Physics Infused LSTM Network for Track Association Based on Marine Vessel Automatic Identification System Data

In marine surveillance, a crucial task is distinguishing between normal and abnormal vessel movements to timely identify potential threats. Subsequently, the vessels need to be monitored and tracked until necessary action can be taken. To achieve this, a track association problem is formulated where multiple vessels\u27 unlabeled geographic and motion parameters are associated with their true labels. These parameters are typically obtained from the Automatic Identification System (AIS) database, which enables real-time tracking of marine vessels equipped with AIS. The parameters are time-stamped and collected over a long period, and therefore, modeling the inherent temporal patterns in the data is crucial for successful track association. The problem is further complicated by infrequent data collection (time gap) and track overlaps. Traditionally, physics-based models and Kalman-filtering algorithms are used for tracking problems. However, the performance of Kalman filtering is limited in the presence of time-gap and overlapping tracks, while physics-based models are unable to model temporal patterns. To address these limitations, this work employs LSTM, a special neural network architecture, for marine vessel track association. LSTM is capable of modeling long-term temporal patterns and associating a data point with its true track. The performance of LSTM is investigated, and its strengths and limitations are identified. To further improve the performance of LSTM, an integration of the physics-based model and LSTM is proposed. The performance of the joint model is evaluated on multiple AIS datasets with varying characteristics. According to the findings, the physics-based model performs better when there is very little or no time gap in the dataset. However, when there are time gaps and multiple overlapping tracks, LSTM outperforms the physics-based model. Additionally, LSTM is more effective with larger datasets as it can learn the historical patterns of the features. Nevertheless, the joint model consistently outperforms the individual models by leveraging the strengths of both approaches. Given that the AIS dataset commonly provides a long stretch of historical information with frequent time gaps, the combined model should improve the accuracy of vessel tracking

Machine Learning for Enhanced Maritime Situation Awareness: Leveraging Historical AIS Data for Ship Trajectory Prediction

In this thesis, methods to support high level situation awareness in ship navigators through appropriate automation are investigated. Situation awareness relates to the perception of the environment (level 1), comprehension of the situation (level 2), and projection of future dynamics (level 3). Ship navigators likely conduct mental simulations of future ship traffic (level 3 projections), that facilitate proactive collision avoidance actions. Such actions may include minor speed and/or heading alterations that can prevent future close-encounter situations from arising, enhancing the overall safety of maritime operations. Currently, there is limited automation support for level 3 projections, where the most common approaches utilize linear predictions based on constant speed and course values. Such approaches, however, are not capable of predicting more complex ship behavior. Ship navigators likely facilitate such predictions by developing models for level 3 situation awareness through experience. It is, therefore, suggested in this thesis to develop methods that emulate the development of high level human situation awareness. This is facilitated by leveraging machine learning, where navigational experience is artificially represented by historical AIS data. First, methods are developed to emulate human situation awareness by developing categorization functions. In this manner, historical ship behavior is categorized to reflect distinct patterns. To facilitate this, machine learning is leveraged to generate meaningful representations of historical AIS trajectories, and discover clusters of specific behavior. Second, methods are developed to facilitate pattern matching of an observed trajectory segment to clusters of historical ship behavior. Finally, the research in this thesis presents methods to predict future ship behavior with respect to a given cluster. Such predictions are, furthermore, on a scale intended to support proactive collision avoidance actions. Two main approaches are used to facilitate these functions. The first utilizes eigendecomposition-based approaches via locally extracted AIS trajectory segments. Anomaly detection is also facilitated via this approach in support of the outlined functions. The second utilizes deep learning-based approaches applied to regionally extracted trajectories. Both approaches are found to be successful in discovering clusters of specific ship behavior in relevant data sets, classifying a trajectory segment to a given cluster or clusters, as well as predicting the future behavior. Furthermore, the local ship behavior techniques can be trained to facilitate live predictions. The deep learning-based techniques, however, require significantly more training time. These models will, therefore, need to be pre-trained. Once trained, however, the deep learning models will facilitate almost instantaneous predictions

