true
        namespace: thymio
        include_id_in_events: false
        maximal_number: 1
      epuck:
        name: e-puck0
        id_variable: id
        accept: true
        namespace: epuck
        include_id_in_events: false
        maximal_number: 1
    </rosparam>
    <rosparam param="script" subst_value="true">
      path: $(find asebaros_examples)/launch/two_nodes.aesl
      constants:
        MY_CONSTANT_THYMIO: 3
        MY_CONSTANT_EPUCK: 333
    </rosparam>
  </node>
</launch>

<!DOCTYPE aesl-source>
<network>

  <!--list of global events-->
  <event size="3" name="ping_thymio"/>
  <event size="3" name="ping_epuck"/>
  <event size="3" name="pong"/>

  <!--list of constants-->
  <constant value="0" name="MY_CONSTANT_THYMIO"/>
  <constant value="0" name="MY_CONSTANT_EPUCK"/>

  <!--show keywords state-->
  <keywords flag="true"/>

  <!--node thymio-II-->
  <node name="thymio-II">
    var value[3] = [MY_CONSTANT_THYMIO, MY_CONSTANT_THYMIO, MY_CONSTANT_THYMIO]
    emit pong value
    onevent ping_thymio
    value = event.args[0:2]
    emit pong value
  </node>

  <!--node e-puck0-->
  <node name="e-puck0">
    var value[3] = [MY_CONSTANT_EPUCK, MY_CONSTANT_EPUCK, MY_CONSTANT_EPUCK]
    emit pong value
    onevent ping_epuck
    value = args[0:2]
    emit pong value
  </node>

</network>

Launch ROS with

roslaunch asebaros_examples two_nodes.launch

In a new tab send pings each second to a specific robot

rostopic pub -r 1 /epuck/aseba/events/ping_epuck asebaros_msgs/Event '{data:  [1, 2, 3]}'

and in another one, listen for pongs

rostopic echo /epuck/aseba/events/pong

A single Thymio

The following launch files configure asebaros to connect to just the first Thymio (i.e., the first Aseba node with name=="thymio-II"), and a script will be automatically loaded into the node.

<launch>

  <arg name="device" default="tcp:host=localhost;port=33333"/>
  <arg name="port" value="44444"/>

  <node name="asebaros" pkg="asebaros" type="asebaros" output="screen">
    <param name="port" value="$(arg port)"/>
    <param name="reload_script_on_reconnect" value="true"/>
    <param name="set_id_variable" value="false"/>
    <param name="shutdown_on_unconnect" value="false"/>
    <param name="highest_acceptable_protocol_version" value="20"/>
    <rosparam param="targets" subst_value="true">
      ["$(arg device)",]
    </rosparam>
    <rosparam param="nodes">
      others:
        accept: false
      thymio:
        type: thymio-II
        id_variable: _id
        accept: true
        name: thymio
        include_id_in_events: false
        maximal_number: 1
    </rosparam>
    <rosparam param="script" subst_value="true">
      path: $(find asebaros_examples)/launch/single_thymio.aesl
      constants:
        OBSTACLE_THRESHOLD: 2500
    </rosparam>
  </node>
</launch>

This time, the node will receive a ROS namespace thymio and the script is specific for the Thymio.

<!DOCTYPE aesl-source>
<network>

  <!--list of global events-->
  <event size="3" name="set_color"/>
  <event size="0" name="obstacle"/>

  <!--list of constants-->
  <constant value="2000" name="OBSTACLE_THRESHOLD"/>

  <!--show keywords state-->
  <keywords flag="true"/>

  <!--node thymio-II-->
  <node name="thymio-II">
    onevent prox
    if (prox.horizontal[2] > OBSTACLE_THRESHOLD) then
      call leds.buttons(32, 32, 32, 32)
      emit obstacle
    else
      call leds.buttons(0, 0, 0, 0)
    end
    onevent set_color
    call leds.top(event.args[0], event.args[1], event.args[2])
  </node>

</network>

The constant OBSTACLE_THRESHOLD controls the onboard behavior that makes the Thymio turn on the button LED to signal a close object. The obstacle event is used to notify ROS of an obstacle while the set_color event is used by ROS to change the Thymio body color.

Launch ROS with

roslaunch asebaros_examples single_thymio.launch

In a new tab set the body LED of the Thymio to cyan

rostopic pub --once /thymio/aseba/events/set_color asebaros_msgs/Event '{data:  [0, 32, 32]}'

and in another one, listen for obstacles (move around the cyan robot)

rostopic echo /thymio/aseba/events/obstacle

Twin Thymios

We want to connect to any Thymio in the network and load the same script. Each of them will get the namespace "thymio_{id}".

