Research On The Algorithm Of Underwater Attitude Calculation

In recent years,the attitude measuring of underwater vehicle get the attention ofmore and more people.And the design of attitude algorithm plays a key role on theunderwater attitude measurement system,but also to a large extent affect the aeeuraey,soproper attitude algorithm focuses of the study.For research background,this paper put forward the project that adopt micro inertialsensors measure and storage angular velocity,acceleration and magnetic intensity ofunderwater carrier,then obtain underwater attitude,position etc of carrier by calculatingmeasure data afer experiment.The following words have been done:(1)Appropriate algorithm is decided.Introduce the principium and method of Eulerangle algorithm,direction cosine algorithm,quaternion algorithm,and rotation vectoralgorithm. On the basis of compare their merits and shortcomings,key-point discuss andanalyze quaternion algorithm and rotationvector algorithm that apply widely inPorject.Then we made ssimulation.By analyzing and comparing,finally choose therunge-kutta algorithm in order to calculate attitude,position.(2)The error analysis of inertial measurement device.The error of inertialmearsurement devices accounted a large proportion in the entire system,which is the focusof the study.The principles and technical parameters of gyros,accelerometers and magneticsensor are introduced.And the sensor error models are analyzed and build.Then the gyrorandom drift error is analyzed by Allan variance method.(3)The design of the algorithm of underwater attitude calculation.After initialalignment,the angular rate outputs of micro-gyroscopes are used to update attitudequartern with the Runge-Kuta method.Micro-accelerometers are used to observe the earth gravity field, and magnetometers are used to observe the earth magnetic field. The outputsof accelerometers and magnetometers can be used to compensate for the gyro bias.Thenthe attitude quartern error estimates is given by the Kalman filter, and used tocompensate for attitude quartern updated.The trajectories would be got by the output ofaccelerometer.(4)The simulation of the algorithm of underwater attitude calculation.The simulation ofthe algorithm is done by the calibration data of the MTI-300.