During navigation to goal or during self exploration task, we are having some problem in laserscan data and robot position is not updated in rviz, however we can see /scan topic is receiving data but we are getting error log saying -

[ERROR] [1455209881.577319725]: Extrapolation Error looking up robot pose: Lookup would require extrapolation into the past.  Requested time 1455209867.514161877 but the earliest data is at time 1455209871.625706346, when looking up transform from frame [base_link] to frame [map]

However this error is not consistent, we get this only for few seconds repeatedly after launching node. If this error continues for sometime, the node stops performing its task.