Nowadays, the use of autonomous vehicles for
ocean research has increased, since these vehicles have a better
cost/performance ratio than crewed vessels or oceanographic
ships. For example, autonomous surface vehicles can be used to
localize underwater targets. This paper describes a mission to find
a crawling robot - Benthic Rover - on the abyssal plain in the north
eastern Pacific, using single-beacon localization from onboard a
Wave Glider autonomous surface vehicle. While the Wave Glider
is moving around the surface in the target zone, it takes ranges
between the target and itself using acoustic modems. With these
ranges it can compute the target location, as a Long Baseline
(LBL) system. The benefit of this approach is the reduction of cost
and complexity relative to deployment of a traditional shipboard
LBL system. Additionally, this is a mobile system, and can cover
long distances, and can geolocate multiple targets over a large
area.Postprint (author's final draft

Gomáriz Castro, Spartacus

Kieft, B

Masmitjà Rusiñol, Ivan

O’Reilly, T

Río Fernandez, Joaquín del

English

Nowadays, the use of autonomous vehicles for ocean research has increased, since these vehicles have a better cost/performance ratio than crewed vessels or oceanographic ships. For example, autonomous surface vehicles can be used to localize underwater targets. This paper describes a mission to find a crawling robot - Benthic Rover - on the abyssal plain in the north eastern Pacific, using single-beacon localization from onboard a Wave Glider autonomous surface vehicle. While the Wave Glider is moving around the surface in the target zone, it takes

ranges between the target and itself using acoustic modems. With these ranges it can compute the target location, as a Long Baseline (LBL) system. The benefit of this approach is the reduction of cost and complexity relative to deployment of a traditional shipboard LBL system. Additionally, this is a mobile system, and can cover long distances, and can geolocate multiple targets over a large area

O'Reilly, Thomas C.

