Precise Positioning System for Autonomous Vehicles and Intelligent Transport

The precise positioning is one of the major problems in the intelligent transport systems (ITS) as the position accuracy and its continuity is very important for the autonomous vehicles. As the standard Global Navigation Satellite System (GNSS) receiver (using the single L1 frequency and C/A code) has a precision of $\mathbf{2 - 5 m}$, the requirements of ITS systems are higher due to the road dimensions. The dual frequency (L1/L2 or L1/L5) GNSS receivers may increase the accuracy to sub-meter level but sometimes is still insufficient for the precise positioning. The Real-time kinematic (RTK) phase measurement method increases the position accuracy of vehicles to sub-centimeter level based on the very accurate pre-known position of the base stations across the road. As the base station coverage is limited to several kilometers, multiple base stations have to be placed along the road infrastructure to guarantee the uninterrupted service. The combination of RTK corrections and MEMS inertial system allow to design precise positioning systems with high update rate for the autonomous vehicles.