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Mavros publishes Odometry without GPS? [closed]

asked 2016-02-17 03:43:53 -0500

quentin gravatar image

Hi everybody,

I am trying to merge pixhawk and px4flow with my ROS localization system (AMCL). In order to do so, I think I am going to use robot_localization.

The low level control will be dealt with by the px4 itself without any feedback from my ROS nodes

The ROS-based localization should be able to read the great odometry information given by px4 and native inav (merging IMU, barometer and px4flow) in order to enhance my AMCL algorithm. But I am only able to get Pose messages via mavros (in mavros/local_position/pose topic). robot_localization sensor fuser does not support posestamped msgs...There should be Odometry in mavros/global_position/local topic but nothing is published. Can I get odometry msgs out of mavros without using a GPS? If yes, how?

For your info, I am running ROS indigo, my board is under px4 and I use a USB connection for the moment. I have hardware troubles with my serial cable!

Thanks in advance for your help

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Closed for the following reason duplicate question by quentin
close date 2016-03-08 20:30:32.515016

2 Answers

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answered 2016-03-07 23:14:01 -0500

quentin gravatar image

updated 2016-03-07 23:14:50 -0500

See here for more details about the solution I am trying to use... Below is in brief:

In order to get relevant covariance information, I am merging the IMU, published by mavros, with the OpticalFlowRad msgs, transformed in a TwistwithcovarianceStamped by optflow_odometry. The covariance is derived from the image quality of the px4flow. The operation is handled by robot_localization.

This gives me a proper sensor based odometry. Then I use another EKF to fuse this odometry with the position published by my localization nodes.

Do you think this workflow is valid?

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This feels like a new question. Would you please post this in a new one, or at least edit the original and put this information there?

Tom Moore gravatar image Tom Moore  ( 2016-03-08 06:48:56 -0500 )edit

Thanks Tom! Here is the new post.

I avoided creating my own covariance in order not to mess around. If smbd wants to try, look at this

quentin gravatar image quentin  ( 2016-03-08 20:29:46 -0500 )edit

answered 2016-03-01 12:41:15 -0500

Tom Moore gravatar image

updated 2016-03-01 12:41:34 -0500

The EKF and UKF in robot_localization do support pose messages; they need to be of type sensor_msgs/PoseWithCovarianceStamped. A sensor_msgs/PoseStamped message does not contain covariance information, which is required by Kalman filters. Without it, the filter doesn't know how much to trust its own prediction vs. the measurements provided.

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Thank you Tom for your answer.

My problem is that mavros is not givng me this error information... Or at least, I don't know how to get it into the right format so that robot_localization can use it.... That why I was also considering the use of the Odometry msgs. Any advice?

quentin gravatar image quentin  ( 2016-03-01 20:24:28 -0500 )edit

An odometry message just contains a PoseWithCovariance and a TwistWithCovariance, so you'll have to find a way to provide that error information regardless.

Tom Moore gravatar image Tom Moore  ( 2016-03-03 07:50:48 -0500 )edit

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Asked: 2016-02-17 03:43:53 -0500

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Last updated: Mar 07 '16