Publications
339 results found
Sun R, Ochieng WY, Feng S, 2015, An integrated solution for lane level irregular driving detection on highways, Transportation Research Part C: Emerging Technologies, Vol: 56, Pages: 61-79, ISSN: 1879-2359
Global Navigation Satellite Systems (GNSS) has been widely used in the provision of Intelligent Transportation System (ITS) services. Current meter level system availability can fulfill the road level applications, such as route guide, fleet management and traffic control. However, meter level of system performance is not sufficient for the advanced safety applications. These lane level safety applications requires centimeter/decimeter positioning accuracy, with high integrity, continuity and availability include lane control, collision avoidance and intelligent speed assistance, etc. Detecting lane level irregular driving behavior is the basic requirement for these safety related ITS applications. The two major issues involved in the lane level irregular driving identification are accessing to high accuracy positioning and vehicle dynamic parameters and extraction of erratic driving behaviour from this and other related information. This paper proposes an integrated solution for the lane level irregular driving detection. Access to high accuracy positioning is enabled by GNSS and Inertial Navigation System (INS) integration using filtering with precise vehicle motion models and lane information. The detection of different types of irregular driving behaviour is based on the application of a Fuzzy Inference System (FIS). The evaluation of the designed integrated systems in the field test shows that 0.5 m accuracy positioning source is required for lane level irregular driving detection algorithm and the designed system can detect irregular driving styles.
Sidiropoulos S, Majumdar A, Han K, et al., 2015, A framework for the classification and prioritization of arrival and departure routes in Multi-Airport Systems Terminal Manoeuvring Areas, 15th AIAA Aviation Technology, Integration, and Operations Conference, Publisher: AIAA Aviation
Typically major cities (London, New York, Tokyo) are served by several airports effectively creating aMulti-Airport System or Metroplex. The operations of the Metroplex airports are highly dependent on oneanother, which renders their efficient management difficult. This paper proposes a framework for theprioritization of arrival and departure routes in Multi-Airport Systems Terminal Manoeuvring Areas. Theframework consists of three components. The first component presents a new procedure for clustering arrivaland departure flights into dynamic routes based on their temporal and spatial distributions through theidentification of the important traffic flow patterns throughout the day of operations. The second componentis a novel Analytic Hierarchy Process model for the prioritization of the dynamic routes, accounting for a setof quantitative and qualitative characteristics important for Multi-Airport Systems operations. The thirdcomponent is a priority-based model for the facility location of the optimal terminal waypoints (fixes), whichaccounts for the derived priorities of each dynamic route, while meeting the required separation distances.The proposed Analytic Hierarchy Process model characteristics are validated by subject matter experts. Thedeveloped framework is applied to the London Metroplex case study.
Mao Q, Zhang L, Li Q, et al., 2015, A Least Squares Collocation Method for Accuracy Improvement of Mobile LiDAR Systems, Remote Sensing, Vol: 7, Pages: 7402-7424, ISSN: 2072-4292
In environments that are hostile to Global Navigation Satellites Systems (GNSS), the precision achieved by a mobile light detection and ranging (LiDAR) system (MLS) can deteriorate into the sub-meter or even the meter range due to errors in the positioning and orientation system (POS). This paper proposes a novel least squares collocation (LSC)-based method to improve the accuracy of the MLS in these hostile environments. Through a thorough consideration of the characteristics of POS errors, the proposed LSC-based method effectively corrects these errors using LiDAR control points, thereby improving the accuracy of the MLS. This method is also applied to the calibration of misalignment between the laser scanner and the POS. Several datasets from different scenarios have been adopted in order to evaluate the effectiveness of the proposed method. The results from experiments indicate that this method would represent a significant improvement in terms of the accuracy of the MLS in environments that are essentially hostile to GNSS and is also effective regarding the calibration of misalignment.
Wilke S, Majumdar A, Ochieng WY, 2015, Modelling runway incursion severity, Accident Analysis & Prevention, Vol: 79, Pages: 88-99, ISSN: 0001-4575
Analysis of the causes underlying runway incursions is fundamental for the development of effective mitigation measures. However, there are significant weaknesses in the current methods to model these factors. This paper proposes a structured framework for modelling causal factors and their relationship to severity, which includes a description of the airport surface system architecture, establishment of terminological definitions, the determination and collection of appropriate data, the analysis of occurrences for severity and causes, and the execution of a statistical analysis framework. It is implemented in the context of U.S. airports, enabling the identification of a number of priority interventions, including the need for better investigation and causal factor capture, recommendations for airfield design, operating scenarios and technologies, and better training for human operators in the system. The framework is recommended for the analysis of runway incursions to support safety improvements and the methodology is transferable to other areas of aviation safety risk analysis.
