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Position, Location and Navigation Symposium, 2008 IEEE/ION

Date 5-8 May 2008

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Displaying Results 1 - 25 of 165
  • IEEE/ION PLANS 2008 May 6 – 8, 2008 Hyatt Regency Hotel Monterey, CA

    Page(s): i - xvii
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    Freely Available from IEEE
  • IEEE/ION plans 2008 conference

    Page(s): xviii - xxx
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    Freely Available from IEEE
  • GPS/INS integration with fault detection and exclusion in shadowed environments

    Page(s): 1 - 8
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (13282 KB) |  | HTML iconHTML  

    This paper presents a method for GPS/INS operation in shadowed environments such as urban canyons and rural foliage cover. Shadowing causes a combination of multipath and signal attenuation which results in increased uncertainty in the GPS observables and sometimes complete loss of satellite tracking. Environment layout and the line-of-sight vector to the affected satellite determines the degree of shadowing in the range domain. Details are provided for the failure modes and effects in such environments. These results are used in the analysis of a fault detection and exclusion (FDE) algorithm to provide integrity to the GPS observables. View full abstract»

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  • Impact of carrier to noise power density, platform dynamics, and IMU quality on deeply integrated navigation

    Page(s): 9 - 16
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    In this paper, the authors investigate how the Carrier to Noise power density ratio (C/N0), platform dynamics, and differing Inertial Measurement Unit (IMU) quality affect the performance of Deeply Integrated (DI) algorithms. Two different DI algorithms are described in detail and analyzed using a high fidelity GPS simulator. The first algorithm is a Vector Delay/Frequency Lock Loop (VDFLL). The second algorithm is a Deeply Integrated GPS/INS system with differing grades of IMUpsilas. The ability of the algorithms to operate at low C/N0 levels and in high dynamics is investigated empirically with the GPS simulator. The VDFLL algorithm can successfully track the received GPS signals through 2 g, 4 g, and 8 g coordinated turns at 19 dB-Hz. Initial results of the Deeply Integrated GPS/INS algorithm show its operation through the 2 g, 4 g, and 8 g coordinated turn at 16 dB-Hz with a tactical grade IMU. View full abstract»

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  • Performance of a deeply coupled commercial grade GPS/INS system from KVH and NovAtel Inc.

    Page(s): 17 - 24
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    NovAtel Inc. and KVH Industries have jointly developed a commercial grade, single enclosure GPS/INS system. The integrated KVH CG-5100 IMU features fiber-optic gyros and MEMs accelerometers, and provides inertial data at 100 Hz. NovAtelpsilas OEMV3 receiver is the GPS engine. Weighing 5.2 lbs, the combined system will feature the tightly coupled architecture that is a key characteristic of NovAtelpsilas SPAN (Synchronized Position Attitude Navigation) technology. The GPS receiver provides aiding information for the INS, and is reciprocally aided by feedback from the INS to improve signal tracking. The feedback from the INS to the GPS engine is the deeply coupled aspect of the system. It is also tightly coupled. GPS measurements are used to update the INS filter, providing high quality aiding information whenever there are least two satellites available. The combined system has an optional wheel sensor, which is used to further aid the INS during times of reduced GPS availability in land vehicle applications. View full abstract»

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  • An evaluation of nonlinear filtering algorithms for integrating GNSS and inertial measurements

    Page(s): 25 - 29
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    The quality of dead reckoning positioning algorithms which are integrating GNSS and INS measurements is a crucial factor for advanced vehicular safety systems. Apart from sensor performances, the most important factor determining this quality is the filter algorithm. Thus, this paper aims to compare and evaluate different nonlinear filtering approaches, focusing on their performance in GNSS/INS integration. The presented approach is based on an advanced motion model which assumes a constant turn rate and longitudinal acceleration of the vehicle. Using this approach, the unscented Kalman Filter is compared to the standard extended Kalman filter. For the evaluation, experimental data obtained by a DGPS receiver with RTK capabilities are used. With this approach, the filter assessment is performed in different scenarios, including urban areas. View full abstract»

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  • Application of the manifold-constrained unscented Kalman filter

