In recent years, Land vehicle navigation system (LVNS) technology is a subject of great interest due to its potential for both consumer and business vehicle markets. GPS/INS ( Global Positioning System/ Inertial Navigation System ) integrated system is an effective solution to realize the LVNS. And how to keep communication between the vehicle and satellite while the vehicle is running in a bad environment is the main task in this thesis. The thesis provides an introduction to beam tracking system and two algorithms of how to improve the performance, then compare these two algorithms and choose the suitable one and implement it on ArduPilotMega board using Arduino language, at last test the integrated GPS/INS system in practice in order to estimate the performance. The requirements of the project are the maximum angular speed and angular acceleration speed of the vehicle are  and , respectively. Two algorithms which are Direction Cosine Matrix (DCM) and Euler Angle are evaluated in the system. In this thesis, there are many rotations due to the hostile environment, and DCM algorithm is not suitable for the requirement according to the results of simulation. Therefore, an innovated method which is Euler Angle Algorithm can be one effective way to solve the probelm. The primary idea of Euler Angle algorithm is to calculate the difference between the reference direction vector and the measurement direction vector from GPS and accelerometers, once there is an error rotation, take the cross product and rotate the incorrect direction vector back to original direction. The simulation results show that by implementing EA algorithm, system requirements can be achievable with a 10kHz update rate antenna and a 4000Hz sampling rate gyroscope, also with EA implementation in ArduPilotMega board, the real system tracking ability can be enhanced effectively.

Wireless sensor network technology has now been widely adopted. In many applications, distributed sensor nodes collect data at different locations and the location information of each node is required. The Global Positioning System is commonly used to identify the location of the nodes in such networks. Although GPS localization has consistent long-term accuracy, it is limited by the inherent dependency on a direct line of sight to 4 or more external satellites. The increasing demand for an embedded system providing reliable navigation solutions regardless of its operational environment has motivated investigations into the use of integrated systems that combine inertial sensors with GPS receivers. This research proposes a hardware architecture for location-based wireless sensor networks. In this architecture, each sensor node consists of a GPS receiver, a reduced set of low cost micro-electro-mechanical-system-based INS and a wireless transceiver. Sensor nodes in WSN are often equipped with irreplaceable batteries, which makes the power consumption crucial. To reduce the energy consumption, a microcontroller is used to control the power supply. Besides, a motion detection scheme is proposed by taking advantage of the ultra low-power wake-up function of the microcontroller. A low-power featured digital signal processor is used to accomplish the navigation computation using the Kalman filter for GPS/INS data fusion. Non-Holonomic Constraints derived velocity updates are applied to reduce the position errors. Field tests are conducted to verify the real-time performance of the proposed system with a positioning update rate of 20 Hz. The first test shows that the 2D INS/GPS integration can maintain the average system position error within 5 meters during a 60-second GPS outage. The second test used low cost inertial sensors. The average position error was 10.17 meters during a 20-second outage. The largest RMS value of position errors among these outages was within 14.5 meters. Furthermore, additional accuracy improvements of approximately 1.4 meters were achieved by utilizing NHC during GPS outages. The third test shows that the average error during a 30-second outage is approximately 20.6 meters for the on-foot scenario and 26.7 meters for the in-vehicle scenario. / Thesis (Master, Electrical & Computer Engineering) -- Queen's University, 2012-01-13 14:46:45.44

