Research And Realization Of Strapdown INS Based On MEMS-IMU

Inertial navigation technology is extensively used in many fields especially in militaryand economic fields. Along with the progress in MEMS technology, the MEMS inertialsensors are improved step by step in precision and stability. The MEMS-IMU(MEMS InertialMeasurement Unit) navigation system that has the advantages of low cost, low powerconsumption, small size, large range and easy to batch production has been paid more andmore attentions in recent years. Because of the low accuracy and bad stability of the MEMSinertial sensors, the system cann’t achieve navigation task alone for a long time. By use ofGPS signal to calibrate the MSINS, the location precision and stability are improvedobviously.This paper focuses on the basic principle and application of strapdown inertial navigationsystem. Validating the use of GPS and magnetometer assist MEMS-IMU strapdown inertialnavigation system offering attitude determination informaton and navigation performance.The main contents are as follows:1．Study on the basic working principle of strapdown inertial navigation system. Threekinds of commonly used the attitude updating algorithms are analyzed and compared. Aimingat the engineering application and MEMS gyroscope characteristics, Quaternion algorithm isselected to be used as attitude updating algorithm. In static condition, the strapdown inertialnavigation algorithm is simulated and analysed to show MEMS inertial measurement uniterrors are large relatively. The results prove that MEMS inertial device cannot directly beused in traditional strapdown inertial navigation algorithm for navigation solution.2．Through the low precision of MEMS-IMU, combination attitude determinationscheme being made up of three-axis MEMS gyroscope, three-axis MEMS accelerometer andthree-axis magnetometer is designed. Using magnetometers and accelerometers observationvalue gets attitude angle by geomagnetic method, then a Calman filtering algorithm isintroduced to optimally estimate it. Raw datas are collected and processed by means of MTiMicro Inertial Measurement system produced by Xsens Company.3．Constructing loose combination system in view of MEMS-IMU/magnetometer/GPS,magnetometer and accelerometer can be used confirm initial attitude angle, the navigation andpositioning information being acquired by GPS revises the velocity and position beingproduced by strapdown inertial navigation system. The theory and simulation verifies thefeasibility of this scheme, and test and verify that this combination navigation system has reliable navigation performance by practical experiment.