http://hdl.handle.net/1974/794 2013-05-26T06:56:42Z 2013-05-26T06:56:42Z Karaim, MALEK http://hdl.handle.net/1974/8026 2013-05-08T05:15:40Z 2013-05-07T04:00:00Z

Title: Real-time Cycle-slip Detection and Correction for Land Vehicle Navigation using Inertial Aiding Authors: Karaim, MALEK Abstract: 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. Description: Thesis (Master, Electrical & Computer Engineering) -- Queen's University, 2013-05-06 18:11:57.076

2013-05-07T04:00:00Z Wahdan, AHMED http://hdl.handle.net/1974/8012 2013-05-02T05:03:04Z 2013-05-01T04:00:00Z

Title: Automatic Magnetometer Calibration with Small Space Coverage Authors: Wahdan, AHMED Abstract: The use of a standalone Global Navigation Satellite System (GNSS) has proved to be insufficient when navigating indoors or in urban canyons due to multipath or obstruction. Recent technological advances in low cost micro-electro-mechanical system (MEMS) – based sensors (like accelerometers, gyroscopes and magnetometers) enabled the development of sensor-based navigation systems. Although MEMS sensors are low-cost, lightweight, small size, and have low-power consumption, they have complex error characteristics. Accurate computation of the heading angle (azimuth) is one of the most important aspects of any navigation system. It can be computed either by gyroscopes or magnetometers. Gyroscopes are inertial sensors that can provide the angular rate from which the heading can be calculated, however, their outputs drift with time. Moreover, the accumulated errors due to mathematical integration, performed to obtain the heading angle, lead to large heading errors. On the other hand, magnetometers do not suffer from drift and the calculation of heading does not suffer from error accumulation. They can provide an absolute heading from the magnetic north by sensing the earth’s magnetic field. However, magnetometer readings are usually affected by magnetic fields, other than the earth magnetic field, and by other error sources; therefore magnetometer calibration is required to use magnetometer as a reliable source of heading in navigation applications. In this thesis, a framework for fast magnetometer calibration is proposed. This framework requires little space coverage with no user involvement in the calibration process, and does not need specific movements to be performed. The proposed techniques are capable of performing both 2-dimensional (2D) and 3-dimensional (3D) calibration for magnetometers. They are developed to consider different scenarios suitable for different applications, and can benefit from natural device movements. Some applications involve tethering the magnetometers to the moving platform (like in cars and machinery applications). Other applications are related to portable navigation (smartphone navigation, whether for pedestrians or while driving). The developed framework was examined through experimental work to verify its performance and robustness. Description: Thesis (Master, Electrical & Computer Engineering) -- Queen's University, 2013-05-01 00:52:30.274

2013-05-01T04:00:00Z Hao, Ting http://hdl.handle.net/1974/8011 2013-05-01T21:17:18Z 2013-05-01T04:00:00Z

Title: Analysis and Design of High Power Factor LED Drivers without Electrolytic Capacitor Authors: Hao, Ting Abstract: With superior longevity, approximately 5 times that of compact fluorescents (CFLs), and high efficacy, around 1.5 times that of CFLs, LEDs are now attracting vast attention from both academic and industrial sectors. Unfortunately, current power supply drivers for LEDs have the following drawbacks: (1) for a two-stage configuration, the power factor correction (PFC) circuit can help LEDs achieve good operating performance but contain too many components and are large in size, have low efficiency and relatively high cost; (2) a single-stage configuration can perform well in PFC and efficiency, however reliability issues occur due to the use of the electrolytic capacitor. In this thesis, the theoretical analysis and implementation of two high power factor, soft-switched, electrolytic-capacitor-less LED drivers are presented. The two drivers solve the aforementioned issues while minimizing its size and cost. The detailed theoretical analysis illustrates the advantages of the presented circuits and provides insight into their design and operation. The simulated and experimental implementations verified the performance of both circuits, which achieve a high power factor, indicating that the drivers have good operating performance. Elimination of the electrolytic capacitors improves the LED drivers’ reliability. In addition, with the help of soft-switching capability, high efficiency is achieved. Simulation and experimental results are presented to support all merits of the two circuits. Description: Thesis (Master, Electrical & Computer Engineering) -- Queen's University, 2013-04-30 13:22:28.471

2013-05-01T04:00:00Z ALMA'AITAH, ABDALLAH http://hdl.handle.net/1974/8010 2013-05-02T05:00:59Z 2013-05-01T04:00:00Z

Title: Enabling Efficient Passive RFID SystemsThrough Modulation Silencing Authors: ALMA'AITAH, ABDALLAH Abstract: RFID technology has attracted much attention due to its wide range of applications, such as inventory control and object tracking. Passive RFID tags are battery-less, mobile and lack intercommunication. Hence, they require a central node (the reader) to power them up, organize their replies, and read their data. In the last decade, several proposals have targeted the channel efficiency in RFID systems to improve time and power efficiencies. While such proposals achieve significant performance improvements, they are limited by the backscattering half-duplex channel in which the reader has to wait for the tag to finish its reply (even if the reply is corrupt or redundant). In this thesis, the Modulation Silencing Mechanism (MSM) is proposed as a novel full-duplex-like communication over half-duplex RFID links. With a simple additional circuit at the tag and upgraded software algorithms at the reader, the reader is capable of terminating the tag's non-useful transmissions. Consequently, we propose three schemes that utilize MSM in key application domains where the tag-reader transaction contains a considerable amount of non-useful transmissions. MSM is utilized to enhance tag identification, tag count estimation and tag authentication. First, we propose a Modulation Silencing Anti-collision (MSA) scheme that targets collision time reduction in time slotted anti-collision protocols. In MSA, the time requirements of state of the art identification protocols are significantly reduced. Moreover, we establish a backward compatibility procedure for proper identification of legacy and MSM-enabled tags. Secondly, a Variance- Modulation Silencing Estimation (VMSE) scheme is proposed to increase tag estimation accuracy and to minimize overall estimation time. Variance-to-mean ratio estimator is proposed to determine the most accurate tag count estimate. VMSE combines both, the accuracy of the variance-to-mean ratio estimator and the time efficiency of MSM and delivers rapid, accurate, and anonymous tag estimation that outperform recent estimation schemes for small and large scale tag deployment. Finally, we propose Unique Hash Sequence Authentication (UHSA) scheme for efficient tag authentication. The UHSA is based on hashed key prefetching algorithm at the reader augmented by the MSM circuitry at the tag. UHSA scheme provides higher time efficiency and robustness against tracking and compromising attacks. Description: Thesis (Ph.D, Electrical & Computer Engineering) -- Queen's University, 2013-04-30 12:38:44.0

2013-05-01T04:00:00Z