Frame of Twist information for robot_localization
Hello,
If i am inputting a nav_msgs/Odometry from the wheel odometry into the robot_localization package, the nav_msgs/Odometry has pose information, and twist information.
I am only using the twist information in the robot_localization package.
The header.frame_id is odom, and the child_frame_id is base_footprint.
Since this is a planar robot, the twist field contains linear.x linear.y angular.z components.
My question is: In which frame are these three values expressed, in the child_frame_id, or in the header.frame_id.
For example, assuming the twist is in the frame of the child_frame_id, then if the robot has arbitrary orientation, and if the robot goes straight, vx will be non-zero, and all others zero. However, if the twist is in the frame of the header.frame_id (odom), then the orientation matters. For example, if the robot is aligned with the negative x-axis, and the robot goes straight, the vx will be negative. If the twist is expressed in the base_footprint frame, the vx will be positive.
So, robot_localization, which frame of reference does it expect the twist field to be expressed in?
Twist
!=Odom
. Which of the two is it?I will edit my question to clarify