Detection of Overhead Contact Lines with a 2D-Digital-Beamforming Radar System for Automatic Guidance of Trolley Trucks

The benefit of trolley truck systems is the substitution of the diesel fuel by the cheaper and more ecological electrical energy. Trolley trucks are powered by electricity from two overhead contact lines, where one is the supply and the other the return conductor. Such trolley trucks are used for haulage at open pit mining sites but could also be used for freight traffic at roadways in the future. Automatic guidance prevents the trolley-powered trucks from leaving the track and thus allows higher operating speeds, higher loading capacity, and greater efficiency. Radar is the ideal sensing technique for automatic guidance in such environments. The presented radar system with two-dimensional digital beamforming capability offers a compact measurement solution as it can be installed on top of the truck. Besides the distance measurement, this radar system allows to detect the location and inclination of the overhead contact lines by digital beamforming in two dimensions. Besides automatic guidance, the knowledge of the inclination of the overhead contact lines could allow automatic speed adaption, which would help to achieve maximum speed especially in hilly terrain. 1. Introduction The benefit of trolley truck systems is the substitution of the diesel fuel by the cheaper and more ecological electrical energy [1]. Trolley trucks are powered by electricity from two overhead contact lines, where one is the supply and the other the return conductor. Such vehicles are often used for haulage at open pit mining sites in order to save fuel and increase productivity [2, 3]. Recently, Siemens AG started the eHighway project [4] for electrification of freight traffic. The system can be installed with only limited alterations to current roadways. These diesel-hybrid driven trucks would help to cut the fossil fuel use and reduce pollution in residential and agricultural areas. Adding an automatic guidance feature to trolley trucks would help to keep the truck on track under the overhead contact lines. Thus, it would provide an increased driving safety and therefore it could allow for higher loading capacities and higher operating speeds. Besides automatic guidance, the knowledge about the inclination of the overhead contact lines allows automatic speed adaption, which would help to achieve maximum speed especially in hilly terrain. Due to its day and night operability and robustness in harsh environments, radar is the ideal sensing technique for such an application. In this proposed guidance solution, radar is used to detect the location and inclination of overhead