I am not able to read data from the ROS file

 msgs = readMessages(bag)

Error using robotics.ros.BagSelection/deserializeMessages (line 444)
Java exception occurred:
org.ros.exception.RosMessageRuntimeException: java.lang.ClassNotFoundException: rt_msgs.Odom

  at org.ros.internal.message.definition.MessageDefinitionReflectionProvider.get(MessageDefinitionReflectionProvider.java:66)

  at org.ros.internal.message.DefaultMessageFactory.newFromType(DefaultMessageFactory.java:42)

  at org.ros.internal.message.DefaultMessageDeserializer.deserialize(DefaultMessageDeserializer.java:42)

Caused by: java.lang.ClassNotFoundException: rt_msgs.Odom

  at java.net.URLClassLoader$1.run(Unknown Source)

  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:62)

  ... 2 more

Error in robotics.ros.BagSelection/readMessages (line 194)
            msgs = obj.deserializeMessages(obj.MessageList, rows);

[Image Analyst]

Personally, I'd call the Mathworks technical support for any Java related errors. Make sure you have the latest Java release - or maybe not - that might be the problem. Who knows?

[Ahmad Drak]

Did you by any chance find a solution to this problem?

Answer 1

[Tohru Kikawada]

You'll need to install custom ROS messages for rt_msgs.Odom. See the following link for details: https://jp.mathworks.com/matlabcentral/answers/329662-unable-to-access-rosbag-topics#answer_259060