The British Antarctic Survey regularly conducts airborne surveys with Twin Otter aircraft equipped with a variety of instruments. Each instrument captures its specific navigation requirements in a dedicated cockpit display that is unique and incompatible with that of other instruments. This creates unwanted logistical problems and training requirements, and necessitates extra air safety certification. In this paper we describe a new avionics display that is sufficiently flexible to capture the requirements of all of our instruments, as well as all of the preferences of our pilots. This Airborne Survey Navigation Device (ASCEND) dynamically routes aircraft within the constraints of the survey and features flexible and intuitive planning and navigation interfaces. ASCEND has been tested and compared to the instrument specific displays and is preferred, both for its ease of use and also for the effective accuracy of the pilot following a survey line.

Indoor localisation has always been a challenging problem due to poor Global Navigation Satellite System (GNSS) availability in such environments. While inertial measurement sensors have become popular solutions for indoor positioning, they suffer large drifts after initialisation. Collaborative positioning enhances positioning robustness by integrating multiple localisation information, especially relative ranging measurements between local users and transmitters. However, not all ranging measurements are useful throughout the whole positioning process and integrating too much data will increase the computation cost. To enable a more reliable positioning system, an adaptive collaborative positioning algorithm is proposed which selects units for the collaborative network and integrates ranging measurement to constrain inertial measurement errors. The algorithm selects the network adaptively from three perspectives: the network geometry, the network size and the accuracy level of the ranging measurements between the units. The collaborative relative constraint is then defined according to the selected network geometry and anticipated measurement quality. In the case of trials with real data, the positioning accuracy is improved by 60% by adjusting the range constraint adaptively according to the selected network situation, while also improving the system robustness.

In the aftermath of the disappearance of the Malaysian 370 (MH370) flight in March 2014, new positioning methods were employed to establish the search area. In the absence of all other positioning technologies (Transponder, Radio communications, Radar), these innovative methods are based on the handshake signals between an INMARSAT satellite and the satellite transceiver on board the aircraft. The log of these signals was made public in order for the scientific community to engage in solving the mystery of the MH370 trajectory. The log indicates the delay between the interrogation and response signals, as well as the relative velocity indications, based on the shift of the carrier frequency due to the Doppler-Fizeau effect. This paper puts forward an original, independent and accurate positioning method and allows the calculation of the MH370 trajectory considering the wind vector field that day, the accurate satellite orbit and an accurate model of the Earth (the WGS-84 ellipsoid). The results were compared to other results published, indicating a different final position of the aircraft from the locations of the published search area.

An assessment of the navigational accuracy of the Mercator world map of 1569 is made, aimed at better understanding how the information was adapted from the contemporary cartography. At the time the map was engraved, navigational charts were constructed on the basis of astronomically-observed latitudes, magnetic courses and estimated distances between places. Before this information could be incorporated into the new world map it should be first transformed in such a way that the longitudinal spacings between places were restored to their correct values, as defined on the surface of the Earth. The question of whether Mercator performed such transformations or just considered that the positions were approximately correct has hitherto never been addressed in the literature. It is demonstrated in this article that Mercator was not fully aware of the complexity of the contemporary charts – which he considered to implicitly comprise a square grid of meridians and parallels – and that all planimetric information was directly imported to the novel world map without correction. It is further shown that the Mercator projection was not compatible with the navigational methods of the time.

This paper describes the first of a two-part research effort to find the optimal detector and estimator that minimise the integrity risk in Receiver Autonomous Integrity Monitoring (RAIM). In this first part, a new method is established to determine a piecewise linear approximation of the optimal detection region in parity space. The paper presents examples suggesting that the optimal detection boundary lays in between that obtained using chi-squared residual-based RAIM, and that provided by Solution Separation (SS) RAIM, as one varies the alert limit requirement. In addition, these examples indicate that for realistic navigation requirements, the SS RAIM method approaches the optimal detection region. The SS RAIM detection tests will be employed in the second part of this work, which focuses on the design of non-least-squares estimators to reduce the integrity risk in exchange for a slight increase in nominal positioning error.

