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Create new messages with all fields needed to define a velocity and transform it #233

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Create new messages with all fields needed to define a velocity and transform it #233

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Create new messages with all fields needed to defined a velocity and …
destogl Nov 30, 2023
391cb0f
Update geometry_msgs/msg/VelocityStamped
destogl Dec 4, 2023
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Suggestions to VelocityStamped
ahcorde Feb 5, 2024
aa70e19
Merge pull request #1 from ahcorde/ahcorde/suggestions/add-velocity-s…
destogl Feb 22, 2024
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11 changes: 11 additions & 0 deletions geometry_msgs/msg/VelocityStamped
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# This expresses the timestamped velocity of a frame 'body_frame_id' in the reference frame 'header.frame_id' expressed from arbitrary observation pose 'observation_pose'.
# The message is often used in simplified versions where:
# - observation pose is not defined, i.e., it is assumed that the observation pose is the origin of the 'header.frame_id';
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# - if the observation pose is an established frame, you may set its frame_id only in the pose (since the relative pose to that frame is Identity);
# - 'body_frame_id' and 'header.frame_id' are identical, i.e., the velocity is observed and defined in the local coordinates system of the body
# which is the usual use-case in mobile robotics.
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I think you can remove this particular line

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I am with you on this, my only concern is not to confuse people that are moving from Twist as used currently in Nav2 and ros2_control.

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# which is the usual use-case in mobile robotics.
# as common in mobile robotics.

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I'm a little confused. if body_frame_id and header.frame_id are identical, shouldn't the velocity be always zero? i.e, we're asking the velocity of a body relative to itself. On the other hand, we could have body_frame_id and observation_pose (via its frame_id) be identical and header.frame_id be something different from the two. This makes sense to me since it's asking the velocity of the body relative to whatever header.frame_id is but expressed in the body frame.


std_msgs/Header header
string body_frame_id
PoseStamped observation_pose
Twist velocity