Setting up navigation stack on p3dx

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The warning that you're receiving from move_base means that, for one reason or another, the costmap is not receiving sensor data on the base_scan topic at the rate it expects. There are a few things to try:

1) Make sure that the move_base node is successfully subscribed to the topic it expects sensor_data on, in this case, that's the "base_scan" topic. Its possible that you have the wrong topic name specified in the costmap configuration.

2) Make sure that the sensor is publishing at a reasonable rate using the "rostopic hz" tool. So, for you, that'd be "rostopic hz base_scan." If the laser is not coming in at a reasonable rate, you'll have to solve that issue before navigation will work well.

3) Check the load on the computer you're running things on. Its possible that there's just too much going on and the system is completely bogged down. If this is the case, you may want to tune the navigation stack to use less CPU. You can do this by changing the update frequency of the costmap: http://www.ros.org/wiki/costmap_2d#Rate_parameters, or the controller_frequency parameter of move_base: http://www.ros.org/wiki/move_base#Parameters.

Hope this helps,

Eitan