Every sailor, at the back of his or her mind, is aware that the nearest land is likely to be directly beneath the ship's keel and he or she is interested to know just how near. For over two thousand years, mariners measured depth of water by using a sounding rod in shallow areas and the lead and line in deeper water. This paper considers how, during the “Dark Ages”, sailors in the North Sea might have navigated, including the use of sounding rods and lead lines for way-finding during a time when no other navigational instruments were available. Because of the lack of contemporary records the authors firstly consider the use of depth finding in earlier and later times to shed light on how the early North Sea sailors might have operated. The latter part of this paper takes account of the earlier discussion, together with some records of North Sea voyaging, to suggest how “Dark Age” sailors might have used sounding rods, the lead and line, and other techniques to navigate around and across the North Sea.

Knowledge of forces and yaw moments which exist between a pair of vessels moving parallel to each other is crucial to the design of their automatic motion control system. Studies involving measurements of forces and moments occurring between a pair of ships were undertaken. The research was carried out on the basis of two real floating training ship models made at 1:24 scale in real conditions on the Silm Lake in Ilawa Kamionka. As a result, suction forces and yaw moments occurring between the pair of vessels calculated according to semi-empirical formula were verified. It was found that the process of overtaking and parallel motion (which is a quasi-stationary motion) could not be modelled in the same way. Nevertheless, the results confirmed the presence of forces and moments with values similar to those in the catch-up and parallel motion phases during the ships’ overtaking manoeuvre. Thanks to this confirmation, it was possible to use the results of the analytical calculation for the catch-up phase during design of the ships' parallel motion automatic control system.

Course keeping for ships is the core of automatic navigation in sea transportation. Much work has concentrated on developing novel control strategies for closed loop systems. We have turned our attention the other way to improve the control performance of marine autopilots in this work by “modulating” the control error using a sine function while the construction of the controller is not changed. The nonlinear feedback signal thus obtained is sent to the controller to replace the control error itself, which used to be the deviation between the output response and the reference input of the system. Such a control scheme is called “nonlinear feedback control” hereafter. Theoretical analysis by using a describing function and robust control theory shows that the same control quality is guaranteed with minor control actions for the nonlinear feedback scheme. Simulation experiments were carried out for the ship Yulong of Dalian Maritime University. It is shown that the method postulated in this paper has advantages of safety and energy saving in navigation; the maximum initial rudder angle is reduced by 31·2% with satisfactory control effect.

This paper describes the genesis, the principle of operation and characteristics of selected radio-navigation positioning systems, which in addition to terrestrial methods formed a system of navigational marking constituting the primary method for determining the location in the sea areas of Poland in the years 1948–2000, and sometimes even later. The major ones are: maritime circular radiobeacons (RC), Decca-Navigator System (DNS) and Differential GPS (DGPS), as well as solutions forgotten today: AD-2 and SYLEDIS. In this paper, due to its limited volume, the authors have omitted the description of the solutions used by the Polish Navy (RYM, BRAS, JEMIOŁUSZKA, TSIKADA) and the global or continental systems (TRANSIT, GPS, GLONASS, OMEGA, EGNOS, LORAN, CONSOL) - described widely in world literature.

As part of the overarching research goal to assess current and potential maritime information sources for use in maritime defence and security in the Canadian north, we examine whether wide-area surveillance data, as represented by Space-based Automatic Identification System (S-AIS) data, offers sufficient information for surveillance requirements in the Canadian north. If S-AIS data are not sufficient, we address how the additional information provided by Long-Range Identification and Tracking (LRIT) can be used to meet the surveillance requirements. A Systems Tool Kit (STK) simulation scenario is constructed that includes five exactEarth satellites collecting AIS data. Simulated AIS transmitters are positioned at 20 northern Canada ground locations. The results indicate that for each location, two thirds of the eight-day simulation is spent without a satellite within range, when using the five satellites. As the number of satellites decreases, intervals in the range of 80 to 105 minutes, during which there are no AIS messages received, increase in frequency. If the end-user requires vessel location information more often than S-AIS consistently provides, augmenting the S-AIS information with LRIT polling should achieve the desired vessel traffic awareness.

