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How to merge two different topics and create a new one?

asked 2017-08-12 16:53:49 -0500

pmundt gravatar image

I am trying to publish odometry data from a STM32-F446re over serial and using rosserial_python for subscribing/publishing.

Since odometry messages are very big to transfer over serial, I only want to publish pose and twist without covariance matrices and would like to construct odom topic at the host side (add covariance at the host side).

How can I merge pose and twist messages to create a odom message?

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If both of these messages are coming from the same source, it might be easier to define a custom message that contains a pose and a twist so that you can publish that on a single topic, and then write a node which converts that into a full odom message.

ahendrix gravatar image ahendrix  ( 2017-08-12 17:07:38 -0500 )edit

Other than creating a custom message and writing a node, can I achieve this with using any tool (like any topic_tools feature)?

pmundt gravatar image pmundt  ( 2017-08-12 17:12:41 -0500 )edit

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answered 2017-08-13 04:20:19 -0500

To the best of my knowledge there is no such tool for automated merging of messages. As in your case a fair amount of additional information would need to be filled (i.e. covariances) your best bet is writing a small node yourself. You could also consider creating a custom message that contains all the data you need in compressed/minimal form (i.e. only transmit yaw angle and x,y etc.). I've taken a similar approach (albeit in the PC -> Arduino direction) for transmitting motion commands: DiffDriveCommand is the minimal pwm message sent over rosserial and the translator node takes care of translating ROS commands (joystick or Twist) to the minimal representation.

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Thank you very much for giving me a starting point.

pmundt gravatar image pmundt  ( 2017-08-13 10:06:30 -0500 )edit

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Asked: 2017-08-12 16:53:49 -0500

Seen: 861 times

Last updated: Aug 13 '17