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To support the operation of advanced receiver autonomous integrity monitoring (ARAIM), an integrity support message indicating a minimum performance level of satellite constellation is required for aircraft navigation. With BDS-3 providing worldwide service since July 2020, it is desirable to undertake a detailed study on its signal-in-space range error characteristics and prior fault probabilities for ARAIM. The latest accuracy criteria released by the China Satellite Navigation Office in May 2021 is validated by the 27 MEO and IGSO satellites in orbit from July 2020 to June 2021, in which 10 single satellite faults were identified and analyzed in detail with no constellation fault found. Based on this one-year data, the probability of single satellite faults and constellation faults can be initially set as 8x10^(-5) and 1x10^(-3), respectively, for BDS-3 in ARAIM.

Magnetic field localization is based on the fact that the Earth’s magnetic field is distorted in the vicinity of ferromagnetic objects. When ferromagnetic objects are in fixed positions, the distortions are also fixed and, thus, contain location information. In our prior work, we proposed a simultaneous localization and calibration (SLAC) algorithm based on a Rao-Blackwellized particle filter that enables magnetic train localization using only uncalibrated magnetometer measurements. In this paper, a lower-complexity version of the SLAC algorithm is proposed that only estimates a subset of calibration parameters. An evaluation compares the full and reduced SLAC approach to a particle filter in which the magnetometer is pre-calibrated with a fixed set of parameters. The results show a clear advantage for both SLAC approaches and that the SLAC algorithm with a reduced set of calibration parameters achieves the same performance as the one with a full set of parameters.

The automation of mining haulage vehicles has great potential in terms of safety and economy. The performance of autonomous vehicles depends largely on highly accurate vehicle state information. Deep mines are especially challenging, as satellite-based localization methods are reaching their limits. Therefore, we introduce a new navigation filter concept for the precise and robust localization of the haulage fleet that can handle temporary GNSS interruptions in deep open-pit mines. The multi-sensor navigation filter utilizes an inertial measurement unit and is aided by GNSS. We introduce a new optical speed sensor update within the tightly coupled unscented Kalman filter. The speed sensor measures the slip-free two-dimensional speed above ground. The filter was validated with an articulated dumper in a gravel pit. The new filter achieved a mean position error of 0.24 m during a test drive of 190 s with a simulated GNSS outage of 90 s.

Faulty signals from global navigation satellite systems (GNSSs) often lead to erroneous position estimates. A variety of fault detection and exclusion (FDE) methods have been proposed in prior research to both detect and exclude faulty measurements. This paper introduces a new technique for the FDE of GNSS measurements using Euclidean distance matrices. After a brief introduction to Euclidean distance matrices, both the detection and exclusion strategy is explained in detail. Euclidean distance matrix-based FDE is verified in two separate real-world data sets and proven to accurately detect and exclude GNSS faults on an average of 1.4-times faster than residual-based FDE and 70-times faster than solution separation FDE.

Self-interference can cause large errors of up to tens of meters on the GPS C/A code pseudorange measurement. Although the probability of an occurrence of large self-interference errors is small, to enable the use of C/A code phase measurements in high accuracy or safety-of-life applications, a detection or mitigation method is needed. A stressful case of self-interference is modeled on a GPS hardware simulator to investigate monitor performance using real signal results. A summary of contributions in this paper follows. Self-interference pseudorange error characteristics within and mitigation requirements for the Ground Based Augmentation System (GBAS) Approach Service Type D (GAST-D) environment are identified. Existing monitors are evaluated for their response to self-interference and their ability to detect the error based on the GAST-D environment. This includes the potential for misidentification of the error. A novel Frequency Domain Cross-Correlation (FDCC) detector is proposed that can uniquely identify self-interference error with no siting constraints.

New GNSS applications demand resilience against radio interference and high position accuracy. Separately, these demands can be fulfilled by multi-antenna systems using spatial filtering and carrier-phase positioning algorithms like real-time kinematic (RTK), respectively. However, combining these approaches encounters a severe issue: The spatial filtering induces a phase offset into the measured carrier phase leading to a loss of position accuracy. This paper presents a new approach to compensate for the phase offset in a blind manner (i.e., without knowing the antenna array radiation pattern or the direction of arrival of the signals). The proposed approach is experimentally validated in two jamming scenarios. One includes a jammer with increasing power and the other includes a moving jammer. The results demonstrate that the approach successfully compensates for the phase offset and, hence, allows for the combined use of RTK positioning and spatial filtering even under jamming.

Communication connectivity is desirable for the safe and efficient operation of multi-robot systems. While decentralized algorithms for connectivity maintenance have been explored in recent literature, the majority of these works do not account for robot motion and sensing uncertainties. These uncertainties are inherent in practical robots and result in robots deviating from their desired positions which could potentially result in a loss of connectivity. In this paper, we present a decentralized connectivity maintenance algorithm accounting for robot motion and sensing uncertainties (DCMU). We, first, propose a novel weighted graph definition for the multi-robot system that accounts for the aforementioned uncertainties along with realistic connectivity constraints such as line-of-sight connectivity and collision avoidance. We, then, design a decentralized gradient-based controller for connectivity maintenance with which we derive the gradients of the weighted graph edge weights required for computing the control. Finally, we perform multiple simulations to validate the connectivity maintenance performance of our DCMU algorithm under robot motion and sensing uncertainties, showing an improvement compared to previous work.

