Research On Low-cost GNSS/INS Integrated Navigation

With the continuous development of global satellite navigation system(GNSS),including American GPS system,European Galileo system,Russian GLONASS,Beidou satellite system in China,QZSS system in Japan and IRNSS system in India,satellite navigation system has been widely used in various fields,and its importance has become increasingly prominent.In December 2018,the service scope of Beidou satellite system in China expanded from Asia-Pacific region to the whole world to realize global positioning and navigation.A lot of universities and research institutes at home and abroad pay attention to the research of Beidou satellite navigation and positioning system and the development of related products.In order to make full use of other satellite systems,a Multi-constellation satellite navigation system has been developed,but the price of navigation system module is still expensive in the market.However,in recent years,cheap single-frequency integrated satellite navigation module has appeared in the market,which greatly expands the application field of satellite navigation system.Although the satellite navigation and positioning system can achieve global positioning at any time and at any place,it will also encounter some special situations,such as tunnels,forests,urban centers,etc.,resulting in weak satellite signals or even unable to receive satellite signals,thus unable to achieve navigation and positioning.In order to remedy the shortcomings of the system,we can add another inertial navigation system.The inertial navigation system is an independent navigation system,but it has an error accumulation effect,but the satellite navigation system can eliminate this error.Therefore,the integrated navigation system of the satellite navigation system and the inertial navigation system can make up for each other's shortcomings and achieve high accuracy and reliability of Navigation positioning.The module of Ublox-M8,an inexpensive single-frequency dual-mode navigation and positioning module of the United States,is used in this paper.It is a single-frequency dual-mode(GPS+BD)navigation and positioning module,realizingcarriers phase difference technology through the Thousand-Search Network Account(CORS).For the reason of signal occlusion in the special circumstances of the system,the HG_INS development board is selected as the inertial navigation components,and it is an inertial navigation system.Since there is no initial position and direction information for the inertial navigation components,the position of the satellite navigation system is used as the initial position of the inertial navigation system before the vehicle starts.The initial heading angle is calculated by the position of the satellite navigation system after the vehicle starts.Then the heading angle is matched with the heading angle output by the inertial navigation components.After the matching is successful,the heading angle is matched as the initial heading angle of inertial navigation system.When the satellite signal is missing,the acceleration and attitude angle information output by HG_INS development board is used to integrate the displacement and heading angle to realize GNSS/INS integrated navigation.Through two campus car experiments,the position errors of cheap integrated navigation are 2.5m and 3.3m respectively within 20 seconds of missing satellite signals,while the maximum missing time of satellite signals is 43 seconds and 46 seconds respectively,resulting in the maximum position errors of cheap integrated navigation being 34.1m and 102.1m respectively.It can realize a low uniform speed positioning system with a long time signal.Therefore,the low-cost integrated navigation scheme in this paper has more accurate positioning accuracy in the absence of GNSS signals in a short time.