Research On Integration GNSS RTK Model And Method

With the rapid development of GNSS technology,its application scenarios are becoming wider and wider.In all industries that require location services,satellite navigation technology has become an indispensable method.Because RTK technology has simple user-side algorithms and the advantages of high processing efficiency,fast convergence,high positioning accuracy and strong reliability.It became one of the most commonly used positioning methods in various high-precision location services.With the promotion of the scope of application,especially RTK technology in automatic driving,the popularization and application in fields closely related to life safety also have higher requirements for the positioning accuracy and reliability of RTK positioning technology.The basis for realizing high-precision and high-reliability services in RTK technology is the ability to correctly resolve ambiguity and the cycle slips can be detected efficiently and effectively.This article focuses on ambiguity resolution and cycle slips in RTK positioning.The main research contents are as follows:(1)Research on the mechanism and characteristics of cycle slips,propose an integration GNSS RTK model,integrate cycle slips into the positioning solution model,and realize the integration of cycle slip detection and positioning solution.The model adopts Kalman filtering parameter estimation.The filtering process is divided into two parts: cycle slip detection and location solution by setting filtering parameters.Cycle slip detection filtering updates the ambiguity parameter with the observation.The floating cycle slip value and its variance covariance value are obtained in real time by making difference to the floating ambiguity obtained by the cycle slip detection filtering of the preceding and the following epoch.The LAMBDA method is used to estimate the cycle slip integer to obtain the integer solution of the cycle slip,and the integer solution is tested.In location solution filtering,cycle slips are processed according to the results of integer estimation and test.Cycle slip repair and ambiguity re-estimation are combined to complete the processing of cycle slips.When obtaining high-precision cycle slip results,the obtained cycle slips can be directly used to repairs the ambiguity.When the accuracy of the cycle slip is low,the ambiguity re-estimation method is used to process the cycle slip,which ensures the reliability and efficiency of cycle slip processing.(2)Research on the method of ambiguity resolution.The core of ambiguity resolution is integer estimation and ambiguity testing.The research content includes representative ambiguity estimation methods.The methods are briefly introduced.The two methods based on statistical difference and success rate are compared and analyzed.In order to improve the usability of the algorithm,the ambiguity is partially fixed based on the ambiguity variance after the correlation is reduced.On the basis of ensuring the correctness of the ambiguity is fixed,increase the ambiguity fixed rate as much as possible.(3)Test the accuracy and anti-cycle slip ability of the integration GNSS RTK model through actual measurement data in different scenarios.For the accuracy of the integration GNSS RTK model,initialization can be quickly completed under a static baseline of ? 50 km to achieve high-precision positioning.In a complex urban environment,the ambiguity fixed rate is much better than the RTKLIB result.In the moveto-motion formation scene,the fixed ambiguity rate reached 98% by partial ambiguity resolution,and compared with the reference value,the error of about 95% of the epoch is within 2 cm.For the anti-cycle slip capability of the integration GNSS RTK model,by adding a large number of different types of continuous cycle slips to the observation value to verify it,in static data,cycle slips can be detected 100% of cycle slips that can be directly repaired,and a high cycle slip recoverable rate can be achieved in different dynamic scenarios.By locating whether there is cycle slip data compared with the results,it is verified that frequent occurrence of a large number of cycle slips does not have a negative impact on the positioning results,and it proves that the integration GNSS RTK model has a strong ability to resist cycle slips and can obtain high-precision positioning results.