Tightly coupled position and attitude determination with two low-cost GNSS receivers

A precise position and attitude information is essential for autonomous driving of any vehicle. Low-cost GNSS receivers and antennas can provide a precise attitude and drift-free position information. However, severe code multipath, frequent half cycle slips and losses of lock might temporarily reduce the accuracy. Inertial sensors are robust to GNSS signal interruption and very precise over short time frames, which enables a reliable cycle slip correction. However, low-cost inertial sensors suffer from a substantial drift. In this paper, we propose a tightly coupled position and attitude determination method for two low-cost GNSS receivers, a gyroscope and an accelerometer. It improves classical tightly coupled solutions by including a synchronization correction, by the estimation of the code multipath for each satellite and receiver, and by the additional determination of satellite-satellite single difference ambiguities. The proposed method was verified in a test drive. We obtained a heading with an accuracy of 0.25°/baseline length [m] and an absolute position with an accuracy of 1 m.