How to subscribe/publish to custom messages using rosmatlab ?

I completed the getting started examples and also did some publishing/subscribing from matlab to standard ros nodes, but only for std_msgs. Now I want to use a custom message (foo_msg) from one of my package (foo), if I use rosmsg in the shell I can see it.

But if, in matlab I try to create publsiher, for a matlab node already created, typing : publisher = rosmatlab.publisher('TOPIC', 'foo/foo_msg', node); I get :

    Error using rosmatlab.node/addPublisher (line 543)
    Java exception occurred:
    org.ros.exception.RosMessageRuntimeException:
    java.lang.ClassNotFoundException: foo.foo_msg
      at
            org.ros.internal.message.definition.MessageDefinitionReflectionProvider.get(MessageDefinitionReflectionProvider.java:58)
              at
            org.ros.internal.message.Md5Generator.generate(Md5Generator.java:44)
              at
            org.ros.internal.message.topic.TopicDescriptionFactory.newFromType(TopicDescriptionFactory.java:36)
              at
            org.ros.internal.node.DefaultNode.newPublisher(DefaultNode.java:270)
              at
            org.ros.internal.node.DefaultNode.newPublisher(DefaultNode.java:280)
            Caused by: java.lang.ClassNotFoundException:
            foo.foo_msg
      at java.net.URLClassLoader$1.run(Unknown Source)
      at
            java.security.AccessController.doPrivileged(Native
            Method)
      at java.net.URLClassLoader.findClass(Unknown
            Source)
      at java.lang.ClassLoader.loadClass(Unknown
            Source)
      at
            sun.misc.Launcher$AppClassLoader.loadClass(Unknown
            Source)
      at java.lang.ClassLoader.loadClass(Unknown
            Source)
      at
            org.ros.internal.message.definition.MessageDefinitionReflectionProvider.get(MessageDefinitionReflectionProvider.java:54)
              ... 4 more

Therefore the publsiher is not created, the same appends for the subscriber.

Does anyone know how to add customs messages ?

Thanks, Nicolas

[Ryan]

I am also having roughly the same problem,

Is it possible to define a new ros message type in matlab?

That way I could create the same message type to use it in matlab and still be able to subscribe and publish to that topic where the rest of the ros nodes would use it,

Thank you

[Nstaub]

Hi Ryan,

I found that <http://wiki.ros.org/rosjava/Tutorials/hydro/Unofficial%20Messages> it may be helpful.

I already had a ROS-Matlab bridge working so I didn't try. Let me know if it solve the issue.

Cheers, Nicolas

Answer 1

[MathWorks Robotics and Autonomous Systems Team]

In 2015a, MathWorks released the ( Robotics System Toolbox ), which provides an interface from MATLAB and Simulink to ROS. You can also generate C++ code for a standalone ROS node from Simulink.

The toolbox natively supports custom messages once you install the Robotics System Toolbox Interface for ROS Custom Messages. This allows you to take arbitrary MSG and SRV files and generate the corresponding MATLAB message and service interfaces.

Answer 2

[Jnk]

I have the same problem. I would like to use brics_actuator messages. Hope that there is a solution for that.

[Jnk]

Found something interesting. In the directory

$matlabroot/toolbox/psp/rootmatlab/jars

there are bunch of jar files, like

geometry_msgs_1.10.2.jar, gazebo_msgs_2.3.3.jar

etc. However I do not have brics_actuator_msgs.jar. I guess that if had it, I could probably use this type of messages. Where should I look for it, I wonder.

[Jnk]

I managed to solve the problem. First I installed the package ros-hydro-rosjava-messages on my Linux machine. This package contains the file

/opt/ros/hydro/share/maven/org/ros/rosjava_messages/brics_actuator/0.5.3/brics_actuator-0.5.3.jar

which I copied to $matlabroot/toolbox/psp/rootmatlab/jars directory on my Windows machine. I had to run rosmatlab_AddClassPath command at the beginning of Matlab session and voilà now I can use brics_actuator messages.