Bringing back the discussion about GPS's, did y'all ever calculate the covariance of x, y, and z for your GPS, because I noticed it was a todo in the code. And further more does it matter? We are going to be putting it into the extended kalman filter provided by ROS, but I am unsure how important these values are for the GPS data. Our GPS has a dynamic kalman filter mode, but does not publish the covariance, it just transparently improves the accuracy given some information about maximum acceleration and/or velocity of the vehicle (they are grouped like walking, boat, car, ariplane, etc). Any insight would be appreciated. Thanks, ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ William Woodall Undergraduate Software Engineering Auburn University w@auburn.edu wjwwood@gmail.com 256-345-9938 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ On Thu, Apr 29, 2010 at 11:06 AM, Jack O'Quin wrote: > On Wed, Apr 28, 2010 at 10:32 AM, Ken Tossell wrote: > > We've been using a message based on gpsd's gps_data_t. It should have > > all of the fields you'd need for any GPS device, but it's pretty big: > > > > http://www.ros.org/doc/api/gpsd_client/html/msg/GPSStatus.html > > I was not aware of that message, thanks for mentioning it. > > As you say, it seems to have all we'd need. Providing all the gpsd > information is a good proof of concept. That looks like a good > starting point for a shared ROS message definition. > > For me, the imbedded GPSFix message would nearly suffice. It could be > published on a separate topic, I suppose. > > I chose to add the UTM easting, northing and zone to our GpsInfo > message. That is obviously unnecessary since those data can be > computed from the raw latitude and longitude by anyone interested. > But, it's a bit of a pain to do that, so I added those fields for our > own convenience. They should *not* be included in any general-purpose > GPS messages. > > I also included the "quality" field from the Player message. That is > useful for detecting when differential GPS is or is not available. > That seems to correspond to the gps_data_t status field of , > but not the gps_fix_t mode field. > > It seems slightly odd that GPSStatus has two Header fields (including > the one in GPSFix), but that makes it easy to publish GPSFix > separately. Perhaps the other status fields could be published by > themselves in a separate topic with the same time stamp. Then only > those needing the extra information would see it and there would be no > message passing overhead if no other node subscribed to it. > -- > joq > _______________________________________________ > ros-users mailing list > ros-users@code.ros.org > https://code.ros.org/mailman/listinfo/ros-users >