شبيه سازي و بررسي دقت سيستم ناوبري اينرسي تلفيقي زير دريا

چكيده انگليسي :

152 Simulation and Accuracy Analysis of Underwater Integrated Inertial Navigation System Mohammad Shabani Sheijani m shabanisheijani@ec iut ac ir Date of Submission 2012 02 07 Department of Electrical and Computer Engineering Isfahan University of Technology Isfahan 84156 83111 Iran Degree M Sc Language FarsiSupervisor Asghar Gholami gholami@cc iut ac irAbstract Strapdown inertial navigation system SINS estimates the position velocity and orientation of thevehicle and consists of an inertial measurement unit composed of three orthogonal accelerometers and threeorthogonal gyros Navigation in the SINS is done based on dead reckoning principle the gyros signals areused to find the attitude of the vehicle subsequently knowing the attitude and the accelerometers signals acceleration values in the navigation coordinates are calculated Finally the acceleration signals are integratedto estimate the velocity and double integrated to find the position of the vehicle Due to differentimperfections in accelerometers and gyros signals due to the noise and bias instability and the consecutiveintegration of the acceleration signals estimation error increases with time and it is acceptable only for shorttimes In order to reduce the error auxiliary sensors together with inertial sensors are utilized In underwaternavigation it is common to use the auxiliary sensors such as Doppler Velocity Log DVL gyrocompass ormagnetic compass depth meter global positioning system GPS and acoustic positioning system APS forreducing the position error Unfortunately the GPS signals are not receivable underwater and the INS GPSintegrated systems for underwater navigation are limited to shallow water applications where the vehiclemust come to the surface regularly to correct its position One alternative solution for navigation ofunderwater vehicles is to make use of APS which estimates absolute position of the vehicle but it requiresadditional transponders to be either installed at sea floor or mounted to a surface vessel Since in thisapproach vehicle must be placed within the coverage area of transponders its operation range is restricted In addition the position calibration of the transponders is difficult and is a time consuming task Theauxiliary sensors utilized in this thesis consist of DVL magnetic compass and depth meter Using thesesensors unlike GPS and APS auxiliary systems keeps the navigation system independent from externalsources In order to combine the data estimated by SINS with the data measured by auxiliary sensors data fusionmethods based on kalman filtering is used The extended kalman filter EKF has been used widely inintegrated navigation systems Since this filter uses only the first order terms of the Taylor series expansionsof the nonlinear functions thus it is not appropriate for severely nonlinear systems To remove this drawback the unscented Kalman filter UKF has been proposed In this filter it is not required to linearize systemdynamic and measurement model through calculating the Jacobian matrix Error State Kalman Filter ESKF is another data fusion method in which the state space model is expressed based on a linearized systemmodel In this thesis a complete navigation simulator for underwater vehicles consisting of a path designer signal simulator and different Kalman filters is designed The inertial sensors imperfection parameters andtheir effect on the estimated position are investigated In order to verify the navigation simulator EKF UKFand ESKF data fusion methods are compared for under water navigation using simulated data and realmeasurements Finally the accuracy of different methods of data fusion is studied for different paths andmaneuvers Keywords Inertial navigation system Integrated navigation system EKF UKF ESKF

شعباني شيجاني، محمد

شبيه سازي و بررسي دقت سيستم ناوبري اينرسي تلفيقي زير دريا

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