In this paper the role of the helmsman in terms of man–machine systems theory, such as is frequently used in aerospace work is considered and the literature of the subject surveyed in so far as it relates to the control of seagoing vessels. Lieutenant-Commander Sutton is in the Control Engineering Department at the Royal Naval Engineering College, Plymouth, and Professor Towill is head of the Department of Mechanical Engineering at UWIST, Cardiff.

This paper summarizes the results of Phase 3 of the Arctic Tanker Risk Analysis Project (ATRA) which provided a prototype Tanker Navigation Safety System (TNSS). TNSS is a ship-board risk management system capable of route planning and decision support based upon a knowledge database. The objective of the project was to provide timely risk assessment information to a mariner or decision-maker in a system capable of integration with existing ECDIS or shipboard PC systems. The historical information was to include: accident location, frequency and type, ice, wind, visibility, environmental sensitivity and other factors. The specifications of the TNSS prototype were expanded so that risk could be assessed for each track in a route plan by applying a predictive accident model patterned after the navigation and collision avoidance process.

Precise control is a key factor in enabling Unmanned Underwater Vehicles (UUVs) to complete various underwater activities. The development of UUV control rules is mostly based on UUV dynamic models. However, such dynamic models contain unknown hydrodynamic parameters that need to be identified. This paper presents a new method, Laser Line Scanning for Hydrodynamic Parameter Identification (LSHPI), which integrates laser line scanning, decoupled dynamics, and evolutionary optimisation to identify the hydrodynamic parameters of an Autonomous Underwater Vehicle (AUV). In this research, laser images, seen from an on board camera's perspective and created using Open Graphics Library (OpenGL), were used to validate LSHPI's feasibility. The accuracy of the AUV positions and Euler angles obtained by the laser image-based methods were investigated for each decoupled One-Dimensional (1D) motion and the influence of other motion disturbances on the accuracy of the obtained AUV positions or Euler angles was also evaluated. In addition, the accuracy of the surge-related hydrodynamic parameters obtained by LSHPI was investigated under different motion disturbances. Based on the hydrodynamic parameter identification results under different motion disturbances, LSHPI's feasibility was successfully validated.

X-ray pulsar navigation is a promising technology for autonomous spacecraft navigation. The key measurement of pulsar navigation is the time delay (phase delay). There are various methods to estimate phase delay, but most of them have high computational complexities. In this paper, a new method for phase delay estimation is proposed, which is based on the time-shift property of Discrete Fourier Transformation (DFT). With this method, the time complexity can be greatly reduced. Also, a delta-function approximation can be used to further decrease the computational cost. Numerical simulation shows that the proposed method is effective for phase delay estimation, and the reduced complexity makes our method more suitable for on board implementation.

The Earth Gravity Model 2008 (EGM2008) is now some years old, and yet information on how to use it to calculate Earth's gravity remains obscure outside the field of geodesy. We describe the mathematics necessary to implement EGM2008, and use this to discuss several points of the model: its sensitivity to the number of spherical harmonics being summed, nuances and a trap for physicists and mathematicians in the normalisation it uses, and a comparison with other work. We conclude that one must not overestimate the precision shown by a global-fit model such as EGM2008.

CAPTAIN JAMES COOK is deservedly esteemed as a great seaman, and he must be acclaimed also in the more particular role of a great navigator. For although he made no specific contribution to the art of navigation as such, he advanced it by sheer force of character. It was, indeed, a task for the mathematicians and astronomers, not for the sailors, to lay down new principles and new observations or calculations by which a ship's position could be found and her course directed when at sea. And it was for the mathematical and optical instrument-makers to design and perfect the instruments by which such observations could be made. But, in the last resort, everything depended upon the ships' captains, the masters and the pilots. They alone could decide whether some novel principle should be mastered, some new instrument actually used. ‘We have piped unto you and ye have not danced’ is a cry which echoes through the ages. For the sailor was not alone in turning a deaf ear to the advice of public men, scientists and his own professional instructors. He was hostile to change, he preferred some old rule of thumb. And this is to be expected from all such men as learn the actual practice of their trade or craft by working beside an experienced master who in turn is passing on the traditions of an earlier generation.

A novel relative spacecraft attitude and position estimation approach based on an Unscented Kalman Filter (UKF) is derived. The integrated sensor suite comprises the gyro sensors on each spacecraft and a vision-based navigation system on the slave spacecraft. In the traditional algorithm, an assumption that the master's body frame coincides with its Local Vertical Local Horizontal (LVLH) frame is made to construct the line-of-sight observations for convenience. To solve this problem, two relative quaternions that map the master's LVLH frame to the slave and master body frames are involved. The general relative equations of motion for eccentric orbits are used to describe the positional dynamics. The implementation equations for the UKF are derived. A modified version of the UKF is presented based on the averaging-quaternion algorithm. Simulation results indicate that the proposed filters provide more accurate estimates of relative attitude and position than the Extended Kalman Filter (EKF).

