Design Of Low-cost GNSS/IMU Integrated Compass System

When a ship is sailing on water,the accurate real-time determination of carrier course is very important.How to obtain the carrier course and horizontal attitude information quickly and accurately has been a major focus of engineering research in the industry.The error of conventional strapdown inertial navigation system will accumulate with time,which cannot meet the requirement of long-time high-precision attitude measurement.With the continuous development of global satellite navigation technology,high-precision satellite navigation positioning and direction finding technology have been increasingly widely used in the field of maritime navigation,which can effectively make up for the shortcomings of traditional inertial navigation system.In this paper,aiming at the application requirements of Marine compass,a set of low-cost composite compass was designed,and global navigation satellite System RTK technology was proposed to be applied to GNSS attitude measurement algorithm,and combined with IMU to obtain high-precision attitude measurement information.In this paper,the basic theory of inertial measurement is first described,the quaternion method is selected to solve the inertial attitude,the attitude measurement algorithm of dual GNSS receiver is designed on the basis of RTK high-precision positioning,the state equation and observation equation of the combined system are derived based on kalman filter theory,and the system performance is verified through simulation.Secondly,based on the combined attitude measurement algorithm,the hardware and software design of the system are completed.Microprocessor system mainly consists of data collection and navigation calculating module,and the ARM microprocessor respectively through the UART interface and SPI interface with NEO-M8 U GNSS receiver and six degrees of freedom inertial sensor ADIS16485 communicate to complete data collection,hardware design for the microprocessor board,inertial device board,two groups of GNSS receiver plate combination of hardware architecture,and completed the system hardware debugging.In software design,the modular idea is adopted to complete the software realization of data acquisition,attitude calculation and data fusion,data storage and communication display and other modules.The upper computer control panel and display interface based on QT are designed.Parameters setting,function calling and information display are carried out for the above modules.The lower unit assembly system is connected to the upper computer through USB interface and RS232 serial port for power supply and data communication.Finally,the thesis completes the system module debugging and the whole machine test,and verifies the feasibility of the system design scheme.Static and dynamic experiments are carried out to verify that the system can realize high-precision attitude measurement under both static and dynamic conditions,which meets the practical application requirements of ships and has certain engineering application value.