UPCommons

Range-only benthic rover localization off the central California coast

UPCommons. Portal del coneixement obert de la UPC

Range-only benthic Rover localization of the central California coastI. Masmitja, S. Gomariz, J. Del Rio SARTI Research Group. Electronics Department Universitat Politècnica de Catalunya Vilanova i la Geltrú, Spain ivan.masmitja@upc.edu  B. Kieft, T. O’Reily  Monterey Bay Aquarium Research Institute (MBARI) Moss Landing, California, U.S.A.    Abstract—. Nowadays, the  use  of  autonomous vehicles for ocean research  has increased, since these  vehicles  have  a better cost/performance ratio than crewed vessels  or  oceanographic ships. For example,  autonomous surface  vehicles can  be  used to localize underwater targets. This paper describes a mission to find a crawling robot - Benthic Rover - on the abyssal plain in the north eastern  Pacific, using single-beacon localization from  onboard  a Wave Glider autonomous surface vehicle. While the Wave Glider is  moving  around the surface in the target zone, it takes ranges between the target  and itself using  acoustic  modems.  With these ranges it can compute the target location, as  a  Long  Baseline (LBL) system. The benefit of this approach is the reduction of cost and complexity relative to deployment of a traditional shipboard LBL system. Additionaly, this is a mobile system, and can cover long  distances,  and can  geolocate multiple targets over a large area.  Keywords— target localization,  underwater, vehicle,  acoustic, benthic rover I. INTRODUCTION One of the main chalenges in oceanographic research is that of underwater positioning. Is wel known that GPS signals sufer a large atenuation underwater. Therefore diferent methods and architectures have been developed using acoustic signals, which have beter underwater performance.  This paper presents a range-only target localization method, using a  Wave  Glider autonomous surface  vehicle [1] that acousticaly ranges to an underwater target while moving on the surface, using the ranges to compute target position. Therefore, we can consider this method as an LBL system  with only one moving transponder on the sea surface.  The method presented in this paper can be used in a wide range  of applications  using the long-duration, autonomous navigation and computational characteristics  of the Wave Glider, to locate stationary  or slowly  moving targets  on the seabed or in the water column. In this work we present results of a mission to find a slowly moving crawling robot on the abyssal plain of the central California coast.  II. MISION CHARACTERISITICS The benthic Rover (fig. 1) is a mobile physiology laboratory designed  by  Dr.  Ken  Smith at  MBARI,  which slowly crawls along the seafloor [2]. Typicaly, it moves about 5 m, stops to take a set of measurements for 3 days, then it moves another 5 meters to the next location. It can stay underwater for six to nine months, therefore it can travel hundreds  of  meters during this period. Therefore it is  necessary to periodicaly determine its position in order to map the location of the measurement sites, and to eventualy recover the  vehicle. The  Rover is equipped with an acoustic modem, to enable data and command exchange and ranging with a surface vehicle.  The most recent Rover deployment is at "Station M" in the north eastern  Pacific, at 34o 50’N,  123o 00’W,  4000  meters depth, 220 km west of the central California coast. This location is approximately  known from previous shipboard acoustic measurements. The  Wave  Glider is equipped  with an acoustic  modem compatible  with the  one instaled  on the  Rover. On  April  14, 2016, we sent the Wave Glider to the Rover target zone to test our auto-localization algorithm. In  our algorithm, the  Wave Glider autonomously swims in a circle  of specified radius, centered near the estimated target location. While swimming in the circle, the  Wave  Glider's  onboard acoustic  modem periodicaly measures the range to the target's acoustic modem. Fig. 1 Mission carried out in Monterey Bay, California, to localize a benthic  Rover (down-right  picture)  using  a  Wave  Glider (up-left picture) as a moving LBL. SEVENTH INTERNATIONAL WORKSHOP ON MARINE TECHNOLOGY, Martech 2016Barcelona, October 26th, 27th and 28th - ISBN: 978-84-617-4152-6Page 114With these ranges and the GPS position of the Wave Glider, our software computes the target location using least squares  or iterative minimization algorithms. Detailed  descriptions  of the algorithm, mission characteristics such as  mission time,  maneuvers, initial deployment and  Rover  movements  wil  be shown in the extended version of this paper.   II. RESULTS The results obtained are shown in fig. 2, in which the circular path executed by the  Wave  Glider (round  dots) and the computed Rover position (triangle) are shown. Furthermore, we can see range obtained for each  Wave  Glider position  on the color  bar. The UTM position for  benthic  Rover obtained  with this algorithm is (500523.820928,  3888509.15227,  3977.3), which is x, y and z in meters.   Figure 2. Target localization results. In this picture we can see the circular path executed by the Wave Glider in order to localize a benthic Rover.  IV. CONCLUSIONS This  work describes a field test conducted to acousticaly localize a  benthic  Rover  deployed at  4000  m  depth from an autonomous surface vehicle. For this purpose a new application using a  Wave  Glider as a single-beacon  LBL has  been developed.  The  work  presented in this  paper  proves the  good performance of this method.           ACKNOWLEDGMENT This  work  was  partialy supported  by the  project  NeXOS from the  European  Union’s  Seventh  Programme for research, technological  development and  demonstration  under  grant agreement  No  614102. We also  had financial support from Spanish  Ministerio  de  Economia  y  Competitividad  under contract  CGL2013- 42557-R (Interoperabilidad e instrumentacion  de  plataformas autonomas  marinas  para la monitorizacion sismica, INTMARSIS). The main author of this work have a grant (FPI-UPC) from UPC for his PhD research. We  gratefuly acknowledge the support  of  MBARI and the David and Lucile Packard foundation.   REFERENCES [1] J. Manley and S. Wilcox, "The Wave Glider: a persistent platform for ocean science", OCEANS 2010, Sydney, Australia, 2010, pp. 1-5. doi:10.1109/OCEANSSYD.2010.560361410.1109/OCEANSSYD.2010.5603614  [2] P. R. McGil, A. D. Sherman, B. W. Hobson, R. G. Henthorn, A. C. Chase and K. L. Smith, "Initial deployments of the Rover, an autonomous botom-transecting instrument platform for long-term measurements in deep benthic environments," OCEANS 2007, Vancouver, BC,  2007,  pp.  1-7. doi: 10.1109/OCEANS.2007.4449315.  .  500400 500600500800 501000Easting(m)501200 5014000200100500400300600700+3.8879e6Northing(m)Target WG4016400840404032402440564048Range(m)SEVENTH INTERNATIONAL WORKSHOP ON MARINE TECHNOLOGY, Martech 2016Barcelona, October 26th, 27th and 28th - ISBN: 978-84-617-4152-6Page 115

Range-only benthic Rover localization off the central California coast

Nowadays, the use of autonomous vehicles for ocean research has
increased, since these vehicles have a better cost/performance ratio than crewed
vessels or oceanographic ships. For example, autonomous surface vehicles can be
used to localize underwater targets. This paper describes a mission to find a crawling
robot - Benthic Rover - on the abyssal plain in the north eastern Pacific, using
single-beacon localization from onboard a Wave Glider autonomous surface vehicle.
While the Wave Glider is moving around the surface in the target zone, it takes
ranges between the target and itself using acoustic modems. With these ranges it
can compute the target location, as a Long Baseline (LBL) system. The benefit of this
approach is the reduction of cost and complexity relative to deployment of a traditional
shipboard LBL system. Additionally, this is a mobile system, and can cover
long distances, and can geolocate multiple targets over a large area.Peer Reviewe

Kieft, Brian

O'Reilly, Tom

86 instrumentation viewpOint- 19 - MARTECH 16ID37- RANGE-ONLY BENTHIC ROVER LOCALIZATION OFF THE CENTRAL CALIFORNIA COASTI. Masmitja174, S. Gomariz175, J. Del Rio182, B. Kieft147, T. O’Reilly148Abstract—. Nowadays, the use of autonomous vehicles for ocean research has increased, since these vehicles have a better cost/performance ratio than crewed vessels or oceanographic ships. For example, autonomous surface vehicles can be used to localize underwater targets. This paper describes a mission to find a crawl-ing robot - Benthic Rover - on the abyssal plain in the north eastern Pacific, using single-beacon localization from onboard a Wave Glider autonomous surface ve-hicle. While the Wave Glider is moving around the surface in the target zone, it takes ranges between the target and itself using acoustic modems. With these ranges it can compute the target location, as a Long Baseline (LBL) system. The benefit of this approach is the reduction of cost and complexity relative to deployment of a tra-ditional shipboard LBL system. Additionally, this is a mobile system, and can cover long distances, and can geolocate multiple targets over a large area.Keywords— target localization, underwater, vehicle, acoustic, benthic roverI. INTRODUCTIONOne of the main challenges in oceanographic research is that of underwater positioning. Is well known that GPS signals suffer a large attenuation underwa-ter. Therefore different methods and architectures have been developed using acoustic signals, which have better underwater performance.This paper presents a range-only target localization method, using a Wave Glid-er autonomous surface vehicle [1] that acoustically ranges to an underwater tar-get while moving on the surface, using the ranges to compute target position. Therefore, we can consider this method as an LBL system with only one moving transponder on the sea surface.The method presented in this paper can be used in a wide range of applications using the long-duration, autonomous navigation and computational character-istics of the Wave Glider, to locate stationary or slowly moving targets on the seabed or in the water column. In this work we present results of a mission to find a slowly moving crawling robot on the abyssal plain off the central Califor-nia coast.II. MISION CHARACTERISITICSThe benthic Rover (fig. 1) is a mobile physiology laboratory designed by Dr. Ken Smith at MBARI, which slowly crawls along the seafloor [2]. Typically, it moves about 5 m, stops to take a set of measurements for 3 days, then it moves another 5 meters to the next location. It can stay underwater for six to nine months, therefore it can travel hundreds of meters during this period. Therefore it is nec-essary to periodically determine its position in order to map the location of the measurement sites, and to eventually recover the vehicle. The Rover is equipped with an acoustic modem, to enable data and command exchange and ranging with a surface vehicle.The most recent Rover deployment is at “Station M” in the north eastern Pacific, at 34o 50’N, 123o 00’W, 4000 meters depth, 220 km west of the central California coast. This location is approximately known from previous shipboard acoustic measurements.The Wave Glider is equipped with an acoustic modem compatible with the one installed on the Rover. On April 14, 2016, we sent the Wave Glider to the Rover target zone to test our auto-localization algorithm. In our algorithm, the Wave Glider autonomously swims in a circle of specified radius, centered near the esti-mated target location. While swimming in the circle, the Wave Glider’s onboard acoustic modem periodically measures the range to the target’s acoustic mo-dem.Fig. 1 Mission carried out in Monterey Bay, California, to localize a benthic Rover (down-right picture) using a Wave Glider (up-left picture) as a moving LBL.With these ranges and the GPS position of the Wave Glider, our software com-putes the target location using least squares or iterative minimization algo-rithms.Detailed descriptions of the algorithm, mission characteristics such as mission time, maneuvers, initial deployment and Rover movements will be shown in the extended version of this paper.III. RESULTSThe results obtained are shown in fig. 2, in which the circular path executed by the Wave Glider (round dots) and the computed Rover position (triangle) are shown. Furthermore, we can see range obtained for each Wave Glider position on the color bar. The UTM position for benthic Rover obtained with this algo-rithm is (500523.820928, 3888509.15227, 3977.3), which is x, y and z in meters.Figure 2. Target localization results. In this picture we can see the circular path executed by the Wave Glider in order to localize a benthic Rover.Figure 2. Target localization results. In this picture we can see the circular path executed by the Wave Glider in order to localize a benthic Rover.Fig. 1 Mission carried out in Monterey Bay, California, to localize a benthic Rover (down-right picture) using a Wave Glider (up-left picture) as a moving LBL.87instrumentation viewpOint- 19 - MARTECH 16 instrumentation viewpOint - 19 - MARTECH 16IV. CONCLUSIONSThis work describes a field test conducted to acoustically localize a benthic Rover deployed at 4000 m depth from an autonomous surface vehicle. For this purpose a new application using a Wave Glider as a single-beacon LBL has been developed. The work presented in this paper proves the good performance of this method.ACKNOWLEDGMENTThis work was partially supported by the project NeXOS from the European Union’s Seventh Programme for research, technological development and demonstration under grant agreement No 614102. We also had financial sup-port from Spanish Ministerio de Economia y Competitividad under contract CGL2013- 42557-R (Interoperabilidad e instrumentacion de plataformas au-tonomas marinas para la monitorizacion sismica, INTMARSIS). The main author of this work have a grant (FPI-UPC) from UPC for his PhD research. We gratefully acknowledge the support of MBARI and the David and Lucile Packard founda-tion.REFERENCES[1] J. Manley and S. Wilcox, “The Wave Glider: a persistent platform for ocean science”, OCEANS 2010, Sydney, Australia, 2010, pp. 1-5. doi:10.1109/OCEANS-SYD.2010.560361410.1109/OCEANSSYD.2010.5603614[2] P. R. McGill, A. D. Sherman, B. W. Hobson, R. G. Henthorn, A. C. Chase and K. L. Smith, “Initial deployments of the Rover, an autonomous bottom-transecting in-strument platform for long-term measurements in deep benthic environments,” OCEANS 2007, Vancouver, BC, 2007, pp. 1-7. doi: 10.1109/OCEANS.2007.4449315.ID38- DATA COMPARISON BETWEEN THREE ACOUSTIC DOPPLER CURRENT PROFILERS DEPLOYED IN OBSEA PLATFORM IN NORTH-WESTERN MEDITERRANEANMatias Carandell Widmer223, Marc Nogueras Cervera222Abstract – Three different Acoustic Doppler Current Profilers (ADCP) have been de-ployed in OBSEA platform, a 20 meters depth underwater observatory cabled with a 4 km mixt cable to Vilanova i la Geltru’s coast. Two months of continuous data have been collected in order to confirm their proper operation and long term North cur-rent characteristic from the area.Keywords – ADCP, Doppler Effect, North currentI. INTRODUCTION TO THE DOPPLER EFFECTThe Doppler effect is the difference in frequency that can be appreciate in a wave when the observer is moving in different directions. In example, an ob-server walking into the waves will see more waves in a given interval than some-one standing still, and this will see even more than an observer moving away [1].ADCPs use the Doppler effect by transmitting sound at a fixed frequency and listening to echoes returning from scatterers in the water. These scatterers are everywhere in the ocean and they float in the water moving on average at the same horizontal velocity as the water. So ADCP receives sound echoed from the scatterers and Doppler-shifted to a different frequency proportional to their movement. The angular motion causes no Doppler shift, only the radial one.ADCPs use multiple beams pointed in different directions in order to calculate different velocity components. With three beams, east, north and up velocity can be calculated and there’s an extra one to estimate the validity of the sensor data.II. OBSEA PLATFORMOBSEA is an underwater observatory connected to the coast with a 4 km mixt cable that provides power and data. It is placed at a depth of 20 meters in a fishing protected area near the coast of Vilanova i la Geltrú. The main advantage of the cable observatory is the capacity to feed the station from the land up to 3.6 kW and the high bandwidth communication link of 1 Gbps. This gives the opportunity of observe in real-time multiple marine environment parameters.The main objective of OBSEA is to have a test bed for the development of ocean-ographic instrumentation while providing real time data to the scientific com-munity.This platform counts on two subsea nodes in series and one Buoy connected to the first one. Further, there’s a secondary buoy connected to the first recently Fig 1. Backscattered sound. (A) Transmitted pulse; (B) A small amount of the sound energy is reflected back (and Doppler shifted), most of the energy goes forward. Fig 2. OBSEA platform distribution

