Advantages of a combined GPS+GLONASS precision sensor for machine control applications in open pit mining

This paper discusses the use of GPS in open pit mining. Existing applications are presented to show how GPS is already being used for dispatch of haul-trucks, navigation and positioning of shovels and drills, as well as conventional survey tasks. The limitations of GPS-based technology are discussed. Of all the problems presented by the mine environment (multipath, high vibration, restricted visibility), one problem stands out as by far the most significant: restricted visibility. A GPS receiver operating in an open-pit mine will often "see" only half the sky, severely restricting the number of satellites available to it. This is of particular importance for high accuracy "RTK" systems (Real-Time Kinematic, delivering centimeter to decimeter accuracy). RTK receivers require five or more satellites to initialize the system. In an environment with 30/spl deg/ mask angles (typical for many open-pit mines), 5 or more GPS satellites are visible only about one-third of the day. A solution to the visibility problem is presented by augmenting the GPS system with other navigation satellites. This paper presents results obtained using GPS receivers augmented by the only other precision navigation satellites available today: the Russian GLONASS system. Comparison of GPS-only sensors to GLONASS-augmented GPS sensors are made. Finally, examples of data from actual operating mines are presented.