What is this error in Gazebo Co-Simulator?

When I request to read a customized topic I get this error.

MATLAB System block 'Gazebo_Interface/Gazebo Subscribe/SourceBlock' error occurred when invoking 'resetImpl' method of 'robotics.slgazebo.internal.GazeboSubscribeBlk'. The error was thrown from '

'C:\Polyspace\toolbox\robotics\robotsimulink\robotslgazebo\+robotics\+slgazebo\+internal\GazeboSubscribeBlk.m' at line 60'.

Caused by:

Failed to subscribe to topic "/gazebo/default/state". The topic must be published by Gazebo simulator.

[Gaurav Bhosale]

Hi Fabricio,

To subscribe "/gazebo/default/state" topic, it should be first published from Gazebo or with Gazebo publish block.

Is "/gazebo/default/state" topic published ? Can you see that in Gazebo topic list?

Thanks.

[Cornelius]

Yes,

When I go to "select" the two topics appear.

[Cornelius]

and Ubuntu terminal the command gz topic -e /gazebo/default/cessna_c172/state work

[Gaurav Bhosale]

The error message shows "/gazebo/default/state" topic is not publish while the published topic is "gazebo/default/cessna_c172/state". Is anything is missing?

Also, how you are publishing message on "gazebo/default/cessna_c172/state" topic from Gazebo ? Do you have plugin?

Also, are you using shipped VM from here https://www.mathworks.com/support/product/robotics/ros2-vm-installation-instructions-v3.html ?

If yes, then I will recommend you to re-intsall plugin by calling packageGazeboPlugin

You can check following example for latest plugin installation

https://www.mathworks.com/help/robotics/ug/perform-co-simulation-between-simulink-and-gazebo.html

Answer 1

[Gaurav Bhosale]

Hi Fabricio,

I am able to replicate enviorment you are using and able to subscribe topic without any issue.

To use custom message, you should follow all these steps,

1] In MATLAB

>>gazebogenmsg(pwd,"GazeboMessageList","gazebo.msgs.Cessna")

2] Follow commands at end of gazebogenmsg call

>> addpath('S:\cessna\install')

>>savepath

3] Create Gazebo plugin

>> packageGazeboPlugin('cessnaPlugin.zip','S:\cessna')

4] Copy-paste 'cessnaPlugin.zip' on Ubuntu VM and build

Use following example to build plugin

https://www.mathworks.com/help/robotics/ug/perform-co-simulation-between-simulink-and-gazebo.html

cd /home/user/src/GazeboPlugin

mkdir build

cd build

cmake ..

make

5] If you have your own cessna.world file then add following line in the cessna.world file

<plugin name="GazeboPlugin" filename="lib/libGazeboCoSimPlugin.so"><portNumber>14581</portNumber></plugin>

Take help of same example ( https://www.mathworks.com/help/robotics/ug/perform-co-simulation-between-simulink-and-gazebo.html)

6] Launch cessna.world file with

cd /home/user/src/GazeboPlugin/export

export SVGA_VGPU10=0

gazebo ../world/cessna.world --verbose

7] Once you launch cessna.world file the you can add Simulink blocks ( pacer and subscribe block) and subscribe 'gazebo/default/cessna_c172/state' topic.

[Cornelius]

Thank you Bhosale =D, I don't know what my problem was.