Unsubscribe and re-subscribe to different joint state topics at runtime

[Gescheld]

• [x] I am at the right place and my issue is directly related to ROS#. General technical questions I would post e.g. at ROS Answers or Stack Overflow. For library-specific questions I would look for help in the corresponding library forums.
• [X] I have thoroughly read the Contributing Guideline and writing this issue is the right thing to do in my case.

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I have a question!

• [X] I searched the Wiki, open and closed issues for an answer. I tried my best to find the answer by myself without success. I believe that the discussion we will have in this issue, and the solutions we might find, will help me, and likely other community members who have a similar problem.

Here is my question: I want to unsubscribe from my current joint state topic and subscribe to an other joint state topic at runtime with the same robot game object. Is there a way to this at runtime?

So far I wait unitl I press a button to subscribe to a joint state topic. But I couldn't figure out how to unsubscribe and re-subscribe. I tried to remove/destroy the comoponents and to add them again with the different topic name, but that didn't work either. Also, I tried to disable the JointStateSubscriber varibale (SetSubscribeJointStates(false)) and enable it again with a different topic at the JointStateSubscriber.cs component.

Those are the scripts components that are added at runtime:

• JointStatePatcher.cs
• JointStateSubscriber.cs

Relevant Code:

1  RosSharpObject.AddComponent<RosSharp.RosBridgeClient.JointStatePatcher>();
2  // Set Urdf Robot gameobject
3  RosSharpObject.GetComponent<RosSharp.RosBridgeClient.JointStatePatcher>().UrdfRobot = robot_hologram.GetComponent<UrdfRobot>();
4 // Set subscribing value for joint states --> adds JointStateSubscriber.cs to game object
5  RosSharpObject.GetComponent<RosSharp.RosBridgeClient.JointStatePatcher>().SetSubscribeJointStates(true);
6  RosSharpObject.GetComponent<RosSharp.RosBridgeClient.JointStateSubscriber>().Topic = TopicDropdown.options[TopicDropdown.value].text;

• My OS is: Windows 10
• My Unity Version is: 2020.3.16f1
• My ROS Distribution is: Noetic
• My Build Target Platform is: UWP

[MartinBischoff]

Hi @Gescheld you will have to modify UnitySubscriber. This basic version just subscribes on Start().

You have to add e.g. the following functionality in e.g. Update(): if your doChangeSubscription condition is satisfied: unsubscribe and resubscribe

[Gescheld]

Hi @MartinBischoff,

Thank you for the fast answer. I don't have the opportunity to try this at the moment, but I will test it next time :)