1,720,995 research outputs found
Editorial Summary to selected papers from the 2020 IMEKO TC19 International Workshop on Metrology for the Sea - “Learning to measure sea health parameters”
No full textTime-Differenced Carrier Phase Technique for Precise Velocity Estimation on an Android Smartphone
No full textGNSS (Global Navigation Satellite System) receivers are not only able to accurately determine position, but also velocity, knowledge of which could be important in several applications. The most adopted technique for velocity estimation exploits the Doppler shift due to the relative motion between the signal source and the receiver. Alternatively, the TDCP (Time-Differenced Carrier Phase) technique, based on the differences between consecutive carrier-phase measurements, can be used. TDCP is theoretically able to achieve better performance compared with the Doppler-based approach, exploiting the high precision of a carrier-phase observable, and without suffering the ambiguity issue. The main objective of this study is to analyze TDCP performance on a smartphone GNSS chip. Smartphones GNSS receivers are usually characterized by noisy observables owing to the low quality of the antenna used; it is, therefore, interesting to compare the smartphone TDCP performance with that of the Doppler-based technique. To evaluate the benefits that TDCP can provide, especially in terms of the smartphone chip, these two approaches to velocity determination are compared using three different devices: a Novatel geodetic receiver, a u-blox multi-frequency receiver, and a Xiaomi Mi8 smartphone. The results demonstrate a performance degradation in the smartphone GNSS chip when TDCP is used, compared with the performance of higher-grade receivers. In fact, the Xiaomi Mi8 maximum errors are greater than those of the Novatel geodetic receiver, but they are still acceptable as they do not exceed 6 cm/s, making the TDCP technique a valid approach for advanced algorithms; indeed, TDCP velocity demonstrates a few mm/s accuracy with a smartphone. The application of a RAIM algorithm enables error reduction and the achievement of reliable information; the obtained solution reliability is about 89%
A prompt methodology to georeference complex hypogea environments
Full text linkActually complex underground structures and facilities occupy a wide space in our cities, most of them are often unsurveyed; cable duct, drainage system are not exception. Furthermore, several inspection operations are performed in critical air condition, that do not allow or make more difficult a conventional survey. In this scenario a prompt methodology to survey and georeferencing such facilities is often indispensable. A visual based approach was proposed in this paper; such methodology provides a 3D model of the environment and the path followed by the camera using the conventional photogrammetric/Structure from motion software tools. The key-role is played by the lens camera; indeed, a fisheye system was employed to obtain a very wide field of view (FOV) and therefore high overlapping among the frames. The camera geometry is in according to a forward motion along the axis camera. Consequently, to avoid instability of bundle adjustment algorithm a preliminary calibration of camera was carried out. A specific case study was reported and the accuracy achieved
Enhancing navigation solution with Galileo HAS
No full textThe employment of GNSS (Global Navigation Satellite System) services and positioning techniques in numerous fields such as maritime, aviation, terrestrial navigation and geodetic survey, have led to a continuous scientific research with the aim to improve the accuracy and precision of the positioning techniques. Currently, GNSSs are providing new services for enabling Precise Point Positioning worldwide. In this framework, the new Galileo High Accuracy Service (HAS) is a fundamental element. It provides to users orbit, clock and measurement correction leading to decimeter level positioning in real time application. This study focuses on the analysis of the benefits of HAS corrections application in different positioning models including code and carrier phase observables. The considered models exploit GPS data, and performance are assessed using dual frequency data collected by a low-cost receiver. The obtained results show an enhanced navigation solution mainly in the vertical channel
High-flexible multi-technique acquisition system for human postural stability tests onboard ships
No full textLow-cost human motion capture system for postural analysis onboard ships
No full textThe study of human equilibrium, also known as postural stability, concerns different research sectors (medicine,
kinesiology, biomechanics, robotics, sport) and is usually performed employing motion analysis techniques for recording
human movements and posture. A wide range of techniques and methodologies has been developed, but the choice of
instrumentations and sensors depends on the requirement of the specific application. Postural stability is a topic of great
interest for the maritime community, since ship motions can make demanding and difficult the maintenance of the
upright stance with hazardous consequences for the safety of people onboard. The need of capturing the motion of an
individual standing on a ship during its daily service does not permit to employ optical systems commonly used for
human motion analysis. These sensors are not designed for operating in disadvantageous environmental conditions
(water, wetness, saltiness) and with not optimal lighting. The solution proposed in this study consists in a motion
acquisition system that could be easily usable onboard ships. It makes use of two different methodologies: (I) motion
capture with videogrammetry and (II) motion measurement with Inertial Measurement Unit (IMU). The developed
image-based motion capture system, made up of three low-cost, light and compact video cameras, was validated against
a commercial optical system and then used for testing the reliability of the inertial sensors. In this paper, the whole
process of planning, designing, calibrating, and assessing the accuracy of the motion capture system is reported and
discussed. Results from the laboratory tests and preliminary campaigns in the field are presented
The EGNOS Augmentation in Maritime Navigation
No full textThe objective of this work is the evaluation of the performances of EGNOS (European Geostationary Navigation Overlay System) augmentation system in maritime navigation by comparing them with those obtained by other positioning methods as Single Point Positioning (SPP) and Differential Global Positioning System (DGPS). Preliminarily, EGNOS performances in an open-sky context were evaluated through static data downloaded by EGNOS RIMS (Ranging and Integrity Monitoring Stations) located in Rome. Then, for the maritime test carried out onboard a boat in the Gulf of Naples, two dual-frequency receivers were used: Xiaomi Mi 8 smartphone and u-blox ZED-F9P multi-band GNSS (Global Navigation Satellite System) receiver, both in kinematic mode. At last, IMO (International Maritime Organization) requirements, established in IMO Resolution A.1046 (27), that a SBAS (Satellite Based Augmentation System) system in particular scenarios (coastal, inland-water, harbor navigation and ocean waters) must respect, were verified
MANATEE Project: Monitoring and Mapping of Marine Habitat with Integrated Geomatics Technologies
No full textItalian seas are home to a unique heritage of biodiversity in terms of species and habitats and are protected by EU conventions and directives. To preserve this richness effectively, monitoring activities are key to assess its state of health and evolution, and to enhance our current knowledge of natural processes and stress factors. Where this heritage is compromised, restoration projects can be undertaken, operations requiring the application of technical and scientific methods to ensure robust, reliable and cost-effective data collection. The ensemble of Geomatics techniques can provide valuable support for marine habitat monitoring, in the form of: localization, navigation and mapping of the site of interest following autonomous or guided approaches; generation of digital twins (3D models) of the habitat at the required resolution and accuracy; extraction from the digital twins of statistically significant metrics to assess the time evolution; presentation and sharing of the results with both the scientific community and the general public to promote awareness of environmental protection issues. MANATEE (Monitoring and mApping of mariNe hAbitat with inTegrated gEomatics technologiEs) project is providing these monitoring solutions via the integration of underwater photogrammetry with auxiliary positioning and navigation techniques based on acoustic, pressure and inertial sensors. The developed approaches is implemented in three complementary underwater vehicles, differing in cost, weight and portability, number and grade of navigation, positioning and 3D modelling sensors, and designed to cover habitats different for extension and depth. An observation class UUV (Unmanned Underwater Vehicle), a low-cost micro ROV (Remotely Operated Vehicle), and a 3D surveying and modelling device for scuba divers will be tested in a real-world experiment focusing on the restoration of a crustose coralline algae, Lithophyllum stictiforme
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