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What is the default noise parameters in sensor inputs in robot_localization?

asked 2020-05-31 08:09:20 -0500

DanielRobotics gravatar image

updated 2020-05-31 12:28:12 -0500

In my yaml parameter file I have not specified any initial noise or process noise for my two sensors. What default noise values will the extended Kalman filter use on these inputs? I have tried to find the default values in the documentation and the source code without success.

In the documentation it states: Missing covariances. If you have configured a given sensor to fuse a given variable into the state estimation node, then the variance for that value (i.e., the covariance matrix value at position (i,i), where i is the index of that variable) should not be 0. If a 0 variance value is encountered for a variable that is being fused, the state estimation nodes will add a small epsilon value (1e−6) to that value. A better solution is for users to set covariances appropriately.

Does this mean that all the noise is set to a small epsilon value (1e−6)? And does this apply for both process and initial noise? Or does it mean that if a value is set to 0 a small epsilon value (1e−6) will be added to that 0?

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answered 2020-06-01 06:22:59 -0500

bob-ROS gravatar image

updated 2020-06-01 07:19:34 -0500

gvdhoorn gravatar image

If the variance in the covariance matrix for a measurement is smaller than 1e-9 it will set it to 1e-9.

In the source code

Also regarding the process noise this is the default values:

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So If I am not defined them it the yaml file I will get the values above?

DanielRobotics gravatar image DanielRobotics  ( 2020-06-01 07:28:23 -0500 )edit

That is correct.

bob-ROS gravatar image bob-ROS  ( 2020-06-01 07:35:58 -0500 )edit

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Asked: 2020-05-31 08:09:20 -0500

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Last updated: Jun 01 '20