Consider attached collision objects in the ComputeFK service

[DaniGarciaLopez]

Description

Currently, the ComputeFK service only works for robot links. By using getFrameTransform we can also consider attached collision objects and their subframes.

Checklist

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[sjahr]

Thanks!

[manadaniel]

@DaniGarciaLopez would you mind giving me a brief idea of what this added „consideration“ implies/improves for the average moveit2 user? Was not clever enough to get it from reading the code as I am unfortunately not familiar with the ComputeFK service. Thx!!

[DaniGarciaLopez]

@DaniGarciaLopez would you mind giving me a brief idea of what this added „consideration“ implies/improves for the average moveit2 user? Was not clever enough to get it from reading the code as I am unfortunately not familiar with the ComputeFK service. Thx!!

The ComputeFK service allows you to calculate forward kinematics, which is the process of determining the Cartesian pose of a given frame from a set of joint positions. This is the opposite of inverse kinematics, where joint positions are determined based on a desired Cartesian pose. Previously, the service only worked with the robot links. With the changes introduced in this PR, you can now also compute the Cartesian pose of collision objects and their subframes if they are attached to the robot.

We mainly use this service for calibration purposes: we attach an object to the end effector of the robot, manually move the robot to a desired location, and then store the current Cartesian pose of the object to calibrate various frames.

Hope this helps!