gmapping and navigation beyond range of LIDAR sensor

Question

I am trying to use gmapping and the navigation stack to navigate around a large mostly empty room. I have two problems:

1. When building my map free areas are only mapped between the robot and obstacles. This leaves the center of the room unmapped. Later the navigation stack tries to navigate around the completely empty center of the room. How do I map the empty space where my Lidar returns inf?
2. I'm worried that while I'm driving through the middle of the room, because I'm essentially dead reckoning, errors will propagate and I will loose a decent position estimate by amcl. Is my only solution to get a sensor with more range?

Cheers!

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Originally posted by patrick_hammer on ROS Answers with karma: 283 on 2013-07-09

Post score: 3

Answer 1

#1: From the documentation about gmapping parameters:

~maxRange (float)

The maximum range of the sensor. If regions with no obstacles within the range of the sensor should appear as free space in the map, set maxUrange < maximum range of the real sensor <= maxRange.

#2: I haven't played with amcl/gmapping very much, but isn't that the desired behavior? You should be able to tweak parameters such that the estimated error matches how good your robot's odometry (and/or inertial sensor) is, but when moving in the absence of sensor data, your pose estimate should degrade.

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Originally posted by lindzey with karma: 1780 on 2013-07-09

This answer was ACCEPTED on the original site

Post score: 5

Answer 2

The practical solution to 1. would be to just open the map file you saved using the map_saver with some graphics program and manually mark the portions you know to be free as such by "painting" them into the map. If you use AMCL and thus a static map you have to only do that once.

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Originally posted by Stefan Kohlbrecher with karma: 24361 on 2013-07-10

This answer was NOT ACCEPTED on the original site

Post score: 2