Browsing by Author "O'Keefe, Kyle P. G."
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Item Open Access Carrier Phase-Based Ionospheric Modeling and Augmentation in Uncombined Precise Point Positioning (UPPP)(2018-09-21) Xiang, Yan; Gao, Yang; O'Keefe, Kyle P. G.; Nielsen, Jorgen; Rangelova, Elena V.; Chen, WuPrecise Point Positioning (PPP) is a stand-alone high-precision positioning technique employing carrier phase measurements and external augmentation or aiding products. PPP reduces labor and equipment costs in contrast to Real-Time Kinematic (RTK) which relies on base stations. However, PPP suffers from a long convergence time of 15 to 60 minutes to reach the centimetre level. This long initialization time restricts the applications of PPP. To address this problem, we make use of accurate and precise ionospheric corrections. This dissertation endeavors to improve the ionospheric observables, Differential Code Biases (DCBs), and Mapping Function (MF). We then leverage these to reduce the convergence time. To obtain more accurate ionospheric corrections, we retrieve ionospheric observables using PPP. The ionospheric observables from the more commonly-used carrier phase smoothed code method are adversely affected by levelling errors. PPP offers a preferable way to reduce the leveling errors and preserve the consistency of ionospheric corrections, beneficial for shortening the convergence time of PPP. We demonstrate that the ionospheric observables retrieved from three PPP models, Traditional Ionosphere-Free, University of Calgary (UofC), and Uncombined (UPPP), all agree in terms of DCBs. The differences of ionospheric observables are at centimetre level. With the improved ionospheric observables using PPP, the stability and internal accuracy of satellite and receiver DCBs are also enhanced. The Root Mean Square (RMS) of the satellite DCB estimates is improved from 0.1 nanoseconds to 0.07 nanoseconds, and the day-to-day stability is enhanced by 0.22 nanoseconds. Another factor affecting ionospheric corrections is the MF which is mostly based on the fixed height Single-Layer Model (SLM). To reduce the effects of the inhomogeneity of the ionosphere, an Ionospheric Varying Height (IVH) is proposed and examined. Results show the mapping errors are reduced by about 15% when the integral varying height is exploited. By applying the improved ionospheric corrections into UPPP, we achieve an accuracy of 0.4 metres for global constraints and 0.2 metres for the regional constraints at the first epoch. The convergence time for the simulated kinematic mode is reduced from 41 to 7.5 minutes in the east at one decimetre, from 14.5 to 4.0 minutes in the north at one decimetre, and from 11.0 to 6.5 minutes in the vertical at two decimetres at a 68% confidence level.Item Open Access Detecting and Correcting for Human Obstacles in BLE Trilateration Using Artificial Intelligence(2020-02-29) Naghdi, Sharareh; O'Keefe, Kyle P. G.One of the popular candidates in wireless technology for indoor positioning is Bluetooth Low Energy (BLE). However, this technology faces challenges related to Received Signal Strength Indicator (RSSI) fluctuations due to the behavior of the different advertising channels and the effect of human body shadowing among other effects. In order to mitigate these effects, the paper proposes and implements a dynamic Artificial Intelligence (AI) model that uses the three different BLE advertising channels to detect human body shadowing and compensate the RSSI values accordingly. An experiment in an indoor office environment is conducted. 70% of the observations are randomly selected and used for training and the remaining 30% are used to evaluate the algorithm. The results show that the AI model can properly detect and significantly compensate RSSI values for a dynamic blockage caused by a human body. This can significantly improve the RSSI-based ranges and the corresponding positioning accuracies.Item Open Access GNSS Code Multipath Mitigation by Cascading Measurement Monitoring Techniques(2018-06-19) Pirsiavash, Ali; Broumandan, Ali; Lachapelle, Gérard; O'Keefe, Kyle P. G.Various measurement monitoring techniques are investigated to mitigate the effect of global navigation satellite systems (GNSS) code multipath through error correction, stochastic weighting of measurements and detection and exclusion (or de-weighting) of affected measurements. Following a comprehensive review of each approach, the paper focuses on detection/exclusion and detection/de-weighting techniques where several single and dual-frequency monitoring metrics are employed in a combination with