Abstract
Attitude and heading estimation methods using the global navigation satellite system (GNSS) are generally based on multi-antenna deployment, where the installation space and system cost increase with the increase in the number of antennas. Since the single-antenna receiver is still the major choice of the mass market, we focus on precise and reliable heading and pitch estimation using a low-cost GNSS receiver. Carrier phase observations are precise but have an ambiguity problem. A single difference between consecutive epochs can eliminate ambiguity and reduce the measurement errors. In this work, a measurement model based on the time-differenced carrier phases (TDCPs) is utilized to estimate the precise delta position of the antenna between two consecutive epochs. Then, considering the motion constraint, the heading and pitch angles of a moving land vehicle can be determined by the components of the estimated receiver delta position. A threshold on the length of the delta position is selected to avoid large errors in static periods. To improve the reliability of the algorithm, the Doppler-aided cycle slip detection method is applied to exclude carrier phases with possible cycle slips. A real vehicular dynamic experiment using a low-cost, single-frequency GNSS receiver is conducted to evaluate the proposed algorithm. The experimental results show that the proposed algorithm is capable of providing precise vehicular heading and pitch estimates, with both the root mean square errors being better than 1.5°. This also indicates that the cycle slip exclusion is indispensable to avoid unexpected large errors.
Highlights
Precise heading and pitch angles are essential building blocks for many vehicular applications
The experimental set-up is presented first, including descriptions related to the utiThe experimental set-up is presented first, including descriptions related to the uti lized devices, testing trajectory, and collected data set, followed by the analysis of the lized devices, testing trajectory, and collected datathe set,single-point followed by the analysis approximate receiver positions that were obtained from positioning
Therethe positioning process was implemented first based on the code measurements to obtain fore, the positioning process was implemented firstprocessing based on flow, the code measurements to the approximate receiver position
Summary
Precise heading and pitch angles are essential building blocks for many vehicular applications. Gade summarized seven ways to find the heading under different application situations, where four of them depend on GNSS technology [6]. Gross et al utilized the signal strength of the global positioning system (GPS) and the derived velocity vector for attitude estimation [10]. Goh and Low conducted a survey of the GPS-based attitude estimation methods [11], and it was shown that the estimation-based methods generally showed better accuracy than the analytical methods. The GNSS compass model relies on a short moving baseline to determine the vehicular heading and pitch angles [12,13,14], where the integer ambiguity resolution (AR) is necessary to improve the estimation accuracy.
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