NEWS
NESSIE ROBOT BY WATERTRACKS
“Nessie”, the robotic dredging solution designed by Watertracks, an underwater constructions company, is equiped with the RTKDuo solution from PLSM. Thanks to the precise and georeferenced positioning system, “Nessie” can be fully programmed and remotely controlled, allowing versatile and cost effective dredging operations.
AQUA-MÈTRE D100-NG
The new version of the diver operated cartography system is now available. Dedicated to diver operated applications, the pointer is now equiped with an Android tablet interface. With this user friendly setup, the diver can now take measurements that are stored in the tablet memory.
NEW GEOREFERENCED GPS RTK BUOY DUAL-ROVER CONFIGURATION
In this configuration, the system is managed from a moving point (a vessel, barge,…), thus, the GNSS receiver inside the Survey Interface can not be used as a RTK reference Base, external RTCM corrections must be provided by the user from an external RTK base station on the shore, or from network RTK (NTRIP protocol, availability depends on the location) using cellular communications.
For more details, check the RTKDuo technical description.
PRODUCTS
AQUA-METRE D100-NG
CARTOGRAPHY BY DIVER
Designed for diver-operated applications, the AQUA-METRE D100-NG
is a local underwater positioning system based on an acoustical
interferometric
scheme (mainly known as Ultra Short Base Line or USBL).
It is particularly well suited for accurate local 3D cartography within
a range of up to 250 meters from the reference point.
This is a user-friendly,easy to set up system. It is completely autonomous
(no cable needed from the seabed and the surface) and can be operated
by a single (unspecialised) diver.
SYSTEM DESCRIPTION
The measurement Base (an AQUA-METRE R300-NG unit) constitutes
the Cartesian reference coordinate system {0,0,0}), and is mounted
at the top of a 2 meter (6 feet) pole. A light portable Pointer
(a MiniPointer R300-NG) interfaced to an underwater tablet
(AllTab 2.0 android tablet from Valtamer company, Finland) allows
the diver to measure positions and save them in the tablet memory.
A single Base can work with several Pointers simultaneously.
Each pointer can be fitted with a stand that allows measurement
offset from the seabed (the length and orientation of the stand
are compensated automatically using internal inclinometers and a compass).
Back to the surface, the measurements are downloaded to the final user
application for processing.
RTKDuo BUOY
INSTRUMENTED BUOY FOR DIRECT
ACCURATE SUBSEA GEOREFERENCED POSITIONING
The new RTKDuo instrumented buoy associated with the AQUA-METRE
R300NG USBL offers a very accurate, light and hassle-free way of providing
underwater georeferenced positions. The instrumented buoy includes:
a dual antenna GNSS RTK Receiver (to measure the position and heading
of the buoy), a mem’s motion reference unit to measure the pitch and roll
and filter the noisy GNSS heading, and a radio-modem (ISM band, 868
or 915MHz) to manage the buoy from the survey PC.
"DUAL ROVER"CONFIGURATION + HEADING
In this configuration, the system is managed from a moving point
(a vessel, barge,...), thus, the GNSS receiver inside the Survey
Interface can not be used as a RTK reference Base, external RTCM
corrections must be provided by the user from an external RTK
base station on the shore, or from network RTK (NTRIP protocol,
availability depends on the location) using cellular communications.
For further detail, check
the RTKDuo technical description
AQUA-METRE R300/R3000-NG
SYSTEM DESCRIPTION
The AQUA-METRE R300-NG and 3000-NG are a light, accurate
and versatile USBL sensors. They have a reach of 250m
and are operational down to 300m and 3000 meters respectively.
An AQUA-METRE configuration includes at least one Base
and one Pointer (MiniPointer R300-NG is well suited to survey ROV).
More than 30 units may be operated simultaneously (Bases & Pointers).
At least one unit is connected to the survey PC, and this unit pilots
the other units through an acoustic network.
MINIPOINTER R300-NG
The MiniPointer R300-NG may be used with a dual hydrophone
in order to measure the underwater heading of ROV or loads.