Global Navigation Satellite Systems (GNSS) for vehicle navigation and timing are widely relied upon by many users in a variety of different sectors such as transit, financial, military, and many others. There are a number of ways for an agent to purposefully degrade a GNSS user's navigation performance. One such attack is a spoofing attack where the agent transmits signals with the same signal structure as GNSS signals, but they are modified to produce an incorrect navigation solution. Resiliency to these attacks is important for GNSS navigation. Two methods for GNSS resiliency are explored in this dissertation. The first method uses a Controlled Reception Pattern Antenna and receiver in order to obtain direction of arrival estimates of all visible signals and their computed pseudoranges. Two contributions were produced for this method. The first contribution is an optimization of a DoA cost metric that use DoA estimates along with known GNSS ephemerides to distinguish authentic signals from spoofed signals. The second contribution of this work is a combined DoA/pseudorange cost metric to improve the classification of authentic signals from spoofed signals as well as improve its robustness to multi-transmitter spoofing attacks. The second method uses a method known as Chimera, which involves authenticating the civilian L1C GPS signal using a digital signature in the navigation message and punctures in the spreading code. This method can be used to distinguish authentic and spoofed signals, however, a delay between the time the signal is tracked by the receiver and the time when it can be determined authentic is inherent in Chimera and degrades navigation performance. This delay can range from 2 seconds to 3 minutes. Four additional contributions have been made in support of Chimera. The first Chimera contribution is the design and evaluation of a navigation system for Chimera using a tightly coupled GPS/INS extended SRIF that accounts for the Chimera authentication delays. The second Chimera contribution is an investigation into staggering of the authentication times of the GPS satellites in order to improve navigation results. The third Chimera contribution is the development of a RMS or maximum steady-state position error metric to compare the accuracy achieved by different authentication group designs when used in conjunction with the previously discussed filter from the first Chimera contribution. The fourth Chimera contribution investigates different authentication group designs to find groups that will produce low value metrics. These investigations included local authentication group optimization, synthesizing a global design using local designs, and the effects of time and IMU grade. Each of these contributions has a significant impact on improving either the resilience of a GPS receiver to spoofing or the navigation accuracy of a GPS receiver that is inherently resilient to spoofing. / Doctor of Philosophy / Global Positioning System (GPS) navigation and timing plays a pivotal role in a variety of different sectors such as transit, financial, military, and many others. There have been instances where a signal is purposefully generated to look similar to a GPS signal in order to mislead a GPS user of their true position, velocity, and timing. This type of attack is known as a spoofing attack. This dissertation discusses two methods to identify these spoofed signals so that they are not used to disrupt nominal navigation and timing. The first method uses multiple GPS antennas to determine the direction of all visible signals. This dissertation provides an algorithm to distinguish the authentic GPS signals from the spoofed signals using the determined signal directions. The second method is for the GPS satellites to watermark the GPS signal they transmit, using modern encryption techniques, to be able to authenticate incoming signals. This method, however, produces a delay between when the signal is received by a GPS user and when it can be deemed authentic. This delay is a problem for navigation. This dissertation develops techniques for dealing with this delay by incorporating an Inertial Measurement Unit (IMU). This dissertation also proposes the idea to stagger the time that the digital signature, which is needed for signal verification, is sent from different GPS satellites. Lastly, this dissertation investigates how different staggered groupings of GPS satellites improve navigation performance and provides a metric for quantifying the navigation performance of different groupings. Overall, the dissertation's contributions to the first method improve the resilience of a receiver to spoofing attacks while the contributions to the second method improve navigation performance of an inherently resilient method.

Processing GPS carrier-phase measurements can provide high positioning accuracy for several navigation applications. However, if not detected, cycle slips in the measured phase can strongly deteriorate the positioning accuracy. Cycle slips frequently occur in areas surrounded by trees, buildings, and other obstacles. The dynamics experienced by the GPS receiver in kinematic mode of navigation also increases the possibility of cycle slips. Detection and correction of these cycle-slips is essential for reliable navigation. One way of detecting and correcting for cycle slips is to use another system to be integrated with GPS. Inertial Navigation Systems (INS), using three-axis accelerometers and three-axis gyroscopes, is integrated with GPS to provide more reliable navigation solution. Moreover, INS was utilized in the past for GPS cycle slip detection and correction. For low cost applications, Micro-Electro-Mechanical-Systems (MEMS) accelerometers and gyroscopes are used inside INS. For land navigation, reduced inertial sensor system (RISS) utilizing two accelerometers, one gyroscope, and the vehicle odometer was suggested. MEMS-based RISS has the advantage of using less number of MEMS-based gyroscopes and accelerometers thus reducing the overall cost and avoiding the complex error characteristics associated with MEMS sensors. In this thesis, we investigate the use of MEMS – based RISS to aid GPS and detect and correct for cycle slips. The Kalman filter was employed in centralized fashion to integrate the measurements from both GPS and RISS. This thesis research also offers a new threshold selection criterion resulting in a more robust cycle slip detection and correction. The proposed method was tested in different scenarios of road tests in land vehicle. Results show accuracy iii improvement over the conventional double differenced pseudoranges-based integrated system. Moreover, the adaptive selection criterion of the detection threshold proposed in this thesis improves the detection rate, especially in the case of small-sized cycle slips. / Thesis (Master, Electrical & Computer Engineering) -- Queen's University, 2013-05-06 18:11:57.076

