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amcl parameters and robot localization without 2D Pose Estimate tool

asked 2019-09-26 08:30:28 -0600

june2473 gravatar image

updated 2019-09-26 08:32:31 -0600

1) so, during navigation we run amcl and move_base. And at first we need to estimate robot's position in Rviz using "2D Pose Estimate" tool. Why do we need to do this? Why do we need to help amcl node to determine robot position?

Maybe I dont understand something about localization, but it looks absolutely unusable. Is there any way to localize robot without clicking by mouse?

2) I see a lot of parameters in amcl.launch such as laser_z_rand or laser_z_hit or laser_likelihood_max_dist. And ros wiki describes them very briefly. Where can I find full information about those parameters?

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answered 2019-10-24 20:24:24 -0600

fergs gravatar image

Asking a robot to localize itself with no prior knowledge has a special name -- "the kidnapped robot problem". As you can imagine, when something has acquired a specific name, it's quite difficult. The algorithm in AMCL is very good at maintaining localization when it has a good prior, decent odometry updates, and the laser can see things to correct for odometry errors/slippage/etc.

Typically, the work around people implement to avoid having to give initial localization is to use other means to get an initial estimate. This could be a wifi thumbprint that tells you roughly where the robot is, some sort of visual indicator, etc. I'm not aware of any maintained, public implementations of such things though.

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answered 2019-09-26 13:56:23 -0600

You can find more about the parameters by reading the code ;-)

But also in reading the common reference book Probabilistic Robotics. There's usually not alot of docs about it since that's the handbook most of us have on our desks. You use the topic directly if you dont want to click somewhere to seed the filter, or use the initial position parameters to boot up at a specific pose.

You can seed the filter evenly over the entire map and it will try to converge to your location, but that's not really the way I imagine you're looking to go. To localize, in general, you need to tell it where it is to start.

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Asked: 2019-09-26 08:30:28 -0600

Seen: 362 times

Last updated: Oct 24 '19