Columbus's first voyage to America has been widely regarded as a considerable feat of navigation. Feat it certainly was, but the great advances in navigation during the fifteenth century were in fact made by the Portuguese, whose adaptation and development of Mediterranean methods to the more demanding requirements of the ocean made the European voyages of discovery possible. It was in Portugal too, probably during the years 1478–85, that Columbus acquired his knowledge of navigation. This paper, which was presented to a meeting at Brown University, USA on 26 September 1989, where the author was Gulbenkian Research Fellow at the John Carter Brown Library, examines navigational practice in the Mediterranean during the late middle ages and its subsequent development during the Great Age of Discovery.

The principal characteristics of the GLONASS system, its current status and deployment outlook are considered. Comparison of the main characteristics of the GPS/GLONASS systems from the user's viewpoint is made. Proposals focused on the operations to be carried out to improve navigation determination accuracy for the users, provided with the combined equipment, are given. The data presented, received simultaneously on the user&s GLONASS equipment and a GP–500 GPS system, indicate that navigational determination accuracies of both systems are approximately equal. The key characteristics of 6–channel user facilities for civil aircraft and helicopters are presented. This equipment has been developed in the Institute of Space Device Engineering (ISDE) in accordance with a standard draft ARING on the combined system. The principal directions of the accuracy characteristic of the GLONASS system updating are considered. It is suggested to use the quantum–optical measurements on the Etalon satellite, launched into GLONASS satellite orbit, so that ephemeris information can be improved. The questions concerning supplying the system integrity and differential corrections information are discussed. It is proposed to combine the global system of integrity signal generation and transmission with differential corrections for regional systems. The version of the information frame developed in ISDE and intended for transmission of this information to users via geostationary satellites by means of signals similar to GPS/GLONASS, and without additional complication of user equipment, is presented here.

European Air Traffic Management is extremely safe. The drawback to this safety record is that it is very difficult to estimate what the ‘underlying’ accident rate for mid-air collisions is now, or to detect any changes over time. The aim is to see if it possible to construct simple ATM safety indicators that correlate with this underlying accident rate. A perfect indicator would be simple to comprehend and capable of being calculated by a checklist process. This problem has been examined using a combination of analogies with simple ‘defensive’ systems with Markov process properties. An important concept is that of ‘system control’: the ability to determine the outcome against reasonably foreseen changes and variations of system parameters. The statistical distribution of future incidents has been analysed by focusing on an index – the Close Proximity Index (CPI) – of separation at the Closest Point of Approach. A promising indicator is ‘Incident Not Resolved by ATC’ (INRA) incidents in which the ground ATC defences have been ‘used up’. ATM Incidents can also be categorised in other ways. Two examples are reviewed: the risk-bearing category for Airproxes and ‘risk of collision/severity’ scores. The second is more promising conceptually, but the existing scoring system has not been demonstrated to have the properties necessary to derive risk estimates. The key question is: if someone says they know how to make a good estimate of the underlying accident rate, then how could this claim be tested? If it correlates very well with INRA, then what would be the argument for saying that it is a better indicator?

In recent years the transition of marine navigation to the digital era has been gaining momentum. Implementation of e-Navigation solutions varies from country to country in terms of their priorities, goals, levels and effects. Maritime authorities in Poland have been setting the pace in this transition process, not only in Poland but also in general as a global solution. The most recent example is the planned deployment of a variety of e-Navigation tools in the Vistula Lagoon: from GNSS-RTK Ground-Based Augmentation System, to virtual and synthetic aids to navigation, high-resolution bathymetry and advanced navigational software for piloting. The major objectives of this paper are, first, to summarise recent dynamics in the e-Navigation field, and second, to present a practical implementation of the e-Navigation concept in the Vistula Lagoon area.

The high seas freedom of navigation, and the lesser rights of transit, archipelagic sea lane and innocent passage applicable in straits used for international navigation, archipelagic sea lanes and the territorial sea respectively, have been said to embrace two notions: ‘one is the right to make progress over the surface of the sea, the other is the duty to make progress only in an orderly way, as to speed, steering, lights and so on – the manner of operation of the right’.

Currently, the 30 nautical mile (nm) minimum longitudinal separation standard is applied on oceanic routes under the Automatic Dependent Surveillance-Contract (ADS-C) environment. However, the periodic position report should be provided at least every ten minutes in Japanese airspace based on previous safety analysis. The position report is usually sent via satellite connection, so less frequent position reports would reduce connection costs by airlines. Since the previous safety analysis estimates the risk of collision conservatively, this paper proposes a refinement of the collision risk model by considering the dependency between two closely separated aircraft. The result shows that the periodic position report interval can be extended without infringing safety.

Navigation is a human activity with the aim being to arrive at a predetermined destination. In order to find the way to the destination, the use of current input from the actual environment while travelling is needed as well as stored and organized knowledge of the local geography. Although the knowledge requirement has been studied extensively in the form of cognitive maps or other spatial representation, few studies deal with how the knowledge is used together with the input from the actual environment while navigating.