The complementary advantages of GPS and INS have been the principle driving factor to integrate these two navigation systems as an integrated GPS/INS system in various architectural forms to provide robust positioning. Although the loosely coupled and tightly coupled GPS/INS systems have been in existence for over a decade or two and performed reasonably well, nevertheless, the tracking performance was still a concern in non-benign environments such as dynamic scenarios, indoor environments, urban areas, under foliages etc., where the GPS tracking loops lose lock due to the signals being weak, subjected to excessive dynamics or completely blocked. The motivation of this research, therefore, was to address these limitations with an integrated GPS/Pseudolite/INS system using ultra-tight integration architecture. The main research contributions are summarised as below: (a) The performance of the tracking loops in dynamic scenarios were analysed in detail with both conventional and ultra-tight software receivers. The stochastic modelling of the INS-derived Doppler is of utmost importantance in enhancing the benefits of ultra-tight integration, and therefore, two popular stochastic techniques??? Gauss Markov (GM) and Autoregressive (AR), were investigated to model the Doppler signal. The simulation results demonstrate that the AR method is capable of producing better accuracies and is more efficient. The algorithms to determine the AR parameters (order and coefficients) were also provided. (b) The various mathematical relationships that elicit the understanding of the ultra-tightly integrated system were derived in detail. The Kalman filter design and its implementation were also provided. Various simulation and real-time experiments were conducted to study the performance of the filter, and the results confirm the underlying assumptions in the theoretical analyses and the mathematical derivations. Covariance analysis was also performed to study the convergence and stability effects of the filter. (c) Interpolator design using signal processing techniques were proposed to increase the sampling rate of the INS-derived Doppler. To efficiently realise the interpolator transfer function, two optimal techniques were investigated ??? Polyphase and Cascaded Integrator Comb (CIC), and our results show that CIC was more efficient than polyphase in accuracy and real-time implementations. (d) The integration of Pseudolites (PL) with INS in ultra-tight configuration was analysed for an indoor environment. The acquisition and tracking performances of ???Pseudolites-only??? and ???Pseudolite/INS??? modes were compared to study the impact of the inertial signals aiding. The results demonstrate that aiding of the inertial signals with the baseband loops (acquisition and tracking) improve the overall tracking performance. An overview on the effects of the pseudolite signal propagation is also given. (e) Simulation and real-time experiments have been conducted to evaluate the proposed algorithms and the overall design of the ultra-tightly integrated system. A comparison was also done between GPS/PL/INS and GPS/INS integrated systems to study the potential advantages of the pseudolite integration. The details of the field experiment are provided. The data from a real-time experiment was processed to further evaluate the robustness of the system. The results confirm that the developed mathematical models and algorithms are correct.

Navigation algorithms integrating measurements from multi-sensor systems overcome the problems that arise from using GPS navigation systems in standalone mode. Algorithms which integrate the data from 2D low-cost reduced inertial sensor system, consisting of a gyroscope and an odometer, along with a GPS via a Kalman filter has proved to be worthy in providing a consistent and more reliable navigation solution compared to the standalone GPS. It has been also shown to be beneficial, especially in GPS-denied environments such as urban canyons and tunnels. The main objective of this research is to narrow the idea-to-implementation gap that follows the algorithm development by realizing a low-cost real-time embedded navigation system that is capable of computing the data-fused positioning solution instantly. The role of the developed system is to synchronize the measurements from the three sensors, GPS, gyroscope and odometer, relative to the pulse per second signal generated from the GPS, after which the navigation algorithm is applied to the synchronized measurements to compute the navigation solution in real-time. Xilinx’s MicroBlaze soft-core processor on a Virtex-4 FPGA is utilized and customized for developing the real-time navigation system. The soft-core processor offers the flexibility to choose or implement a set of features and peripherals that are tailored to the specific application to be developed. An embedded system design model is chosen to act as a framework for the work flow to be carried through the system life cycle starting from the system specification phase and ending with the system release. The developed navigation system is tested first on a mobile robot to reveal system bugs and integration problems, and then on a land vehicle testing platform for further testing. The real-time solution from the implemented system when compared to the solution of a high-end navigation system, proved to be successful in providing a comparable consistent real-time navigation solution. Employing a soft-core processor in the kernel of the navigation system, provided the flexibility for communicating with the various sensors and the computation capability required by the Kalman filter integration algorithm. / Thesis (Master, Electrical & Computer Engineering) -- Queen's University, 2010-10-11 16:08:38.811

