Search for: inertial-navigation-systems
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    A back-propagation approach to compensate velocity and position errors in an integrated inertial/celestial navigation system using unscented Kalman filter

    , Article Proceedings of the Institution of Mechanical Engineers, Part G: Journal of Aerospace Engineering ; Vol. 228, issue. 10 , 2014 , pp. 1702-1712 ; ISSN: 09544100 Nobahari, H ; Ghanbarpour Asl, H ; Abtahi, S. F ; Sharif University of Technology
    This article aims to compensate the velocity and position errors that exist when the star sensor starts to work in a strapdown inertial navigation system aided by celestial navigation. These systems are integrated via unscented Kalman filter to estimate the current attitude and the gyros fixed bias, precisely. Since an accurate integration is desired, the nonlinear attitude equations are utilized in filter and these equations are propagated through a precise discretization method. Then, implementing the back-propagation and smoothing techniques, the initial attitude and the accelerometers fixed bias are also estimated. Finally, carrying out a parallel navigation, the velocity and position... 

    Transfer Alignment Algorithm Development for Aerial Launch Space Launch Vehicle Navigation System Using the Carrying Airplane Navigation System

    , M.Sc. Thesis Sharif University of Technology Shokatian, Mohammad (Author) ; Fathi, Mohsen (Supervisor)
    In this research the problem is the development and simulation of Transfer Alignment algorithm for an aerial launch space launch vehicle. In the references there is no complete study on development of this algorithm for the case space launch vehicle. In order to develop the algorithm, the carrying airplane and the space launch navigation systems are considered as the Master INS and Slave INS respectively. First a 6DOF simulation of the airplane is presented. Then the desired inputs for simulation of Master and Slave INS are generated. Also the differences of the inputs of Slave INS caused by the distance between the Master and Slave INS is considered. Master INS performs as an ideal INS and... 

    Accuracy analysis of an integrated inertial navigation system in slow maneuvers

    , Article Navigation, Journal of the Institute of Navigation ; 2017 ; 00281522 (ISSN) Nobahari, H ; Mohammadkarimi, H ; Sharif University of Technology
    Wiley-Blackwell  2017
    In-motion alignment of a strapdown inertial navigation system, during slow maneuvers, is studied. Terrestrial velocity is fed back to the navigation system to estimate and compensate for the navigation errors. Observability of the errors is analyzed since the integrated navigation system is not fully observable. Then, the accuracy bounds of the navigation system in different motion scenarios are obtained analytically. Also, in order to minimize the errors of the navigation system, special maneuvers are designed based on the analytical derivations. The analytical results, obtained using the linearized error model, are verified through nonlinear simulation of different maneuvering and... 

    Design and simulation of an off-line internal navigation system for pipeline inspection applications

    , Article ASME International Mechanical Engineering Congress and Exposition, IMECE 2007, Seattle, WA, 11 November 2007 through 15 November 2007 ; Volume 9 PART A , 2008 , Pages 521-526 ; 0791843033 (ISBN); 9780791843031 (ISBN) Durali, M ; Nabi, A ; Fazeli, A ; Sharif University of Technology
    The aim of this paper is to design an inertial navigation system (INS) for use in a geometry pipe inspection gauge, capable of measuring pipeline movements and producing the line's 3D map with a reasonable accuracy. A suitable reference path was generated as a design platform. Solving the navigation equations and compensating for the errors, by using extended Kaiman filter (EKF) approach, the INS path was generated and its position errors in all three directions were considered. Divergence problems due to far apart GPS position observations, was overcome by defining suitable threshold for the variances of the estimated errors. Copyright © 2007 by ASME  

    Application of model aided inertial navigation for precise altimetry of unmanned aerial vehicles in ground proximity

    , Article Aerospace Science and Technology ; Volume 69 , 2017 , Pages 650-658 ; 12709638 (ISSN) Nobahari, H ; Mohammadkarimi, H ; Sharif University of Technology
    In this research, Model Aided Inertial Navigation (MAIN) is used during the automatic landing of an Unmanned Aerial Vehicle (UAV). A new MAIN algorithm is proposed which is fast and accurate enough to be used in this phase. In this algorithm, the six Degree of Freedom (6DoF) flight simulation of the UAV is integrated with the Inertial Navigation System (INS) such that the 6DoF model acts as an aiding system for the INS. In the last parts of the landing phase, when the UAV flies in proximity of the ground surface, the proposed integrated navigation system can estimate the altitude of UAV utilizing the “ground effect” phenomenon. Therefore, the method does not have the drawbacks of active... 