Ali BS, Majumdar A, Ochieng WY, et al., 2015, A causal factors analysis of aircraft incidents due to radar limitations: The Norway case study, JOURNAL OF AIR TRANSPORT MANAGEMENT, Vol: 44-45, Pages: 103-109, ISSN: 0969-6997
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- Citations: 6
Ali BS, Schuster W, Ochieng W, et al., 2015, Analysis of anomalies in ADS-B and its GPS data, GPS Solutions, Vol: 20, Pages: 429-438, ISSN: 1080-5370
Traditionally, the surveillance component of the air traffic management system has been based on radar, which consists of two separate systems: primary radar and secondary radar, which both enable the measurement of the aircraft range and bearing to the radar station. Primary radar is based on signals emitted by a ground station simply being reflected off an object and detected by a ground-based receiver. Secondary radar also emits signals, but relies upon a transponder onboard the aircraft to emit a signal itself, modulated among others by a four-digit aircraft identity (Mode A), aircraft altitude (Mode C) and/or 24-bit unique address (Mode S). Typical accuracies of secondary radar are of the order of 0.03 NM in range and 0.07° in azimuth. However, no position integrity report is provided. Air traffic density is expected to significantly increase in the future. In order to maintain or enhance air travel efficiency, while maintaining safety, more accurate surveillance systems, with the required integrity, will be required. Automatic dependent surveillance–broadcast (ADS-B) is a new aviation surveillance system, envisioned to overcome the limitations of radar and to enhance surveillance performance and thereby increase airspace capacity. However, its high dependence on external systems such as onboard navigation and communication systems also increases the number of potential points of failure. It is important to understand and mitigate these failure modes before the system can reliably be implemented. The present study emerged as an exploratory research as part of a safety assessment framework development for the ADS-B system. It reviews the ADS-B failure modes, data collection and analysis of ADS-B and its corresponding onboard GPS data. The study identifies a set of failures common to certain aircraft models, with consistent error patterns. A key failure mode was found to be associated with the navigation data from the onboard GPS. We discuss the identif
Anvari B, angeloudis, ochieng, 2015, Multi-Objective GA-based Optimisation for Manufacturing, Transportation and Assembly of Precast Construction, 17th British-French-German Conference on Optimization
Anvari B, Angeloudis P, Ochieng W, 2015, Multi-Objective GA-based Optimisation for Manufacturing, Transportation and Assembly of Precast Construction, Publisher: 17th British-French-German Conference on Optimization
Precast production is an enhanced method to utilize construction schedule, cost, workforce, safety and quality. Making production schedules which satisfy multiple objectives is the most important part of precast construction planning. The Manufacturing, transportation and Assembly (MtA) sectors are often strongly linked to each other in construction projects. These sectors require a considerable amount of time, workforce and budget. In addition, the available resources for each sector have specific constraints. The difficulty is due mainly to the high number of constraints in the real-world application. It is important to evaluate the impact of consequential decisions from the manufacturing up to assembly in minimising project's time and cost while maximizing safety. Reducing the number of on-site workforce from congested construction site maximises the safety, and prefabricating components in a controlled and protected environment maximises the quality of the elements. In this paper, a Resource-constrained Complex Flexible Job Shop Scheduling (RCFJSS) optimisation approach is presented for minimising makespan and cost of precast techniques. At the same time, the number of on-site workers is minimised considering the holistic MtA system. A multi-objective Genetic Algorithm-based (GA-based) searching technique is used to provide optimal most advantageous solution in consideration of resource constraints. The output of this RCFJSS model provides an optimal allocation of resources on operations for the overall project duration, cost and on-site labour. Using this optimisation model, optimal solutions for different levels of prefabrication can be determined and compared with respect to projects horizon and budget.
Zis T, Angeloudis P, North R, et al., 2015, The environmental balance of vessel emission strategies, TRB
Quddus MA, Ochieng WY, Noland RB, 2015, Map matching algorithms for intelligent transport systems applications
Map matching algorithms play a key role in providing the navigation solution for many Intelligent Transport Systems (ITS) and Location Based Services (LBS). It is essential that the map matching algorithm used in the navigation module meets the specified requirements set for a particular service. Although the performance of a map matching algorithm depends on the characteristics of data inputs, the technique used in the algorithm can enhance the overall performance. This paper sets out to report on map matching algorithms developed by the authors in earlier work, and whether these can satisfy the required navigation performance (RNP) of various ITS services and LBS applications. This is achieved by testing the algorithms using real-world field data. The results suggest that these algorithms are capable of supporting the navigation function of many services including route guidance, bus priority at junctions, fleet management, etc.
