  Last two decades, the problem of robotic mapping has made a lot of progress
in the research community. However, since the data provided by the sensor still
contains noise, how to obtain an accurate map is still an open problem. In this
note, we analyze the problem from the perspective of mathematical analysis and
propose a probabilistic map update method based on multiple explorations. The
proposed method can help us estimate the number of rounds of robot exploration,
which is meaningful for the hardware and time costs of the task.
