[ros-users] Sonar sensor and PTZ actuators on Erratic

[Pablo Iñigo Blasco]

Hi Brian, Anton and ROS community.

Our group is working with erratic robots. As we
talked<http://ros-users.122217.n3.nabble.com/erratic-player-vs-ua-erratic-player-td768165.html>the
ua_erratic_player package is the current official erratic package. So
we've been working with it for a while. However it has some lacks, e.g. we
can't read sonar sensor values and we can't use neither the vision-ptz
actuator nor the ranger-tilt-actuator.

Given that the node implementation uses the player framework it's relatively
easy to extend it and add such functionality. We did it but now we have got
some doubts about how the design the erratic-node interface following ROS
conventions:

- There isn't a standard sonar array message (like e.g. LaserScan.msg), is
it? Such kind of message may not have sense since sonar array may not be
considered a device itself and it usually has a custom arrangement. e.g. The
erratic robot has 8 sonar sensors but they aren't regularly arranged (in the
same way as laserscans are: angle_min,angle_mas,angle_increment,etc). In the
other hand 8 topics of type (Header/float) don't look a good solution. We're
planning to extend the erratic urdf by adding the sonar devices frames and
creating a message like this:
Header
string[] frames
float[] ranges

- Regarding the vision-ptz actuator. What would be a good way to send
commands? JointArray + robot_state_publisher? Maybe a look_at command topic
of type Point3D??
- For the ranger-tilt actuator I guess is better a topic of type
(Header/float).

What do you think about this? Suggestion, correction or Ideas are welcome.

Thanks in advance.
Regards.

-- 
Pablo Iñigo Blasco.
Computer Architecture Department. Universidad de Sevilla (Spain)
http://es.linkedin.com/in/pibgeus | http://geus.wordpress.com
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