It also includes an accurate pressure gauge (0.05% of full scale)
to allow for precise depth measurements.
CONFIGURATION
An AQUA-METRE configuration includes at least one Base
and one Pointer (MiniPointer R300-NG is well suited to survey ROV).
More than 30 units may be operated simultaneously (Bases & Pointers).
At least one unit is connected to the survey PC, and this unit pilots
the other units through an acoustic network.
The Base unit measures
the 3D coordinates of Pointer(s).
AQUA-METRE R3000-NG SPECIFICITIES
The AQUA-METRE R3000-NG is designed for deep offshore metrology
(down to 3000 metres). The system is operated through a set of commands
(monitor commands and acoustic commands) and may be operated using
the AQUA-CAD software provided by PLSM that allows real time interface
to BricsCad range of CAD tools.
The AQUA-METRE R3000-NG has the same electrical and mechanical
interfaces as the R300-NG version. However, the casing is made from
a special aluminium to withstand high pressures, as well as the interferometric
frame which can endure up to 350 bars (>5000psi). There is no MiniPointer,
but a larger pointer with a large battery pack in order to keep it on sleeping
mode several weeks before operation if needed.
AQUA-CAD SOFTWARE
SOFTWARE TO MANAGE ANY AQUA-METRE CONFIGURATION
PLSM offers the AQUA-CAD software to manage any AQUA-METRE configuration
using a simple graphical user interface (GUI) and get access to a real-time interface
with a CAD software (BricsCad family, fully .dxf and .dwg compatible).
The AQUA-CAD sofware is compatible with Windows (XP, 7, 8, and 10).
SERVICES
RENTING AQUA-METRE SYSTEMS
The full range of AQUA-METRE systems can be rented from one up to several weeks. Freight may be managed by PLSM depending on customer requirement. Special long-duration fares are offered to customers who do not wish to make a big investment.
SIMPLE TRAINING UP TO FULL TECHNICAL ASSISTANCE
PLSM offers training courses in the company premises or in customer premises when required. PLSM also offers full technical assistance if the customer prefers to focus on their main job (ROV inspection for instance) and subcontracts the full positioning/metrology part of its activities.The technical assistance can be reduced to the system set-up and few days of training on the field. PLSM is open to any customer suggestion.
CUSTOM SOLUTIONS
For customers that need a specific solution related to underwater positioning, PLSM is ready to propose a custom solution elaborated from current hardware and software products. Please contact PLSM to check the possibilities.
APPLICATIONS
GOAL
This mission consists in surveying all submerged parts of the dam: the wall
and sealsbetween concrete blocks, the water inlet, sluice gates, bottom outlet, etc.
This used to be done by draining the whole reservoir prior to a visual inspection.
But when reliable ROV were available, it appeared to be far less expensive and safer
for the dam structure to do it using a ROV equipped with a video camera
(and now also acoustic camera). The positioning system is then necessary
to navigate
the ROV, especially in case of poor visibility, and to offer
a traceability of all measurements and recordings.
EQUIPMENT
The AQUA-METRE R300-NG associated with the RTKDuo buoy is the perfect solution
for a dam survey, since it delivers georeferenced coordinates of the ROV directly
(no calibration required). The RTKDuo buoy can operate in narrow canyons, thanks
to the multi-constellation GNSS receiver. The MiniPointer R300-NG used for the ROV
positioning, can be simply attached to the ROV: no need for an electrical interface
since it is powered by an internal battery pack and communicates through acoustic network.
The path and current location of the ROV, as well as the model of the dam are displayed
in 3D using the BricsCad software (dwg compatible, interfaced to AQUA-CAD).
AQUA-CAD also manages to overlay all geo- and time-stamp recordings onto the video.
AQUA-CAD RESULTS EXAMPLE
SPOOL & JUMPER METROLOGY
Due to a recurrent demand for spool piece or jumper metrology, PLSM
has developed a specific script for this purpose, using AQUA-CAD software.
This script automatically manages the underwater units measurements
and directly computes the metrology results in a CAD software, taking
into account all mechanical interface offsets. This method considerably
speeds up the survey report and avoids processing errors, as well as
a headache for the survey operator...
