| Attitude Measurement based on GNSS is playing a more important role in maritime, aviation, transport, mapping and military fields with its low-cost, long-endurance and high accuracy, and is beginning to replace the traditional posture measuring equipment. Currently, four global satellite navigation systems provide services to humanity, including our self-developed BeiDou satellite system (BDS). So, how to use BeiDou satellites system in combination with other satellite systems to compose a multi-satellite system attitude determination system has become a hot topic.GPS/BDS attitude determination system based on dual antenna receiver with one common clock is proposed in this paper. Around this system, we carried out the following studies:1. This paper studies BDS and GPS. Around the differences between the two systems, the key technologies of the coordinate system, the time system and other problems are discussed, especially the correlation of the dual-system combined observations.These knowledge and theory provide the combination of BDS and GPS with theoretic foundation.2. This paper studies multi-antenna technology with one common clock. Combined with the characteristics of multi-antenna receiver, based on the carrier phase measurement technology, a new single difference baseline model is established. The impact of uncalibrated phase delay (UPD) is considered in this model.And UPD is regarded as a parameter and calculated with baseline parameter, greatly improving the accuracy of baseline.3. This paper studies the ambiguity fixing problem of GPS/BDS attitude measurement system. Through studies, we find that the UPD parameter in single difference model has highly correlation with single difference ambiguity. Taking the advantage of high correlation and the theory of general constraints, we propose an ambiguity fixing algorithm. According to the application, criteria of ambiguity fixing algorithm is developed. The algorithm does not need a lot of search and reduction processes in the ambiguity fixing process, which can fix integer ambiguities fast.4. Another key issue in attitude measurement is the problem of detection and repairing cycle slips. We found that combining the theory of general constraints, cycle slips can be detected and repaired in Kalman filtering process. Based on the above theory, we realized a method of detecting and repairing cycle slips based on Kalman filtering method, which has a repair rate of up to 99.92%.5. Based on the above contents, an attitude determination system is proposed in this paper. Several static and dynamic vehicle attitude determination experiments are conducted to prove the feasibility and the accuracy of the system. Experimental results show that the ambiguity fixing method and cycle slip detection methods used in the system used is entirely feasible. And the accuracy of yaw angle in static experiment is up to 0.002609 degrees/(5.003-meter baseline),0.009038 degrees /(5.003-meter baseline); In dynamic experiments, the accuracy of yaw angle is equivalent to Trimble receivers’results and the accuracy of pitch angle is significantly is higher than the Trimble receiver’s. The accuracy of yaw angle is up to 0.3776/(2.10-meter baseline) and the pitch angle is up to 0.2917 degrees/(2.10-meter baseline). Whether static or dynamic, the accuracy of angle can meet the requirements. At the same time, by studying the impact of satellite elevation mask on attitude determination, the advantages of BeiDou heterogeneous constellation, single difference model and combination of two systems are proved. |
