Navigation Speed Research Articles

Influence of Linear Springing on the Fatigue Damage of Ultra Large Ore Carriers

Springing occurs more frequently to ultra large ships, as their natural frequencies are relatively low and approaches the spectral peak of the wave energy spectrum in certain sea states. Springing is a resonance phenomenon between the waves and the ship hull, and this high frequency vibration has a significant influence on the fatigue damage of hull structures. This paper deals with the influence of springing on the fatigue damage of ultra large ore carriers. The springing responses of ultra large ore carriers are calculated by a three-dimensional linear hydroelasticity method in the frequency domain. A fatigue damage calculation method accounting for the springing effect is applied that is based on the fatigue spectrum analysis method and the approximation method of joint narrowband. The fatigue damage of the deck and bottom longitudinals in the deck and bottom of ultra large ore carriers of various sizes has been calculated by this method. The influences of ship size, structural damping, sea state, wave heading, navigational speed, and loading condition on the structure fatigue damage ratio of ultra large ore carrier are analyzed.

A Virtual Object-Location Task for Children: Gender and Videogame Experience Influence Navigation; Age Impacts Memory and Completion Time.

The use of virtual reality-based tasks for studying memory has increased considerably. Most of the studies that have looked at child population factors that influence performance on such tasks have been focused on cognitive variables. However, little attention has been paid to the impact of non-cognitive skills. In the present paper, we tested 52 typically-developing children aged 5–12 years in a virtual object-location task. The task assessed their spatial short-term memory for the location of three objects in a virtual city. The virtual task environment was presented using a 3D application consisting of a 120″ stereoscopic screen and a gamepad interface. Measures of learning and displacement indicators in the virtual environment, 3D perception, satisfaction, and usability were obtained. We assessed the children’s videogame experience, their visuospatial span, their ability to build blocks, and emotional and behavioral outcomes. The results indicate that learning improved with age. Significant effects on the speed of navigation were found favoring boys and those more experienced with videogames. Visuospatial skills correlated mainly with ability to recall object positions, but the correlation was weak. Longer paths were related with higher scores of withdrawal behavior, attention problems, and a lower visuospatial span. Aggressiveness and experience with the device used for interaction were related with faster navigation. However, the correlations indicated only weak associations among these variables.

Investigating the effects of vibrotactile feedback on human performance in navigation tasks

Vibrotactile feedback which can provide real, comfortable and effective interaction experiences has become indispensable in human computer interaction. Many researchers working with vibrotactile feedback in navigation scenarios have proposed a variety of different methods of vibration. However, there is little work that has explored the relationship between navigation speed and vibration feedback both in intensity and modes. In order to find the answer, we implemented a prototype supplying with several vibration feedback modes and designed two exploratory studies to evaluate the human performance with different navigation speeds. We found using a hand-held vibration feedback device can reduce the workload of visual and auditory channels. The results also show that the speed of navigation has a significant influence on the rate of vibration mode identification. This paper contributes to the basic understanding of vibration feedback and offers implications for the future design of vibration feedback in navigation scenarios.

Map-Matching Algorithms for Robot Self-Localization: A Comparison Between Perfect Match, Iterative Closest Point and Normal Distributions Transform

The self-localization of mobile robots in the environment is one of the most fundamental problems in the robotics navigation field. It is a complex and challenging problem due to the high requirements of autonomous mobile vehicles, particularly with regard to the algorithms accuracy, robustness and computational efficiency. In this paper, we present a comparison of three of the most used map-matching algorithms applied in localization based on natural landmarks: our implementation of the Perfect Match (PM) and the Point Cloud Library (PCL) implementation of the Iterative Closest Point (ICP) and the Normal Distribution Transform (NDT). For the purpose of this comparison we have considered a set of representative metrics, such as pose estimation accuracy, computational efficiency, convergence speed, maximum admissible initialization error and robustness to the presence of outliers in the robots sensors data. The test results were retrieved using our ROS natural landmark public dataset, containing several tests with simulated and real sensor data. The performance and robustness of the Perfect Match is highlighted throughout this article and is of paramount importance for real-time embedded systems with limited computing power that require accurate pose estimation and fast reaction times for high speed navigation. Moreover, we added to PCL a new algorithm for performing correspondence estimation using lookup tables that was inspired by the PM approach to solve this problem. This new method for computing the closest map point to a given sensor reading proved to be 40 to 60 times faster than the existing k-d tree approach in PCL and allowed the Iterative Closest Point algorithm to perform point cloud registration 5 to 9 times faster.