    Page(s): 30 - 43
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    This document describes the rationale and methodology behind the application of a Kalman-type filter to a system that has two properties which lead to inaccuracy or instability in traditional filters: highly non-linear system models along with a state that is constrained to a non-linear Riemannian manifold. The non-linear models are handled by the use of the unscented transformation, while the constrained state is dealt with using both a modified unscented transformation and a modified time-update model. The application that requires these treatments is the system identification of a super-light unmanned aerial vehicle, where the dynamics of the vehicle are such that an unconstrained orientation must be dealt with as a unit-quaternion, the high-order of the model requires maximum precision be maintained, and the vehicle itself requires the lowest-mass sensors available, leading to relatively high sensor noise in an already noisy measurement environment. The new filter is explained in this context, implementation details are given, and results of simulation and flight trials are explored. In addition, square-root extensions to this filter are described that increase the filter's computational efficiency without sacrificing its accuracy, stability, or robustness. View full abstract»

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  • Application of a sigma-point Kalman filter for alignment of MEMS-IMU

    Page(s): 44 - 52
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (336 KB) |  | HTML iconHTML  

    The extended Kalman filter (EKF) is widely used for the integration of measurements form the Global Positioning System (GPS) and inertial navigation system technologies. The EKF is applied to nonlinear systems via a linearization of the system, and is reliable for weakly linear systems. For strong linear systems however, the EKF sometimes suffers from divergence. To overcome this shortcoming the so-called sigma-point Kalman filter (SPKF) has been proposed. The SPKF uses a finite number of sigma points to implement the nonlinear transformations directly instead of linearizing them. This paper applies the SPKF to the initial alignment problem, because it could compensate for the influence of linearization error on MEMS-IMU measurements. The nonlinear error models for a MEMS-IMU are derived by representing the orientation in the quaternion. Both simulation and field test results are presented to demonstrate the state estimation performance of the SPKF. The simulation results show that the SPKF converges faster than the EKF for the same filter precision. The state estimation precision of the two filters is compared - the covariance estimation accuracy of SPKF is better than that of EKF. These advantages make the SPKF suitable for fast and highly maneuverable trajectories. View full abstract»

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  • Development of an Italian low cost GNSS/INS system universally suitable for mobile mapping

    Page(s): 53 - 59
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    The first studies for the mobile mapping and creation of a vehicle for this kind of research were carried out by Canadian Researchers in the 1980psilas. Since then these vehicles have been widely employed in several applications (road cadastre maps, terrestrial photogrammetry, road sign recognition etc.) for both commercial and research purposes throughout the world. Many GNSS/INS vehicles which can be equipped in different ways with one or more GPS, inertial sensors and one or several cameras, have been realized. A characteristic shared by most of these devices concerns the high costs of the sensors, of the realization and of the maintenance.For this reason, a GNSS/INS system, that is suitable for any vehicle, made up of low cost devices (two GPS receivers, an INS and a camera rigidly placed on a metallic bar), has been designed and built by our Research Group. Two tests run at different velocities have been carried out to evaluate the reliability of the system. After a presentation of the system, the differences that were witnessed during the application of these calibration methods are explained in this paper. View full abstract»

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  • Efficient Gaussian mixture filter for hybrid positioning

    Page(s): 60 - 66
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (209 KB) |  | HTML iconHTML  

    This paper presents a new way to apply Gaussian mixture filter (GMF) to hybrid positioning. The idea of this new GMF (efficient Gaussian mixture filter, EGMF) is to split the state space into pieces using parallel planes and approximate posterior in every piece as Gaussian. EGMF outperforms the traditional single-component positioning filters, for example the extended Kalman filter and the unscented Kalman filter, in nonlinear hybrid positioning. Furthermore, EGMF has some advantages with respect to other GMF variants, for example EGMF gives the same or better performance than the sigma point Gaussian mixture (SPGM) [1] with a smaller number of mixture components, i.e. smaller computational and memory requirements. If we consider only one time step, EGMF gives optimal results in the linear case, in the sense of mean and covariance, whereas other GMFs gives suboptimal results. View full abstract»

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  • Issues in wearable biomechanical inertial sensor systems

    Page(s): 210 - 216
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    Wearable inertial sensors present designers with additional challenges not seen in conventional systems where power at fixed voltage is abundant. This work discusses the critical concerns in designing a wearable inertial sensor including component selection, power distribution and the use of sleep/shutdown modes. View full abstract»

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  • Eyeball: An inertial helmet mounted cueing system

    Page(s): 217 - 224
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    Eyeball (EB) is a helmet-mounted cueing system used to display cueing symbology for target designation and location on a helmet-mounted display. In order to provide information and interact with the environment, the EB consists of two basic subsystems: a helmet-mounted inertial sensor unit that measures the accelerations and angular rates at which the head of the pilot is exposed and a helmet mounted display. When appropriately initialized and maintained, the inertial measurements can be used to determine the line-of-sight of the pilot wearing the helmet. Since the pointing direction is computed with respect to an external inertial reference frame, this line-of-sight can then be used for slaving any external system sharing the same inertial reference. View full abstract»