<launch>

  <arg name="device" default="tcp:host=localhost;port=33333"/>
  <arg name="port" value="44444"/>

  <node name="asebaros" pkg="asebaros" type="asebaros" output="screen">
    <param name="port" value="$(arg port)"/>
    <param name="reload_script_on_reconnect" value="true"/>
    <param name="set_id_variable" value="true"/>
    <param name="shutdown_on_unconnect" value="false"/>
    <param name="highest_acceptable_protocol_version" value="20"/>
    <rosparam param="targets" subst_value="true">
      ["$(arg device)",]
    </rosparam>
    <rosparam param="nodes">
      others:
        accept: false
      thymio:
        name: thymio-II
        id_variable: _id
        accept: true
        prefix: thymio_
        include_id_in_events: true
    </rosparam>
    <rosparam param="script" subst_value="true">
      path: $(find asebaros_examples)/launch/twin_thymios.aesl
      constants:
        OBSTACLE_THRESHOLD: 2500
    </rosparam>
  </node>
</launch>

Because the paramer include_id_in_events is set to true, asebaros will include the [target] robot id in the event set_color. The script checks that the command targets the current robot, else it ignores it.

<!DOCTYPE aesl-source>
<network>

<!--list of global events-->
<event size="4" name="set_color"/>
<event size="0" name="obstacle"/>

<!--list of constants-->
<constant value="2000" name="OBSTACLE_THRESHOLD"/>

<!--show keywords state-->
<keywords flag="true"/>

<!--node thymio-II-->
<node name="thymio-II">
  onevent prox
    if (prox.horizontal[2] > OBSTACLE_THRESHOLD) then
      call leds.buttons(32, 32, 32, 32)
      emit obstacle
    else
      call leds.buttons(0, 0, 0, 0)
    end
  onevent set_color
    if (event.args[0] == _id) then
      call leds.top(event.args[1], event.args[2], event.args[3])
    end
</node>

</network>

Launch ROS with

roslaunch asebaros_examples twin_thymios.launch

In a new tab set the body LED of Thymio to cyan and of the other to yellow

rostopic pub --once /thymio_14031/aseba/events/set_color asebaros_msgs/Event '{data:  [32, 32, 0]}'
rostopic pub --once /thymio_21181/aseba/events/set_color asebaros_msgs/Event '{data:  [0, 32, 32]}'

Two Thymios

In this example, we want connect to two specific Thymio identified by id, assign them to predefined namespaces (Thymio 21181 to "red" and Thymio 14031 to "green"), and automatically set their body LED color coherently.

<launch>

  <arg name="device" default="tcp:host=localhost;port=33333"/>
  <arg name="port" value="44444"/>

  <node name="asebaros" pkg="asebaros" type="asebaros" output="screen">
    <param name="port" value="$(arg port)"/>
    <param name="reload_script_on_reconnect" value="true"/>
    <param name="set_id_variable" value="true"/>
    <param name="shutdown_on_unconnect" value="false"/>
    <param name="highest_acceptable_protocol_version" value="20"/>
    <rosparam param="targets" subst_value="true">
      ["$(arg device)",]
    </rosparam>
    <rosparam param="nodes">
      others:
        accept: false
      thymio:
        name: thymio-II
        id_variable: _id
        accept: false
        include_id_in_events: false
      thymio_21181:
        id: 21181
        name: thymio-II
        accept: true
        namespace: red
      thymio_14031:
        id: 14031
        name: thymio-II
        accept: true
        namespace: green
    </rosparam>
    <rosparam param="script" subst_value="true">
      path: $(find asebaros_examples)/launch/two_thymios.aesl
    </rosparam>
  </node>
</launch>

Different code get uploaded to each of them: one will turn red, while the other green.

<!DOCTYPE aesl-source>
<network>

<!--list of global events-->

<!--list of constants-->

<!--show keywords state-->
<keywords flag="true"/>

<!--node thymio-II-->
<node nodeId="21181" name="thymio-II">
  call leds.top(32, 0, 0)
</node>
<node nodeId="14031" name="thymio-II">
  call leds.top(0, 32, 0)
</node>

</network>

Launch ROS with

roslaunch asebaros_examples two_thymios.launch

Check that the correct namespaces are being used

rostopic list