AIS data-driven ship trajectory prediction modelling and analysis based on machine learning and deep learning methods

Maritime transport faces new safety challenges in an increasingly complex traffic environment caused by large-scale and high-speed ships, particularly with the introduction of intelligent and autonomous ships. It is evident that Automatic Identification System (AIS) data-driven ship trajectory prediction can effectively aid in identifying abnormal ship behaviours and reducing maritime risks such as collision, stranding, and contact. Furthermore, trajectory prediction is widely recognised as one of the critical technologies for realising safe autonomous navigation. The prediction methods and their performance are the key factors for future safe and automatic shipping. Currently, ship trajectory prediction lacks the real performance measurement and analysis of different algorithms, including classical machine learning and emerging deep learning methods. This paper aims to systematically analyse the performance of ship trajectory prediction methods and pioneer experimental tests to reveal their advantages and disadvantages as well as fitness in different scenarios involving complicated systems. To do so, five machine learning methods (i.e., Kalman Filter (KF), Support Vector Progression (SVR), Back Propagation network (BP), Gaussian Process Regression (GPR), and Random Forest (RF)) and seven deep learning methods (i.e., Recurrent Neural Network (RNN), Long Short-Term Memory (LSTM), Gate Recurrent Unit (GRU), Bi-directional Long Short-Term Memory (Bi-LSTM), Sequence to Sequence (Seq2seq), Bi-directional Gate Recurrent Unit (Bi-GRU), and Transformer) are first extracted from the state-of-the-art literature review and then employed to implement the trajectory prediction and compare their prediction performance in the real world. Three AIS datasets are collected from the waters of representative traffic features, including a normal channel (i.e., the Chengshan Jiao Promontory), complex traffic (i.e., the Zhoushan Archipelago), and a port area (i.e., Caofeidian port). They are selected to test and analyse the performance of all twelve methods based on six evaluation indexes and explore the characteristics and effectiveness of the twelve trajectory prediction methods in detail. The experimental results provide a novel perspective, comparison, and benchmark for ship trajectory prediction research, which not only demonstrates the fitness of each method in different maritime traffic scenarios, but also makes significant contributions to maritime safety and autonomous shipping development

An extension of the linear regression model for improved vessel trajectory prediction utilising a priori AIS Information