A ship's perception of risk is an important basis for collision avoidance. To improve such perception, several risk measurement parameters on the ship domain are determined, including the approach factor, the time to domain violation (TDV) and the possible collision domain. Then, a risk hierarchy prewarning (RHP) model based on the violation detection of a ship domain is proposed, in which a two-level alarm scheme is adopted accordingly. A low-intensity alarm will be activated by reaching the minimum approach factor and the TDV threshold, and a high-intensity alarm will be activated by the factor of the possible collision domain and the TDV threshold. Subsequently, a novel guard zone in ARPA radar utilising the RHP model has been developed to establish a ship's risk perception system for officers on watch at sea. The model proposed in this paper can not only enhance the veracity of risk assessment around our own ship, but also be used as a decision support system for collision avoidance.

When anchorages are arranged in a harbour, the manoeuvering difficulty of a ship navigating between anchored ships should be considered. However, until now, nobody has researched how to design the arrangement of anchorages from the viewpoint of manoeuvering difficulty. In this paper, the relationship between the arrangement of anchorages and manoeuvering difficulty is systematically analysed by applying the Environmental Stress Model to the problems of a ship navigating between anchored ships. Based on this analysis, a method of designing the arrangement of anchorages is considered that ensures manoeuvering difficulty is at an acceptable level for mariners. The distance needed between the anchored ships has been proposed to accord with the length of the navigating ship and the mean length of anchored ships.

This paper and the following three papers were presented at the RIN97 Conference held in Oxford under the auspices of the Animal Navigation Special Interest Group, April 1997. The full proceedings, under the title Orientation and Navigation – Birds, Humans and Other Animals, can be obtained from the Director (£30 to Members, £50 to non-Members).

Studies of the compass mechanisms involved in the migratory orientation of birds have revealed a complex web of interactions, both during the development of orientation behaviour in young birds and in mature individuals exhibiting migratory activity. In young birds, the acquisition of compass orientation capabilities involves the interplay of apparently genetically programmed information with a suite of innate learning rules. The latter canalise the ways in which experience with relevant orientation information from the environment impinges on development. There are many general similarities with the development of singing behaviour in songbirds, although that system is more thoroughly understood, especially at the neuronal level.

Here we shall attempt to synthesise what is known about the development of compass mechanisms in a framework of innate information and learning rules. The way in which orientation behaviour develops leaves open the possibility for plasticity that enables birds to compensate for variability in the environmental cues that form the basis of their compasses. For at least some components of the system, behavioural plasticity remains into adulthood, allowing the bird on migration to respond in apparently adaptive ways to spatial and temporal variability in orientation information that it may encounter while enroute. We have studied these questions in the Savannah sparrow (Passerculus sandwichensis), a medium-distance North American emberizine nocturnal migrant. We will focus on that species, relating the results of our work to relevant studies on others.

Errors of different positioning algorithms for tracked targets used in the ARPA systems and their influence on estimated speed of targets is analysed. Examples show their significance in tracking targets at low ranges.

This paper is based on work done originally for the Chevron Shipping Company, whose agreement to its publication in its present form is gratefully acknowledged.

Ever since the International Regulations for Prevention of Collision at Sea (IRPCS) were introduced as a control system for collision avoidance, there have been disputes and arguments about exactly what they mean, and how they should have been applied in particular collision incidents. The principle of deciding by international agreement which ships should be given the duty of keeping clear of other ships generally works well but, as traffic volumes increase, so do situations in which the IRPCS alone do not provide a clear indication of what is expected of the mariner. Various solutions have been addressed to this problem, ranging from proposed radical revisions of the whole principle of collision avoidance, through periodic thoughtful adjustments to the details of the IRPCS, to informal additions and requirements imposed by individual shipowners on their fleets. The residual problem with any solution (except perhaps the first mentioned) is that there will always be exceptions where the rules are unclear or ambiguous. Adding adjustments may reduce these exceptions but, unless all uncertainties can be removed, the adjustments may create a new and even more complex set of exceptions, which are yet more difficult to interpret.

Celestial navigation is an important means of maritime navigation; it can automatically achieve inertially referenced positioning and orientation after a long period of development. However, the impact of different accuracy of observations and the influence of nonstationary states, such as ship speed change and steering, are not taken into account in existing algorithms. To solve this problem, this paper proposes an adaptively robust maritime celestial navigation algorithm, in which each observation value is given an equivalent weight according to the robust estimation theory, and the dynamic balance between astronomical observation and prediction values of vessel motion is adjusted by applying the adaptive factor. With this system, compared with the frequently used least square method and extended Kalman filter algorithm, not only are the real-time and high-precision navigation parameters, such as position, course, and speed for the vessel, calculated simultaneously, but also the influence of abnormal observation and vessel motion status change could be well suppressed.