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  • MEMS IMU for AHRS applications

    Page(s): 225 - 231
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    Northrop Grumman, LITEF is developing MEMS (micro-electro-mechanical systems) based Inertial Measurement Units (IMU) for future attitude and heading reference systems (AHRS) with a target accuracy of 5 deg/h for the gyroscopes and 2.5 mg for the accelerometers. Within the technology development phase, prototype single axis gyroscopes have been realized and extensively tested for effects including temperature, acoustic and vibration sensitivities. These devices employ micro-machined all-silicon gyroscope sensor chips processed with deep reactive ion etching (DRIE). Silicon fusion bonding ensures pressures smaller than 3middot10-2 mbar. Sophisticated analog electronics and digital signal processing condition the capacitive pick-off signals and realize full closed loop operation. The current results with overall bias error smaller than 2 deg/h to 5 deg/h, scale factor error <1200 ppm, measurement range >1000 deg/s and angular random walk <0.4 radic/vh indicate that stable production of 5 deg/h gyroscopes is realistic. The fabrication technology for capacitive, pendulous accelerometer chips is based on that used for the gyros with only an increase in the enclosed pressure to obtain overcritical damping. Pulse width modulation (PWM) within a digital control loop is used to realize closed loop operation. Accelerometer chips have been tested over temperature with a residual bias error <2.0 mg and a scale factor error <1400 ppm. These sensor chips have been integrated into an IMU whereby the power budget and size of the sensor electronics have been optimized. In this paper the salient features of the gyro and accelerometer designs are presented together with an overview of the IMU system architecture. Measurement results, with a focus on environmental characteristics and robustness, are included. View full abstract»

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  • Gun hard inertial measurement unit based on MEMS capacitive accelerometer and rate sensor

    Page(s): 232 - 237
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    Smart munitions and missiles are increasingly incorporating inertial measurement units for guidance of short range weapon systems. In addition to usual high performance of the required sensors, namely, accelerometers and gyros, this application requires high shock survivability and post shock stability of the sensors. Colibrys has successfully developed a gun hard version of its accelerometer product and AIS has integrated these acceleration sensors and rate gyro to a gun hard IMU. The IMU has been extensively tested and characterized over the full temperature range, at Aerobutt and in many live shooting trials. The extreme shock performance of the IMU has been maintained by making the accelerometer shock resistant. This has been achieved by placing a specially designed mechanical stopper over the sensing element to protect the sensor from extreme shock levels by limiting the mechanical displacement of the MEMS element. This approach has resulted in excellent post shock performance of the acceleration sensor. Beyond this a special assembly technology has been developed at AIS to ensure that key shock components are filtered out and their energy is not transferred into the sensing element; and the vibrating elements are not affected by the components of the firing shock. View full abstract»

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  • A set of high accuracy low cost metallic resonator CVG

    Page(s): 238 - 243
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    A set of all-digital metallic cylindrical CVGs of different diameters are presented in this paper. Innalabs CVG43 with resonator diameter of 43 mm, having natural frequency in the range 3 kHz and made of low damping and temperature stable material, is placed under vacuum cap with residual pressure of about 5 times 10-4 arm. The resonator Q factors reach values of 20000 - 30000 depending on resonator design and material used. CVG43 bias instability is about 0.03 deg/hr at stable temperature and about 0.5 deg/hr through its full temperature range (using temperature ramp of 1degC/min). Innalabs CVG25, which uses a 25 mm resonator diameter, has a bias instability of about 0.15-0.5 deg/hr, and a natural frequency approaching 6 kHz; is presented in Allan variance graphs at constant temperature and throughout its operating temperature range. Innalabs CVG17 gyro based on 17 mm resonator diameter has a bias instability of about 2.5 deg/hr and can survive many thousands of g's shock. This gyro is presented in Allan variance graphs and photos. This gyro sensor weighs about 20 grams and is ideal for unmanned aerial and underwater vehicle applications. Gyro accuracy through a wide temperature range is discussed and test results are presented. Three-axis units based on all types of these gyros are presented, as well. Future opportunities of each of these gyros are discussed. View full abstract»

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  • Precision navigation for UAVs, mini-munitions, and handhelds through application of low cost accurate MEMS IMU/INS technology

    Page(s): 244 - 252
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    GPS has previously been integrated with mobile PDApsilas and/or with Inertial Measurement Units (IMUs). However, to date, no low-cost, low-power, miniature (i.e., less than 2 in.3) IMU/INS has been integrated into smart munitions, electronics, handheld GPS units or miniaturized cooperative low cost interceptors to create a miniature G hardened multi-functional module. Several DoD contractors are evaluating the JayMart Sensors low cost miniature IMU/INS module for smart munitions, mini-missile and micro-UAV weapons. A commercial company will soon link the module to a network of mobile PDApsilas enabled with GPS to provide location-based coverage indoors for emergency workers and DoD is scheduled to gun launch the module to test its ruggedness later this year. View full abstract»

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  • Accurate positioning using a planar pseudolite array

    Page(s): 433 - 440
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    When pseudolites are used, as in the wide area augmentation system (WAAS), or, when a Locata type array is used for accurately positioning of ground vehicles, a high vertical GDOP is invariably encountered. The latter translates into poor altitude estimates and potentially also poor position estimates, even in the case of a good planar geometry and where the user is near the center of the pseudolite array. Hence, the use of altitude measurements or terrain elevation information supplied by a GIS data base is investigated. In this paper concepts of operation are developed and algorithms are designed such that the best possible altitude and horizontal position estimates are obtained from the available measurements. View full abstract»

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  • Hardware-in-the-loop testing of the NATO standardisation agreement 4572 interface using high precision navigation equations

    Page(s): 441 - 448
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    This paper describes the development of a real-time navigation system, embodying high precision navigation equations, which was designed, built, and used by QinetiQ specifically for comprehensive hardware-in-the-loop testing of the STANAG 4572 inertial measurement unit interface standard. The results provided give confidence that the STANAG 4572 interface is fundamentally more than adequate for implementation within a deeply integrated (ultra-tightly-coupled) navigation system as well as an external test interface for deeply integrated navigation systems. View full abstract»

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  • Determination of GPS RF signal strengths

    Page(s): 449 - 458
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    A methodology for determining GPS RF C/A signal strengths is provided by combined measurement and analysis. Sky temperature, antenna front-end RF gain and noise characterizations are also provided. This methodology is especially applicable for calibration of GPS signal and noise levels for receiver testing. View full abstract»

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  • Radio interference effects on commercial GNSS receivers using measured data

    Page(s): 459 - 467
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    Nowadays more and more services rely on the positioning and time synchronization provided by the U.S. Global Positioning System (GPS) which is worldwide available. The requirements on accuracy are increasing with the number of applications using a Global Navigation Satellite System (GNSS). As more systems in transport, communication and other areas are based on GNSS a degradation of performance might lead to unpredictable risks to economy and safety. Man-made radio frequency interference is one of the last remaining challenges which may result in unforeseeable and potentially devastating threats to GNSS positioning. Therefore the German Aerospace Center performed a measurements campaign in 2006. Out of the radio signals recorded a narrowband pulsed interferer, a communication signal and a wideband colored noise process were extracted and modeled. The impact of these interferers on a commercial GPS receiver was studied in hardware simulations. The results are carried out on pseudorange level as bias, variance and distribution of the range estimate. View full abstract»

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  • A unique approach to wavefront calibration

    Page(s): 468 - 472
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    Significant progress has been made in recent years in wavefront technology using Global Positioning System (GPS) simulators. We demonstrate here a novel approach to surpassing some of the limiting obstacles that plague the simulation world in achieving notable carrier-phase parameters. The controlled reception pattern antenna (CRPA) realistically collects and sends the RF downlink data to the antenna electronics (AE) through the natural order of physics through the atmosphere. The dilemma in the simulation environment is to achieve realistic numbers in carrier-phase calibration to mimic a natural RF environment. We found that a unique approach is to characterize the AE under test by using a vector network analyzer that measures the RF delays between the reference node in relation to the six auxiliary nodes. This in conjunction with a discriminating carrier-phase receiver technique that outputs the required data files enables our wavefront to achieve results of better than a tenth of a degree of precision in the L1 frequency. The significance of these two pieces of equipment working in unison is to limit the movement of the radio frequency (RF) cables that are connected from the GPS simulators to the AE. Previous methods involved connecting and reconnecting RF cables through combiners and amplifiers that individually added errors to the system. The modification to the original method increased calibration accuracy thus better emulating the actual RF environment. View full abstract»