Many navigation services, such as car navigation services, provide users with praxic navigational instructions (such as “turn left after 200 metres, then turn right after 150 metres”), however people usually associate directions with visual cues (e.g. “turn right at the square”) when giving navigational instructions in their daily conversations. Landmarks can play an equally important role in navigation and routing services. Landmarks are unique and easy-to-recognise and remember features; therefore, in order to remember when exploring an unfamiliar environment, they would be assets. In addition, Landmarks can be found both indoors and outdoors and their locations are usually fixed. Any positioning techniques which use landmarks as reference points can potentially provide seamless (indoor and outdoor) positioning solutions. For example, users can be localised with respect to landmarks if they can take a photograph of a registered landmark and use an application for image processing and feature extraction to identify the landmark and its location. Landmarks can also be used in pedestrian-specific path finding services. Landmarks can be considered as an important parameter in a path finding algorithm to calculate a route passing more landmarks (to make the user visit a more tourist-focussed area, pass along an easier-to-follow route, etc.). Landmarks can also be used as a part of the navigational instructions provided to users; a landmark-based navigation service makes users sure that they are on the correct route, as the user is reassured by seeing the landmark whose information/picture has just been provided as a part of navigational instruction. This paper shows how landmarks can help improve positioning and praxic navigational instructions in all these ways.

In this study, we develop a Multi-constellation Global Navigation Satellite System (GNSS) Receiver Differential Code Bias (MGR-DCB) model. The model estimates the receiver DCBs for the Global Positioning System (GPS), BeiDou and Galileo signals from the ionosphere-corrected geometry-free linear combinations of the code observations. In order to account for the ionospheric delay, a Regional Ionospheric Model (RIM) over Europe is developed. GPS observations from 60 International GNSS Servoce (IGS) and EUREF reference stations are processed in the Bernese-5·2 Precise Point Positioning (PPP) module to estimate the Vertical Total Electron Content (VTEC). The RIM has spatial and temporal resolutions of 1° × 1° and 15 minutes, respectively. The receiver DCBs for three stations from the International GNSS Service Multi-GNSS Experiment (IGS-MGEX) are estimated for three different days. The estimated DCBs are compared with the MGEX published values. The results show agreement with the MGEX values with mean difference and Root Mean Square Error (RMSE) values less than 1 ns. In addition, the combined GPS, BeiDou and Galileo VTEC values are evaluated and compared with the IGS Global Ionospheric Maps (IGS-GIM) counterparts. The results show agreement with the GIM values with mean difference and RMSE values less than 1 Total Electron Content Unit (TECU).

A magnetic compass has too large a heading error for many applications, and it is often not obvious how to achieve an accurate heading, in particular for low-cost navigation systems. However, there are several different methods available for finding heading, and their feasibility depends on the given scenario. Some of the methods may seem very different, but they can all be related and categorised into a list by studying the vector that each method is using when achieving heading. A list of possible methods is very useful when ensuring that all relevant methods are being considered for a given application. For practical navigation, we have identified seven different vectors in use for heading estimation, and we define seven corresponding methods. The methods are magnetic and gyrocompass, two methods based on observations, multi-antenna Global Navigation Satellite Systems (GNSS), and two methods based on vehicle motion.

Based on the candidate architectures of the libration point satellite navigation system, a Mars navigation performance analysis is conducted in this paper to further verify the feasibility of the Universe Lighthouse. Firstly, a high-fidelity Mars exploration mission is developed as the reference scenario. Then, with the use of a novel adaptive unscented Kalman filter, navigation performance of the candidate Earth-Moon L1,2,4,5 four-satellite constellations is evaluated by Monte-Carlo simulations. The final results indicate that the libration point satellite navigation system is available for Mars navigation and the effects of different constellation configurations and measurement types are also compared and analysed.

Developing adequate ship domain models may significantly benefit vessel navigation safety. In essence, navigation safety is collectively affected by the navigable waterway condition, the size and shape of the ship, and operators' skills. The existing ship domains mainly use constant values for the model input parameters, making them incapable of handling site-specific conditions. This study proposes dynamic ship domain models that take into consideration navigable waterway conditions, ship behaviours, ship types and sizes, and operators' skills in a holistic manner. Specifically, the conditions of restricted waterways are classified into navigating along the channel, crossing the channel, joining another flow and turning. The ship types considered include ships that transport non-hazardous goods and Liquid Natural Gas (LNG) ships that are in need of additional security zones. A computational experiment is conducted for model application using data on water channel design and ship traffic volumes related to navigating along the channel, joining another flow and turning. Comparisons of results obtained between the proposed dynamic models with real ship traffic counts reveal that the proposed models could achieve a higher level of accuracy in estimating the capacity of restricted water channels. It therefore could potentially deliver safety enhancements of waterway transportation.

