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Hello all
I am facing an issue when trying to navigate, the laser and the saved map data don't match causing some problems when giving a goal location and even when i give a pose there is still a big miss match between them .. how could solve this issue and what might by the cause for it ?
I am using RPlidar that is mounted on top of the robot with a differential drive robot that is getting odom data from two incremental encoders.
You need to add a new ros node that corrects for the odometry drift. Some people use the ros amcl package for this.
amcl is a Global Localizer. It takes the laser scan and the map as input, and aligns multiple lidar scans to the map to determine the robot's current map pose. Then it publishes a new map->odom transform, which has the effect of correcting any drift in the odom->base_link transform. If I remember correctly, the standard ros amcl node does this calculation only once, so you'll need code to re-trigger the calculation after it finishes.
The reason you need both amcl and wheel-encoder-odom for robot pose is that amcl is slow - it can take more than 1 second for it to decide where the robot is currently.
The amcl node provides a ros service to do this. Here's how it's used from the command line:
rosservice call /global_localization "{}"
I wouldn't try to do this too often; keep at least a few seconds between calls.
Instead of amcl, the laser_scan_matcher can also be used to correct odom drift. It's much faster. Just be aware this is a Tracker, not a Global Localizer.
http://wiki.ros.org/laser_scan_matcher
It's harder to use because it doesn't publish map->odom for you.
Asked: 2022-06-18 09:27:34 -0500
Seen: 384 times
Last updated: Jun 19 '22
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Over time, the odometry pose from your wheel encoders will slowly accumulate error. How are you correcting for this?
I don't know, the problem happens when the robot is rotating when the navigation goal is a straight line it work well