    Pseudo DVL reconstruction by an evolutionary TS-fuzzy algorithm for ocean vehicles

    , Article Measurement: Journal of the International Measurement Confederation ; Volume 147 , 2019 ; 02632241 (ISSN) Ansari-Rad, S ; Hashemi, M ; Salarieh, H ; Sharif University of Technology
    Elsevier B.V  2019
    By development of ocean exploration, autonomous vehicles are employed to perform on-water and underwater tasks. Using an extended Kalman filter, Inertial Navigation System/Doppler Velocity Log (INS/DVL) integrated systems are trying to navigate in oceans and underwater environments when Global Positioning System (GPS) signals are not accessible. The dependency of DVL signals on acoustic environments may cause any DVL malfunction due to sea creatures or strong wave-absorbing material. In this paper, an improved version of evolutionary TS-fuzzy (eTS) is proposed in order to predict DVL sensor outputs at DVL malfunction moment, by utilizing an artificial intelligent (AI) aided integrated... 

    Underwater Navigation by Acoustic Sensors and INS data Fusion

    , M.Sc. Thesis Sharif University of Technology Karmozdi, Ali (Author) ; Salarieh, Hassan (Supervisor)
    In this study, by INS and auxiliary acoustic sensors data fusion, underwater navigation algorithm is implemented and validated by computer simulations. Extended Kalman Filter based on perturbation analysis is used as combination algorithm. The outputs of the INS forms equations of mechanism. The variational variables are state variables estimated in the Kalman filter. Because of the weakness of the GPS signals due to electromagnetic signals Attenuation in water, acoustic sensors are used as auxiliary sensors in underwater navigation. Here those acoustic sensors that implementing them in this country is impossible or very costly would not be examined.In this research the output of Doppler... 

    Nonlinear Filters Applied to Tightly Coupled Integration of INS/GPS/PL for Precise Navigation in Automatic Landing of UAVs

    , M.Sc. Thesis Sharif University of Technology Heidari Darani, Mohammad Mehdi (Author) ; Nobahari, Hadi (Supervisor) ; Ghanbarpour Asl, Habib (Supervisor)
    One of the most dangerous phases of the flight is landing. Newly automatic landing is noticed. The vital element in an automatic landing system is navigation system. In this document, a PL/INS/DGPS auto landing system is introduced.In a PL based navigation system, accuracy is highly under the influence of relative geometry between PLs position and flight path. Therefore, it is necessary to locate PLs on the best position. An optimization is used to find PLs best configuration that increases the navigation performance. Tightly coupling of INS and GPS/PL is preferred, because some problems lead to GPS satellite signal unavailability  

    Design and Construction of Autonomous Underwater Vehicles

    , M.Sc. Thesis Sharif University of Technology Spehrband, Poria (Author) ; Seif, Mohammad Saeid (Supervisor)
    In recent years, unmanned vehicles have intensively been developed to reduce human dangers for marine applications. Predicting the hydrodynamic coefficients of an autonomous underwater vehicle is important during the vehicle’s design phase. In other words to design an AUV, one must clarify its maneuverability and controllability based on a mathematical model. The mathematical model contains various hydrodynamic forces and moments expressed collectively in terms of hydrodynamic coefficients. Therefore, the correct values of the coefficients must be known to precisely design the controller of AUVs.SUT-2 is an AUV, being developed by Marine Engineering Laboratory of Sharif University of... 

    High Precision Localization by Optical Flow and INS Sensor data Fusion

    , M.Sc. Thesis Sharif University of Technology Azizi, Arash (Author) ; Vossoughi, Gholamreza (Supervisor)
    Robot navigation and guidance is an important issue in robotic. Navigation by itself includes localization, path planning and guidance. For having a successful navigation it is necessary to succeed in all of those parts. The localization precision as basic part of localization is important and having more accurate information of robot position is important. Recently, sensors which use optical flow technic and are widely used in optical mouses are so common and they are able to measure displacement with resolution of 3 to 63 micron. In this research, a localization method for micro robot localization based on optical flow and INS sensor data fusion is presented.
    Two data fusion method... 

