Advanced tracking systems design and analysis

The results of an assessment of several types of high-accuracy tracking systems proposed to track the spacecraft in the National Aeronautics and Space Administration (NASA) Advanced Tracking and Data Relay Satellite System (ATDRSS) are summarized. Tracking systems based on the use of interferometry and ranging are investigated. For each system, the top-level system design and operations concept are provided. A comparative system assessment is presented in terms of orbit determination performance, ATDRSS impacts, life-cycle cost, and technological risk

Investigating the feasibility of solar photovoltaic systems in Kuwait

This thesis presents work undertaken to investigate the feasibility of implementing solar photovoltaic (PV) systems in Kuwait. Performance parameters, environmental, and economic evaluations and assessments, as well as a numerical modelling study, were conducted as the main investigative elements to help judge the feasibility. The effect of using single-axis and dual-axis tracking systems was also considered. An assessment of the performance parameters of the proposed PV systems at selected locations in Kuwait was conducted on a monthly basis, using different tracking systems to compare the sites. Moreover, an annual basis analysis was carried out to compare the obtained results with those of different studies in the existing literature. An environmental assessment was conducted in the form of a Life Cycle Assessment (LCA), estimating the levels of greenhouse gas (GHG) emissions that could be avoided. An economic assessment of implementing the proposed PV systems at the selected locations, and a cost-benefit analysis were conducted. In addition, modelling of a two-axis solar tracker was performed to ensure the stability and reliability of the proposed solar tracker in Kuwait. This was done using a 3D finite element model to examine the soil-structure interaction using COMSOL Multiphysics software. [Continues.

A framework for evaluating stereo-based pedestrian detection techniques

Automated pedestrian detection, counting, and tracking have received significant attention in the computer vision community of late. As such, a variety of techniques have been investigated using both traditional 2-D computer vision techniques and, more recently, 3-D stereo information. However, to date, a quantitative assessment of the performance of stereo-based pedestrian detection has been problematic, mainly due to the lack of standard stereo-based test data and an agreed methodology for carrying out the evaluation. This has forced researchers into making subjective comparisons between competing approaches. In this paper, we propose a framework for the quantitative evaluation of a short-baseline stereo-based pedestrian detection system. We provide freely available synthetic and real-world test data and recommend a set of evaluation metrics. This allows researchers to benchmark systems, not only with respect to other stereo-based approaches, but also with more traditional 2-D approaches. In order to illustrate its usefulness, we demonstrate the application of this framework to evaluate our own recently proposed technique for pedestrian detection and tracking

Survey of Motion Tracking Methods Based on Inertial Sensors: A Focus on Upper Limb Human Motion

Motion tracking based on commercial inertial measurements units (IMUs) has been widely studied in the latter years as it is a cost-effective enabling technology for those applications in which motion tracking based on optical technologies is unsuitable. This measurement method has a high impact in human performance assessment and human-robot interaction. IMU motion tracking systems are indeed self-contained and wearable, allowing for long-lasting tracking of the user motion in situated environments. After a survey on IMU-based human tracking, five techniques for motion reconstruction were selected and compared to reconstruct a human arm motion. IMU based estimation was matched against motion tracking based on the Vicon marker-based motion tracking system considered as ground truth. Results show that all but one of the selected models perform similarly (about 35 mm average position estimation error)

