# Apriltag landing fixed frame ROS interface

Source: https://forum.modalai.com/topic/1375/apriltag-landing-fixed-frame-ros-interface
Category: General Questions (https://forum.modalai.com/category/2/general-questions)
Posted: 2022-09-23 19:44:06 UTC by mkwan
Replies: 0 · Views: 598

## mkwan · 2022-09-23 19:44:06 UTC

Re: [How can I see the apriltag offset in ROS](/topic/239/how-can-i-see-the-apriltag-offset-in-ros)

Hello, I encountered some unexpected behavior when using Apriltag Relocalization to try to land with an offboard command like [this](https://gitlab.com/voxl-public/voxl-docker-images/voxl-docker-mavsdk-python/-/blob/master/offboard_position_ned2.py#L41). 

I'd like to be able to parse current location data so I can add safety checks to my offboard code. However, `voxl-mpa-to-ros` doesn't seem to output the fixed frame tf data. 

It seems like there isn't an interface for the `pose_vel_6dof_t` type such as `/run/mpa/vvpx4_body_wrt_fixed` or `/run/mpa/vvpx4_body_wrt_local`: [interface_manager](https://gitlab.com/voxl-public/voxl-sdk/utilities/voxl-mpa-to-ros/-/blob/sdk-0.8/catkin_ws/src/src/interface_manager.cpp#L136) , [interfaces](https://gitlab.com/voxl-public/voxl-sdk/utilities/voxl-mpa-to-ros/-/tree/sdk-0.8/catkin_ws/src/src/interfaces)

I'm running voxl-suite:   0.8.1

Is there a way I can interface with the fixed frame tf so that I can do Apriltag landing with some safety checks?