Controlling Gazebo Cessna Plane with ROS

asked 2019-03-16 07:01:53 -0600

Hi.

I am new to Gazebo and ROS and i want to control the example Cessna plane in Gazebo using ROS.

I am starting the Gazebo using following command:

gazebo --verbose worlds/cessna_demo.world

When i do

gz topic -l

I have all related topics with cessna plane and simulation environment but when i do

rostopic list

I get the following error in ROS terminal

Traceback (most recent call last):
File "/opt/ros/melodic/bin/rostopic", line 35, in <module> rostopic.rostopicmain() File "/opt/ros/melodic/lib/python2.7/dist-packages/rostopic/__init__.py", line 2119, in rostopicmain _rostopic_cmd_list(argv) File "/opt/ros/melodic/lib/python2.7/dist-packages/rostopic/__init__.py", line 2059, in _rostopic_cmd_list exitval = _rostopic_list(topic, verbose=options.verbose, subscribers_only=options.subscribers, publishers_only=options.publishers, group_by_host=options.hostname) or 0
File "/opt/ros/melodic/lib/python2.7/dist-packages/rostopic/__init__.py", line 1225, in _rostopic_list pubs, subs = get_topic_list(master=master) File "/opt/ros/melodic/lib/python2.7/dist-packages/rostopic/__init__.py", line 1164, in get_topic_list state = master.getSystemState() File "/opt/ros/melodic/lib/python2.7/dist-packages/rosgraph/masterapi.py", line 481, in getSystemState return self._succeed(self.handle.getSystemState(self.caller_id)) File "/usr/lib/python2.7/xmlrpclib.py", line 1243, in __call__ return self.__send(self.__name, args) File "/usr/lib/python2.7/xmlrpclib.py", line 1602, in __request verbose=self.__verbose File "/usr/lib/python2.7/xmlrpclib.py", line 1283, in request return self.single_request(host, handler, request_body, verbose) File "/usr/lib/python2.7/xmlrpclib.py", line 1316, in single_request return self.parse_response(response) File "/usr/lib/python2.7/xmlrpclib.py", line 1487, in parse_response p.feed(data) File "/usr/lib/python2.7/xmlrpclib.py", line 558, in feed self._parser.Parse(data, 0) xml.parsers.expat.ExpatError: syntax error: line 1, column 0

And following error in Gazebo terminal:

[Err] [Connection.hh:267] Header is empty [Err] [Connection.hh:267] Header is empty [Err] [Connection.hh:267] Header is empty [Err] [Connection.hh:267] Header is empty [Err] [Connection.hh:267] Header is empty [Err] [Connection.hh:267] Header is empty [Err] [Connection.hh:267] Header is empty Master Unknown message type[] From[47356] Master Unknown message type[] From[47356] Master Unknown message type[] From[47356] [libprotobuf ERROR google/protobuf/message_lite.cc:118] Can't parse message of type "gazebo.msgs.Packet" because it is missing required fields: stamp, type, serialized_data Master Unknown message type[] From[47356] Master Unknown message type[] From[47356]

What am i missing?

Thanks...

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