The complementary advantages of GPS and INS have been the principle driving factor to integrate these two navigation systems as an integrated GPS/INS system in various architectural forms to provide robust positioning. Although the loosely coupled and tightly coupled GPS/INS systems have been in existence for over a decade or two and performed reasonably well, nevertheless, the tracking performance was still a concern in non-benign environments such as dynamic scenarios, indoor environments, urban areas, under foliages etc., where the GPS tracking loops lose lock due to the signals being weak, subjected to excessive dynamics or completely blocked. The motivation of this research, therefore, was to address these limitations with an integrated GPS/Pseudolite/INS system using ultra-tight integration architecture. The main research contributions are summarised as below: (a) The performance of the tracking loops in dynamic scenarios were analysed in detail with both conventional and ultra-tight software receivers. The stochastic modelling of the INS-derived Doppler is of utmost importantance in enhancing the benefits of ultra-tight integration, and therefore, two popular stochastic techniques??? Gauss Markov (GM) and Autoregressive (AR), were investigated to model the Doppler signal. The simulation results demonstrate that the AR method is capable of producing better accuracies and is more efficient. The algorithms to determine the AR parameters (order and coefficients) were also provided. (b) The various mathematical relationships that elicit the understanding of the ultra-tightly integrated system were derived in detail. The Kalman filter design and its implementation were also provided. Various simulation and real-time experiments were conducted to study the performance of the filter, and the results confirm the underlying assumptions in the theoretical analyses and the mathematical derivations. Covariance analysis was also performed to study the convergence and stability effects of the filter. (c) Interpolator design using signal processing techniques were proposed to increase the sampling rate of the INS-derived Doppler. To efficiently realise the interpolator transfer function, two optimal techniques were investigated ??? Polyphase and Cascaded Integrator Comb (CIC), and our results show that CIC was more efficient than polyphase in accuracy and real-time implementations. (d) The integration of Pseudolites (PL) with INS in ultra-tight configuration was analysed for an indoor environment. The acquisition and tracking performances of ???Pseudolites-only??? and ???Pseudolite/INS??? modes were compared to study the impact of the inertial signals aiding. The results demonstrate that aiding of the inertial signals with the baseband loops (acquisition and tracking) improve the overall tracking performance. An overview on the effects of the pseudolite signal propagation is also given. (e) Simulation and real-time experiments have been conducted to evaluate the proposed algorithms and the overall design of the ultra-tightly integrated system. A comparison was also done between GPS/PL/INS and GPS/INS integrated systems to study the potential advantages of the pseudolite integration. The details of the field experiment are provided. The data from a real-time experiment was processed to further evaluate the robustness of the system. The results confirm that the developed mathematical models and algorithms are correct.

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International Telemetering Conference Proceedings / October 25-28, 1999 / Riviera Hotel and Convention Center, Las Vegas, Nevada / The GPS/INS equipment is used at the Air Force Flight Test Center (AFFTC) to collect time space position information (TSPI) during testing. The GPS-based test instrumentation is lagging behind available commercial technologies. Advancing technologies for test use requires investigation of affordable commercial equipment. To enable technology insertion for state of the art testing, there is a need for more robust, flexible, reliable, modular, affordable low cost TSPI systems capable of operating in all flight environments. Modular (plug-and-play) hardware and software, quick and easy to re-configure, are required for supporting various test platforms from fighter aircraft to cargo size aircraft. Flight testing dynamics are such that, GPS-only systems tend to lose data during critical maneuvers. To minimize this data loss, inertial measurement systems coupled with GPS sensors are used in most sophisticated range instrumentation packages. However, these packages have required fairly expensive inertial units, are usually very large and not very flexible in terms of quick and easy reconfiguration to meet the unique needs of AFFTC’s test customers. WADDAN SYSTEMS has begun to address this problem with a modular design concept, which incorporates their high-performance navigation quality inertial measurement unit, but with costs comparative to that of lower-end performance inertial units. This paper describes WADDAN’s concept and the components that make up MAGI; and addresses some of the preliminary testing and near-term proposed activities. In general, the system will provide GPS, inertial and discrete MIL-STD 1553, RS-232/422 and video data from the participant. The MAGI will be structured around the Compact personal computer interface (PCI) backplane bus with on-board recording and processing and will include real-time command and control through a UHF data link.