A variable buoyancy system for deep ocean vehicles

Worall, Mark; Jamieson, Alan J.; Holford, A.; Neilson, Richard David; Player, M.A.; Bagley, P.M.

doi:10.1109/oceanse.2007.4302317

Cited by 24 publications

(8 citation statements)

References 2 publications

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“…Later for deep water depth operations in the ocean, a VBS was proposed by Worall et al [11] for depth up to 6000 m and 30 kg buoyancy capability. In their work, no results were reported for the performance of AUV integrated with its VBS either through simulation or experimental testing.…”

Section: Research Contributionmentioning

confidence: 99%

Design and Analysis of a Variable Buoyancy System for Efficient Hovering Control of Underwater Vehicles with State Feedback Controller

Tiwari

Sharma

2020

JMSE

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The design process for Variable Buoyancy System (VBS) is not known in full, and existing approaches are not scalable. Furthermore, almost all the small size Autonomous Underwater Vehicles/Gliders (AUVs/G's) use very low capacity of buoyancy change (in the range of few milliliters) and the large size AUVs require large buoyancy change. Especially for adverse weather conditions, emergency recovery or defense-related applications, higher rate of rising/sinking (heave velocity) is needed along with an ability to hover at certain depth of operation. Depth of UVs can be controlled either by changing the displaced volume or by changing the overall weight and, herein, our focus is on the later. This article presents the problem of design and analysis of VBS for efficient hovering control of underwater vehicles at desired depth using the state feedback controller. We formulate and analyze the design and analysis approach of VBS using the fundamental of mechanics, system dynamics integration and control theory. Buoyancy is controlled by changing the overall weight of the vehicle using the ballasting/de-ballasting of water in ballast tanks through the use of Positive Displacement Pump (PDP) for control in heave velocity and hovering depth. Furthermore, detailed mass metric analysis of scalable design of VBS for different buoyancy capacities is performed to analyze the overall performance of the VBS. Also, the performances of AUVs integrated with VBS of different buoyancy capacities are investigated in both the open loop and closed loop with the LQR state feedback controller. Hovering performance results are presented for three Design Examples (DEs) of AUVs with 2.8 m, 4.0 m and 5.0 m length and they are integrated with various buoyancy capacities at 9 kg/min rate of change of buoyancy. Results indicate that the AUVs achieve the desired depth with almost negligible steady state error and when they reach the desired hovering depth of 400 m the maximum pitch angle achieved of 16.5 degree for all the Des is observed. Maximum heave velocity achieved during sinking is 0.44 m/s and it reduces to zero when the vehicle reaches the desired depth of hovering. The presented computer simulation results indicate good performance and demonstrate that the designed VBS is effective and efficient in changing the buoyancy, controlling and maintaining the depth, controlling the heave velocity and can be used in rescue/attack operations of both the civil and defense UVs.Keywords: variable buoyancy system (VBS); autonomous underwater vehicle (AUV); positive displacement pump (PDP); brush-less direct current (BLDC) motor; linear quadratic controller (LQR)This scene demands vehicles that can be used for surveying the oceans for high endurance and operable at high depths. These requirements have motivated the researchers to design and develop new age Underwater Vehicles (UVs). UVs are designed to perform underwater survey missions such as detecting and mapping submerged wrecks, rocks and obstructions that can pose a hazard, primarily for efficient ...

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Section: Research Contributionmentioning

confidence: 99%

Design and Analysis of a Variable Buoyancy System for Efficient Hovering Control of Underwater Vehicles with State Feedback Controller

Tiwari

Sharma

2020

JMSE

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“…Water hydraulic VBSs, or VBSs for short hereafter, are generally divided into two types according to whether or not the flowrate is continuously regulatable. The most widely designed type are on-off type VBSs, which can only accept three kinds of flowrate command (+1: inject water into ballast tank, −1: discharge water out from ballast tank, 0: turn off valves and close pump) without controlling the flowrate of the in/out ballast water [18,29,30]. The on-off type VBS in [18] uses a single speed motor and a fixed displacement pump, resulting in a constant pump rate, and electric valves controlling whether water is pumped into or out of each tank or whether the tanks are closed to the outside or open to seawater.…”

Section: Introductionmentioning

confidence: 99%

Combined Depth Control Strategy for Low-Speed and Long-Range Autonomous Underwater Vehicles

Zhao

Zhang

et al. 2020

JMSE

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Autonomous underwater vehicles (AUVs) are increasingly being applied to highly detailed survey and inspection tasks over large ocean regions. These vehicles are required to have underwater hovering and low-speed cruising capabilities, and energy-saving property to enable long-range missions. To this end, a combined depth control strategy is proposed in which an on-off type variable ballast system (VBS) is adopted for satisfactory hovering or fast descending/ascending without propulsion to reach the designated cruising depth, whereas the bow and stern fins act as the actuator to maintain the cruising depth for more energy saving. A hierarchical architecture-based VBS controller, which comprises a ballast water mass planner and an on-off mass flowrate controller, is developed to assure good hovering performance of the on-off type VBS. Both numerical studies and basin tests are conducted on a middle-sized AUV to verify the feasibility and validity of this depth control strategy.

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“…Similar to the pumped water system, the buoyancy is varied by pumping the oil in and out of a pressure housing. 11,12,13 Almost all the above-mentioned techniques rely on change in mass to get net positive or negative buoyancy, without any changes in the overall volume of the system. A VBS based on volume change is reported by Shibuya and Yoshii 14 which uses the phase transition of material (wax) between solid and liquid states to change the volume of a bellows.…”

Section: Introductionmentioning

confidence: 99%

Design of a controllable variable buoyancy module and its performance analysis as a cascaded system for selective underwater deployment

Ranganathan

Singh

Nair

et al. 2017

Proceedings of the Institution of Mechanical Engineers, Part M:

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Variable buoyancy systems (VBSs) are commonly used in underwater vehicles to achieve efficient heave motion. Most of the time, these systems are used as a part of conventional underwater vehicles with diverse methods to achieve the necessary buoyancy variation. The potential of VBSs as standalone systems for heave motion underwater has not been given due attention and is still an unexplored area. In this paper, the design of a VBS as a standalone module for heave control and the possibility of using multiple such modules in a cascaded structure for selective underwater deployment is presented. Such cascaded systems have a variety of applications ranging from coastal surveillance to selective deployment for ocean sampling, and so on. A metallic-bellows-based variable buoyancy module (VBM), actuated using linear actuators, is proposed here. The mathematical modelling of the VBM and its open-loop performance are analysed for suitability with regards to the system to be cascaded. Two prototypes have been developed based on the optimal design requirements and tested. The developed modules are simple and efficient for shallow water applications, and can be used as add-ons for existing underwater vehicles or can just be used as standalone systems. These two modules are then cascaded and the performance of the cascaded system is analysed with simulations and experiments. The analysis shows the suitability of the system for selective deployment at various depths.

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A variable buoyancy system for deep ocean vehicles

Cited by 24 publications

References 2 publications

Design and Analysis of a Variable Buoyancy System for Efficient Hovering Control of Underwater Vehicles with State Feedback Controller

Design and Analysis of a Variable Buoyancy System for Efficient Hovering Control of Underwater Vehicles with State Feedback Controller

Combined Depth Control Strategy for Low-Speed and Long-Range Autonomous Underwater Vehicles

Design of a controllable variable buoyancy module and its performance analysis as a cascaded system for selective underwater deployment

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