بررسي وبهبود ناوبري زيرسطحي بر اساس اطلاعات نواحي بستر

چكيده انگليسي :

Review and improvement of subsurface navigation based on bed information Jaber Resalati j resalati@ec iut ac ir Date of Submission 2018 06 17 Department of Communication Engineering Isfahan University of Technology Isfahan 84156 83111 Iran Degree M Sc Language FarsiSupervisor Ehsan Yazdian yazdian@cc iut ac irSupervisor Mohammad Mehdi Naghsh mm naghsh@cc iut ac irAbstractAn Inertial Navigation System INS can individually produce the navigation data i e position velocity ofthe vehicle However a large amount of error is introduced by INS sensors resulting in an unacceptabledrift in the output positioning data Therefore in most cases external aids are employed to correct the outputof INS Using these aids an integrated navigation structure is developed to produce accurate positioningdata In an integrated navigation system INS output is used to calculate current navigation states andexternal navigation systems supply further measurements Various aided navigation systems are employedin the state of the art integrated navigation systems to provide the most probable corrections to theestimated state One of the integrated navigation systems is Terrain Aided Navigation TAN TAN is atechnique to estimate the position of a moving vehicle by comparing the measured terrain profile under thevehicle to a stored Digital Elevation Map DEM Several TAN techniques are proposed in the literaturewhich can be classified into two main categories Batch processing and Recursive processing methods Themost widely known TAN algorithm is TERCOM which is based on the processing of batch of information The principle of TERCOM is collecting terrain measurement information during the moving path andcorrelating these measurements with the terrain elevation map Although this is a robust method againstnoise and benifits from the simplicity of the implementation this method has a high computational burdenwhich makes it is suitable for employing in the parts of the route where the initial error is high Also thismethod has not appropriate performance on flat and smooth surfaces and cannot be used continuously inthe navigation system SITAN Sandia Inertial TAN is one of the most well known recursive processingmethods widely used in TAN systems This algorithm employs an Extended Kalman Filter EKF and somelinearization techniques to continuously process the measured data throughout the track Due to the use of aone observation in the SITAN Kalman filter the estimation has not a good performance and uncertaintiescaused by observation noise and instantaneous changes in motion parameters such as acceleration degradesits performance greatly In this thesis positioning methods for underwater vehicles are proposed with thehelp of terrain information Using these methods the vehicle can determine its position with the help of aDoppler velocity Log DVL and a pre stored reference topography map This thesis focuses on thepositioning of underwater vehicles however most of the results can also be applied directly to flyingvehicles One of the equipment used in navigation for most sub surface vehicle is the Doppler Velocity Log DVL DVL is based on sonar and it send 4 beams of acoustic waves to determine the speed of the vehiclein all three directions In this thesis instead of using single axis altimeters in the conventional SITANalgorithm we propose a method based on all 4 outputs of DVL With four independent views of vehicleheight in different angles SITAN s performance is enhanced significantly Simulation results show theadvantages of the proposed method compared to conventional methods in real oceans fields Keywords Inertial Navigation SONAR TERCOM Kalman Filter SITAN

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بررسي وبهبود ناوبري زيرسطحي بر اساس اطلاعات نواحي بستر

ناوبري اينرسي , سونار , تركام , فيلتر كالمن , سيتان