Input to robot_pose_ekf from IMU and Encoder frames IDs ?

edit

Thank you for your answer. I meant that the frame_id of the /encoder "odom_combined" is not on my tree and not the child_frame_id. I only have "odom" in the tree. I have made the edit in the question. Thanks.

My guess was that robot_pose_ekf doesn't really look at the frame and assumes they are in a certain frame. In any case, I changed the frame_id and child_frame_id of the /encoder msg to be odom and base_footprint respectively. And I changed the /imu frame_id to be base_footprint.

Should this be fine? Or does /imu have to be in odom? I am asking because although the output *seems* to be alright, I don't want it to have a problem later on. Thank you for your responses :)

You can make the frame_id of the IMU base_footprint, but that assumes it has no rotational or translational offset from the base_footprint frame. The IMU typically has its own frame that is a child of base_link or base_footprint. I'd use static_transform_publisher to define that transform.

I would have thought so too. But the robot I am working with (Clearpath Husky) publishes the IMU info in the base_footprint frame. So I don't think they have a frame defined for the IMU in the default start-up.

Also, I am assuming that since the IMU is mounted fairly securely to the robot, there will be no rotational or translational offset from the base_footprint.

It's not really a question of the security of the mount. If you had a robot (and I realize you don't) whose IMU was mounted, say, upside-down, you'd have to define a transform from base_link to imu with pi radians of roll. If the Husky reports the IMU in base_footprint, you're fine.

@pmukherj, can you verify?