How to correctly run explore_pr2 package to let PR2 navigate in the environment automatically? [closed]

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I want to use the pr2_exploration package to let PR2 navigate in the environment automatically, and I executed the commands in two terminals

In the first terminal: roslaunch pr2_gazebo pr2_wg_world.launch

In the second terminal: export ROBOT=sim & roslaunch explore_pr2 explore_pr2.launch

However, I got some errors, the. You can find overall output messages here.

It seems like the key lies in these message:

[ERROR] [1366390413.797578744, 131.566000000]: Client [/explore] wants topic /base_scan_marking to have datatype/md5sum [sensor_msgs/PointCloud/d8e9c3f5afbdd8a130fd1d2763945fca], but our version has [sensor_msgs/PointCloud2/1158d486dd51d683ce2f1be655c3c181]. Dropping connection.

Because I got repeated message like:

[ WARN] [1366390421.398585539, 134.533000000]: The /base_scan_marking observation buffer has not been updated for 3.01 seconds, and it should be updated every 0.20 seconds.
[ WARN] [1366390423.807004380, 135.433000000]: Costmap2DROS transform timeout. Current time: 135.4330, global_pose stamp: 135.1820, tolerance: 0.2000
[ WARN] [1366390423.807063444, 135.433000000]: Could not get robot pose, cancelling reconfiguration
[ WARN] [1366390424.058372392, 135.533000000]: The /base_scan_marking observation buffer has not been updated for 4.01 seconds, and it should be updated every 0.20 seconds.
[ WARN] [1366390426.880916825, 136.533000000]: The /base_scan_marking observation buffer has not been updated for 5.01 seconds, and it should be updated every 0.20 seconds.

But I am not sure and don't know how to solve it, does anyone know how to correct this?

Thanks in advance.