Carrier-Phase-Based Initial Heading Alignment for Land Vehicular MEMS GNSS/INS Navigation System

Abstract

For a micro-electromechanical system (MEMS)-based inertial navigation system (INS) and global navigation satellite system (GNSS) integrated system in land vehicular applications, rapid and accurate initial heading alignment is still a challenge. We propose an initial heading alignment method for MEMS INS using the GNSS carrier-phase measurement, based on the basic principle of trajectory similarity. The proposed method performs “trajectory matching” in the line-of-sight direction of satellites, where the angle is obtained by comparing the actual observed time-differenced carrier phase (TDCP) and INS-derived TDCP. Experimental results show that the initial heading could be determined accurate to 0.65° and 1.68° at a 95% confidence level within 5 s under open sky conditions and in typical urban environments, respectively, using a typical MEMS inertial measurement unit (e.g., STIM300, Safran Sensing Technologies Norway) and high-quality GNSS receiver (NovAtel OEM6). The proposed method is also verified using low-cost GNSS receivers and low-cost IMU chip under different environment. The proposed method performs better than existing approaches in terms of both time efficiency and accuracy.