EVEN-VE: Eyes Visibility Based Egocentric Navigation for Virtual Environments

Navigation is one of the 3D interactions often needed to interact with a synthetic world. The latest advancements in image processing have made possible gesture based interaction with a virtual world. However, the speed with which a 3D virtual world responds to a user’s gesture is far greater than posing of the gesture itself. To incorporate faster and natural postures in the realm of Virtual Environment (VE), this paper presents a novel eyes-based interaction technique for navigation and panning. Dynamic wavering and positioning of eyes are deemed as interaction instructions by the system. The opening of eyes preceded by closing for a distinct time-threshold, activates forward or backward navigation. Supporting 2-Degree of Freedom head’s gestures (Rolling and Pitching) panning is performed over the xy-plane. The proposed technique was implemented in a case-study project; EWI (Eyes Wavering based Interaction). With EWI, real time detection and tracking of eyes are performed by the libraries of OpenCV at the backend. To interactively follow trajectory of both the eyes, dynamic mapping is performed in OpenGL. The technique was evaluated in two separate sessions by a total of 28 users to assess accuracy, speed and suitability of the system in Virtual Reality (VR). Using an ordinary camera, an average accuracy of 91% was achieved. However, assessment made by using a high quality camera testified that accuracy of the system could be raised to a higher level besides increase in navigation speed. Results of the unbiased statistical evaluations suggest/demonstrate applicability of the system in the emerging domains of virtual and augmented realities.

Location-based applications, services and technologies in aid of flight planning and GPS-based navigation for visual flight rules in developing countries: with a case study

General aviation flights range from gliders and powered parachutes to corporate business jet flights. The majority of the world's air traffic falls into this category which covers a large range of activities, both commercial and non-commercial. As such, general aviation plays an important role in the economic development. This paper treats the importance of VFR flight planning while using a navigational database, navigation points, restricted zones, obstacles, positioning, air speed and routes based on global positioning system (GPS). It provides an overview of a spatial database for flight planning and registration of navigational coordinates. The paper continues with an analysis of the planning process and the impact of an e-system for flight planning and navigation safety during VFR flights in Kosovo airspace. The practical implementation of this paper will result in the development of a bespoke software application for planning electronic flights.

Stable Path-Following Control for a Quadrotor Helicopter Considering Energy Consumption

A substantial interest in aerial robots has grown in recent years. However, the energetic cost of flying is one of the key challenges nowadays. Rotorcrafts are heavier-than-air flying machines that use lift generated by one or several rotors (vertically oriented propellers), and because of this, they spend a large proportion of their available energy to maintain their own weight in the air. In this brief, this concept is used to evaluate the relationship between navigation speed and energy consumption in a miniature quadrotor helicopter, which travels over a desired path. A novel path-following controller is proposed in which the speed of the rotorcraft is a dynamic profile that varies with the geometric requirements of the desired path. The stability of the control law is proved using the Lyapunov theory. The experimental results using a real quadrotor show the good performance of the proposed controller, and the percentages of involved energy are quantified using a model of a lithium polymer battery that was previously identified.

New reference trajectory optimization algorithm for a flight management system inspired in beam search

With the objective of reducing the flight cost and the amount of polluting emissions released in the atmosphere, a new optimization algorithm considering the climb, cruise and descent phases is presented for the reference vertical flight trajectory. The selection of the reference vertical navigation speeds and altitudes was solved as a discrete combinatory problem by means of a graph-tree passing through nodes using the beam search optimization technique. To achieve a compromise between the execution time and the algorithm’s ability to find the global optimal solution, a heuristic methodology introducing a parameter called “optimism coefficient was used in order to estimate the trajectory’s flight cost at every node. The optimal trajectory cost obtained with the developed algorithm was compared with the cost of the optimal trajectory provided by a commercial flight management system(FMS). The global optimal solution was validated against an exhaustive search algorithm(ESA), other than the proposed algorithm. The developed algorithm takes into account weather effects, step climbs during cruise and air traffic management constraints such as constant altitude segments, constant cruise Mach, and a pre-defined reference lateral navigation route. The aircraft fuel burn was computed using a numerical performance model which was created and validated using flight test experimental data.

