(1)    the LRF measurement.
(2)  coordinate of the LRF measurement.
(3)  The number of the LRF measurement points.
(4)  Expected range of the road surface points
(5)  for   to
(6)     if   , then
(7)    save as candidate for the road surface.
(8)    angle of candidate for the road surface.
(9)    The number of candidates for the road surface.
(10)  end if
(11)  end for
(12) for   to
(13)  if   , then
(14)     save as the road surface.
(15)  end if
(16) end for
(17) return  ( )
Algorithm 1: Road surface extraction.