High-precision positioning methods have drawn great attention in recent years due to the rapid development of smart vehicles as well as automatics driving technology. The Real-Time Kinematic (RTK) technique is a mature tool to achieve centimeter-level positioning accuracy in open-sky areas. However, the users who drive under dense urban conditions are always confronted with harsh global navigation satellite system (GNSS) environments. Skyscrapers and overpasses block the signals and reduce the number of visible satellites, making it difficult to achieve continuous and precise positioning. Considering that the road is relatively smooth in most urban areas, vehicles are expected to travel on the same plane when they are close to each other. The road plane information is a promising candidate to enhance the performance of the RTK method in constrained environments. In this paper, we propose a plane-constrained RTK (PCRTK) method using the positioning information from cooperative vehicles. In a vehicle-to-vehicle (V2V) network, the positions of cooperative vehicles are used to fit a road plane for the target vehicle. The parameters of the plane fitting are treated as new measurements to enhance the performance of the float estimator. The relationship between the plane parameters and the state of the estimator is derived in our study. To validate the performance of the proposed method, several experiments with a four-vehicle fleet were carried out in open-sky areas and dense urban areas in Beijing, China. Simulations and experimental results show that the proposed method can take advantage of the plane constraint and obtain more accurate positioning results compared to the traditional RTK method.

Integrity, a safety-of-life framework from civil aviation for satellite navigation, is greatly under-explored in visual navigation. A new two-factor approach to rejecting measurement outliers is proposed for navigation integrity in stereo visual odometry (VO). In contrast to other treatments using reprojection error as measurement residuals, our choice of landmark matching error inherently connects navigation solutions and integrity monitoring. We propose two methods to detect large measurement residuals that cannot otherwise be identified by existing outlier rejection methods in state-of-the-art VO pipelines. By rejecting these outliers, measurement residuals can be bounded by the distribution overbounding method that provides fundamental inputs for integrity computations. We evaluate our methods using an open-source data set. Overbounding performance is improved in terms of tightness, computational efficiency, and most important of all, scenario tolerance. This could be a good starting point for developing future integrity monitoring algorithms for visual navigation and in particular, stereo VO.

Deep neural networks (DNNs) are a promising tool for global navigation satellite system (GNSS) positioning in the presence of multipath and non-line-of-sight errors, owing to their ability to model complex errors using data. However, developing a DNN for GNSS positioning presents various challenges, such as (a) poor numerical conditioning caused by large variations in measurements and position values across the globe, (b) varying number and order within the set of measurements due to changing satellite visibility, and (c) overfitting to available data. In this work, we address the aforementioned challenges and propose an approach for GNSS positioning by applying DNN-based corrections to an initial position guess. Our DNN learns to output the position correction using the set of pseudorange residuals and satellite line-of-sight vectors as inputs. The limited variation in these input and output values improves the numerical conditioning for our DNN. We design our DNN architecture to combine information from the available GNSS measurements, which vary both in number and order, by leveraging recent advancements in set-based deep learning methods. Furthermore, we present a data augmentation strategy to reduce overfitting in the DNN by randomizing the initial position guesses. We, first, perform simulations and show an improvement in the initial positioning error when our DNN-based corrections are applied. After this, we demonstrate that our approach outperforms a weighted least squares (WLS) baseline on real-world data. Our implementation is available at github.com/Stanford-NavLab/deep_gnss.

In this paper, we develop new stochastic orbit and clock error models for positioning, fault detection, and integrity monitoring over time. GPS and Galileo orbit and clock data are evaluated and ranging errors are analyzed and modeled over time. This work is intended for time-sequential safety-critical navigation systems including global navigation satellite systems (GNSSs) integrated with inertial navigation systems (INSs) and Kalman filter implementations of Advanced Receiver Autonomous Integrity Monitoring (ARAIM).

The Autonomous and Resilient Management of All-source Sensors (ARMAS) framework monitors residual-space test statistics across unique sensor-exclusion banks of filters (known as subfilters) to provide a resilient, fault-resistant all-source navigation architecture with assurance. A critical assumption of this architecture, demonstrated in this paper, is fully overlapping state observability across all subfilters. All-source sensors, particularly those that only provide partial state information (altimeters, TDoA, AOB, etc.), do not intrinsically meet this requirement. This paper presents a novel method to monitor real-time overlapping position state observability and introduces an observability bank within the ARMAS framework, known as stable observability monitoring (SOM). SOM uses a monitoring-epoch stability analysis to provide an intrinsic awareness to ARMAS of the capabilities of the fault detection and exclusion (FDE) functionality. We define the ability to maintain consistent all-source FDE to recover failed sensors as navigation resilience. A resilient FDE capability is one that is aware of when it requires more sensor information to protect the consistency of the FDE and integrity functions from corruption. SOM is the first demonstration of such a system for all-source sensors that the authors are aware of. A multi-agent 3D environment simulating both GNSS and position and velocity alternative navigation sensors was created and individual GNSS pseudorange sensor anomalies are utilized to demonstrate the capabilities of the novel algorithm. This paper demonstrates that SOM seamlessly integrates within the ARMAS framework, provides timely prompts to augment new sensor information from other agents, and indicates when framework stability and preservation of all-source navigation integrity are achieved.