CONFIGURATION
One Base is set up on each flange, the first one is called the Reference Base
and defines the relative coordinate system. All results are transmitted according
to this Base coordinate system (which is defined by the interferometric frame).
The other Base is called the Offset Base and is attached to the second flange.
One Pointer is placed on a seabed support in order to create an approximate
isosceles triangle (see sketch).
Each Base to flange mechanical interface has to be defined in a CAD drawing (.dwg)
prior to starting the metrology. A Pointer attached to (and preferably powered by)
the ROV is linked up to the survey room through a bi-directional RS232 channel.
It acts as the Communication Master, thus sending commands to and receiving results
from the others units working on batteries (2 Bases and one Pointer in this case).
For further detail, check the How To Manual
for Surveyors for the Aqua-Metre R3000-NG
METROLOGY SCRIPT STEPS
A Pointer attached to (and preferably powered by) the ROV is linked up to the survey
room through a bi-directional RS232 channel. It acts as the Communication Master,
thus sending commands to and receiving results from the others units working
on batterie (2 Bases and one Pointer in this case).
1 - Measurement of Offset Base location from Reference Base,
2 - Step #2: Measurement of Rotation locking Pointer from Reference Base,
3 - Measurement of Reference Base location from Offset Base,
4 - Measurement of Rotation locking Pointer from Offset Base,
All these acoustic measurements (four times Azimuth, Elevation and Distance)
re processed by AQUA-CAD to produce a final drawing of the metrology including
the mechanical interfaces, subsequently getting direct access to the flange-to-flange dimensions.
NEARSHORE BUILDING
CONSTRUCTION APPLICATIONS
The AQUA-METRE/RTKDuo buoy is frequently used
on different coastal construction sites, especially for:
- Ballast levelling at depths between 10 and 25 meters.
(leveling frame fine tuning),
- Emissaries, drilling positionning,
- Construction block positionning for dock constructions (first layer setup)
RENEWABLE ENERGIES
BREAKWATER SURVEY
BREAK WATER SURVEY
Armoured breakwaters are intended to protect seashore installations
(arbour, oil terminal, etc) against waves. They are usually covered by concrete
blocks with different sizes and shapes. Some bloc types allow for a ‘single layer”
configuration which reduces the total concrete volume necessary to build
the breakwater, but requires a precise placement during construction.
The AQUA-METRE R300 is used by a diver to survey the position
of the breakwater blocks. The Base is placed on the seabed at about 10 metres
from the edge of the breakwater on top of a small mast. It is then linked using
a surface radio-modem buoy or simply using a direct cable to the survey cabin.
CONFIGURATION
The diver holds the Pointer and is able to speak to the survey cabin.
His work consists of swimming from bloc to bloc and pointing at the bloc
centre with the Pointer and waiting for measurement completion,
which is managed from the survey cabin. The AQUA-METRE is operated
using AQUA-CAD and Intellicad softwares, then working directly with the
breakwater drawing/map.
The transformation from local acoustic to an absolute cartographic coordinate
system is defined by measuring the acoustic coordinates of two reference points
named pivot and lever. The absolute coordinates of these two reference points
is measured at 2/3 metres depth using a total station from the pier.
Then, the calibration just consists of directing the diver to the reference points
and picking the position in the Autocad drawing and waiting for acoustic
measurement completion. The calibration lasts about 15 minutes
and is valid until the next Base translation.
COMPANY
PLSM is a small, creative and highly responsive company. The business was created in late 1999 following the development of an innovative solution for underwater archaeology mapping : the AQUA-METRE D100.
Since 1999, PLSM has extended its practice by introducing new AQUA-METRE derivatives, the AQUA-METRE R300 and R3000 particularly. These underwater positioning systems address a broad range of activities such as dam surveying, shallow and deep offshore metrology, and seaweed mapping among others.
2-4 rue Jean-Baptiste HUET
BP 18
78354 Jouy en Josas
FRANCE
(+33) 1 8541 0124
infos[@]plsm.eu