Laser level selection

A system for guiding a grading machine in a job site comprising:

• a satellite positioning system (SATPS) receiver configured to obtain the rough position coordinates Xrough—machine, Yrough—machine, Zrough—machine) of said grading machine;
• a laser tracker connected to said SATPS receiver, said laser tracker configured to latch on a single laser beam at each location of said grading machine, each said laser beam being generated by a laser system, each said laser system being part of a plurality of laser systems covering said job site, each said laser beam providing a reference plane having a high accuracy vertical coordinate (Zlaser) at each said location (Xrough—machine, Yrough—machine, Zrough—machine) of said grading machine;
• a signal system connected to said laser tracker and connected to said SATPS receiver;
• said signal system further including:
• an electronic design file configured to store a plurality of road design surfaces;
• and
• an on-board computer;
• wherein said on-board computer is configured to select a road design surface;
• and wherein said on-board computer is configured to determine the rough position coordinates (Xrough—machine, Yrough—machine, Zrough—machine) for each location of said grading machine using said SATPS receiver;
• and
• a software package TRIMDESIGN used for said selected road design to calculate an optimum K number of laser systems to place on said job site, K being an integer, and to calculate the optimum positions (Xoptk-laser, Yoptk-laser, Zoptk-laser) for each said “j”-th laser system, j being an integer less than or equal to K;
• wherein said plurality of K laser systems provides a plurality of K reference planes optimally covering said selected road design;
• and wherein said on-board computer for said selected road design surface is configured to identify actual position coordinates (Xi-laser, Yi-laser, Zi-laser) for each said “i”-th laser system, i being an integer less than or equal to N, N being an integer;
• and wherein said on-board computer for each location of said grading machine is configured to select a single optimum laser system that is used by said laser tracker to obtain the precise vertical coordinate (Zlaser) of said grading machine;
• and wherein said signal system is configured to precisely guide said grading machine according to a given road design by generating a signal proportional to the difference between a design vertical coordinate (Zdesign) and a real time vertical coordinate (Zlaser) at each said location (Xrough—machine, Yrough—machine, Zrough—machine) of said grading machine;
• and wherein said on-board computer at each said ground position (Xgrade—machine, Ygrade—machine) of said grading machine is configured to determine the cut or fill (Zdesign-Zlaser) by comparing the road design vertical coordinate (Zdesign) with said vertical coordinate Zlaser).