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Fusion of odometry from different sourses

asked 2016-12-05 22:14:37 -0500

shashank gravatar image

I have three different sensor generating odometry . The three sources are 1. laser 2. Wheel 3. camera i want to fuse these odometry using robot localization package .

Do the fame_id of the all the sources generating odometry be parent odom child base_link or it should be different for different source ( odom_laser-->base_link) ?

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Missing details to answer: The point of the whole tf tree is to link the different objects (e.g. sensors) together. One sensor could be e.g. rotated by 90° or placed 1m away. The tf then needs to reflect that.

Humpelstilzchen gravatar imageHumpelstilzchen ( 2016-12-06 03:09:40 -0500 )edit

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answered 2016-12-06 17:30:15 -0500

paulbovbel gravatar image

updated 2016-12-06 18:14:23 -0500

This is tricky because if you're fusing N>1 Odometry messages, each Odometry needs a unique frame for header.frame_id.

Since frames can only have one parent, these frames (such as the proposed odom_laser) typically end up children of base_link, and must be broadcast by your components, while the fused odom frame broadcast by robot_localization ends up the parent of base_link.

Another approach may be to have your sensors publish TwistWithCovarianceStamped, which will be transformed to the local frame of the vehicle and does not require a distinct coordinate frame.

See http://docs.ros.org/kinetic/api/robot...

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according to my understanding your are saying that my frame ids should be ( base_link-->laser_odom , base_link--> camera_odom, base_link-->wheel_odom) . The ekf_localization should publish me odom-->base_link. Am i correct ???

shashank gravatar imageshashank ( 2016-12-07 02:22:32 -0500 )edit

that's correct

paulbovbel gravatar imagepaulbovbel ( 2016-12-07 07:33:53 -0500 )edit
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Note that the odometry messages/inputs can have the same frame_id, but unless the measurements are in agreement with each other (e.g., odom0 and odom1 both provide measurements that don't diverge), it's going to produce ugly results. I try to stick to one pose and N velocity inputs.

Tom Moore gravatar imageTom Moore ( 2016-12-19 03:49:21 -0500 )edit

So u are saying i should choose the pose input from the most reliable source of odometry(say laser odometry) and for rest odometry (camera,wheel) source i should only choose twist(velocity) messages and omit out pose. Am i correct??

shashank gravatar imageshashank ( 2016-12-19 23:13:27 -0500 )edit

Yes, correct.

Tom Moore gravatar imageTom Moore ( 2017-01-04 02:33:59 -0500 )edit

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Asked: 2016-12-05 22:14:37 -0500

Seen: 756 times

Last updated: Dec 06 '16