Unlike many urban localization methods that return point-valued estimates, a set-valued representation enables robustness by ensuring that a continuum of possible positions obeys safety constraints. One strategy with the potential for set-valued estimation is GNSS-based shadow matching (SM) in which one uses a three-dimensional (3D) map to compute GNSS shadows (where line-of-sight is blocked). However, SM requires a point-valued grid for computational tractability, with accuracy limited by grid resolution. We propose zonotope shadow matching (ZSM) for set-valued 3D-map-aided GNSS localization. ZSM represents buildings and GNSS shadows using constrained zonotopes, a convex polytope representation that enables propagating set-valued estimates using fast vector concatenation operations. Starting from a coarse set-valued position, ZSM refines the estimate depending on the receiver being inside or outside each shadow as judged by received carrier-to-noise density. We demonstrate our algorithm’s performance using simulated experiments on a simple 3D example map and on a dense 3D map of San Francisco.

Welcome to the Winter 2022 issue of NAVIGATION. In this issue, we again feature articles on a wide range of topics including GNSS orbit and clock modeling, monitoring GNSS signals, characterizing the ionosphere and its effects on navigation, and improved GNSS positioning using a variety of tools. ION continues to promote the research of journal authors through compulsory video abstracts hosted on the ION website. The latest video abstracts are documented below. You can find the video abstract for any recently published article under the article’s supplemental menu item on the journal’s website. ION also engages with the PNT community, through its webinar series, to highlight current topics of interest to the community. The most recent webinar is also documented below. Remember, we have a dedicated website for our journal: https://navi.ion.org/. From the home page, you can find the current issue, early view articles to be compiled into the next issue, recent archived issues, and other information about the journal. The full archive of NAVIGATION is available on the ION website: https://www.ion.org/publications/browse.cfm.

Signal quality monitoring (SQM) is a technique utilized by satellite- and ground-based augmentation systems (SBAS/GBAS) to detect potential hazardous deformations in signals and better protect integrity for safety-critical users. The next generation of SBASs will incorporate dual-frequency multi-constellation (DFMC) techniques, for which SQM is particularly important since signal deformations might be the largest source of uncertainty in ranging error after first-order ionospheric delays are eliminated. However, the performance bounds of the traditional multi-correlator-based SQM technique face some challenges because of the raised requirement on detection sensitivity by dual-frequency ionosphere-free measurements and multiple modulation modes of civilian signals from multi-constellation techniques. To mitigate the challenges and improve overall performance, SQM based on chip domain observables (CDOs) is emerging, but has not yet been systematically studied. We propose a design methodology for CDO-based SQM, consisting of derivations and corresponding massive simulations. Correctness and effectiveness are assessed to confirm the methodology, and a simplification process by checking the sensitivity of CDOs is demonstrated in terms of implementation.

Real-time precise global navigation satellite system (GNSS) orbit and clock products play a key role for real-time GNSS-based applications, both in the scientific and industrial communities. Different from the typical two-step procedure to generate orbit and clock solutions separately, we estimate the real-time orbit and clock products simultaneously using a Kalman filter. For this purpose, we developed a GNSS data processing software that can run in pseudo-real-time mode with RINEX files and is ready to run in real-time mode once given the real-time observation stream. Meanwhile, a quasi-orbit-fixed solar radiation pressure (SRP) model is developed. In order to verify the performance of the software and the new SRP model, several experiments with a global network of 60 tracking stations over a time span of three months were conducted to generate real-time Global Positioning System (GPS) orbit and clock products. Then, the results were assessed in terms of accuracy and efficiency, both critical for real-time precise GNSS applications. Compared to the International GNSS Service (IGS) final orbits, the real-time GPS orbit accuracy was 2.82 cm, 5.45 cm, and 5.47 cm in the radial, along-track, and cross-track components, respectively. The precision of the clock product in terms of standard deviation (STD) value was about 0.1 ns. Moreover, the average execution time per epoch was usually less than 1.0 s, which ensures the high efficiency of the processing.

The performance of a proposed high-frequency (HF) navigation concept is analyzed using simulated data. The method relies on pseudorange and beat carrier-phase measurements of signals that propagate in the ionosphere along curved trajectories, where signals are refracted back downwards from the ionosphere. It has been demonstrated that the location of a receiver can be determined if several signals, broadcast from beacons at different locations, are received and processed at a user receiver. A challenge of determining exact signal paths is the uncertainty in the ionosphere’s electron density distribution. This is addressed by a batch filter that simultaneously estimates the receiver position along with corrections to a parametric model of the ionosphere. A previous paper developed the theory and batch filter for this concept. The present study examines its potential performance. Total horizontal position errors on the order of tens to hundreds of meters are achieved, depending on the case’s characteristics.

Recently, the Snapshot Real-Time Kinematic (SRTK) technique was demonstrated, which aims at achieving high accuracy navigation solutions with a very short signal collection. The main challenge in implementing SRTK is the generation of valid carrier-phase measurements, which relies on a data bit ambiguity (DBA) resolution process. For pilot signals, this step is equivalent to the correct selection of secondary code indexes (SCIs) from the ambiguous sets obtained from a multi-hypotheses (MH) acquisition process. Currently, SCI ambiguities are solved independently for each satellite. However, this method is ineffective when the snapshot signal is relatively short. In order to tackle this problem, this article proposes a new method that makes use of assistance data and processes information from all satellites to jointly solve the DBA issue. This new method is shown to be more effective in determining the correct SCI and enabling valid snapshot carrier-phase measurements, largely expanding the scope of high-accuracy snapshot positioning.

A fast Monte Carlo technique to simulate equatorial ionospheric scintillation on global navigation satellite system signals is proposed. The algorithm uses a single-layer phase-screen model of the ionosphere and the scintillation is expressed as a Huygens-Fresnel integral (HFI). By assuming a specially-tailored random phase screen, the HFI can be expressed in closed form as a combination of Fresnel integrals. We statistically characterize the amplitude and phase computed by the HFI for different values of the scintillation index S4. Results for the L1, L2, and L5 bands were obtained and compared with real data, showing good agreement. Some of the advantages of the proposed technique are: (a) the amplitude and phase of the scintillation process are simultaneously obtained; (b) arbitrarily long ionospheric scintillation time series with pre-defined stationary characteristics are synthesized; and (c) several scintillation time series corresponding to different carrier frequencies are generated using a common phase-screen model.

In recent decades, GNSS radio occultation (RO) soundings have proven to be an invaluable input to global weather forecasting. The success of government programs such as COSMIC is now complemented by commercial low-cost cubesats. The result is access to more than 10,000 soundings per day. We examine aerial platforms for commercial GNSS-RO, specifically high-altitude balloons and commercial aviation. Meteorological balloons (radiosondes) are deployed daily in over 900 locations globally. Adding GNSS-RO capability to radiosondes would expand capability and enable local area monitoring. Commercial aviation offers scale with more than 100,000 flights daily. A barrier to entry for the inclusion of GNSS-RO sensors is cost and complexity, as GNSS-RO traditionally requires highly specialized equipment. This paper describes a low-cost and scalable approach to aerial GNSS-RO based on commercial-off-the-shelf (COTS) GNSS receivers. We present hardware prototypes and data processing techniques that demonstrate technical feasibility through the results from several flight testing campaigns.

Besides its obvious benefits, the Electronic Chart Display and Information System (ECDIS) continues to develop as a sophisticated, complex system. With ever-growing features and the integration of external data and sources, it is nowadays normally considered as one among the compact elements forming a part of an even more complex Integrated Navigation System (INS). The ECDIS handling requires a certain level of technical knowledge and operational skills to be gained, besides the usual navigational background. In order to utilize the system efficiently and safely, the navigator has to obtain several levels of education. The Generic ECDIS Training (GT), as defined in the respective International Maritime Organization (IMO) Model Course, introduces the navigator with fundamental, required operational (however introductory) and theoretical knowledge. Apart from the GT, there is an optional, ECDIS manufacturer-approved Equipment Specific Training (EST). The latter represents a special type of training where the navigator improves its theoretical knowledge, understanding, and proficiency, together with competence demonstration on a specific approved ECDIS model. This paper elaborates the dynamics of worldwide regulations pertaining to the ECDIS Education and Training (EET) plan. The reference is given to training procedures in the Republic of Croatia, placing its educational framework in the broader context. Although it is of a non-mandatory nature, the EST is unofficially considered that way, and there is a stable and reasonable ground to consider the opinions and arguments of the navigators who prefer the EST. This is also supported by the fact that there is a large number of approved systems on the market. Apart from fulfilling the performance standards regulated by the International Maritime Organization (IMO), ECDIS models differ significantly regarding handling, interface, and interpretation of data and information, therefore biasing the required knowledge and the purposefulness of the system. The survey among navigational ranks was used to support the study and to relate the existing programs with the actual navigational situation. The motivation was the consideration of the current relationship between defined EET programs, their inequalities, and the actual user needs, referring to the systematisation of the fulfillment of the system as a basic navigation tool. The selected questions referred to the possession of ECDIS certificates and basic education and knowledge, and the navigational ranks’ opinions regarding the opportunity to enhance their knowledge during the EST. The latter considered lack of standardisation (including terminology), apart from different levels of education. As expected, the answers were not uniform, revealing differences in opinion as well as in basic system interpretation. The latter could have possible causes and relation to the particular education system in the first place. The current educational framework was discussed in terms of EET enhancements and the development of the navigation curricula. The study results have been presented and discussed systematically, leading to observations on the potential safety of navigation improvement.

SAFEMODE is an EU-funded project under the Horizon 2020 programme. The project brings together experience from the whole safety value chain including manufacturers, service providers, regulators, academia, and small-medium enterprises. This paper focuses on two core aspects the project is addressing: 1) the systematic collection, analysis, and categorization of Human Factors (HF) data from maritime and aviation safety events, and 2) the development of a Just Culture framework for maritime to encourage reporting of safety events and learning from them, and at which respondents feel they are treated in a fair and just manner when reporting. Learning from safety events is only possible if root causes of accidents and incidents are properly and systematically identified, analysed, and categorized, and reporters know that reporting is a “safe” and beneficial practice. The implementation of these two outcomes as part of the institutionalization strategy of the project includes recommendations to industry guidance and practice and proposals to the International Maritime Organization (IMO).

The Intercept Method (originally known as the Intercept Azimuth method) was created in 1875 by the French captain (latter admiral) Marq de Saint Hilaire. The method is still used today and is accepted by the International Maritime Organization as an component element of the Standards of Training, Certification and Watch-keeping for Seafarers. This paper aims to present the way of graphically determination of the vessel's fix position with two astronomical position lines computed using the intercept method.