Preparation and Characterization of a Novel Hydrogel-Based Fouling Release Coating

With the rapid development of marine transportation industry, biological fouling not only affects the speed of navigation but also highly increases fuel consumption. In the paper, a novel hydrogel-based fouling release coating is developed to address the issue by a combination of non-stick property with a low surface tension of the coating. A hydrogel-based silicone fouling release coating was synthesized and two kinds of different intermediate coatings were studied to give a proper match as the tie layer between the substrate coated with primer and the hydrogel silicone on the surface. The adhesion strength, surface tension as well as surface topography of the fouling release coating were studied. The corrosion resistance and anti-fouling performance of the substrates sprayed with the coating were characterized by salt spray test and immersion test in a simulated marine system. The results show that the adhesion between the substrate and the fouling release coating is grade two measured by grid test. The water contact angle of the coating is 104.8o and Rz of the coating is 10.71μm. The specimen is intact after 1000 hours under salt spray test. No diatom was found settled on the specimens in a simulated static marine system while a little diatom was observed on the specimens in a simulated dynamic marine system. It has been found that the intermediate coating comprising of epoxy resin gives proper match between the primer and the fouling release coating consisting of PDMS resin. The coating exhibits superior anti-fouling performance under stationary state.

Perceptual ambiguity maps for robot localizability with range perception

Abstract A mobile robot equipped with 2D or 3D range sensors can move without changing its range readings if the perceived environment is poor in features. This is an ambiguous situation because a single perception can be associated with several robot poses. In consequence, robot localization capability is reduced. The problem we address is the quantification of this perceptual ambiguity as a property inherent to the system composed of the sensor and the static environment. Perceptual ambiguity is different from uncertainty of robot localization, although it is a cause of it. We propose an ambiguity model independent of the robot navigation system. It includes a probabilistic model of the indistinguishability of range readings, a generic range sensor model that supports laser and sonar sensors, and a generic range scanner model that supports any 2D or 3D range perception platform. Ambiguity is expressed in colour floor maps, which may be available before navigation starts, and where “bad localization” zones are easily detected. Experiments with virtual and real environments perceived from 2D laser and sonar scanners are presented, including the validation of the model with a real scans dataset. Results show how ambiguous zones are precisely determined, how to determine the optimum scanner orientation and aperture, and how to reduce the number of readings per scan for improving the robot's computational load and navigation speed.

The Modern Flight

A modern flight involves both a great flight quality and high safety throughout. You can’t speak of a quality of flight today unless it provides increased comfort to all passengers in full safety and relaxation. Regardless of the aircraft design type, a minimum level of comfort is required in the passenger cabin so that they feel safe, comfortable, quiet, plus not having the time to get bored if the flight is longer, but to keep constant the sensation of pleasure. For longer journeys, passengers must have the feeling of a vacation and not of a travel that doesn't over. Today, modern ships struggle to provide passengers with extra comfort, who no longer have to look on the walls or on a possible common screen that diffuses a movie that is known or not interesting for passengers as being a bad movie of a bad cinema. Every passenger must have his own laptop, which he can work on, navigate, communicate, or watch a pleasant, personally chosen film so that time passes easily and quickly and the journey being one as special as possible. Another aspect of a successful journey is to ensure increased safety throughout it. This is not easy to accomplish, especially in modern, complicated times, with all sorts of dangers that can occur during a flight. Nor is the fact that the ship is giant, full of people, workers, supervisors, can not completely eliminate all the dangers of a possible terrorist attack on board or from outside the ship, the dangers of air voids, globular lightning, frost, birds, a completely free route ... A large mass of specialists is constantly working to solve these problems. The propulsion system of the ship and its maintenance in the air, are, in the opinion of the authors of this paper, the two essential factors of ensuring one safer flight. For this reason, the paper will focus on the modern propulsion systems of an aircraft and in the most normal way of keeping it in the air. The safest way to keep an airplane in the air known from the oldest to the present day is the use of a navigable airship. On such a flying device, which automatically keeps everything in the air, without the danger of collapsing, with minimal fuel and energy consumption, with great flight safety and high comfort, it is only the problem of the maximum speed of navigation, which may be limited by the high resistance of the aircraft to advance. When we have a pleasure trip, or one on short or medium distances, navigating with airships is always preferred. What can be done when the journey takes place over very long distances and travelers are rushed to arrive at the destination, with the high speed of the aircraft being a priority? At first glance, in such cases, an airship can no longer be used. And yet a modifiable one could be used successfully and in such situations. This is an essential point to be discussed during this work.

Integrating High Speed Navigation System to Avoid Accidents

Integrating High Speed Navigation System to Avoid Accidents

Increasing Navigation Speed at Endoluminal CT Colonography Reduces Colonic Visualization and Polyp Identification.

Purpose To investigate the effect of increasing navigation speed on the visual search and decision making during polyp identification for computed tomography (CT) colonography Materials and Methods Institutional review board permission was obtained to use deidentified CT colonography data for this prospective reader study. After obtaining informed consent from the readers, 12 CT colonography fly-through examinations that depicted eight polyps were presented at four different fixed navigation speeds to 23 radiologists. Speeds ranged from 1 cm/sec to 4.5 cm/sec. Gaze position was tracked by using an infrared eye tracker, and readers indicated that they saw a polyp by clicking a mouse. Patterns of searching and decision making by speed were investigated graphically and by multilevel modeling. Results Readers identified polyps correctly in 56 of 77 (72.7%) of viewings at the slowest speed but in only 137 of 225 (60.9%) of viewings at the fastest speed (P = .004). They also identified fewer false-positive features at faster speeds (42 of 115; 36.5%) of videos at slowest speed, 89 of 345 (25.8%) at fastest, P = .02). Gaze location was highly concentrated toward the central quarter of the screen area at faster speeds (mean gaze points at slowest speed vs fastest speed, 86% vs 97%, respectively). Conclusion Faster navigation speed at endoluminal CT colonography led to progressive restriction of visual search patterns. Greater speed also reduced both true-positive and false-positive colorectal polyp identification. © RSNA, 2017 Online supplemental material is available for this article.

Measuring and modeling the speed of human navigation

ABSTRACTNavigation, the goal-related movement through space and time to reach a destination, is a fundamental human activity. Geographers, physiologists, anthropologists, and psychologists have long been interested in the spatial and temporal aspects of navigation speed. Hikers, search and rescue teams, firefighters, the military, and others navigate on foot, and their success depends on understanding how the dynamics of foot-based navigation affect individual capabilities. This research modeled the speed of movement of humans engaged in navigation in wooded environments with varied terrain. Movement models were developed using spatiotemporal analysis of multiple subjects’ trajectories. Speed estimates were collected via satellite positioning from 200 subjects engaged in foot-based navigation. Trajectory data were merged with land-cover data to analyze human navigation over varying slopes and terrain. Generalizing these characteristics provided a model of navigational speed of movement from an origin to a destination along an unknown route. Tobler’s hiking function and Naismith’s rule were used in an analysis of the trajectory data. The model created from this study was shown to outperform those classic human movement speed estimators by predicting route completion time within 10% accuracy (M = 11.1min, 95% CI [9.8, 12.4] min). These models help explain the human dynamics of navigation.]

Study on the Safety Degree of Ship Capsizing in Stochastic Waves

To quantify ship capsizing, from the energy perspective, the safety degree of a ship in waves is estimated based on stochastic Melnikov function and phase space transport theory. Considering the influence of nonlinear damping moment, nonlinear restoring moment, as well as the random waves, a nonlinear single degree of freedom differential equation for ship rolling is established. Transform the random wave moment from time domain to frequency domain by fast Fourier transformation, the random Melnikov function and rate of phase flux are extended to include the effects of navigation speed and heading angle and the safety degree of ship capsizing is quantified according to its statistical characteristics. Through an example, the accuracy of Melnikov function and phase space transport theory are verified and the effects of ship speed and heading angle on phase space transport rate are also quantified. This method is demonstrated properly to quantify the safety degree of ship capsizing and some valuable reference can be provided for the further research on ship stability criteria.

Comparison of Driver Navigation at Turbo Roundabouts and Modern Two-Lane Roundabouts: Simulation Study

Roundabouts can be a solution to safety concerns common to conventional intersections. Recently in the United States, there has been an increase in the conversion of problematic intersections to roundabouts to improve their safety. However, there are some important considerations and challenges to make roundabouts safe for all users, especially multilane roundabouts. There may also be challenges for drivers to navigate a newly built or a new type of roundabout. Roundabout features such as pavement markings and signage play an important role in driver navigational performance. This research was an effort to evaluate new roundabout design and existing roundabout safety and operational features such as signs and pavement markings. The focus was on how such features influenced the performance of drivers, specifically at multilane roundabouts. Two-lane roundabouts and rotor turbo roundabouts were evaluated. A driving simulator was employed to test various simulation scenarios in a virtual world. The results indicate that lane keeping and higher navigation speeds are still problems at multilane roundabouts. The rotor turbo roundabout outperforms the two-lane roundabout in enabling correct lane choice and navigation speed control by drivers. Furthermore, it was found that roundabout signs and pavement markings used in the United States can be adopted for turbo roundabouts.