time-averaging and the M of N detection strategy. A new Geometry-Free (GF) detection metric is proposed given its capability to be combined with a preceding Code-Minus-Carrier (CMC)-based error correction to reduce the number of excluded or de-weighted measurements and thus preserve the measurement geometry. Three geometry-based algorithms, namely measurement subset testing, consecutive exclusion and iterative change of measurement weights are investigated to address multipath scenarios with multiple simultaneously affected measurements. Experimental results are provided using GPS L1, L2C and L5 data collected in multipath environments for static and kinematic scenarios. For GPS L1, the proposed combined method shows more than 38% improvement over a conventional Carrier-to-Noise-density ratio (C/N₀)-based Least-Squares (LS) solution in all but deep urban canyons. Lower performance was observed for L2C and L5 frequencies with a limited number of satellites in view.Item Open Access Handheld Antenna Assessment Based on CV Ego-motion Position and Orientation Estimation of a Mobile Device(2020-01-21) Guo, Yi Ran; Nielsen, John; Sesay, Abu B.; O'Keefe, Kyle P. G.5G wireless communication features the development of millimetre-wave antenna array and the beamforming technology. 5G antenna array will require regular calibration as its performance depends on the physical orientation and movement of the device, the nearfield electromagnetic wave scattering which changes over time, as well as the body absorption factors. Unfortunately, the conventional calibration method that needs to be carried out in an anechoic chamber is very inconvenient for performing frequent calibration, this method also lacks the flexibility to emulate the daily usage scenarios accurately. A potentially better solution is to devise a method to compute the dynamics of the device movement and then use it in the antenna array calibration. The underlying hypothesis is that if the pose of the mobile device can be estimated with sub-millimetre accuracy over a time epoch, then a quantitative assessment of the array performance would be possible. This thesis made use of a single antenna to demonstrate the alignment between the pose estimates obtained using Computer Vision techniques and the antenna phase measurements, thus providing a feasible solution to its future application in the assessment of the 5G antenna array.Item Open Access Improving Bluetooth-based Indoor Positioning Using Vision and Artificial Networks(2020-07-09) Naghdi, Sharareh; O'Keefe, Kyle P. G.; Noureldin, Aboelmagd M.; Lichti, Derek D.; Liang, Steve H. L.; Barsocchi, PaoloThe demands for accurate positioning and navigation applications in complex indoor environments such as emergency call positioning, fire-fighting services, and rescue operations are increasing continuously. Global Navigation Satellite Systems (GNSS) receivers, while ubiquitous in outdoor positioning, are not effective indoors. One of the best solutions to solve this problem and increase the accuracy of the user's position in indoor areas is to apply other sensors. This research takes advantage of Bluetooth Low Energy (BLE) technology, vision systems, and Artificial Neural Networks (ANNs) to improve the accuracy of the position solutions in indoor environments for pedestrian applications. BLE technology faces challenges related to the Received Signal Strength Indicator (RSSI) fluctuations caused by human body shadowing. This thesis presents methods to compensate for losses in the RSSI values by applying ANN algorithms to RSSI measurements from three BLE advertising channels. The resulting improved RSSI values are then converted into ranges using path loss models and trilateration is applied to obtain indoor positions. Two neural network algorithms were implemented. The first used only the RSSI values while the second incorporated a wearable camera as an additional source of information about the presence or absence of human obstacles. The results showed that the two proposed artificial-based systems could enhance RSSI due to human body shadowing and provide significantly better ranging and positioning solutions than fingerprinting and trilateration techniques with uncorrected RSSI values. Two proposed systems provided 3.7 m and 6.7 m positioning accuracy in 90 % of the time in a complex environment with the presence of the human body, nevertheless, the fingerprinting and the classic algorithms offered 8.7 m and 12.3 m position accuracy in the same situation, respectively.Item Open Access Improving the Accuracy of GNSS Receivers in Urban Canyons using an Upward-Facing