As @tfoote suggested it is extremely unusual to have GPS antennas on a movable part of any robot. You really wonna have an exact known offset between your antenna(s) and point in which you control your tractor (probably center of the rear axis, that is base_link). If you use very precise GPS (< 5cm) then you can very well just continue using it alone. That is how we did navigation here: https://www.youtube.com/watch?v=GhPAgYRJ5l8. You can use this function to convert your Lat/Lon into utm: https://github.com/cra-ros-pkg/robot_localization/blob/kinetic-devel/include/robot_localization/navsat_conversions.h#L185. Since you have 2 antennas you will be able to infer rotation of the tractor as you already figured it out above. Otherwise @xqms gave you all the right steps above. If you need some help with the initial URDF and TF transforms I can find some time next weekend. --- [Visit Topic](https://discourse.ros.org/t/tractobots-my-attempts-at-field-robots/1486/17) or reply to this email to respond. If you do not want to receive messages from ros-users please use the unsubscribe link below. If you use the one above, you will stop all of ros-users from receiving updates. ______________________________________________________________________________ ros-users mailing list ros-users@lists.ros.org http://lists.ros.org/mailman/listinfo/ros-users Unsubscribe: