China
Africa
Explore chapters and articles related to this topic
Overview of GNSS
Published in Basudeb Bhatta, Global Navigation Satellite Systems, 2021
Identifying points of reference was easy on land. But it became a matter of life and survival when man started to explore the oceans, where the only visible objects were the Sun, the Moon, and the stars. Naturally, they became the ‘points of reference’ and the era of celestial navigation began. Celestial navigation and positioning was the first serious solution to the problem of finding one’s position in unknown territories, where the Sun, the Moon, and stars were used as points of reference. Celestial navigation is the process where angles between objects in the sky (celestial objects) and the horizon were used to locate one’s position on the earth. At any given instant of time, any celestial object (e.g., the Sun, the Moon, or stars) can be located directly over a particular geographic position on the earth. This geographic position (on the earth’s surface) is known as the celestial object’s subpoint, and its location (e.g., its latitude and longitude) can be determined by referring to tables in a nautical almanac or air almanac (Bowditch 1995).
Sensors for Autonomous Vehicles in Infrastructure Inspection Applications
Published in Diego Galar, Uday Kumar, Dammika Seneviratne, Robots, Drones, UAVs and UGVs for Operation and Maintenance, 2020
Diego Galar, Uday Kumar, Dammika Seneviratne
The five basic forms of navigation are as follows: Pilotage, which essentially relies on recognizing landmarks to know where you are.Dead reckoning, which relies on knowing where you started from, plus some form of heading information and some estimate of speed.Celestial navigation, which uses time and the angles between local vertical and known celestial objects (e.g., sun, moon, or stars).Radio navigation, which relies on radio frequency sources with known locations (including GPS satellites).Inertial navigation, which relies on knowing your initial position, velocity, and attitude and thereafter measuring your attitude rates and accelerations. It is the only form of navigation that does not rely on external references.
Interacting with technology
Published in Michelle Rita Grech, Tim John Horberry, Thomas Koester, HUMAN FACTORS in the MARITIME DOMAIN, 2019
Michelle Rita Grech, Tim John Horberry, Thomas Koester
In this chapter we have already mentioned some new developments in maritime technologies and systems such as IBS. Here we introduce another emerging maritime topic, E-Navigation. E-Navigation (sometimes known as Enhanced Marine Navigation or simply E-Nav) can be defined as the coordinated collection, processing, integration, and display of maritime information, either aboard or ashore, by electronic means to enhance navigation, safety, and security, as well as protection of the environment. Successful E-Nav will require comprehensive electronic navigation charts, fail-safe positioning signals, reliable transmissions (ship-to-ship, ship-to-shore, and shore-to-ship), optimized displays, and agreed ways to prioritize information (e.g., in an emergency situation). As such, it would use both existing and new navigation tools to develop a global system that would be useful for all ships. Of course, many previously mentioned existing navigational and communication technologies and services would be involved.
The automated driver as a new road user
Published in Transport Reviews, 2021
Ane Dalsnes Storsæter, Kelly Pitera, Edward D. McCormack
Accelerometers and gyroscopes are widely used in the automotive industry to obtain information about the vehicle’s velocity, position and heading by measuring forces and rotations (Elkaim, Lie, & Gebre-Egziabher, 2015; Salychev, 2017). Often found as a set of three accelerometers and three gyroscopes, they produce a six degree of freedom sensor system used in the inertial measurement unit (IMU), the output of which is converted to navigation parameters by the inertial navigation system (INS) (Elkaim et al., 2015). INSs are self-contained non-jammable systems, but suffer errors that have an exponential growth over time and GPS-measurements are used to correct this issue (Spangenberg, Calmettes, & Tourneret, 2007). In the absence of GPS or other external sources of positioning, the vehicle relies on so-called dead-reckoning navigation. Dead-reckoning uses the initial position and calculates the following positions with the use of the IMU, the errors of which can be counteracted with the use of additional sensors such as odometers which alleviates drift, and magnetometers that provide heading and inclination data (Barbour, 2004). Another way to improve localisation performance is by using map-matching techniques (Spangenberg et al., 2007).
A Unified Analysis of Structured Sonar-Terrain Data Using Bayesian Functional Mixed Models
Published in Technometrics, 2018
Hongxiao Zhu, Philip Caspers, Jeffrey S. Morris, Xiaowei Wu, Rolf Müller
Sonar (Sound Navigation and Ranging) is a technique that uses sound propagation to detect, localize, and identify objects for purposes such as navigation. An active sonar system transmits acoustic waves with a known time waveform and receives the echoes reflected by obstacles. During propagation and reflection, the transmitted waves will be transformed due to physical effects such as propagation delays, frequency-dependent attenuation, frequency-shifts, and the addition of noise. These modifications are captured in the received echoes and can be used to infer the characteristics of the targets (Le Chevalier 2002) and the propagation channel. In complex, natural environments, an echo signal often consists of reflected waveforms from numerous scatterers that are distributed in space (e.g., tree leaves, rocks), thus can be nonstationary, non-Gaussian, and highly stochastic (Müller and Kuc 2000; Yovel et al. 2008). This makes identification and navigation with over-simplified physical models unrealistic. Statistical approaches are therefore highly desirable to study sonar responses to targets, and extract useful information about the environment (Robertson 1996; Vicente Martinez Diaz 1999).
Spatio-temporal Network-Constrained Trajectory Data Model and Service Reliability Assessment
Published in IETE Journal of Research, 2018
Muhammad Burhan Khalid, Muhammad Haris, Qudsia Gulzar, Muhammad Hamid Ch, Nida Samad
GPS is a Global Navigation Satellite System for location determination. From the last three decades, GPS has been widely used for trajectory data collection. The GPS has emerged for civilian use in the 1990s as the space geodetic technique being accurate and affordable [5]. Trajectory data acquired with the help of GPS are X and Y locations in sequence with time stamp. As these data are in digital format, it can be directly handled in GIS applications. There are many advantages: under-reporting of trips is less likely, the data are immediately available in a digital form and can be analysed in a Geographical Information System (GIS) environment, and, in general, more data are available at a finer level of resolution [6–8].