Camera(2018-07-03) Gakne, Paul Verlaine; O'Keefe, Kyle P. G.; Gao, Yang; Wang, Ruisheng; Fapojuwo, Abraham Olatunji; Ruotsalainen, LauraGlobal Navigation Satellite Systems are widely used as localization systems for various applications in indoor and outdoor environments. Autonomous vehicles for example rely on navigation sensors such as GNSS receivers, INS, odometers, LiDAR, radar, etc. However, none of these sensors alone is able to provide satisfactory position solutions in terms of accuracy, availability and reliability all the time and in all environments. This thesis presents a new tightly coupling method fusing the egomotion of a land vehicle estimated from a sky-pointing camera with GNSS signals and a digital map for navigation purposes in harsh urban canyon environments. The advantages of this configuration are three-fold: firstly, for the GNSS signals, the upward-facing camera will be used to classify the acquired images into sky and non-sky (known as segmentation). A satellite falling into the non-sky areas (e.g., buildings) will be rejected and not considered for the final position solution computation. Secondly, the narrow field of view sky-pointing camera is helpful for urban area egomotion estimation in the sense that it does not see most of the moving objects (e.g., cars) and thus is able to estimate the egomotion with fewer outliers than is typical with a forward-facing camera. Thirdly, the skyline can be extracted and serves as a finger print of the vehicle location in the city. This information can then be correlated with a 3D city model to obtain the vehicle location. In order to obtain an accurate solution from the proposed method, a few intermediate steps had to be taken into account. An improved image segmentation algorithm is presented. The output of this algorithm served for the skyline positioning and the camera-based multipath mitigation. Also, an accurate visual odometry was implemented. Moreover, the monocular-based visual odometry is able to determine the vehicle translation accurately but up to a scale only. An integrated system that tackles the scale factor issue is designed. From five datasets evaluated in this research, the proposed method has shown to be robust and provide more accurate position, velocity and attitude solution at least 83% of the time than the GNSS-only and loosely coupled GNSS/vision solutions.Item Open Access Low-Cost Real-Time Precise Point Positioning (PPP) Correction Service with High Availability and Accuracy(2020-04-24) Zhou, Peiyuan; Gao, Yang; El-Sheimy, Naser; O'Keefe, Kyle P. G.; Sesay, Abu B.; Wang, JinlingThanks to the availability of real-time state-space correction services, real-time Precise Point Positioning (PPP) is drawing increasing interests from various applications. However, the current real-time PPP correction services are mainly designed to support professional users using high-end GNSS systems. To support many emerging applications such as precise positioning with smartphones and self-driving cars which demand high availability and accuracy as well as high cost-effectiveness, such correction services must be improved. A low-cost real-time PPP correction service has been proposed which is based on an Improved Legacy Navigation message (ILNAV) to represent and disseminate real-time precise satellite orbit, clock, and code bias with improved availability and scalability. The ILNAV can provide real-time precise satellite orbit and clock corrections for up to two hours when correction outages occur. The update rates of the ILNAV are fully scalable to accommodate various requirements in terms of communication bandwidth and accuracy. The precise satellite Differential Code Bias (DCB) is estimated with Low-Earth Orbit (LEO) satellite onboard GPS observations, which is integrated into the ILNAV as Timing Group Delay (TGD) parameter to reduce the communication load of standalone code bias messages. Since the ILNAV provides fully consistent representation and user algorithms as the standard LNAV, it can also support convenient transitions from standard LNAV to ILNAV for improved positioning performance. To support low-cost GNSS users for further improved positioning accuracy and accelerated filter convergence, highly available and precise atmospheric corrections are estimated using real-time uncombined PPP and ILNAV. The Spherical Harmonic Function (SHF) model is used to represent global ionospheric Vertical Total Electron Content (VTEC) corrections, while the Slant Total Electron Content (STEC) map and polynomial model are developed for representing regional slant ionospheric and zenith wet tropospheric