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Trajectory Planning in Autonomous Vehicles using GPS and Digital Compass
Published in P. C. Thomas, Vishal John Mathai, Geevarghese Titus, Emerging Technologies for Sustainability, 2020
In Global Positioning Systems (GPS), trilateration is used to determine the location. In trilateration, data from a single satellite provides a general location of a point on the Earth’s surface. Adding data from a second satellite allows the GPS to narrow down the specific location of the point down to a region where the two area of the satellite data intersect. Adding data from a third satellite provides an accurate position of the point on the Earth’s surface. Further adding data from a fourth satellite can provide the altitude information. These measurements can have error (in meters), which is not acceptable as it can turn to be disastrous. Therefore, a step called localization is included in determining the location. Localization is a step implemented in the majority of robots and vehicles to locate with a very small margin of error, usually in the order of 10cms.
Positioning and Tracking Approaches and Technologies
Published in Hassan A. Karimi, Advanced Location-Based Technologies and Services, 2016
Dorota Grejner-Brzezinska, Allison Kealy
The main principle behind positioning with GPS is trilateration in space, based on the measurement of a range (pseudorange or phase range) between the receiver and the satellites (Figure 1.5). Essentially, the problem can be specified as follows: given the position vectors of GPS satellites (such as ρs of satellite s in Figure 1.5) tracked by a receiver r, and given a set of range measurements (such as Prs) to these satellites, determine a position vector of the user, ρr. A single range measurement to a satellite places the user somewhere on a sphere with a radius equal to the measured range. Three simultaneously measured ranges to three different satellites place the user on the intersection of three spheres, which correspond to two points in space. One of them is usually an impossible solution that can be discarded by the receiver. Even though there are three fundamental unknowns (coordinates of the user’s receiver), a minimum of four satellites must be simultaneously observed to provide a unique solution in space (Figure 1.6).
Boxes or wheels: types of systems
Published in Jonathan Higgins, Satellite Newsgathering, 2012
The GPS concept of operation is based upon satellite ranging. A constant stream of timing and position information generated from a highly accurate atomic clock on each satellite is broadcast, and on the ground a GPS receiver can receive and read this information from at least three, and often four, satellites. By comparing the signal from each satellite with the time of its own local clock, the GPS receiver calculates the distance to each satellite it receives, and then uses ‘trilateration’ techniques from the information to calculate its location, providing a position accurate to within centimeters for military use. This is the technology behind the ability to provide the military with the exact positional information required for modern warfare, including the precision required by ‘smart’ bombs and missiles.
A survey of deep learning approaches for WiFi-based indoor positioning
Published in Journal of Information and Telecommunication, 2022
Xu Feng, Khuong An Nguyen, Zhiyuan Luo
WiFi received signal strength (RSS) technology is the most popular one used in WiFi indoor positioning. This technology uses the signal strength received by the user to estimate the user's location. Generally, WiFi RSS database contains RSS values from different access points collected at each location and the labels of the data. An example of WiFi RSS data is shown in Table 1 where values in column WAP001 to column WAP520 represent the RSS signals received from the specific WiFi access point (e.g. the values below the heading WAP001 represent RSS signals from the No.1 access point). Each row represents a reference point where its RSS signals were collected. The unit of the RSS is dBm. The value of 100 means that the RSS from the specific access point could not be received at the reference point. The columns of FLOOR and BUILDINGID indicate the labels of the RSS data while the columns of LONGITUDE and LATITUDE represent the 2D coordinates of the reference points. Trilateration, approximate perception, and fingerprinting are possible approaches to utilizing WiFi RSS for indoor positioning. Trilateration, more like GPS, makes use of three or more access points and the distance between the receiver and transmitters to calculate the possible location of the user. Approximate perception is much simpler, it estimates the final location based on the access point that gives the strongest WiFi RSS. These two methods do not require machine learning methods, so they are not included in the scope of this review.
IoT-based child tracking using RFID and GPS
Published in International Journal of Computers and Applications, 2023
Nadia Ahmed, Sadik Kamel Gharghan, Ammar Hussein Mutlag
GSM, one of the most popular mobile phone networks, can achieve highly accurate, cost-efficient indoor and outdoor localization when properly configured without the need for additional hardware. However, a global positioning system (GPS) is more effective for outdoor location tracking than indoor location tracking [36]. The trilateration technique, which involves using three base stations, is a relatively simple method for determining coordinates [37]. By calculating distances and coordinates, the coordinates at the intersection can be estimated. GPS technology, which is extensively used in smartphones, modern cars, and person-tracking systems in outdoor areas like playgrounds and parks, has been incorporated in numerous studies, such as [38, 39].
Accuracy enhancement of roadway anomaly localization using connected vehicles
Published in International Journal of Pavement Engineering, 2018
Raj Bridgelall, Denver Tolliver
According to GPS system administrators (USDHS 1996), the variance from trilateration errors can be substantial because of random changes in atmospheric effects, multipath propagation and GPS receiver performance. System administrators expect that the 95% confidence interval for horizontal position precision under direct line-of-sight conditions will be about 6.7 m. However, this uncertainty could increase to more than 10 m when multi-path reflections from buildings, large trees and other tall structures distort the weak satellite signals.