    Workspace measurement of the surgeon's upper limb during an arthroscopy and three laparoscopy operations using inertial sensor systems

    , Article 2013 E-Health and Bioengineering Conference, EHB 2013 ; 2013 ; 9781479923731 (ISBN) Soroush, A ; Farahmand, F ; Sharif University of Technology
    The aim of this study was to determine the workspace of surgeon's body for designing more efficient surgical robots in the operation rooms. Five wearable inertial sensors were placed near the wrist and elbow joints and also on the thorax of surgeons to track the orientation of upper limb. Assuming that the lengths of five segments of an upper limb were known, measurements of the inertial sensors were used to determine the position of the wrist and elbow joints via an established kinematic model. subsequently, to assess the workspace of surgeon upper body, raw data were collected in the arthroscopy and laparoscopy operations. Experimental results demonstrated that the workspaces of surgeon's... 

    Analysis and Increase Robustness of INS-DVL Navigation Using Rotational Model of AUV in the Presence of Model Uncertainty

    , M.Sc. Thesis Sharif University of Technology Ramezanifard, Amir Hossein (Author) ; Alasti, Aria (Supervisor) ; Salarieh, Hasaan (Supervisor) ; Hashemi, Mojtaba (Co-Supervisor)
    Autonomous underwater vehicle are among the subsurface vehicles used today in applications such as ocean floor mapping, environmental studies, finding the wreckage of drowned vehicles, and military applications such as finding mines. The need for control over the navigation components and the importance of the precise position of the mission have made AUV navigation an important issue in these vehicles. Due to the attenuation of the GPS signal underwater, it is not possible to use this method for subsurface navigation. Therefore, inertial navigation (dead reckoning navigation) is usually used for this purpose. Due to the unlimited growth of inertial sensor error over time, this error must be... 

    A new approximative method for attitude correction in inertial navigation systems

    , Article Proceedings of 2016 7th International Conference on Mechanical and Aerospace Engineering, ICMAE 2016, 18 July 2016 through 20 July 2016 ; 2016 , Pages 394-399 ; 9781467388290 (ISBN) Mohammadkarimi, H ; Nobahari, H ; Sharifi, A ; Sharif University of Technology
    Institute of Electrical and Electronics Engineers Inc  2016
    In this paper, a novel algorithm for correcting the error of attitude in inertial navigation systems is introduced. Since the oftenly used differential equations of the navigation errors show the small rotation angles instead of the error of Euler angles, the nonlinear equation between the small rotation angles and the error of Euler angles, are derived. To obtain an approximative solution for the derived equations, third order multiplication of the small rotation angles are ignored and error of Euler angles are expressed explicitly as functions of the Euler angles and the small rotation angles. Based on the obtained solution, a new algorithm for attitude correction in inertial navigation is... 

    Integration of the inertial navigation system with consecutive images of a camera by relative position and attitude updating

    , Article Proceedings of the Institution of Mechanical Engineers, Part G: Journal of Aerospace Engineering ; Volume 233, Issue 15 , 2019 , Pages 5592-5605 ; 09544100 (ISSN) Ghanbarpour Asl, H ; Dehghani Firouzabadi, A ; Sharif University of Technology
    SAGE Publications Ltd  2019
    This paper introduces a new method for improving the inertial navigation system errors using information provided by the camera. An unscented Kalman filter is used for integrating the inertial measurement unit data with the features’ constraints extracted from the camera’s image. The constraints, in our approach, comprise epipolar geometry of two consecutive images with more than 65% coverage. Tracking down a known feature in two consecutive images results in emergence of stochastic epipolar constraint. It emerges in the form of an implicit measurement equation of the Kalman filter. Correctly matching features of the two images is necessary for reducing the navigation system errors because... 

    Model identification of a Marine robot in presence of IMU-DVL misalignment using TUKF

    , Article Ocean Engineering ; Volume 206 , 2020 Ghanipoor, F ; Alasty, A ; Salarieh, H ; Hashemi, M ; Shahbazi, M ; Sharif University of Technology
    Elsevier Ltd  2020
    In today's world, control and navigation of autonomous underwater vehicles (AUVs) are quite challenging issues. In these fields, obtaining an identified dynamic model of AUV is a vital part. In this paper, a method for parameter estimation of an AUV planar model is proposed, which uses augmented state space technique and Square Root Transformed Unscented Kalman Filter (SR-TUKF) as an estimator. Furthermore, by modeling, misalignment between Inertial Measurement Unit (IMU) and Doppler Velocity Log (DVL) is estimated, simultaneously. Parameter identification is conducted using data of an AUV, equipped with Gyroscope, DVL and Encoder for measuring control inputs, in a planar maneuver. According... 