A multi-region scene matching-based localisation system for automated navigation of Unmanned Aerial Vehicles (UAV) is proposed. This system may serve as a backup navigation error correction system to support autonomous navigation in the absence of a global positioning system such as a Global Navigation Satellite System. Conceptually, the system computes the location of the UAV by comparing the sensed images taken by an on board optical camera with a library of pre-recorded geo-referenced images. Several challenging issues in building such a system are addressed, including the colour variability problem and elimination of time-varying details from the pairs of images. The overall algorithm is an iterative process involving four sub-processes: firstly, exact histogram matching is applied to sensed images to overcome the colour variability issues; secondly, regions are automatically extracted from the sensed image where landmarks are detected via their colour histograms; thirdly, these regions are matched against the library, while eliminating inconsistent regions between underlying image pairs in the registration process; and finally the location of the UAV is computed using an optimisation procedure which minimises the localisation error using affine transformations. Experimental results demonstrate the proposed system in terms of accuracy, robustness and computational efficiency.

This paper is the second part of a two-part research effort to find the optimal detector and estimator that minimise the integrity risk in Receiver Autonomous Integrity Monitoring (RAIM). Part 1 shows that for realistic navigation requirements, the solution separation RAIM method can approach the optimal detection region when using a least-squares estimator. This paper constitutes Part 2. It presents new methods to design Non-Least-Squares (NLS) estimators, which, in exchange for a slight increase in nominal positioning error, can substantially lower the integrity risk. A first method is formulated as a multi-dimensional minimisation problem, which directly minimises integrity risk, but can only be solved using a time-consuming iterative process. Parity space representations are then exploited to develop a computationally-efficient, near-optimal NLS-estimator-design method. Performance analyses for an example multi-constellation Advanced RAIM (ARAIM) application show that this new method enables significant integrity risk reduction in real-time implementations where computational resources are limited.

There are limited studies on the use of ship domain as the safety criterion for ship navigation within confined waters. In this paper, a free-form ship domain has been developed empirically for navigation in confined waters. Two individual domains of an asymmetrical polygonal shape have been assumed around the own ship and target ship, and the size of the ship domains is assumed to be dynamically enlarged with increased ship speeds. The required safe distance modelled using the proposed ship domain takes into account dynamic changes in relative bearing and heading. The model is calibrated using the data of vessel movements in Singapore Strait and Singapore Port. An innovative process has been adopted that iteratively adjusts the parameters in the basic ship domain of a stationary ship; a speed function as well as a weight function to maximise the usage of the dataset. The resulting ship domain model compares well with existing ship domains for typical encounters, such as those of Fujii and Coldwell but represents non-typical encounters more effectively than existing models.

In C-Band transfer measuring systems, the Precise Orbit Determination (POD) precision of Geostationary Earth Orbit (GEO) satellites is limited by signal biases such as the station delay biases, transponder delay biases, the ionospheric delay model bias, etc. In order to improve the POD precision, the signal biases of the Chinese Area Positioning System (CAPS) are calibrated using Satellite Laser Ranging (SLR) and C-Band Transfer Ranging (CBTR) observations. Since the Changchun SLR site and C-Band station are close to each other, the signal biases of the Changchun C-Band station are calibrated using the co-location comparison method. Then the signal biases of the other two CAPS C-Band stations, located in Linton and Kashi, are calibrated using the combined POD method, with the signal biases of the Changchun C-Band station being fixed. After the signal biases are calibrated, the RMS of the line-of-sight residuals of the Changchun SLR observations decrease by 0·4 m, with the percentage improvement being 75·19%.

Facilitated by recent establishment of terrestrial networks and satellite constellations of Automatic Identification System (AIS) receivers, ship trajectories are becoming increasingly available and the size of recorded trajectories is getting larger. Large sets of trajectories create problems of storing, transmitting and processing data. Using appropriate methods, an accurate representation of the original trajectories can be obtained by compressing redundant information, while maintaining the main characteristic elements. In this paper, a new scheme and the implementation of the Douglas-Peucker (DP) algorithm are presented, which can simplify AIS trajectories by extracting characteristic points. As for the simplification threshold, the solo parameter of the DP algorithm, a new AIS-based minimum ship domain evaluation method is proposed and acts as criteria for simplification threshold determination. Finally, a validation is made to examine the effectiveness of the DP simplification algorithm and the rationality of the simplification threshold. The result indicates that the DP algorithm can simplify AIS trajectories effectively; the simplification threshold is scientific and reasonable.