Feng S, Wang S, Liu J, et al., 2015, A beidou based multiple-GNSS positioning algorithm for mission critical applications, Pages: 143-155, ISSN: 1876-1100
With the development of the Global Navigation Satellite Systems (GNSS), countries that own a GNSS have realised that critically national infrastructures using Position Navigation and Timing (PNT) services and a portion of the national economy associated with GNSS applications should not be over reliant on other countries. Recently, both China and Russia have made their systems mandatory for some applications. This paper addresses this issue and proposes a Beidou based multiple-GNSS positioning algorithm. It involves three stages: (1) Understanding of the quality of Beidou solutions. This was achieved by Receiver Autonomous Integrity Monitoring (RAIM) embedded in the Beidou positioning algorithm. (2) A real time validation and modelling algorithm for the measurements from the other constellations if Beidou solution is proved good in stage 1. The measurement residual errors relative to the Beidou position solution are assessed. (3) Introduction of measurements from the other constellations if there is not enough Beidou measurements. At this stage, the models derived in stage 2 are applied to the non-Beidou measurements. The tests were carried out using the Beidou and GPS data from a reference station. The signal blockage of Beidou and GPS constellation is simulated. The test results show that the proposed methods can benefit from the validated measurements from the GPS constellation. The performance can be significantly improved in terms of accuracy, continuity, integrity and availability in difficult environments. It can be extended for critical applications where any constellation is mandated.
Zis T, North RJ, Angeloudis P, et al., 2015, Environmental balance of shipping emissions reduction strategies, Transportation Research Record, Vol: 2479, Pages: 25-33
Goldbeck N, Angeloudis P, Ochieng W, 2015, Analysis of cascading failures across interdependent dynamic networks, 27th European Conference on Operational Research
Zis T, Angeloudis P, Ochieng W, et al., 2015, The environmental balance of vessel emission strategies, Transportation Research Record-Series, ISSN: 0361-1981
Anvari B, Bell MGH, Sivakumar A, et al., 2015, Modelling shared space users via rule-based social force model, Transportation Research Part C: Emerging Technologies, Vol: 51, Pages: 83-103
Sidiropoulos S, Majumdar A, Ochieng W, et al., 2014, Levels of organisation in Multi-Airport System, Transportation Research Board 94th Annual Meeting
Subotic B, Schuster W, Majumdar A, et al., 2014, Controller recovery from equipment failures in air traffic control: a framework for the quantitative assessment of the recovery context, Reliability Engineering and System Safety, Vol: 132, Pages: 60-71, ISSN: 0951-8320
Air Traffic Control (ATC) involves a complex interaction of human operators (primarily air traffic controllers), equipment and procedures. On the rare occasions when equipment malfunctions, controllers play a crucial role in the recovery process of the ATC system for continued safe operation. Research on human performance in other safety critical industries using human reliability assessment techniques has shown that the context in which recovery from failures takes place has a significant influence on the outcome of the process. This paper investigates the importance of context in which air traffic controller recovery from equipment failures takes place, defining it in terms of 20 Recovery Influencing Factors (RIFs). The RIFs are used to develop a novel approach for the quantitative assessment of the recovery context based on a metric referred to as the Recovery Context Indicator (RCI). The method is validated by a series of simulation exercises conducted at a specific ATC Centre. The proposed method is useful to assess recovery enhancement approaches within ATC centres.
Zhao YX, Li W, Feng S, et al., 2014, An Improved Differential Evolution Algorithm for Maritime Collision Avoidance Route Planning, Abstract and Applied Analysis, Vol: 2014, ISSN: 1687-0409
High accuracy navigation and surveillance systems are pivotal to ensure efficient ship route planning and marine safety. Based on existing ship navigation and maritime collision prevention rules, an improved approach for collision avoidance route planning using a differential evolution algorithm was developed. Simulation results show that the algorithm is capable of significantly enhancing the optimized route over current methods. It has the potential to be used as a tool to generate optimal vessel routing in the presence of conflicts.