corrections, respectively. The low-cost real-time PPP correction service is evaluated with an application to Android Nexus 9 tablet and u-blox devices. The results demonstrate that submeter-level horizontal positioning accuracy can be achieved with the Android Nexus 9 tablet under favorable environments, while accuracy improvement to decimeter-level can be obtained using u-blox M8T/F9P receivers with a patch antenna.Item Open Access Microphysics of Ion and Electron Energization in the Topside Ionosphere(2019-10-30) Shen, Yangyang; Knudsen, David J.; Cully, Christopher M.; Jackel, Brian J.; Moazzen-Ahmadi, Nasser; O'Keefe, Kyle P. G.; Moore, Thomas E.Ionospheric ion and electron energization and field-aligned transport are critical processes of magnetosphere-ionosphere-thermosphere coupling. The Canadian Enhanced Polar Outflow Probe (e-POP) satellite carries particle and field instruments specifically designed to study micro-scale characteristics of ion energization and outflow processes in the topside (325-1,500 km) ionosphere. The Suprathermal Electron/Ion Imager (SEI) instrument onboard e-POP has the capability of resolving two-dimensional low-energy (from sub-eV to 325 eV) particle distributions at 10-ms time scale, or less than 100-m spatial scale. This dissertation presents techniques to derive and validate the ion bulk flow velocity and temperature from SEI and reports several discoveries resulting from direct measurements of particles, waves and magnetic fields from e-POP. First, to identify the dominant drivers of ion upflow at near 1000 km altitude, I present three cleft ion fountain events with intense (>1.6 km/s) ion upflow velocities during quiet periods. Conjunctional observations from multiple satellites and radars indicate that the observed ion upflows are primarily driven by ambipolar electric fields due to soft electron precipitation. Second, to test the statistical significance of wave-ion heating at low altitudes (325-730 km), we show that significant transverse O+ ion heating from broadband extremely low frequency (BBELF) waves is occurring and even dominating at altitudes as low as 350 km, a boundary that is lower than previously reported. Ion heating in association with ion downflows rather than upflows suggests an active ``pressure cooker'' in the low-altitude return current region. Third, using numerical test particle simulations that take into account ion-neutral collisions to explain BBELF-induced ion heating at low altitudes, we find that the most effective mechanism is through collisional cyclotron heating by short-scale electrostatic ion cyclotron (EIC) waves. The interplay between finite perpendicular wavelengths, wave amplitudes, and ion-neutral collision frequencies collectively determine the ionospheric ion heating limit, which has been derived both numerically and analytically. Finally, we present the first direct observations of suprathermal (tens to hundreds of eV) electron acceleration perpendicular to B in the topside (900-1,500 km) ionosphere. These are a counterpart to transverse ion acceleration which has been reported extensively since the 1970's.Item Open Access A Model-based, Optimal Design System for Terrestrial Laser Scanning Networks in Complex Sites(2019-08-29) Jia, Fengman; Lichti, Derek D.; O'Keefe, Kyle P. G.; Wang, Ruisheng; Shahbazi, Mozhdeh M.; Lindenbergh, Roderik C.With the rapid increase of terrestrial laser scanner (TLS) applications, especially for the high-accuracy modelling of large-volume, complex objects, a design system is required to provide the optimal solutions for both scanner and target placement, so that the project requirements in terms of coverage, precision, economy and reliability can be met. In this thesis, a model-based, optimal design system for terrestrial laser scanning networks in complex sites is proposed. First, a hierarchical TLS viewpoint planning strategy driven by an improved optimization method is developed to solve the optimal scanner placement problem. The main contribution of the proposed method is to improve the efficiency in design without jeopardizing the optimality of the solution, compared with the traditional method with the extensive search strategy. In addition, the target placement for registration, which draws limited attention in the existing research, is determined by optimizing the target arrangement criterion, and the number of target locations is minimized by accepting the close to optimal target arrangement. Finally, the quality of the design, including the sensitivity of the object coverage to viewpoint placement and the precision of the point cloud are provided. The