Radar-based collision avoidance for unmanned surface vehicles

Unmanned surface vehicles (USVs) have become a focus of research because of their extensive applications. To ensure safety and reliability and to perform complex tasks autonomously, USVs are required to possess accurate perception of the environment and effective collision avoidance capabilities. To achieve these, investigation into realtime marine radar target detection and autonomous collision avoidance technologies is required, aiming at solving the problems of noise jamming, uneven brightness, target loss, and blind areas in marine radar images. These technologies should also satisfy the requirements of real-time and reliability related to high navigation speeds of USVs. Therefore, this study developed an embedded collision avoidance system based on the marine radar, investigated a highly real-time target detection method which contains adaptive smoothing algorithm and robust segmentation algorithm, developed a stable and reliable dynamic local environment model to ensure the safety of USV navigation, and constructed a collision avoidance algorithm based on velocity obstacle (V-obstacle) which adjusts the USV’s heading and speed in real-time. Sea trials results in multi-obstacle avoidance firstly demonstrate the effectiveness and efficiency of the proposed avoidance system, and then verify its great adaptability and relative stability when a USV sailing in a real and complex marine environment. The obtained results will improve the intelligent level of USV and guarantee the safety of USV independent sailing.

The mathematical model evaluation error determine the extension time of the combat vehicle from the zone of «shade» in the line of sight of the goal

In the considered assessment of the timing error for the nomination battle machines (firepower units) from the zone of «shading» in the zone of direct visibility goal. The dependence of this bias from the accuracy of the geographic information system of coordinates of the nearest chain border zone «shading», positioning accuracy vehicle navigation system and speed the movement of machine on the battlefield. The mathematical model of evaluation of error determine the time of the nomination battle machines from the zone «shading» in the zone of direct visibility goal. Mathematical modelling was conducted using the application package in Wednesday for the most common Maple arrangements combat vehicle to the nearest chain border zone «shading». It is shown that positioning error nearest to battle machine chain border zone «shading» geoinformation system and positioning errors of combat vehicle navigation system commensurate with the contribution to the total amount of error in determining the time of the nomination battle machines from the zone «shading» in the zone of direct visibility goal. The magnitude of the error in determining the extension time of the combat vehicle from the zone of «shade» in the line of sight of the goal decreases with increase in the speed of movement of the combat vehicle, and is increased by increasing the error of determining the coordinates of the nearest combat car circuit border zone «shading» and the error of determination of coordinates of a combat vehicle. The obtained analytical relation that allows to make demands to the magnitude of the measurement errors of the coordinates closest to the military machine of the circuit of the border zone, «shading» geoinformational system and coordinates combat vehicle navigation system according to the specified requirements for the size of the error in determining the extension time of the combat vehicle from the zone of «shade» in the line of sight of the target.

Prediction of structural response of naval vessels based on available structural health monitoring data

Structural health monitoring (SHM) can be beneficial in reducing epistemic uncertainties associated with fatigue life prediction. For naval ships, available SHM data can be discretized into operational cells, each referring to a certain navigation speed, heading angle, and sea condition. Cell-based approaches for predicting future fatigue life can be applied if monitoring information is known for all cells. However, available SHM data may populate some, but not all, potential cells. Moreover, since SHM data is only available for a given set of operating conditions, potential changes in climate or operational profiles cannot be accounted for. Accordingly, there is a need for an approach to predict structural responses in unmonitored cells as a function of limited available monitoring data. This paper proposes a methodology to predict the responses of naval vessels in unobserved cells by incorporating data from the limited number of observed cells. The power spectral density (PSD) of the SHM data is fit using generalized functions, based on sea wave spectra, and integrated into the prediction of the PSD for unobserved cells. The proposed methodology enables both spectral and time-domain fatigue methods. The methodology is illustrated on the SHM data from a high speed aluminum catamaran.

Real-time optimization of ship energy efficiency based on the prediction technology of working condition

Ship energy efficiency management and control is an effective strategy to improve the marine economy and reduce CO2 emission. The determination of the best navigation speed under different working conditions is the basis and premise for real-time improvement of ship energy efficiency. In this paper, the working condition in short distance ahead of the ship related to navigation environment factors was predicted by the method of wavelet neural network, and then the best engine speed for the optimal energy efficiency under different working conditions could be determined through the established ship energy efficiency real-time optimization model. Further, by presetting the ship engine at this optimal speed, the ship energy efficiency could be guaranteed at the optimal state when the ship arrived at the navigation environment ahead of the ship, thus achieving real-time optimization of ship energy efficiency under different navigation environment factors. Experimental studies showed that the proposed optimization model was effective in energy saving and emission reduction, which could provide theoretical guidance for optimal sailing of the ship in service. Compared to traditional setting speed navigation methods, our proposed method has more practical significance to the improvement of ship energy efficiency.