Multimodal Noncontact Tracking of Surgical Instruments

For many procedures, open surgery is being replaced with minimally invasive surgical (MIS) techniques. The advantages of MIS include reduced operative trauma and fewer complications leading to faster patient recovery, better cosmetic results and shorter hospital stays. As the demand for MIS procedures increases, effective surgical training tools must be developed to improve procedure efficiency and patient safety. Motion tracking of laparoscopic instruments can provide objective skills assessment for novices and experienced users. The most common approaches to noncontact motion capture are optical and electromagnetic (EM) tracking systems, though each approach has operational limitations. Optical trackers are prone to occlusion and the performance of EM trackers degrades in the presence of magnetic and ferromagnetic material. The cost of these systems also limits their availability for surgical training and clinical environments. This thesis describes the development and validation of a novel, noncontact laparoscopic tracking system as an inexpensive alternative to current technology. This system is based on the fusion of inertial, magnetic and distance sensing to generate real-time, 6-DOF pose data. Orientation is estimated using a Kalman-filtered attitude-heading reference system (AHRS) and restricted motion at the trocar provides a datum from which position information can be recovered. The Inertial and Range-Enhanced Surgical (IRES) Tracker was prototyped, then validated using a MIS training box and by comparison to an EM tracking system. Results of IRES tracker testing showed similar performance to an EM tracker with position error as low as 1.25 mm RMS and orientation error \u3c0.58 degrees RMS along each axis. The IRES tracker also displayed greater precision and superior magnetic interference rejection capabilities. At a fraction of the cost of current laparoscopic tracking methods, the IRES tracking system would provide an excellent alternative for use in surgical training and skills assessment

Quality assessment of an Ultra-Wide Band positioning system for indoor wheelchair court sports

Ultra-Wide Band radio positioning systems are maturing very quickly and now represent a good candidate for indoor positioning. The aim of this study was to undertake a quality assessment on the use of a commercial Ultra-Wide Band positioning system for the tracking of athletes during indoor wheelchair court sports. Several aspects have been investigated including system set-up, calibration, sensor positioning, determination of sport performance indicators and quality assessment of the output. With a simple set-up procedure, it has been demonstrated that athletes tracking can be achieved with an average horizontal positioning error of 0.37 m (s = 6 0.24 m). The distance covered can be computed after data processing with an error below 0.5% of the course length. It has also been demonstrated that the tag update rate and the number of wheelchairs on the court do not affect significantly the positioning quality; however, for highly dynamic movement tracking, higher rates are recommended for a finer dynamic recording

Selection on performance and tracking

Tracking is widely used in secondary schools around the world. Some countries put more emphasis on the use of performance to place students into tracks (e.g. the Netherlands), while in other countries parents have more influence on the track their child will go to (e.g. Germany). This article examines whether selection into tracks based on performance has an effect on the relation between tracking and student performance and educational opportunities. Using data from the Programme for International Student Assessment for around 185000 students in 31 countries, different estimation models are compared. The results indicate that a highly differentiated system is best for performance when schools always consider prior performance when deciding on student acceptance. In systems with a few tracks, there is no such impact. Equality of opportunity is best provided for in a system with many tracks when schools always consider prior performance

Quality assessment of an UWB positioning system for indoor wheelchair court sports

Ultra-Wide Band radio positioning systems are maturing very quickly and now represent a good candidate for indoor positioning. The aim of this study was to undertake a quality assessment on the use of a commercial Ultra-Wide Band positioning system for the tracking of athletes during indoor wheelchair court sports. Several aspects have been investigated including system setup, calibration, sensor positioning, determination of sport performance indicators and quality assessment of the output. With a simple setup procedure, it has been demonstrated that athletes tracking can be achieved with an average horizontal positioning error of 0.37 m (σ = ± 0.24 m). Distance covered can be computed after data processing with an error below 0.5% of the course length. It has also been demonstrated that the tag update rate and the number of wheelchairs on the court does not affect significantly the positioning quality; however, for highly dynamic movement tracking, higher rates are recommended for a finer dynamic recording

Efficient availability assessment of reconfigurable complex multi-state systems with interdependencies

Complex topology, multi-state behaviour, component interdependencies and interactions with external phenomena are prominent attributes of many realistic systems. Analytical reliability evaluation techniques have limited applicability to such systems and efficient simulation models are therefore required. In this paper, we present a simulation framework to simplify the availability assessment of these systems. It allows tracking of changes in performance levels of components from which system performance is deduced by solving a set of flow equations. This framework is adapted to the availability modelling of an offshore plant with interdependencies, operated in the presence of limited maintenance teams and operational loops. The underlying principles of the approach are based on an extension of the load-flow simulation presented recently by the current authors (George-Williams & Patelli 2016)