proposed methods were verified by the relatively small network first and then applied on two building complexes located on the University of Calgary campus. The design for scanner placement was compared with the “brute force” strategy in terms of the optimality of the solutions and runtime. The results showed that the proposed strategy provided scanning networks with a compatible quality but a significantly improved efficiency in design. The number of target locations necessary for registration from the proposed system was surprisingly small, considering the volume and complexity of the networks. Through the quality assessments, the sensitivity of the object coverage to the scanner placement indicated where users might need to consider viewpoint densification, and the point cloud precision indicated if the network design could meet the project requirements.Item Open Access A Modular System for Radio Frequency Heating of Hydrocarbon Reservoirs(2019-10-29) Apperley, Thomas; Okoniewski, Michal M.; Nielsen, John; Belostotski, Leonid; Fear, Elise C.; O'Keefe, Kyle P. G.; Bridges, GregRadio frequency (RF) heating is an enhanced oil recovery method with the potential to revolutionize oil sands resource development. In the author's opinion, RF heating currently faces four major practical challenges: heating pattern control, downhole transmission loss, sensitivity to changing reservoir environments and the cost and efficiency of RF generation. This thesis pursues a system concept and laboratory prototypes that can address these issues. The first two challenges can be addressed using a modular system. Sensitivity to the reservoir can be resolved using a single conductor transmission line launcher with two coaxial discontinuities and field quasi-symmetry, which was validated using a frequency-scaled prototype. Power combined switching oscillators can ensure high-efficiency RF generation at high output power, while the use of silicon carbide transistor technology can prospectively reduce cost while providing ruggedness. A new E/Fodd oscillator was devised and a prototype using two power combined oscillators is presented.Item Open Access Multimodal Spatiotemporal Collaborative Positioning Framework for Indoor Environments(2019-07-10) Sakr, Mostafa; El-Sheimy, Naser; Gao, Yang; Noureldin, Aboelmagd; O'Keefe, Kyle P. G.; Hassanein, Hossam S.This thesis proposes and evaluates a unified collaborative and multimodal framework for indoor positioning and mapping using smartphones. The proposed framework aims to harness the potential of collaboration between different nodes for the positioning and mapping tasks, using only smartphones, without assuming the existence of any specific infrastructure. This objective is achieved by first exploring and enhancing the different building blocks of the proposed framework; followed by evaluating the accuracy gains from using a collaborative approach to the positioning problem. The first building block to be studied is the standalone navigation filter. The standard extended Kalman filter, the unscented Kalman filter, and the particle filter were evaluated for node positioning using the pedestrian dead reckoning model as a system model, while the measurement update is achieved using Wi-Fi fingerprinting with a Gaussian process model. The second component of the system is the Wi-Fi radio map. The proposed framework utilizes a new sparse Gaussian process model to represents the Wi-Fi radio map, used for Wi-Fi signal strength-based fingerprinting. The map building algorithm using the proposed model and its performance are presented and discussed. The collaboration between different nodes is examined in detail, and a new family of distributed particle filters for collaborative positioning applications are introduced. The detailed derivation of the filtering equation along with simulation evaluation of the filters are presented. The collaboration model used in the proposed framework is based on the relative range measurements. A ranging device based on ultra-wideband (UWB) technology is designed and implemented to evaluate the framework. The ranging device is based on the DW1000 UWB transceiver from Decawave. The device can reach centimetre-level ranging accuracy and connects to a host microcontroller which controls the flow of ranging messages, computes the range, and communicate with a paired smartphone through Bluetooth Low Energy interface. On the smartphone, a logging application saves the range information from the UWB device along with other sensors data such as accelerometer, gyroscope, magnetometer, pressure, and Wi-Fi signal strength. Along with this