Nowadays, the use of autonomous vehicles for ocean research has
increased, since these vehicles have a better cost/performance ratio than crewed
vessels or oceanographic ships. For example, autonomous surface vehicles can be
used to localize underwater targets. This paper describes a mission to find a crawling
robot - Benthic Rover - on the abyssal plain in the north eastern Pacific, using
single-beacon localization from onboard a Wave Glider autonomous surface vehicle.
While the Wave Glider is moving around the surface in the target zone, it takes
ranges between the target and itself using acoustic modems. With these ranges it
can compute the target location, as a Long Baseline (LBL) system. The benefit of this
approach is the reduction of cost and complexity relative to deployment of a traditional
shipboard LBL system. Additionally, this is a mobile system, and can cover
long distances, and can geolocate multiple targets over a large area

Revistes Catalanes amb Accés Obert

Nowadays, the use of autonomous vehicles for ocean research has increased, since these vehicles have a better cost/performance ratio than crewed vessels or oceanographic ships. For example, autonomous surface vehicles can be used to localize underwater targets. This paper describes a mission to find a crawling robot - Benthic Rover - on the abyssal plain in the north eastern Pacific, using single-beacon localization from onboard a Wave Glider autonomous surface vehicle. While the Wave Glider is moving around the surface in the target zone, it takes
ranges between the target and itself using acoustic modems. With these ranges it can compute the target location, as a Long Baseline (LBL) system. The benefit of this approach is the reduction of cost and complexity relative to deployment of a traditional shipboard LBL system. Additionally, this is a mobile system, and can cover long distances, and can geolocate multiple targets over a large area.Postprint (published version

