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A compact system to extract topography information from scenes viewed by a miniaturized submersible explorer
Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Microsystems Technology. (ÅSTC)
Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Microsystems Technology. (ÅSTC)
Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Microsystems Technology. (ÅSTC)
Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Microsystems Technology. (ÅSTC)
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2012 (English)In: Sensors and Actuators A-Physical, ISSN 0924-4247, E-ISSN 1873-3069, Vol. 188, no SI, 401-410 p.Article in journal, Meeting abstract (Refereed) Published
Abstract [en]

In images taken underwater, it is generally difficult to correctly extract distances and geometric informationof objects. Different techniques, collectively referred to as photogrammetry, exist to measurefeatures in images. One of these is to project a reference pattern onto an object in a scene viewed by acamera, and register the distortion of this pattern, to calculate the shape of, and distance to, that object.This method is implemented here on a miniaturized submersible explorer equipped with, among manyother instruments, a camera. Diffractive optical elements (DOEs) have been designed and manufacturedusing microsystems technology, to, together with a laser diode, camera, and in-house developed software,provide a compact system for projecting reference patterns and analyzing their deformations. Thesystem has been characterized by measuring the distances and angles of objects in a water tank, andattempting to reproduce their shapes. The range of operation of the system, verified to be at least onemeter, is limited by the compact mounting in the small submersible and the cameras’ performance.The system was found to work well under turbid conditions as well as in water containing larger particles.Together with a vehicle-mounted camera, the compact and low-power DOE laser projection systemenables topographical measurement.

Place, publisher, year, edition, pages
2012. Vol. 188, no SI, 401-410 p.
Keyword [en]
Photogrammetry, Diffractive, Laser, Underwater, Images, Miniaturized
National Category
Engineering and Technology
Research subject
Engineering Science with specialization in Microsystems Technology
Identifiers
URN: urn:nbn:se:uu:diva-171732DOI: 10.1016/j.sna.2012.02.034ISI: 000312692500054OAI: oai:DiVA.org:uu-171732DiVA: diva2:512217
Conference
The 16th International Conference on Solid-State Sensors, Actuators and Microsystems, 5-9 June, 2011, Beijing, CHINA
Projects
Deeper Access, Deeper Understanding (DADU)
Available from: 2012-03-26 Created: 2012-03-26 Last updated: 2017-12-07Bibliographically approved
In thesis
1. Microsystems Technology for Underwater Vehicle Applications
Open this publication in new window or tab >>Microsystems Technology for Underwater Vehicle Applications
2012 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

The aim of this thesis work has been to investigate how miniaturization, such as microsystems technology, can potentially increase the scientific throughput in exploration of hard-to-reach underwater environments, such as the subglacial lakes of Antarctica, or other challenging environments, including cave systems and wrecks. A number of instruments and subsystems applicable to miniature submersibles have been developed and studied, and their potential to provide a high functionality density for size-restricted exploration platforms has been assessed.

To provide an onboard camera system with measurement capabilities, simulation and design tools for diffractive optics were developed, and microoptics realized to project reference patterns onto objects to reveal their topography. The influence of murky water on the measurement accuracy was also studied.

For longer-range mapping of the surroundings, and under conditions with even less visibility, the performance of a very small, high-frequency side-scanning sonar was investigated using extensive modeling and physical testing. In particular, the interference on the acoustic beam from tight mounting in a hull was investigated. A range in excess of 30 m and centimeter resolution were obtained.

Besides these systems, which can be used to navigate and map environments, a two-dimensional, thermal sensor for minute flows was developed. Measuring speed and direction of water flows, this sensor can aid in the general classification of the environment and also monitor the submersible’s movement. As the flow of waters in subglacial lakes is estimated to be minute, the detection limit and sensitivity were investigated.

Measurements of water properties are facilitated by the chip-based conductivity, temperature, and depth sensor system developed. Macroscopically, this is an essential oceanographic instrument with which salinity is determined. Contrary to what was expected, MHz frequencies proved to be advantageous for conductivity measurements.

Finally, sampling of water using an acoustically enriching microdevice, and even enabling return of pristine samples via the use of integrated latchable, high-pressure valves, was realized and evaluated. Particularly, investigations of the device’s ability to capture and hold on to microorganisms, were conducted.

Further developed and studied, these devices – as subsystems to miniature submersibles, or as stand-alone instruments – should enable exploration of previously unreachable submerged environments.

Place, publisher, year, edition, pages
Uppsala: Acta Universitatis Upsaliensis, 2012. 88 p.
Series
Digital Comprehensive Summaries of Uppsala Dissertations from the Faculty of Science and Technology, ISSN 1651-6214 ; 914
Keyword
Aquatic, Submersible, Underwater, Micro, Miniaturized, Sonar, Sidescan, Topography, Laser, Diffractive, Optics, Sampler, Particle, Microorganism, Acoustic, Enriching, Conductivity, Temperature, Depth, CTD, Flow
National Category
Engineering and Technology
Research subject
Engineering Science with specialization in Microsystems Technology
Identifiers
urn:nbn:se:uu:diva-171742 (URN)978-91-554-8323-4 (ISBN)
Public defence
2012-05-11, Polhelmsalen, Ångströmlaboratoriet, Lägerhyddsvägen 1, Polacksbacken, Uppsala, 10:15 (Swedish)
Opponent
Supervisors
Projects
Deeper Access, Deeper Understanding (DADU)
Available from: 2012-04-20 Created: 2012-03-27 Last updated: 2013-02-20

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Jonsson, JonasBerglund, MartinKratz, HenrikNguyen, HugoThornell, Greger

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