Organizational structure of a ship changes under the influence of technological development. Processes on board a ship change as well. Major change refers to the role of the crew and consequently leads to the change of a method of determining competences. Equipment and working processes are becoming more complicated. They have a strong impact on the crew, i.e. on their competences. Competences prescribed in STCW Convention are not in accordance with the changed role of the crew in the processes on board. In STCW Convention, competences have been grouped according to the ship’s functions at different levels of responsibility. Competences have not been prescribed on the basis of the working processes within a system. Such a situation has led to the absence of the proper upgrade of needed competences. Based on the analysis of the functional organizational structure of a ship, the paper suggests more elaborated approach to defining competences. Such an approach links competences with equipment and working processes on board a ship.

A study of the dynamic loading of the carrying structure of a tank wagon during transportation on a railway ferry was carried out. The studies were carried out with the angular displacements of the railway ferry around the longitudinal axis (lurch), as the case of the highest load on the carrying structure of the tank wagon. It was found that the acceleration total value that acts on the outermost tank wagon from the bulwark is 0.31g. The resulting value of acceleration, as a component of the dynamic load, was taken into account when calculating the strength of the carrying structure of the tank wagon, taking into account the typical scheme of interaction with chain ties. The research carried out will contribute to the creation of recommendations for the safe operation of tank wagons in international rail and water traffic and increasing the efficiency of rail transport functioning.

The Electronic Chart Display and Information System (ECDIS) became the central navigational tool on modern ships. The system comprises numerous navigational and other components, each of them with its limitations and reliability. Due to ECDIS's revolutionary features, navigators are tempted to place excessive reliance on the system. Such reliance on it as a sole navigational aid is undoubtedly a problematic issue. The proposed paper is a segment of a systematically carried out research among ECDIS stakeholders. ECDIS EHO (Experience, Handling, and Opinion) research aims through research activities based on a user-centred approach to develop and improve the educational framework. The overreliance on the ECDIS system motivated the proposed research, which focused on system users' opinions and practice regarding confirmation of the accuracy of information displayed on ECDIS, particularly concerning positional sensors. Analysis of answers collected by the ECDIS EHO questionnaire represents a backbone of the research supported by previous achievements. The answers have been categorized and discussed, revealing certain worrying aspects referring to the system's positional error experienced by users. Furthermore, preferred methods of cross-checking ECDIS information have been identified and have differed among respondents based on their rank on board. Additionally, answers indicate certain doubts between users’ interpretation of the best confirmation method and the actual selection of the used method. The importance of cross-checking navigational data in avoiding overreliance and maintaining situational awareness has been presented in the conclusion chapter and the proposal for further work.

Over the last few decades, the International Maritime Organization (IMO) has very heavily utilized the Safety of Life at Sea (SOLAS), 1974 Convention as the main legal instrument (and implementation tool) concerning safety at sea for merchant vessels engaged in international trade. During this more than a century of existence and continuous improvement of the Convention, wide-ranging safety risks have been addressed via SOLAS and certain relevant “supporting” Codes, covering for example the issues of design, construction and equipment of ships, as well as paving the way for the introduction of a structured framework of operational procedures that ensures a high level of professional performance for the crew onboard those seagoing vessels (the International Management Code for the Safe Operation of Ships and for Pollution Prevention-ISM Code) and even including human factors topics. Until this point in time, the IMO has developed the SOLAS Convention with fourteen (14) chapters that are covering all the main risks associated with shipping operations and are working in parallel with other related Conventions and Codes to enhance the level of safety at sea, under a holistic approach that is working under the principle of interrelation. This paper aims to briefly discuss SOLAS’ history of development and highlight just a few of those important risks that this Convention is addressing, with certain emphasis on the topic of “safety of navigation”. Apart from helping to understand the way this Convention and other IMO’s legal instruments are interrelated, it will also provide a few educated guesses about the “upcoming” challenges that in the near future should also be included into the scope of the SOLAS, with the topic of Maritime Autonomous Surface Ships (MAAS) clearly standing out.

Decision support systems (DSS) recently have been increasingly in use during ships operation. They require realistic input data regarding different aspects of navigation. To address the optimal weather routing of a ship, which is one of the most promising field of DSS application, it is necessary to accurately predict an actually attainable speed of a ship and corresponding fuel consumption at given loading conditions and predicted weather conditions. In this paper, authors present a combined calculation method to predict those values. First, a deterministic modeling is applied and then an artificial neural network (ANN) is structured and trained to quickly mimic the calculations. The sensitivity of the ANN to adopted settings is analyzed as well. The research results confirm a more than satisfactory quality of reproduction of speed and fuel consumption data as the ANN response meet the calculation results with high accuracy. The ANN-based approach, however, requires a significantly shorter time of execution. The directions of future research are outlined.

This paper is an extension of work originally presented in 2019 EUROPEAN NAVIGATION CONFERENCE (ENC) [4]. The paper has described the important role of the Stockholm Agreement in safety of the Ro-Ro/Passenger ships in the north European waters. The present work describes the way in which we can improve the safety in strong chance of destruction of ship at sea. All results are generalized for a given group of ships. The specific construction of the RO-RO/ Passenger ships, being characterized by flat vehicle decks which are practically open, un-subdivided, and additional passenger accommodation space, with ramp fitted astern and in some cases in fore or side of the ship, giving access to cars, trucks and trailers, or specific trains which remain on board in their laden state, has resulted in international regulation requiring, amongst other things, strengthening the damage stability requirements for this type of ships. The more stringent damage stability criteria has been adopted on a regional basis by northern European countries as STOCKHOLM Agreement, in 1996. The paper concerns an analyze of damage stability calculations results in compliance with the STOCKHOLM Agreement, when the Ro-Ro/ Passenger ship is fully loaded, with maximum Deadweight (DWT) and maximum draught, or partly loaded, with reduced DWT, and occurs Minor or Major penetration of destroyed compartments.