    Design and Implementation of a Real-time Heuristic Algorithm for In-Motion Alignment of a Strapdown Inertial Navigation System

    , M.Sc. Thesis Sharif University of Technology Ashrafifar, Asghar (Author) ; Bahari, Hadi (Supervisor)
    In this work, the in-motion estimation of Euler angles of a strapdown inertial navigation system is studied using a speedometer, as an aided navigation sensor. First, the derivation of governing error equations has been done. Then, the most appropriate heuristic filters available in references have been chosen for this study. Among this filters, unscented particle filter, that has better performance and conditions for the real-time implementation, has been chosen. Then, an innovative solution for improving the performance of this filter is presented. The proposed filter uses particle swarm optimization to resample the particles. The proposed... 

    Inertial Navigation System Error Correction by Combining IMU Unit Information and Consecutive Images in an Unknown Environment

    , M.Sc. Thesis Sharif University of Technology Dehghani Firouzabadi, Abbas (Author) ; Nobahari, Hadi (Supervisor) ; Ghanbarpour Asl, Habib (Supervisor)
    In this research, INS error will be corrected with the help of the unscented kalman filter, by combining the IMU sensors and flight consecutive images information. Measurement equation of the Kalman filter is the epipolar Constraint of geometry of two consecutive images of the camera. In epipolar Constraint, the common points of two consecutive images of the camera field of view have an important role. This points will be extracted by SIFT and SURF algorithms. These algorithms have many mistakes in the process of images matching, but in this research, a solution based on the error covariance of the position of the ground point corresponding to the two common points of two images is presented... 

    Development of a Real-Time Heuristic Algorithm to Integrate Inertial and Celestial Navigation Systems

    , M.Sc. Thesis Sharif University of Technology Abtahi, Farhad (Author) ; Nobahari, Hadi (Supervisor) ; GhanbarpourAsl, Habib (Supervisor)
    Unscented kalman filter is able to integrate strapdown inertial navigation system (SINS) and celestial navigation system (CNS) and estimate current attitude and gyro drift precisely. However, initial attitude error, accelerometer bias and attitude error caused by gyro drift prior to CNS setting to work may cause large errors in velocity and position. So a novel method is presented for compensating these errors. The proposed method implements Fixed-interval smoothing to the integrated system. The procedure of filtering, smoothing and accelerometer bias estimation has been explained in details. The validity of the designed method has been proved through a simulation which admits the capability... 

    Image Flow and INS Sensor Fusion for the Accurate Localization of Planner Micro Robots

    , M.Sc. Thesis Sharif University of Technology khomejani, Shabnaz (Author) ; Vossoughi, Gholamreza (Supervisor)
    This research focuses on the robust mobile robot localization exploiting motion information acquired from an optical mouse operating based on optical flow technology. Most techniques of visual motion measurement are based on the well research discipline called “optical flow”. Theoretically, optical flow as a method of localization can be highly accurate, but it is sensitive to the noise and surface texture/optical characteristics and distance variations between the CCD detector and surface. As one could not achieve acceptable results in practical situations, to handle these problems, we propose to attach an acceleration – gyro (INS) sensor on the CCD detector (optical mouse) to improve the... 

    Design and Real-time Code-in-the-Loop Implementation of a Cooperative Inertial Navigation Algorithm

    , M.Sc. Thesis Sharif University of Technology Zarein, Mohammad Ghasem (Author) ; Nobahari, Hadi (Supervisor)
    In this study, the cooperative inertial navigation systems are used to prevent the error growth of the inertial navigation system in unmanned aerial vehicles that fly in group. Here, the navigation problem is defined for a group of unmanned vehicles, flying with full six degrees of freedom and the objective is to estimate the navigation information of all cooperators. Due to the nonlinear equations, the decentralized extended Kalman filter is used to estimate the states of the system. This means that there is a Kalman filter in each vehicle. The inputs of this filter are the range and the bearing angles between the vehicle and the cooperators, the estimated position of the cooperators and...