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  • Performance assessment of indoor location technologies

    Page(s): 624 - 632
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    Location based services (LBS) are currently enjoying a strong success as a result of well-proven GNSS positioning technology (GPS, assisted GPS). However, the future generation of LBS will have to address the challenge of accurate and reliable indoor localization. In fact, this need has already been clearly expressed by various communities of professional end users (firemen, security forces, etc.) in the context of LIAISON and WearlTork projects funded by the European community's sixth framework program. In order to assess the performance of the location technologies most suited to cope with the stringent constraints of indoor LBSs oriented towards the needs of professional users, in particular those of the firemen, a "location trial" composed of several test scenarios was organized, putting face to face in a common systematic reference the following positioning technologies: - Inertial MEMS coupled with GNSS, using two different algorithmic approaches for the inertial component: signal pattern recognition associated with human biomechanical walking models and conventional inertial navigation using zero velocity updates at footfalls; - UWB radio-based localization prototype system. The results from this "location trial" show that inertial technology achieves interesting performances (stand-alone positioning accuracy better than 3 meters RMS after 4 minutes and less than 6 meters RMS after 8 minutes of continuous pedestrian walk), but still lacks robustness against specific environmental conditions (in particular magnetic disturbances affecting orientation estimation) and users' walking behavior. As for the UWB prototype system, it provides good positioning accuracy (less than 3 meters RMS) for nominal operational conditions, but but it can experience severe degradation under certain circumstances. By highlighting the pros and cons of each technology under a common framework, this "location trial" has provided a clearer understanding how their seamless combination - - can realistically address all users' needs: accuracy, reliability, robustness, coverage, deployability and wearability. View full abstract»

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  • System and algorithms for accurate indoor tracking using low-cost hardware

    Page(s): 633 - 640
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    In this paper we present a novel radio location system for indoor tracking and navigation. The system has been designed for applications such as emergency first responders where high accuracy is required, all nodes have only wireless connections, and the system must be able to be rapidly deployed. The application requirements are best satisfied using time-of-arrival based radio location, however the challenge is to do this at low cost. Specific issues addressed by the system include achieving frequency and time synchronization using low cost oscillators in each node and overcoming the variable propagation delay in the analog electronics from the use of low cost radio components, while operating in an environment characterized by strong multipath interference. Our approach has been to use low cost highly integrated electronic components and to use sophisticated signal processing to compensate for the limitations in the radio electronics. The system has been implemented and we demonstrate a median error of 0.15 m outdoors and 0.49 m in an indoor office environment with measurements performed through multiple walls. View full abstract»

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  • SLL: Relations to Kohonen SOMs

    Page(s): 641 - 645
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    The simultaneous localization and learning (SLL) is an indoor localization technique based on existent radio communication networks. It originally takes received signal strength (RSS) as measured feature, used as input on an adaptive and iterative process based on Kohonen self organizing maps (SOMs) in order to learn and improve a feature map. The present paper points the main characteristics from both SLL and SOM, their differences and similarities. The somewhat generic formulation for SOMs acquire physical meanings with SLL that act as a constrainment, making the SLL a very particular case of SOM. The proofs for one dimensional SOMs are complemented by the proofs presented for the SLL by the authors in previous articles. View full abstract»

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  • Wi-Fi based indoor localization and tracking using sigma-point Kalman filtering methods

    Page(s): 646 - 659
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (2170 KB) |  | HTML iconHTML  

    Estimating the location of people and tracking them in an indoor environment poses a fundamental challenge in ubiquitous computing. The accuracy of explicit positioning sensors such as GPS is often limited for indoor environments. In this study, we evaluate the feasibility of building an indoor location tracking system that is cost effective for large scale deployments, can operate over existing Wi-Fi networks, and can provide flexibility to accommodate new sensor observations as they become available. At the core of our system is a novel location and tracking algorithm using a sigma-point Kalman smoother (SPKS) based Bayesian inference approach. The proposed SPKS fuses a predictive model of human walking with a number of low-cost sensors to track 2D position and velocity. Available sensors include Wi-Fi received signal strength indication (RSSI), binary infrared (IR) motion sensors, and binary foot-switches. Wi-Fi signal strength is measured using a receiver tag developed by Ekahau Inc. The performance of the proposed algorithm is compared with a commercially available positioning engine, also developed by Ekahau Inc. The superior accuracy of our approach over a number of trials is demonstrated. View full abstract»

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