Positionnement Dynamique Flashcards
What are the advantages of a dynamic positioning system?
- Excellente manoeuvrabilité
- Pas dépendant de la profondeur d’eau
- Rapide
- Pas d’obstruction du fond de l’eau
These advantages make dynamic positioning systems suitable for various marine operations.
What are the disadvantages of a dynamic positioning system?
- Système compliqué
- Cher à l’installation
- Cher d’essence
- Beaucoup de maintenance
The complexity and cost can limit the use of dynamic positioning systems in certain scenarios.
List some applications of dynamic positioning systems.
- Poseur de câble
- Sea Launch
- Navire foreur
- Navire grues
- Navire de croisière
- Shuttle tanker
These applications highlight the versatility of dynamic positioning systems in the maritime industry.
What is an open-loop system?
Système où l’action contrôlée est indépendante du résultat obtenu.
Open-loop systems do not adjust based on feedback from the output.
What is a closed-loop system?
Système où l’action contrôlée est dépendante du résultat obtenu.
Closed-loop systems adjust their actions based on the feedback from the output to achieve desired results.
Qu’est-ce que le positionnement dynamique (DP) ?
Un système contrôlé par ordinateur permettant à un navire de maintenir sa position et son cap en utilisant ses propres moyens de propulsion.
Quels paramètres doivent être calculés pour contrôler le positionnement dynamique d’un navire ?
La position et le cap du navire, ainsi que, selon les systèmes, les mouvements du navire.
Combien de systèmes de référence de positionnement sont nécessaires pour le DP ?
Au moins deux systèmes de référence de positionnement.
Quel est le terme mieux connu pour désigner les systèmes de référence de positionnement ?
Position Reference System (PRS).
Listez quelques types de systèmes de référence de positionnement utilisés dans le DP.
- Satellitaires
- Laser
- Ondes électromagnétiques
- Hydroacoustique
- Mécanique
What are the three main components of the system architecture?
- Capteurs ou instruments de mesure
- Console informatique
- Actionneurs
Each component plays a crucial role in the overall functioning of the system.
What types of sensors are included in the measurement instruments?
Anémomètres, girouettes, accéléromètres, PRS (Position Reference System), instruments de mesure du cap
These instruments help in collecting data necessary for system operation.
What is the role of the console informatique?
Effectue les calculs à l’aide du modèle mathématique et des données fournies par les capteurs
It also serves as an interface for the operator.
True or False: The operator can modify maneuver parameters in DP mode.
True
DP mode allows flexibility in operational parameters.
What are the actions performed by the actionneurs?
Agissent selon les commandes de l’ordinateur central
They include various propulsors, turbines, rudders, and/or propellers.
Fill in the blank: The _______ processes data using mathematical models and sensor inputs.
console informatique
This component is essential for decision-making in the system.
What is the absolute DP mode?
Maintenir une position géographique
This mode refers to maintaining a fixed geographic position.
What does relative DP mode maintain?
Maintenir sa position par rapport à un objet
This mode ensures the position is maintained relative to another object.
What is autotrack in DP modes?
Maintenir sa position, sa vitesse et son cap sur une route donnée
Autotrack helps in maintaining position, speed, and heading along a specified route.
What does the term ‘weathervane’ refer to in DP modes?
Maintenir son cap
This mode involves maintaining a specific heading.
What is the optimum heading facility in DP?
Weathervane ou optimum heading facility
This facility assists in determining the best heading based on environmental conditions.
What is the most commonly used positioning system?
DGPS
DGPS stands for Differential Global Positioning System.
What is a key advantage of DGPS?
La référence de positionnement est globale
The positioning reference is global and varies according to the GNSS.
How often is GPS available?
365/24
GPS is available 24 hours a day, 365 days a year.
What is a benefit of using DGPS equipment?
L’équipement est relativement bon marché et simple d’utilisation
DGPS equipment is relatively inexpensive and user-friendly.
What type of signals are DGPS signals?
Gratuits
The basic signals used in DGPS are free of charge.
What level of precision does DGPS offer for DP?
Assez précis
DGPS provides sufficient accuracy for dynamic positioning.
What is a feature of some DGPS receivers?
