ROS MAV Message Specifications

[Jimmy Paulos]

Hello all,

It seems a significant outcome of this SIG would be a set of message specifications appropriate for MAV in a ROS environment.

The SIG homepage [1] links to a working draft of candidate messages [2]. 

[1] http://wiki.ros.org/sig/MicroAirVehicle

[2] https://docs.google.com/document/d/1pyEz3p3AQ-6icFiyxe6u6vLAdqU33FQuduWSFT3VHHA/edit#

For those new to ROS, a great number of well-supported and widely-adopted messages already exist [3], many of which are directly applicable to MAV.  In my mind, these messages are the backbone of ROS as-it-exists.  Crucially, these messages are composable: for example, a Pose consists of a Point and a Quaternion.

[3] http://wiki.ros.org/common_msgs

With this background, I have a few suggestions/requests regarding the draft message document.

1) Please specify messages in the convention of ROS common_msgs and using the proper names of existing ROS messages wherever possible.  First, ROS is the common language shared by the diverse subscribers of this SIG.  Secondly this highlights opportunities for reuse of existing interfaces.

2) Since ROS messages are composable, let us not force extra complexity on end users through the messages, but instead strive to find basic building blocks.  For example, I support the inline comment that "time-at-target" is "too fancy" for a humble attitude control message.

3) Perhaps explicitly identifying existing end users and use cases (ie publications) for these messages would be helpful.  For example, it's not self-evident to me who the existing end user is who wants to specify both attitude and a 3D force vector.  If it's you, please add a link to your work -- I'd like to see how you use it.  While forward-looking is good, if there isn't an agreement on what a message means semantically or how to use it, then it's not really an interoperable standard.

Jimmy

James Paulos

jpa...@seas.upenn.edu

University of Pennsylvania