Ali BS, Ochieng W, Majumdar A, et al., 2014, ADS-B System Failure Modes and Models, JOURNAL OF NAVIGATION, Vol: 67, Pages: 995-1017, ISSN: 0373-4633
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- Citations: 14
Li Q, Zhang L, Mao Q, et al., 2014, Motion field estimation for a dynamic scene using a 3D LiDAR, Sensors, Vol: 14, Pages: 16672-16691, ISSN: 1424-2818
This paper proposes a novel motion field estimation method based on a 3D light detection and ranging (LiDAR) sensor for motion sensing for intelligent driverless vehicles and active collision avoidance systems. Unlike multiple target tracking methods, which estimate the motion state of detected targets, such as cars and pedestrians, motion field estimation regards the whole scene as a motion field in which each little element has its own motion state. Compared to multiple target tracking, segmentation errors and data association errors have much less significance in motion field estimation, making it more accurate and robust. This paper presents an intact 3D LiDAR-based motion field estimation method, including pre-processing, a theoretical framework for the motion field estimation problem and practical solutions. The 3D LiDAR measurements are first projected to small-scale polar grids, and then, after data association and Kalman filtering, the motion state of every moving grid is estimated. To reduce computing time, a fast data association algorithm is proposed. Furthermore, considering the spatial correlation of motion among neighboring grids, a novel spatial-smoothing algorithm is also presented to optimize the motion field. The experimental results using several data sets captured in different cities indicate that the proposed motion field estimation is able to run in real-time and performs robustly and effectively.
Nascimento F, Majumdar A, Ochieng W, et al., 2014, Initial Evidence-based Analysis of Risk Levels per Phases of Flight, Recency Requirements and Visual Approach Design in Nighttime Offshore Helicopter Operations, 40th European Rotorcraft Forum 2014
Jing S, Zhan X, Lu J, et al., 2014, Characterisation of GNSS Space Service Volume, Journal of Navigation, Vol: 68, Pages: 107-125, ISSN: 0373-4633
There is increasing demand for navigation capability for space vehicles. The idea to extend the application of Global Navigation Satellite Systems (GNSS) from terrestrial to space applications by the use of main beam and side lobe signals has been shown to be feasible. In order to understand the performance and the potential space applications GNSS can support, this paper characterises the Space Service Volume (SSV) in terms of the four parameters of minimum received power, satellite visibility, pseudorange accuracy and Geometric Dilution of Precision (GDOP). This new definition enables the position errors to be estimated. An analytical methodology is proposed to characterise minimum received power for the worst location. Satellite visibility and GDOP are assessed based on grid points at different height layers (to capture the relationship between height and visibility) for single and multiple GNSS constellations, the former represented by BeiDou III (BDS III) and the latter, BDS III in various combinations with GPS, GLONASS and GALILEO. Additional simulation shows that GNSS can potentially support lunar exploration spacecraft at the Earth phasing orbit. This initial assessment of SSV shows the potential of GNSS for space vehicle navigation.
Tobaruela G, Schuster W, Majumdar A, et al., 2014, A method to estimate air traffic controller mental workload based on traffic clearances, JOURNAL OF AIR TRANSPORT MANAGEMENT, Vol: 39, Pages: 59-71, ISSN: 0969-6997
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- Citations: 24
Tobaruela G, Fransen P, Schuster W, et al., 2014, Air traffic predictability framework - Development, performance evaluation and application, JOURNAL OF AIR TRANSPORT MANAGEMENT, Vol: 39, Pages: 48-58, ISSN: 0969-6997
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- Citations: 9
moradi, schuster, feng S, et al., 2014, New stochastic model for carrier multipath in linear combinations, New Navigator Seminar 2014
Ali BS, Schuster W, Ochieng W, et al., 2014, Framework for ADS-B Performance Assessment: the London TMA Case Study, NAVIGATION-JOURNAL OF THE INSTITUTE OF NAVIGATION, Vol: 61, Pages: 39-52, ISSN: 0028-1522
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- Citations: 5
Moradi R, Schuster W, Feng S, et al., 2014, The carrier-multipath observable: a new carrier-phase multipath mitigation technique, GPS Solutions, Vol: 19, Pages: 73-82, ISSN: 1080-5370
Modeling and mitigating carrier-phase multi-path errors continue to be a significant challenge for high-accuracy positioning using global navigation satellite sys-tems. The multipath error is dependent on the operationalenvironment and therefore cannot be mitigated by differ-encing techniques. The effect of multipath is accentuatedwhen observables based on linear combinations of mea-surements from two or more frequencies are formulated.We develop a new carrier-phase multipath error observablethat isolates the inter-frequency carrier-phase multipatherror for linear combinations of observables, such as wide-lane (WL). Real-time kinematic positioning results fromvarying baseline lengths show that a significant reductionin between 14 and 47 % in the time to initial ambiguityresolution are achieved by correcting the WL observableusing the new carrier-phase multipath error observable.
