What's my heading?

[kylerlaird]

NVS_node is configured to wait for a valid heading before sending data to /gps/dict. It wasn't getting the heading inside the (steel) shed. I pulled it outside and data started flowing.

I was expecting to see something I could turn into a heading inside /odometry/ekf. This is what I get: header: seq: 14147 stamp: secs: 1493658130 nsecs: 594615936 frame_id: odom child_frame_id: base_link pose: pose: position: x: -0.00985476895698 y: 0.00972524574094 z: 0.0 orientation: x: 0.0 y: 0.0 z: -8.73040367015e-17 w: 1.0 covariance: [0.00039253267712238167, 1.666558084805763e-14, 0.0, 0.0, 0.0, 9.518600658027148e-15, 1.666558084805752e-14, 0.00039253267708218076, 0.0, 0.0, 0.0, 3.0448707283347426e-15, 0.0, 0.0, 4.99466012386162e-07, -2.3253085198804283e-17, -7.443283501101155e-18, 0.0, 0.0, 0.0, -2.325308519880429e-17, 4.98935434568174e-07, -3.241262152625954e-25, 0.0, 0.0, 0.0, -7.443283501101155e-18, -3.241262152625955e-25, 4.98935434568174e-07, 0.0, 9.518600658027147e-15, 3.0448707283347414e-15, 0.0, 0.0, 0.0, 9.99999884346526e-10] twist: twist: linear: x: 0.000418813637639 y: -0.00131750284521 z: 0.0 angular: x: 0.0 y: 0.0 z: 5.61539802258e-18 covariance: [0.060459342164204455, 3.931886817812853e-11, 0.0, 0.0, 0.0, 6.578709381273442e-16, 3.931886817812851e-11, 0.060459342162705335, 0.0, 0.0, 0.0, 2.1895411174917162e-16, 0.0, 0.0, 4.992002993674259e-07, -5.663545818270628e-26, -1.8128942023305826e-26, 0.0, 0.0, 0.0, -5.663545818270629e-26, 4.968465520662621e-07, -3.1075401283808264e-33, 0.0, 0.0, 0.0, -1.8128942023305826e-26, -3.107540125243711e-33, 4.968465520662621e-07, 0.0, 6.578709381273446e-16, 2.1895411174917177e-16, 0.0, 0.0, 0.0, 9.999996526993436e-10]

The tractor is facing South.

[solosito]

Where is this msg coming from? What is the name of the topic? Just with the orientation quaternion you are able to get the heading of what you are measuring.

[kylerlaird]

OK, I see that /odometry/ekf is not useful. Where should I get the orientation quaternion? I don't see anything with "rostopic find geometry_msgs/Quaternion".

[solosito]

Why do you say it is not useful? Could you provide more info about this?

The odometry message contains a PoseWithCovariance message which contains a Pose message which contains a Quaternion message describing the orientation. Take a look here:

http://docs.ros.org/api/nav_msgs/html/msg/Odometry.html