86 instrumentation viewpOint- 19 - MARTECH 16ID37- RANGE-ONLY BENTHIC ROVER LOCALIZATION OFF THE CENTRAL CALIFORNIA COASTI. Masmitja174, S. Gomariz175, J. Del Rio182, B. Kieft147, T. O’Reilly148Abstract—. Nowadays, the use of autonomous vehicles for ocean research has increased, since these vehicles have a better cost/performance ratio than crewed vessels or oceanographic ships. For example, autonomous surface vehicles can be used to localize underwater targets. This paper describes a mission to find a crawl-ing robot - Benthic Rover - on the abyssal plain in the north eastern Pacific, using single-beacon localization from onboard a Wave Glider autonomous surface ve-hicle. While the Wave Glider is moving around the surface in the target zone, it takes ranges between the target and itself using acoustic modems. With these ranges it can compute the target location, as a Long Baseline (LBL) system. The benefit of this approach is the reduction of cost and complexity relative to deployment of a tra-ditional shipboard LBL system. Additionally, this is a mobile system, and can cover long distances, and can geolocate multiple targets over a large area.Keywords— target localization, underwater, vehicle, acoustic, benthic roverI. INTRODUCTIONOne of the main challenges in oceanographic research is that of underwater positioning. Is well known that GPS signals suffer a large attenuation underwa-ter. Therefore different methods and architectures have been developed using acoustic signals, which have better underwater performance.This paper presents a range-only target localization method, using a Wave Glid-er autonomous surface vehicle [1] that acoustically ranges to an underwater tar-get while moving on the surface, using the ranges to compute target position. Therefore, we can consider this method as an LBL system with only one moving transponder on the sea surface.The method presented in this paper can be used in a wide range of applications using the long-duration, autonomous navigation and computational character-istics of the Wave Glider, to locate stationary or slowly moving targets on the seabed or in the water column. In this work we present results of a mission to find a slowly moving crawling robot on the abyssal plain off the central Califor-nia coast.II. MISION CHARACTERISITICSThe benthic Rover (fig. 1) is a mobile physiology laboratory designed by Dr. Ken Smith at MBARI, which slowly crawls along the seafloor [2]. Typically, it moves about 5 m, stops to take a set of measurements for 3 days, then it moves another 5 meters to the next location. It can stay underwater for six to nine months, therefore it can travel hundreds of meters during this period. Therefore it is nec-essary to periodically determine its position in order to map the location of the measurement sites, and to eventually recover the vehicle. The Rover is equipped with an acoustic modem, to enable data and command exchange and ranging with a surface vehicle.The most recent Rover deployment is at “Station M” in the north eastern Pacific, at 34o 50’N, 123o 00’W, 4000 meters depth, 220 km west of the central California coast. This location is approximately known from previous shipboard acoustic measurements.The Wave Glider is equipped with an acoustic modem compatible with the one installed on the Rover. On April 14, 2016, we sent the Wave Glider to the Rover target zone to test our auto-localization algorithm. In our algorithm, the Wave Glider autonomously swims in a circle of specified radius, centered near the esti-mated target location. While swimming in the circle, the Wave Glider’s onboard acoustic modem periodically measures the range to the target’s acoustic mo-dem.Fig. 1 Mission carried out in Monterey Bay, California, to localize a benthic Rover (down-right picture) using a Wave Glider (up-left picture) as a moving LBL.With these ranges and the GPS position of the Wave Glider, our software com-putes the target location using least squares or iterative minimization algo-rithms.Detailed descriptions of the algorithm, mission characteristics such as mission time, maneuvers, initial deployment and Rover movements will be shown in the extended version of this paper.III. RESULTSThe results obtained are shown in fig. 2, in which the circular path executed by the Wave Glider (round dots) and the computed Rover position (triangle) are shown. Furthermore, we can see range obtained for each Wave Glider position on the color bar. The UTM position for benthic Rover obtained with this algo-rithm is (500523.820928, 3888509.15227, 3977.3), which is x, y and z in meters.Figure 2. Target localization results. In this picture we can see the circular path executed by the Wave Glider in order to localize a benthic Rover.Figure 2. Target localization results. In this picture we can see the circular path executed by the Wave Glider in order to localize a benthic Rover.Fig. 1 Mission carried out in Monterey Bay, California, to localize a benthic Rover (down-right picture) using a Wave Glider (up-left picture) as a moving LBL.87instrumentation viewpOint - 19 - MARTECH 16IV. CONCLUSIONSThis work describes a field test conducted to acoustically localize a benthic Rover deployed at 4000 m depth from an autonomous surface vehicle. For this purpose a new application using a Wave Glider as a single-beacon LBL has been developed. The work presented in this paper proves the good performance of this method.ACKNOWLEDGMENTThis work was partially supported by the project NeXOS from the European Union’s Seventh Programme for research, technological development and demonstration under grant agreement No 614102. We also had financial sup-port from Spanish Ministerio de Economia y Competitividad under contract CGL2013- 42557-R (Interoperabilidad e instrumentacion de plataformas au-tonomas marinas para la monitorizacion sismica, INTMARSIS). The main author of this work have a grant (FPI-UPC) from UPC for his PhD research. We gratefully acknowledge the support of MBARI and the David and Lucile Packard founda-tion.REFERENCES[1] J. Manley and S. Wilcox, “The Wave Glider: a persistent platform for ocean science”, OCEANS 2010, Sydney, Australia, 2010, pp. 1-5. doi:10.1109/OCEANS-SYD.2010.560361410.1109/OCEANSSYD.2010.5603614[2] P. R. McGill, A. D. Sherman, B. W. Hobson, R. G. Henthorn, A. C. Chase and K. L. Smith, “Initial deployments of the Rover, an autonomous bottom-transecting in-strument platform for long-term measurements in deep benthic environments,” OCEANS 2007, Vancouver, BC, 2007, pp. 1-7. doi: 10.1109/OCEANS.2007.4449315.ID38- DATA COMPARISON BETWEEN THREE ACOUSTIC DOPPLER CURRENT PROFILERS DEPLOYED IN OBSEA PLATFORM IN NORTH-WESTERN MEDITERRANEANMatias Carandell Widmer223, Marc Nogueras Cervera222Abstract – Three different Acoustic Doppler Current Profilers (ADCP) have been de-ployed in OBSEA platform, a 20 meters depth underwater observatory cabled with a 4 km mixt cable to Vilanova i la Geltru’s coast. Two months of continuous data have been collected in order to confirm their proper operation and long term North cur-rent characteristic from the area.Keywords – ADCP, Doppler Effect, North currentI. INTRODUCTION TO THE DOPPLER EFFECTThe Doppler effect is the difference in frequency that can be appreciate in a wave when the observer is moving in different directions. In example, an ob-server walking into the waves will see more waves in a given interval than some-one standing still, and this will see even more than an observer moving away [1].ADCPs use the Doppler effect by transmitting sound at a fixed frequency and listening to echoes returning from scatterers in the water. These scatterers are everywhere in the ocean and they float in the water moving on average at the same horizontal velocity as the water. So ADCP receives sound echoed from the scatterers and Doppler-shifted to a different frequency proportional to their movement. The angular motion causes no Doppler shift, only the radial one.ADCPs use multiple beams pointed in different directions in order to calculate different velocity components. With three beams, east, north and up velocity can be calculated and there’s an extra one to estimate the validity of the sensor data.II. OBSEA PLATFORMOBSEA is an underwater observatory connected to the coast with a 4 km mixt cable that provides power and data. It is placed at a depth of 20 meters in a fishing protected area near the coast of Vilanova i la Geltrú. The main advantage of the cable observatory is the capacity to feed the station from the land up to 3.6 kW and the high bandwidth communication link of 1 Gbps. This gives the opportunity of observe in real-time multiple marine environment parameters.The main objective of OBSEA is to have a test bed for the development of ocean-ographic instrumentation while providing real time data to the scientific com-munity.This platform counts on two subsea nodes in series and one Buoy connected to the first one. Further, there’s a secondary buoy connected to the first recently Fig 1. Backscattered sound. (A) Transmitted pulse; (B) A small amount of the sound energy is reflected back (and Doppler shifted), most of the energy goes forward. Fig 2. OBSEA platform distribution