In recent decades, there has been noticed a continuous growth of passengers on cruise ships. Technical as well as technological development follow this growth side to side as far as construction, transport of passengers and strict legal regulations are concerned. However, recent maritime accidents, such as the Costa Concordia’s accident, question the level of maritime safety on cruise ships. Maritime accidents on cruise ships are almost entirely linked to human factor, directly or indirectly. Apart from the parameters affecting human factor, the literature mentions very frequently the importance of education, training and crew competences in the process of reducing the number of maritime accidents. However, very few researches have been done on competences that can affect strongly the level of maritime safety on cruise ships, i.e., that can reduce the effects of human factor on it. The purpose of this study was to find a connection between reducing the effects of human factor on accidents and the crew competences on cruise ships. The research lasted for two years and consisted of two phases. Qualitative as well as quantitative methods of analysis were used in both phases. Competences that are the essential part of obligatory programmes the crew members on cruise ships have to master, and that are prescribed by the STCW Convention were analysed in the first part of the research. The second part of the research analysed competences that are essential part of programmes resulting from the cruise companies’ demands. Cruise companies have defined and determined additional programmes and competences that seafarers, navigating on their ships, have to complete and develop. The aim of the research was to determine what type of competences the cruise companies look for through additional education programmes and to determine the amount of time needed to develop them.

Audio watermarking (AW) technology in cooperation with GPS synchronization of watermarked frames is proposed for application in the maritime VHF communication for automatic identification of radiotelephone messages. Automatic identification ensures efficient messaging from the very beginning of a radio transmission, while eliminating the human factor inherent in voice identification. AW refers to inaudible embedding of additional data just into the post microphone signal, using standard marine installations without any additional radio channel resources. The designed algorithm is based on data embedding in the Fast Fourier Transform domain with the rate of 32 bit/s. The experimental prototype of the device is designed on the base of micro-controller development kit 32F429IDISCOVERY and GPS module NEO-6M-0-001. Designed system, applied for automatic ship’s identification, provides the full compatibility with the existing radio installation, and does not require replacement of standard VHF transceivers and operational procedures. Besides automatic identification the system may be used in the special applications, for example, by the threat of terrorist attack; generally contributes to navigation safety and information security.

Rapid changes in technologies and digitalization challenges caused by Industry 4.0 with the integration of the AI, machine learning algorithms, internet of things’ technologies, introduction of maritime autonomous surface ships and the development of digital shipping and logistics processes require proper education and training of specialists working in maritime industry to ensure safety and security of people, oceans, goods and environment. The shipping and logistic processes and operations, including the decision-making processes, on the global scale and on the scale of whole-organisation ecosystems become more dependent on the manipulation of data from different unstructured open sources and private data sets, increased amount of data stream from sensorial systems. The specialists working with automated systems need competences to use and interpret special data, engineering and analysis algorithms, and skills in using modelling tools of optimised solutions in shipping and logistics. Educational institutions have to be ready to present effective solutions to educate quickly adaptable specialists able to meet volatile labour market needs able to meet digitalization challenges. The case study of the Lithuanian Maritime Academy (LMA) presented in the paper is based on the use of an integrative approach and work integrated learning with the aim of enabling the educational environment to develop proper competencies of the specialists of shipping and logistics information systems.

The growing demand for transportation has brought even larger quantities of traffic in spatially limited port areas. Considering a diverse traffic mix, infrastructural overcapacity and busy schedule, port communities have started to face possible degradation of safety and environmental standards. To mitigate these problems, a number of different monitoring solutions of marine environment were deployed. Since conventional environmental and traffic data gathering by physical monitoring and sampling was logistically complicated and inefficient in time and resources, different approaches had to be considered. With the rise of accessible Internet of Things (IoT) technology some ports already installed smart monitoring devices such as smart buoys. The goal of this paper is to examine the concept and benefits of an automated smart buoy as a cost effective, easy to install device capable of real-time remote information sharing. Furthermore, the design and operational processes of existing automated smart buoy will be presented, along with solutions for tackling navigational safety and environmental problems.

The idea of the proposed concept is to optimize information exchange between ship managers and potential charterers. There are many attempts to create electronic system for facilitation of information exchange, but all of them are aimed to find solution in particular area: container or oil trade, collecting data on ships or some other Port State Control issues. Existing technical solutions in most cases are not taking into account possibility of data change, which may vary significantly during ship’s trip. Moreover, there is no deep analysis of each proposed variant, which can take into account all variable factors. Also – there is no complex solution, applicable to any ship / any cargo. Proposed concept describes the system of electronic data exchange, which assists in decision-making and based on risk assessment of changing scenario in the process of choosing the best solution for fixing the ship.

As ships and maritime transport have evolved, knowledge of navigation methods has also evolved, reaching today modern means that require less of the skills and time of navigators to determine the position of the ship on sees and oceans. However, the IMO resolutions maintain the obligation for seafarers to know the procedure for deter-mining the position of the ship based on the use of astronomical position lines, a process known simply as the "Intercept Method". As is well known, the classical "Intercept Method" involves a graphical stage aimed to determine the geographical coordinate of Fix position. This paper presents a combined method which eliminates the graphical construction which may involve plotting errors. The method introduces mathematical computation of fix geographical coordinates.

