Patent ID: 8794867

Claim:
A road milling machine control for a road milling machine of the type which mills a pavement surface over which the road milling machine travels, said road milling machine having a milling machine body, a rotatable milling drum mounted on the lower portion of said milling machine body, said bottom surface of said milling drum contacting said pavement surface to mill said surface to a design elevation, said milling machine further including a plurality of machine body supports which may be adjusted to raise or lower the height of the milling machine body and the rotatable milling drum with respect to the pavement surface, thereby defining the elevation of the surface that results from milling with said drum, said control comprising: a floating plate, mounted to the side of said milling machine and said rotatable milling drum, for sliding over the unmilled pavement surface adjacent to the area to be milled, said floating plate being vertically movable with respect to said machine body and said rotatable milling drum, a GNSS receiver on said machine body for determining the two dimensional coordinates of said floating plate, a memory storing data defining a three dimensional map of said unmilled pavement surface, and storing data defining a design surface which is to be milled by said road milling machine, a sensor for detecting the relative vertical position of said floating plate with respect to said machine body and the rotatable milling drum and providing a sensor output, and a processor, responsive to said GNSS receiver and said sensor, and operating in conjunction with said memory, for determining the desired elevation of said design surface in the area where the milling machine drum is in operation, for determining the elevation of said bottom surface of said milling drum, and for generating a correction value specifying the amount by which the milling machine drum is to be raised or lowered to bring the bottom surface of said milling machine drum to the desired elevation of said design surface, in which the elevation of said lower surface of said milling machine drum is determined by the relative elevation of the unmilled pavement surface over which said floating plate slides.