Thesis (MSc)--Stellenbosch University, 2022.ENGLISH ABSTRACT: As maritime activities increase globally, there is a greater dependency on technology in monitoring, control and surveillance of vessel activity. One of the most prominent systems for monitoring vessel activity is the Automatic Identification System (AIS). An increase in both vessels fitted with AIS transponders, and satellite- and terrestrial receivers has resulted in a significant increase in AIS messages received globally. This resultant rich spatial and temporal data source related to vessel activity provides analysts with the ability to perform enhanced vessel movement analytics, of which a pertinent example is the improvement of vessel location predictions. In this thesis, we propose a novel method for predicting future locations of vessels by making use of historic AIS data. The proposed method extends a Linear Regression Model (LRM), utilising historic AIS movement data in the form of a priori generated spatial maps of the course over ground (LRMAC). The LRMAC has low complexity and is programmatically easy to implement, and attains accurate prediction results. We first compare the LRM with a Discrete Kalman Filter (DKF) on linear trajectories. We then extend the LRM to form the LRMAC. The LRMAC is compared to another method in literature called the Single Point Neighbour Search (SPNS). For the use case of predicting Cargo and Tanker vessel trajectories, with a prediction horizon of up to six hours, the LRMAC has an improved execution time and performance compared to the SPNS.AFRIKAANSE OPSOMMING: As gevolg van die toename in maritieme aktiwiteite wˆereldwyd, het die afhanklikheid van tegnologie in die monitering, beheer en toesig van vaartuigaktiwiteite ook toegeneem. Een van die mees prominente stelsels vir die monitering van vaartuigaktiwiteit is die Outomatiese Identifikasiestelsel (OIS). ’n Toename in vaartuie wat toegerus is met OIS-transponders, en die toename in satelliet- en terrestri¨ele ontvangers, het gelei tot ’n aansienlike groei in OIS-boodskappe wat wˆereldwyd ontvang is. Dit het weer gelei tot die toename in dataryke ruimte-temporele bronne, wat verband hou met vaartuigaktiwiteite. Dit gee ontleders die vermo¨e om gevorderde vaartuig-bewegingsanalise uit te voer, waarvan ’n toepaslike voorbeeld, die verbetering van vaartuig-liggingvoorspelling is. In hierdie tesis stel ons ’n nuwe strategie voor om toekomstige liggings van vaartuie te voorspel, wat gebruik maak van historiese OIS-data. Die voorgestelde metode brei ’n Lineˆere Regressie Model (LRM) uit, deur gebruik te maak van historiese bewegingsdata en ruimte kaarte van a priori koers oor grond inligting (LRMAK). Die LRMAK het ’n lae kompleksiteit en is programmaties eenvoudig om te implementeer, met relatiewe akkurate voorspelling resultate. Ons vergelyk eers die LRM met ’n Diskrete Kalman Filter (DKF) op lineˆere trajekte. Dan brei ons die LRM uit om die LRMAK te vorm. Die LRMAK word vergelyk met ’n ander metode in literatuur wat die Enkel-punt Buur soektog (EPBS) genoem word. In die geval van trajek-voorspelling vir vrag- en tenkwa-vaartuie, het die LRMAK ’n verbeterde uitvoeringstyd en is vergelykbaar met ’n ander algoritme in literatuur, die EPBS, tot en met ’n voorspellingstydperk van ses-ure.Master

Using Machine Learning to Predict Port Congestion : A study of the port of Paranaguá

Being able to accurately predict future levels of port congestion is of great value to both port and ship operators. However, such a prediction tool is currently not available. In this thesis, a Long Short-Term Memory Recurrent Neural Network is built to fulfill this need. The prediction model uses information mined from Automatic Identification Systems (AIS) data, vessel characteristics, weather data, and commodity price data as input variables to predict the future level of congestion in the port of Paranaguå, Brazil. All data used in this study are publicly available. The predictions of the proposed model are shown to be promising with a satisfactory level of accuracy. The conclusion and evaluation of the presented model are that it serves its purpose and fulfills its objective within the constraints set by the authors and its inherent limitations.nhhma

Design and analysis of computer experiments for stochastic systems

Ph.DDOCTOR OF PHILOSOPH

It’s Better to Enjoy Learning than Playing: Motivational Effects of an Educational Live Action Role-playing Game

Game-based learning is supposed to motivate learners. However, to what degree does motivation driven by interest in playing an instructional game affect learning outcomes compared to motivation driven by interest in the very learning process? This is not known. In this study with a unique design and intervention, young adults (N = 128; a heterogeneous sample) learned how to control an electro-mechanical device in a 40-minute-long learning session integrated into a 2-hour-long educational live action role-playing game (edu-LARP). Edu-LARPs are supposedly engaging games where players take part in team role-playing by physically enacting characters in a fictional universe. In our edu-LARP, players had to understand how the to-be-learned device worked in order to win the game. Departing from typical game-based learning research, learning- and playing-related variables were assessed for each learner separately (i.e., a within-subject design). Affective-motivational factors related to playing (rather than learning) predicted learning outcomes in a positive, but considerably weaker, way compared to learning-related, affective-motivational factors. Developed interest in LARP-like games was primarily related to enjoying the game rather than better learning outcomes; whereas, developed interest in the instructional domain was primarily related to enjoyment of learning and better learning outcomes. Overall, autonomous motivation to play was connected to higher learning outcomes, but this connection was weak. &nbsp