Real-time Ultra-tight Integration of GPS L1/L2C and Vehicle Sensors

ABSTRACT Modern vehicle systems are often equipped with Global Positioning System (GPS) receivers and vehicle sensors to provide position, velocity and attitude information. A typical vehicle sensor setup is likely to have two horizontal accelerometers and one vertical gyroscope along with individual wheel speed sensors. Recently, with modernized GPS including the new civil signal on the L2 frequency band, namely L2C, they can be used to overcome some limitations experienced by the legacy L1 C/A signals. The combination of L1 and L2C signals in a GPS receiver expects to offer improved observability and therefore better navigation performance. This paper proposes and implements a real-time GPS receiver with ultra-tight integration of GPS L1/L2C and vehicle sensors for cost sensitive land vehicle applications. A field test was performed to evaluate both the real-time capabilities and navigation performance of the proposed system. INTRODUCTION An ultra-tight (or deep) GNSS receiver has been proposed by previous researchers to enhance the performance in weak or jammed signal environments (e.g., Gebre-Egziabher et al. 2005, Brown et al 2005, Badu & Wang 2006, Pany et al. 2005, Landis et al. 2006 Ohlmeyer ,2066, Petovello et al 2008, Soloviev et al 2007). These receivers a capable of providing pseudorange remeasurements forsatellite signals attenuated by up to approximately 25 dB. Typically, the IMUs used for the ultra-tight GPS and INS integration are full IMUs with three accelerometers and three gyroscopes. However, for reduced Micro Electro-Mechanical Systems (MEMS) IMUs with two accelerometers and one gyroscope, or three accelerometers and one gyroscopehave been used recently (Li et al 2010, Sun et al 2008In order to ). integrate reduced IMUs without loosing too much navigation accuracy, several algorithms have been