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Using robot_localization_package with a car like robot

asked 2016-04-13 02:50:18 -0500

Igel gravatar image

Hi,

I would like to use the robot_localization_package with a car like robot. The odometry calculation for the ackerman steering includes some corrections terms like the side slip angle, so in my opinion its not possible to feed the ekf with differential values for the odometry, right?

Is it a valid idea to just feed the absolute odometry pose and use it together with an IMU and a GPS, or will I have to make some improvements on the package itself (integration stage and prediction stage).

Cheers!

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answered 2016-04-13 07:36:35 -0500

Tom Moore gravatar image

You can feed it those data sources, yes. The prediction step won't match your vehicle's kinematics, but you can try to compensate for that by having higher frequency odometry data and increasing the process_noise_covariance for the affected variables. The model doesn't work at the level of wheel velocities and doesn't use Ackermann kinematics. I don't intend on changing that model, but I do plan to move to a plugin-based architecture that will let users implement their own models. In the meantime, it would be pretty straightforward to add a different model with the existing architecture, though if you want to work with raw wheel velocities, you'd have to also add support for the reception of the those messages and new parameters (e.g., wheel radii, wheel separation distance, etc.).

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Does that mean that robot_localization don't use twist.angular.z value in consideration ?? Please Could you see this log? https://answers.ros.org/question/2961...

Mahmoud Kamel gravatar imageMahmoud Kamel ( 2018-07-05 08:04:47 -0500 )edit

The EKF tracks pose and velocity in 3D (see the wiki). It uses angular.z. I said the model doesn't work with wheel velocities. angular.z is a body-frame velocity.

Tom Moore gravatar imageTom Moore ( 2018-07-05 08:08:26 -0500 )edit

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Asked: 2016-04-13 02:50:18 -0500

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Last updated: Apr 13 '16