software, a simulation environment is developed to model the motion of random nodes inside an indoor environment. This simulator was used in the evaluation of the proposed particle filters family. The thesis concludes by evaluating the proposed framework using multiple test trajectories and different operating scenarios in a challenging indoor environment.Item Open Access New Approaches for Secure Distance- Bounding(2018-05-23) Ahmadi Fatlaki, Ahmad; Safavi-Naini, Reihaneh S.; Fong, Philip W. L.; Jacobson, Michael J.; O'Keefe, Kyle P. G.; Valaee, ShahrokhIn this thesis we design and implement three aspects of secure distance-bounding (DB) schemes as a type of authentication scheme that considers distance as an extra verification parameter. By adding this new parameter to authentication schemes, we can prevent certain attacks that are related to distance, such as relay attack. In fact, the attacking scenarios can be much more complex than the simple relay attack, in addition to the classic authentication scheme attacks. In this thesis we consider the most advanced distance-bounding attack scenarios in a variety of authentication models. We consider three authentication models in order to add the distance as an extra authentication factor: public-key and anonymous DB are the main fields of this thesis that consider strong adversary with access to directional antenna, and we consider One-Shot DB as a one-message authentication scheme. Each of these fields make a chapter of this thesis. Public-Key Distance-Bounding. In a public-key DB scheme, a prover who owns a key pair and is located within a distance bound to a verifier, who has access to the public-key of the prover, tries to convince the verifier that it is authentic and located within the distance bound. We provide a formal model and two protocols with security proofs. Anonymous Distance-Bounding. In an anonymous DB scheme, a prover who owns a registration certificate and is located within a distance bound to a verifier, who only has access to the public parameters of the system, tries to convince the verifier that it is authentic and located within the distance bound without revealing its identity. We provide a formal model and two secure protocols. One-Shot Distance-Bounding. In an one-shot DB scheme, a prover who owns a secret key and is located within a distance bound to a verifier, who has access to the corresponding key of the prover, tries to convince the verifier that it is authentic and located within the distance bound without receiving any message from the verifier. We provide a formal model and a secure protocol.Item Open Access New GNSS Navigation Messages for Inherent Fast TTFF and High Sensitivity - Underlying Theory Study and System Analysis(2018-05-08) Zhang, Wentao; Gao, Yang; El-Badry, Mamdouh; Chen, Ruizhi; El-Sheimy, Naser; O'Keefe, Kyle P. G.In the navigation applications on mobile devices, the extreme demands for fast Time To First position Fix (TTFF) and high sensitivity have been driving the technology innovations in these areas in recent years. Assisted GNSS (AGNSS) and Ephemeris Extension (EE) technologies constitute the efforts to improve the TTFF and sensitivity. However, it is challenging for both AGNSS and EE. For AGNSS, while it attempts to improve TTFF on sensitivity on mobile devices, it is subject to frequent ephemeris expiration and therefore it requires the mobile devices to be always or frequently connected to the assisting networks. For EE - a technology complementary to the AGNSS to improve TTFF, although it requires little connectivity to assisting networks by directly using some extended ephemerides (valid for days) in the first position fix, such extended ephemerides can be hardly used as the aiding data for tracking weak signals. In the analysis of the challenges, this thesis points out that, such challenges are originated from the weakness in the fundamental design of the existing GNSSs – the life expectancy of ephemeris is too short. Then this thesis proposes an alternative solution for future GNSSs, to fundamentally resolve the above issues by broadcasting some new navigation (NAV) messages with validity for up to 24 hours instead of those used by current GNSSs. Through the study of the TTFF and sensitivity fundamentals, this thesis fully explains how the ephemeris life expectancy relates to TTFF and sensitivity; and through fundamental study on orbital determination theories and ephemeris extension practices, this thesis confirms the feasibility to obtain long-validity ephemerides; and through some simulated uses of the long-validity ephemerides in some typical