Research On High Accuracy Attitude Algorithm And Performance Optimization Of Strapdown Inertial Attitude And Heading Reference System Based On Optic Gyro

As an important airborne equipment, Strapdown Inertial Attitude and Heading Reference Systemmainly exports three-dimensional attitude. The paper studied on the airborne FOG AHRS which ispart of a country key model. The high accuracy attitude algorithm and performance optimizationtechnology is deeply studied and analyzed. Then comprehensive test on performance and reliability iscarried out.Firstly, the requirements of navigation computer solution used in AHRS which has beenself-developed is analyzed. The DSP+CPLD structure means stronger ability of interfacemanagement and no hiden danger of data bus collision. The navigation computer is fully tested onperformance and proved to have good ability in interface communication and satisfy the applicationrequirements of AHRS.Secondly, the paper is deeply studied on solutions to improve the accuracy of FOG AHRS.The noise characteristics of inertial measurement change during long time flights. The paperproposed noise-adaptive algorithm of reduced-order Kalman Filter based on accelerometerinformation fusion. The algorithm increases the attitude accuracy by monitoring sensor noisecharacteristics and changing parameter of Kalman Filter online to adapt it.The accelerometer information validity should be examined before attitude fusion to ensure thatthere’s no extra acceleration. Traditional examining algorithm is restricted by the accuracy ofgyroscope. The paper proposed a examining solution in complex flight situation to imcrease theaccuracy and environmental suitability.The error of attitude calculation caused by IMU timing confusion is analyzed by simulation. Theresult emphasizes the advantage of DSP+CPLD structure in keeping system real-time.The temperature drift of FIMU caused by temperature change in flight worsens system accuracy.The paper studied characteristic of temperature drift of IFOG by experiment. The polynomialapproximation method is adapted to compensate temperature drift of FIMU and increase accuracy ofAHRS within full temperature range.Vibration during flight is also a factor of accuracy reduction. The paper analyzed the coning errorcaused by vibration. The noise characteristic is analyzed using IMU data recorded in repeatedlyvibration experiment. And adaptive variable-step moving average filter is proposed to restrain thenoise of accelerometers. The experiment shows that the filter can effectively improve the accuracy of AHRS attitude output.Finally, the paper is based on AHRS and DSP+CPLD structure navigation computer. And highaccuracy attitude algorithm and performance optimization technology is deeply studied to improve theenvironmental suitability and performance of engineering application. The simulation and experimentresult shows that the research work in this paper strengthens environmental suitability of AHRS and isof high reference value.