The article presents factors influencing decision making by Dynamic Positioning Operator (DPO) and statistics of the DPOs behaviour in an emergency situation. Considering that supply operation is performed by a DP vessel at a distance comparable to its width of the hull to the installation, unit, or another vessel, the thruster failure may lead to a rapidly developing incident such as collision, pollution, or human injuries. Based on the IMO guidelines on formal safety assessment authors suggested a risk model of platform supply operation in dynamic positioning mode. It is shown that different approaches shall be applied for rule-making and active decision support applications. While rulemaking can be mainly based on retrospective incident-based data, decision support shall be developed on the basis of the dynamic state of the system. Therefore, it is necessary to understand the nature of the human element in the specific operation to build up proper technological and organizational barriers to prevent the forthcoming critical error.

In this study, changes in maritime traffic flow due to the installation of virtual buoys were analysed from the perspective of collision, based on the obstacle zone by target (OZT) method. The existence of an OZT within ±2° in the bow direction is considered to be dangerous; all the OZTs that a vessel encountered at the time when this orientation prevailed were subjected to analysis. For the calculation of the OZT model, an SD3 model was used. The estimated OZT was used to calculate the OZT density, and the positions of the ships that were encountering the OZT were used for the analysis. It was found that the OZT density at the locations where collisions had occurred in the past was approximately 0.01 [times/km2]. After the installation of virtual buoys, most places around there were reduced to around approximately 0.005 [times/km2]. The results imply that the installation of virtual buoys has reduced the risk of collisions. In contrast, the OZT density in the southern region of Buoy 1 increased from approximately 0.005 [times/km2] to approximately 0.01 [times/km2], suggesting that a more detailed analysis of this area is required.

The article presents the results of determining the dynamic load of the load-bearing structure of the tank container placed on a roll-trailer during transportation by railway ferry. For this purpose, a mathematical model was developed, which takes into account the dynamic loading of the tank container during angular displacements of the railway ferry. It is taken into account that the roll trailer is rigidly fixed on the deck, and the tank container and the liquid cargo in the boiler have their own degrees of freedom. The obtained accelerations are taken into account when calculating the stability of the tank container on the roll trailer. Thus the stability of the tank container is provided at lurch angles to 240. The carried-out researches will allow increasing safety of transportations of tank-containers on railway ferries by the sea, and also the efficiency of functioning of combined transportations in the international communication.

High level solution S4 of the IMO E-navigation Strategy Implementation Plan provides integration and presentation of available information in graphical displays received via communication equipment. At the same time, the problem of the correct application of digital selective calling (DSC) operational procedures in navigation practice has existed since the introduction of the GMDSS and requires a solution. This problem may be resolved on the base of integration maritime navigation and radiocommunication equipment. The article proposes approach for practical realization of this integration by implementing a SMART (specific, measurable, assignable, realistic, and timely) DSC interface within S4. Using this approach the practical realisation integration of AIS – DSC – Information display was implemented. It makes possible implementation of user-friendly human-machine interface (HMI) for navigator. An experimental prototype of communication graphical interface is designed, which allows effective decision-making on radio communication control/monitoring. The use IEC 61162-1/2 (Maritime navigation and radiocommunication equipment – Digital interfaces) data transfer provides standard inter-module connections and eliminates the negative impact of the equipment diversity from different manufacturers by means uniform HMI implementation.

In this paper we solve the problem of the influence of the mutual position of the users of the communication network on the accuracy of the telemetric navigation system. We present the principle of operation of a telemetry navigation system and examine the accuracy of determining the position of users of the communication network depending on their mutual position. The telemetric method of determining the position of users of a communication network can be used in shipping or air transport. The simulation of the telemetry system will be performed in the Matlab software environment.

Biofouling is a natural phenomenon that consists of the accumulation of living organisms on an artificial surface submerged or in contact with water like Offshore platforms. This study highlights the need for offshore floating wind farms structures to consider the choice of material used in offshore applications to minimize microbial-associated and corrosion problems. For this purpose, differences in the total of seawater biofouling attached on two coated paints and three ceramic coatings in carbon steel for offshore structures were evaluated and compared. All ceramic coatings were made of incorporating, by electrophoretic deposition, active ceramic particles against biofouling as copper, silver, zinc and titanium. This experiment consisted of testing ceramic coatings and conventional paints in a real environment with high biological activity and at the same time in a shallow marine environment for a period of 1 year, which provided positive comparisons with the standard system (ASTM-D3623) for using in protecting offshore marine structures.

Risk of an accident is an ever-present component in the maritime transportation process, especially in congested waters such as port areas. Since safety is of crucial importance in the maritime industry, different models of risk assessments were developed to ensure minimal navigational danger. The aim of this paper is the development of modular, dynamic sets of parameters, applicable for future risk assessment models on port approaches by introducing top-down expert appraisal structure methodology organised in three steps. Firstly, approaches and criteria from relevant international recommendations and scientific studies on maritime risk assessment models were analysed and compared, in order to obtain general categories of navigational safety parameters. Secondly, existing risk assessment parameters were structured and combined into new dynamic sets. In the third step, these dynamic sets of parameters were selected, and numerical values were assigned to them according to the specific context of the port. Finally, this top-down methodology aims to provide relevant dynamic sets of criteria for navigational safety risk assessment development that are flexible and widely applicable for the needs and characteristics of different ports.