scenarios, this thesis further confirms the navigation availability and accuracy using the proposed new NAV messages are comparable to those using the current NAV messages. Therefore, for a GNSS that deploys the proposed NAV messages, the capability to achieve fast TTFF and high sensitivity on a mobile device is inherently enhanced, with minimum or even no reliance on assisting infrastructures.Item Open Access Receiver-level Signal and Measurement Quality Monitoring for Reliable GNSS-based Navigation(2019-01-09) Pirsiavash, Ali; Lachapelle, Gerard Jules; O'Keefe, Kyle P. G.; Broumandan, Ali; Lichti, Derek D.; Gao, Yang; Lohan, Elena-SimonaGlobal Navigation Satellite Systems (GNSS) are widely used in everyday and safety of life services as the main system for positioning and timing solutions. Reliability and service integrity are of utmost importance given a variety of error sources and threats. In the case of aviation and maritime applications, system integrity includes ground and space-based augmentation systems. These externally-aided monitoring systems do not provide a satisfactory solution for land users due to the multiplicity of error sources in the user's local environment, such as multipath. This research investigates receiver level stand-alone integrity monitoring solutions for such users. The methodology is based on Signal and Measurement Quality Monitoring (SQM and MQM) to detect and exclude or de-weight faulty measurements, with multipath and spoofing being the major concerns. Different monitoring metrics are defined and investigated for multipath detection and new geometry-based exclusion and de-weighting techniques are developed. Following an analytical discussion of metric sensitivity and effectiveness, simulated and field data analysis are provided to verify practical performance. Results obtained for the designed SQM and MQM-based detection metrics show reliable performance of 3 to 5 m Minimum Detectable Multipath Error (MDME). Although limited by multipath characteristics and measurement geometry, when detected faulty measurements are excluded or de-weighted, positioning performance improves for various multipath scenarios. In order to effectively classify multipath and spoofing, a spoofing simulator is designed, implemented and tested for selected time and position spoofing scenarios. A new spoofing strategy is described to investigate the minimum number of satellite signals required for an effective spoofing attack. Results show that in an overlapped spoofing scenario, at least 60% of signals are spoofed and thus distorted. This rate of signal distortion is not the case in all but harsh multipath scenarios and is used to distinguish spoofing attacks from multipath. More importantly, it is shown that distortion of more than half of the signals makes position solutions unreliable regardless of the error source. For selected scenarios, two-dimensional time/frequency widely-spaced SQM metrics are also developed to detect spoofing signals with about 3% false alarm probability imposed by multipath and other sources of signal distortion.Item Open Access Using Step Size and Lower Limb Segment Orientation from Multiple Low-Cost Wearable Inertial/Magnetic Sensors for Pedestrian Navigation(2019-07-17) O'Keefe, Kyle P. G.; Tjhai, ChandraThis paper demonstrates the use of multiple low-cost inertial/magnetic sensors as a pedestrian navigation system for indoor positioning. This research looks at the problem of pedestrian navigation in a practical manner by investigating dead-reckoning methods using low-cost sensors. This work uses the estimated sensor orientation angles to compute the step size from the kinematics of a skeletal model. The orientations of limbs are represented by the tilt angles estimated from the inertial measurements, especially the pitch angle. In addition, different step size estimation methods are compared. A sensor data logging system is developed in order to record all motion data from every limb segment using a single platform and similar types of sensors. A skeletal model of five segments is chosen to model the forward kinematics of the lower limbs. A treadmill walk experiment with an optical motion capture system is conducted for algorithm evaluation. The mean error of the estimated orientation angles of the limbs is less than 6 degrees. The results show that the step length mean error is 3.2 cm, the left stride length mean error is 12.5 cm, and the right stride length mean error is 9 cm. The expected positioning error is less than 5% of the total distance travelled.Item Open Access Wheel Odometry Aided Visual-Inertial Odometry in Winter Urban