Feng S, Jokinen A, Ochieng W, et al., 2014, Receiver autonomous integrity monitoring for fixed ambiguity precise point positioning, Pages: 159-169, ISSN: 1876-1100
There are still many challenges in Precise Point Positioning (PPP) including formulation of mathematical models, fast resolution of integer ambiguities, ambiguity validation and integrity monitoring. Research to date has focused on error modelling and ambiguity resolution. The ambiguity validation and integrity monitoring is still to be investigated in detail. Early research on PPP integrity has addressed the transferability of the Carrier phase based Receiver Autonomous Integrity Monitoring (CRAIM) algorithms developed for conventional Real Time Kinematic positioning (cRTK). However, there are significant differences between cRTK and PPP in the characteristics of the corresponding residual errors. For example, the satellite clock errors are removed in cRTK; while there are still satellites clock errors remaining in PPP after the application of correction products. The magnitude of these residual satellite clock errors depends on the quality of the products used. The residual errors in PPP are expected to be bigger than those in cRTK. These errors have significant negative impacts on ambiguity validation and integrity monitoring. This paper addresses these challenges. A Doubly Non-Central F distribution (DNCF) is justified for the use with popular ratio test for ambiguity validation. The residual errors in the PPP are characterised for the two key processes in RAIM, failure detection and derivation of protection levels. The correction products used for tests were from Centre National d'Etudes Spatiales (CNES). The GNSS measurement data used were from the American National Oceanic and Atmospheric Administration (NOAA). This selection is to ensure that data from same stations used to test the method are not part of the data sets for the generation of correction products. A dataset from 2 NOAA stations was used for testing. Test results show that the PPP algorithm with the DNCF based ambiguity validation can reach sub-decimetre accuracy. The protection levels calculate
Feng S, Wang S, Ochieng W, 2014, A core constellation based multiple-GNSS positioning and integrity monitoring algorithm, Pages: 307-314
With the modernization of existing Global Navigation Satellite Systems (GNSS) and the deployment new GNSS, it is expected that the full operation of multiple constellations is on the horizon. This will bring opportunities for user level positioning and integrity monitoring including more satellites, frequencies, message types, and better signal design and geometry. Considerable research has been undertaken on positioning and integrity monitoring using multiple GNSS. The existing methods do not have constrains on the use of any constellation. However, some countries have made their systems mandatory for some applications. This suggests that countries that own a GNSS are beginning to realise that critically national infrastructures using Position Navigation and Timing (PNT) services and a portion of the national economy associated with GNSS should not be over reliant on other countries. This paper addresses the technical issues of the existing methods and proposes a core constellation (as specified by individual countries) based multiple-GNSS positioning and integrity monitoring algorithm. A Receiver Autonomous Integrity Monitoring (RAIM) is embedded in the positioning algorithm with the core constellation. In order to benefit from the other constellations without compromise the performance of the core constellation, a real time validation algorithm for the measurements from the other constellations is developed using the solution from the core constellation. The measurements from other constellations are pre-processed with conventional methods including correcting for satellite clock, ionosphere effect and troposphere delay. The measurement residual errors relative to the position solution from the core constellation are assessed. Upon passing the validation process, the measurements from other constellations sire integrated to benefit from the feature of multiple constellations and generate a better solution when core constellation suffers problems. The tests were c
Moradi R, Schuster W, Feng S, et al., 2014, A new carrier phase multipath mitigation technique for ionosphere-free combination, Institute of Navigation International Technical Meeting 2014, ITM 2014, Pages: 562-567
The ionosphere layer of the atmosphere impacts the speed of electromagnetic waves such as those used by Global Navigation Satellite Systems (GNSS). If dual frequency measurements are available, the dependency of ionospheric errors on the frequency can be exploited to remove a significant fraction of these errors using the ionosphere-free (IF) combination. However, although such combination reduces the ionosphere-induced errors significantly, it also magnifies the noise and multipath errors. A new IF multipath mitigation technique is developed in this paper. In this technique, mitigation is achieved by extracting Inter Frequency carrier Multipath (IFM) errors for Global Positioning System (GPS) L1 and L2 and removing them from the IF carrier phase observation. Three test scenarios with different baselines were conducted using real data sets collected in static mode, and post processed in Real-Time Kinematic (RTK) mode. By mitigating the multipath errors in the ionosphere-free combination using the new technique developed in this paper, the horizontal Root Mean Square (RMS) error was reduced by 27% to 45% and the horizontal mean errors were reduced by 25% to 33%.
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