Nowadays, the use of autonomous vehicles for

ocean research has increased, since these vehicles have a better

cost/performance ratio than crewed vessels or oceanographic

ships. For example, autonomous surface vehicles can be used to

localize underwater targets. This paper describes a mission to find

a crawling robot - Benthic Rover - on the abyssal plain in the north

eastern Pacific, using single-beacon localization from onboard a

Wave Glider autonomous surface vehicle. While the Wave Glider

is moving around the surface in the target zone, it takes ranges

between the target and itself using acoustic modems. With these

ranges it can compute the target location, as a Long Baseline

(LBL) system. The benefit of this approach is the reduction of cost

and complexity relative to deployment of a traditional shipboard

LBL system. Additionally, this is a mobile system, and can cover

long distances, and can geolocate multiple targets over a large

area

Nowadays, the use of autonomous vehicles for ocean research has

increased, since these vehicles have a better cost/performance ratio than crewed

vessels or oceanographic ships. For example, autonomous surface vehicles can be

used to localize underwater targets. This paper describes a mission to find a crawling

robot - Benthic Rover - on the abyssal plain in the north eastern Pacific, using

single-beacon localization from onboard a Wave Glider autonomous surface vehicle.

While the Wave Glider is moving around the surface in the target zone, it takes

ranges between the target and itself using acoustic modems. With these ranges it

can compute the target location, as a Long Baseline (LBL) system. The benefit of this

approach is the reduction of cost and complexity relative to deployment of a traditional

shipboard LBL system. Additionally, this is a mobile system, and can cover

long distances, and can geolocate multiple targets over a large area.Peer Reviewe

https://upcommons.upc.edu/bitstream/2117/99530/1/37.pdf

Range-only benthic Rover localization off the central California coast

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