Environments(2021-01-20) Huang, Cheng; O'Keefe, Kyle P. G.; O'Keefe, Kyle P. G.; Gao, Yang; El-Sheimy, NaserOver the last decade or so, the world has witnessed the rapid changes in the way people drive. How to ensure the navigation performance in challenging environments such as complex urban canyon environments or winter road environment with a relatively low-cost navigation system has become a popular research topic. Global Navigation Satellite System (GNSS) positioning is commonly used for land vehicle navigation. However, the accuracy of GNSS positioning is reduced in such challenging environments due to obstructions and multipath effects. Thus, the development of an alternative, accurate, inexpensive, and self-contained land vehicle navigation systems to bridge the GNSS gaps is significant for land vehicle navigation systems. Visual-inertial odometry (VIO) is an accurate, inexpensive, and complementary approach for land vehicle navigation in GNSS signal-denied environments. VIO is subject to scale drift because it estimates forward direction translation using distant feature points that are generally located only in the forward direction. Wheel odometer measurements can be obtained from the CANBUS interface of most modern passenger vehicles and these provide reliable estimates of the forward wheel speed. In this thesis, an innovative approach to incorporate wheel odometry (WO) and non-holonomic constraints (NHC) together with tightly-coupled monocular visual-inertial odometry using the Multi-State Constraint Kalman Filter (MSCKF) is proposed and implemented. The algorithm is first validated using the public KITTI Dataset [1] with simulated wheel odometer data. Then, the KAIST Complex Urban Dataset [2] is used to test the performance of IMU+Vision+WO integration system in urban canyon environments. Winter driving data is collected in Calgary and used to evaluate the influence of winter road conditions on the proposed algorithm. The results demonstrate that WO and NHC are able to control the scale drift, and as a result are able to control both scale and orientation over longer periods than IMU+Vision alone. IMU+Vision+WO achieved 1.814 m horizontal position error in a 1-minute drive in an urban canyon environment in the KAIST Complex Urban Dataset and 19.649 m and 3.456 m horizontal position errors in two 1-minute drives in our Calgary winter urban environment. The results demonstrate that IMU+Vision+WO is a very promising method to bridge the GNSS outages and performs very well in some challenging environments.Item Open Access Wide-angle Lens Camera Calibration using Automatic Target Recognition(2020-05-15) Jarron, David Mackenzie; Lichti, Derek D.; Shahbazi, Mozhdeh M.; O'Keefe, Kyle P. G.; Detchev, Ivan D.The focus of this thesis is the calibration and integration of the Ladybug5 multi-camera system into a Mobile Mapping System. To calibrate this system an efficient and accurate automatic target recognition methodology that could work with a multi-camera system was needed. This automatic target recognition methodology was developed and works by projecting the known coordinates of the surveyed calibration targets into the camera frame through a series of simulated or measured orientations and matching to signalized targets already detected in the image to a very high degree of accuracy. Through calibration of this system and rigorous modelling of its intrinsic properties, it became apparent that there was ambiguity in the research field about the most precise projection model to use for wide angle lens cameras and camera systems. A series of camera calibrations were carried out on two wide angle camera systems. Both camera systems exhibit properties that make them difficult to classify as either a central perspective camera or as a fisheye camera. Calibrations were performed on both camera systems using both central perspective and fisheye projection models. The calibrations that utilized a fisheye projection model estimated calibration parameters that more closely fit the observations. Finally, the calibration of the Ladybug5 as a multi-camera system, utilizing ROP stability constraints was performed to rectify issues relating to issues with the panoramic image generation of the Ladybug5. These panoramic images are important for point cloud coloration, and other aspects of multi-camera system integration with mobile mapping systems. It was determined that the calibration of the Ladybug5 using relative orientation stability constraints allowed for the generation of more seamless panoramic images, allowing the camera to better integrate with mobile mapping systems.