How long the cruise ship is staying in port? Does that value change during the year? Is the period linked to the number of passengers and the size of the ship? What influences overall period of the stay in port? These questions are just a sample of questions appeared before the research team which tried to establish rules of the Cruise ships seasonal pattern on the East Coast of the Adriatic Sea several questions appeared. Answers to cited questions are presented in this article, obtained by analysing the behaviour of cruise vessels in three biggest ports on the East Coast of the Adriatic Sea during the period of two years.

The essence of the article is the use of multi-criteria static optimization of object motion, based on a set of optimal Pareto points in the space of possible variants of solutions for a new approach to the problem as a game control. Using the example of the two-criteria optimization of the final payoff of the object game control during the safe evasion of the encountered objects, six methods of multi-criteria static optimization are presented—Bentham's utilitarian rule, Rawls's principle of justice, Salukvadze's benchmark, Benson's weighted sums, Haimes's constraints, and goal-oriented programming. In the end, the results obtained by the two-criteria optimization are compared with regard to the values of the components of the final game payoff—the risk of collision and the deviation of the object from the safe route of the set trajectory of movement. The directions for the development of multi-criteria optimization methods, both static and dynamic, and the game are indicated.

For the future lunar navigation satellite system (LNSS), a GPS-like constellation for the Moon, NASA has expressed interest in using a smallsat platform. However, many design decisions have yet to be finalized, including the orbit, constellation, and onboard clock. Furthermore, designing a dedicated smallsat-based LNSS limits the payload capacity, thus restricting the size, weight, and power (SWaP) of the onboard clock. We propose an LNSS design with time transfer from intermittently available GPS signals wherein we design a Kalman filter to estimate timing corrections for a low-SWaP clock. Additionally, we devise a lunar User Equivalent Range Error (UERE) metric to characterize the ranging accuracy of signals transmitted by an LNSS satellite. We further validate our time-transfer technique with simulations of an LNSS satellite in an elliptical lunar frozen orbit (ELFO) with an onboard chip scale atomic clock (CSAC) while analyzing the visibility effects of GPS, timing errors, and lunar UERE across ELFOs.

For GNSS signal power monitoring systems, the characterization of satellite antennas plays an important role. Recently, gain pattern reconstructions of Galileo satellite antennas have been obtained using single-station observations. However, due to the characteristics of GPS orbits, such an approach is less suitable for GPS satellite antennas. This study introduces a methodology for multi-station satellite antenna gain pattern reconstruction. To overcome the unavailability of receiver antenna gain patterns at the employed stations, a dedicated algorithm is introduced that uses an antenna at a base station to remotely characterize the antennas in network stations. Obtained reconstructions of L1 antenna gain patterns of selected GPS satellites show a consistency at the 0.3–0.4 dB level (95%) with data provided by the manufacturer and better than 0.3 dB (95%) with ground-based observations using a high-gain antenna. The introduced methodology may be employed in the establishment of permanent multi-constellation GNSS signal power monitoring systems.

Onboard time synchronization is an important requirement for a wide range of low Earth orbit (LEO) missions such as altimetry or communication services, and extends to future position, navigation, and timing (PNT) services in LEO. For GNSS-based time synchronization, continuous knowledge about the satellite’s position is required and, eventually, the quality of the position solution defines the timing precision attainable through GNSS measurements. Previous research has shown that real-time GNSS orbit determination of LEO satellites can achieve decimeter-level accuracy. This paper characterizes the performance of GNSS-based real-time clock synchronization in LEO using the satellite Sentinel-6A as a real-world case study. The satellite’s ultra-stable oscillator (USO) and triple-frequency GPS/Galileo receiver provide measurements for a navigation filter representative of real-time onboard processing. Continuous evaluation of actual flight data over 14 days shows that a 3D orbit root-mean-square (RMS) error of 11 cm and a 0.9-ns clock standard deviation can be achieved.

Current satellite navigation systems are providing more and more dual-frequency capabilities, enabling improved navigation accuracy and a reduction of residual errors (e.g., from ionosphere). Recently, the aviation community has started an effort to achieve new standardized Minimum Operational Performance Specifications (MOPS) for GNSS equipment in order to allow for the use of dual-frequency multi-constellation (DFMC) systems in the future, with clear benefits in terms of obtainable navigation performance. In such conditions, residual errors introduced by the user GNSS antenna become even more relevant and need to be properly identified and bounded, both in antenna specifications and in the models for aircraft multipath. The present work investigates this problem and shows the results of an activity aiming at new airborne multipath models for L1/E1 and L5/E5a frequency bands and for their ionospheric-free combination. The paper outlines a detailed investigation of the physical rationale of such errors.

The need to successfully navigate in the absence of GNSS has grown in recent years. In particular, light aircraft such as UAVs are growing in popularity for a variety of applications vulnerable to GPS denial. The research presented here develops a GPS-denied navigation scheme for light aircraft employing images formed from a synthetic aperture radar system. Past research has explored the utility of radar telemetry in GPS-denied systems. This research advances previous work by exploiting radar images to obtain range and cross-range position measurements. Images are formed using the Range-Doppler Algorithm, an efficient image formation algorithm ideal for the sometimes limited processing packages available to light aircraft. An inertial navigation and radar processing system is implemented using both real and simulated radar images to aid in estimating an aircraft’s state in a GPS-denied environment. The results show that navigation in the absence of GPS using synthetic aperture radar is feasible with converging and bounded estimation errors.