Research On Anti-interference Attitude Algorithm Of Marg Measurement System

In recent years, the attitude measurement system has been widely used in military field,such as aviation missile、UAV、aviation as well as civilian fields, such as body posturetracking, indoor robot and so on. The navigation measurement based on MARG sensor withcharacteristics of small sizes and low power is more and more attention. The accumulatederrors of gyroscope can be compensated by the combination of accelerometer and magneticsensors. But the magnetic interference and linear acceleration can influence the result ofmeasurement. So how to reduce interference effectively by use the algorithm is the mainproblem in this paper.Meanwhile how to realize the unity of the sensor coordinate system isanother problem in this paper.Aiming at the existence of MARG sensors system errors, calibration method based onellipsoid fitting is put forward. This method can realize the unified calibration of MARGsensors. Aiming at the problem of sensor coordinate system is not unified, the four positioncalibration method is proposed, which can realize the unification of sensor coordinate system.The three axis accelerometer, gyroscope and three axis three magnetic sensors are calibratedbase on the platform of MARG sensor measurement system composed of a MPU6050sensormodule and HMC5883L Experiments show that, the calibration errors of accelerometer canmeet the requirements of intensive reading. At the same time, the calibration methodproposed in this paper greatly reduce the reliance on precision calibration equipment at thesame time, the calibration method and the steps are simple which are easy to operate;For the problem of inaccuracy attitude solve for harmful acceleration in the process ofvehicle movement or the local magnetic field around. The output of the sensor signal ispreprocessed. When the output is above a certain threshold, we think the sensor signal isinvalid. Then reconstructs the system. Thereby the anti-interference ability of the system isincreased. And simulation experiments under different conditions of vehicle-mounted were designed, Simulation results show that,compared with the traditional attitude algorithm, thethree kinds of adaptive filtering proposed by this paper can effectively reduce the interferenceof the local magnetic field in and around and the harmful acceleration. At the same time, byfurther simulation comparison, adaptive complementary filtering algorithm is selected asinterference attitude algorithm. Which the maximum error of yaw angle can within0.8°，andthe pitch and roll are within0.5°.And the calculating time of a single sampling less thansampling time. Which meet the requirements of actual calculates；Finally, in order to verify the algorithm is practical，the static non-magnetic turntableexperiment and dynamic vehicle experiment are designed. Experiments show that comparedwith the traditional gyroscope decoding attitude and electronic compass attitudealgorithm,the adaptive complementary filter algorithm proposed in this paper can not onlycompensation the cumulative errors of gyro drift, but also effectively restrain the harmfulacceleration and the surrounding local magnetic field interference on the influence of attitudeangle calculating precision.In static environment, the mean and standard are less than0.4°,which reduce74.6%，93.8%，74.2%compared with electronic compass. Under thedynamic environment, the attitude errors can respectively is yaw error:3.25°,pitcherror:0.58°,roll error:0.48°, the errors reduce77.5%，95%，46.6%compared with electroniccompass. Experiment show that the algorithm can be used for the attitude measurement ofUAV, vehicle and human body, which can be influenced by harmful acceleration and magneticfield interference.