[ros-users] ROS and OPC/OPC-UA

[Meßmer, Felix]

Hi Brian,

hi Shaun,

hi all,

 

the (long-term) scenario I have in mind is the following:

We have a mobile platform using ROS that - equipped with some sensors - is supposed to perform inspection tasks in an industrial environment.

These inspection tasks are performed by an operator in a tele-operation mode.

We now want to control the platform remotely, get visual feedback by displaying an environment model created using the sensor data and augment this visualization with additional data that e.g. comes from a machine the robot is currently looking at via OPC/OPC-UA.

A second scenario might be the integration of such a mobile platform into an MES (Manufacturing Execution System) to send the platform to a machine that just notified the MES that it has finished some execution (e.g. manipulation of a work piece) and needs to be unloaded.

 

In both scenarios, I am interested in providing ROS-topics as OPC-Variables (e.g. /tf or camera data for visualization) as well as read OPC-Variables and generate ROS-messages out of them (e.g. velocity commands).

 

So far, I was able to read commands from a joystick on a remote PC, transform the /joy message to an OPC-Variable, load the values to the OPC-Server, there read it and compose a new /joy-message on the robot and execute it. Also sending information (ROS -topics) from  the robot to the OPC-client is  possible.

In this first trial, the implementation was very hard-coded. i.e. the OPC-variable was explicitly implemented for a certain topic and it is not general at all.

In a next step, I am thinking about serializing ROS-topics so that all ROS -topics can be transformed into a common format, i.e. header with information such as topic name, topic type,... and a byte stream containing the serialized message. This header and the byte stream are then the content of the OPC-variable. To recover the ROS -message, the OPC-Variable is de-serialized on the other side.

 

I'm not sure right now, what the best practice is here, since I am quite familiar with ROS but new to OPC-UA.

 

 

If you have some suggestions or further questions please let me know!

 

 

 

Best regards,

 

Felix

 

 

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