Bi-fréquences
Some receivers operate on dual frequencies.
Fill in the blank: Les corrections différentielles sont ______.
payantes
Differential corrections often come at a cost.
What issue can occur near platforms and structures?
Problèmes récurrents de multi-trajet
Multipath issues can affect signal reception near structures.
What can lead to loss of differential signals?
Présence des plateformes et autres structures
The presence of platforms can obstruct or degrade signal quality.
What is a limitation related to GNSS?
Âge des corrections
The age of corrections can affect their accuracy and reliability.
What is a fundamental principle of hydroacoustic reference?
Un transducteur est installé sous la coque du navire
A transducer is installed under the hull of the ship, similar to an echo sounder.
What does the transducer emit?
Signaux sous formes d’impulsions
The transducer sends out signals in the form of mechanical waves.
What is the purpose of the transponder in hydroacoustic positioning?
Déposés sur le fond marin à un endroit connu
The transponder is placed on the seabed at a precisely known location.
What does the reception of signals allow in hydroacoustic systems?
Générer des données de positionnement
The received signal is used to produce positioning data.
What are the two main types of HPR systems?
• Ultra-short Baseline HPR (USBL)
• Long Baseline HPR (LBL)
What is a characteristic feature of the Ultra-short Baseline HPR (USBL)?
Un seul transpondeur est utilisé
What does the transpondeur in USBL do?
Il répond aux impulsions codées du transducteur
Where is the transpondeur installed in a USBL system?
À l’extrémité d’une tige de 4 à 5 mètres sous la coque du navire
How is the distance separating the navire from the transpondeur determined in USBL?
Le signal reçu par le transducteur est traité
What type of measurements does the transducteur in USBL allow?
Mesurer la direction du signal de retour en 3D
What additional inputs are used in USBL to enhance measurement accuracy?
GYRO et MRU
What is the precision range of the USBL system?
Précision de l’ordre de 1 à 2% de la profondeur
What is one advantage of the USBL system?
Indépendant des autres parties, par exemple, DGPS relatif
What is a disadvantage of the USBL system?
Complexe et dispendieux
What factors can affect the precision of the USBL system?
• Présence de larges structures sous-marines
• Bruits, à l’aération, couches d’eau, turbulences et impuretés de l’eau
In what types of water is USBL considered ineffective?
Eaux peu profondes et très profondes
What problem can arise with USBL concerning other HPR systems?
Interférence possible avec d’autres HPR
What does the precision of the USBL system depend on?
Le gyrocompas
Fill in the blank: The USBL system can track _______ in motion.
des cibles
What is a key limitation of the USBL system in deep waters?
Loses precision due to limitations in angular calculation at the transducer
How does the LBL system differ from the USBL system regarding angle calculation?
No need to calculate angle at the transducer
How are transducers installed in the LBL system?
Installed the same way as with USBL
How many transponders are typically placed on the seabed in the LBL system?
4 or 5 transponders
What is the purpose of the transducer emitting a signal towards the seabed?
To measure distance between each transducer/transponder pair
What method is used to determine the position of the vessel in the LBL system?
Trilatération
What effect do ship movements have on positioning in the LBL system?
No effect on positioning since no angular measurement is made
What is the precision range of the LBL system?
0.2 to 0.4% of the depth
What is one advantage of the LBL system regarding independence?
Independent of other parts, e.g., relative DGPS
Can the LBL system be referenced globally?
Yes
What are some disadvantages of the LBL system?
Complex and expensive; issues with noise, aeration, water layers, turbulence, and impurities
How can the presence of large underwater structures affect the LBL system?
It can affect precision
In which water conditions is the LBL system ineffective?
Shallow and very deep waters
What does the precision of the LBL system depend on?
Gyrocompass
Is there a possibility of interference with other HPR systems in LBL?
Yes, but this issue is resolved with multi-user systems
What calibration possibility exists for the LBL system?
Calibrate for the actual density of the water column with specific transponders
What is the average frequency range for hydroacoustic reference systems?
Between 18 and 32 kHz
What is a feature of multi-user systems in the LBL context?
Hydrophone on the vessel to limit acoustic saturation possibilities
Can some LBL systems be used as USBL?
Yes
