Conceptual design of a Submersible Remotely Operated Swimming Dredger (SROSD)
- Authors: Sarkar, Mridul , Bose, Neil , Chai, Shuhong , Dowling, Kim
- Date: 2011
- Type: Text , Conference proceedings
- Full Text: false
- Description: Increasing use of deep-water dredging and mining vehicles has been anticipated for resource collection, engineering construction and environmental protection. Existing deep-dredging or mining equipment can be classified as i) diver-assisted dredging tools, ii) surfacefloating dredgers with deep-dredging capability and iii) submersible dredgers. Diver assisted dredging tools have limited capacity and involve human risk. Surface floating dredgers can work to a specific dredging depth controlled by their ladder length, but modification is limited by their large size and significant cost. Submersible dredgers are deployed for sub-sea operations and are the focus of this research. Submersible crawlers and walkers work in a submerged terrain-contact condition and depend on their apparent weight and ground reactions to counteract the excavation forces. Crawlers are inefficient in negotiating difficult subsea terrain and walking submersibles are slow moving over long-distances. Considering the constraints of dredging depth, negotiation of uneven terrain, slow motion, interchange ability of excavation or transport sub-system components and station keeping during operation, a new type of submersible dredger or miner was conceived. In working mode, it imitates a walking motion by spuds that are also used for station keeping during dredging. For longdistance travel, the vehicle can swim by means of vector thrusters. The vector thrusters also help in position-keeping and motion-control during swimming. To offset higher forces generated during excavation of hard materials, spuds, variable buoyancy tanks and control planes are included as secondary station-keeping devices. The paper describes the general arrangement and the distinguished sub-systems of the conceptualised vehicle. Special attention was given to working and swimming locomotion and the methods of station keeping during operation. Investigations about the station-keeping, propulsion and controlling conditions of the vehicle are in progress. Experiments to measure the cutting forces from the cutter design are described. It is expected that the new design will significantly contribute to the evolution of existing deep-dredging equipment with improved efficiency, increased mobility and location control while minimising larger environmental disturbances. Copyright © 2011 by ASME.
Turbidity caused by spillage from a dredging/mining transverse axis cutter
- Authors: Sarkar, Mridul , Bose, Neil , Sarkar, Sritama , Dowling, Kim
- Date: 2013
- Type: Text , Conference paper
- Relation: 20th World dredging congress and exhibition 2013 (WODCON XX): The art of dredging p. 636-645
- Full Text: false
- Reviewed:
Discussions on locomotion and excavation systems of 'SROSD II' : A new concept of submersible dredger
- Authors: Sarkar, Mridul , Sarkar, Sritama , Bose, Neil , Chai, Shuhong , Dowling, Kim
- Date: 2015
- Type: Text , Conference proceedings
- Full Text: false
- Description: Different types of submersible dredgers are conceived, modeled and even some prototype and full-scale vehicles are built for prospective subsea excavation purposes by various researchers and commercial companies. Most common type of submersible dredgers is tracked vehicle. Walking submersible dredgers are also available which can be further subdivided into passive legged systems (locomotion performed by moving frames) and active legged systems (locomotion performed by individually controlled legs). An Archimedian screw system is also conceived for a subsea mining vehicle. Continuous ground contact is necessary for tracks and Archimedan screw types of locomotion systems. Legged locomotion also requires intermittent contact with the terrain. Generation of adequate friction for locomotion purposes in very soft cohesive sediments or submerged rocky terrain is often critical. In soft cohesive terrain, the vehicle can capsize due to insufficient bearing capacity. Additional ground contact forces are necessary to counteract the excavation and environmental forces. In low-friction and/or low bearing capacity subsea terrains, achieving the force balance for the stability of the above mentioned submersible dredgers can thus be difficult. Also, the subsea terrain can be uneven with steep slopes and can be unchartered. Hence, a conceptual design of a submersible remotely-operated swimming dredger (SROSD II) is conceived. The SROSD II can swim with the aid of multiple control planes and thruster system in order to avoid difficult subsea terrains. For disjointed working areas, SROSD II can swim and thus can significantly reduce the non-working time. During excavation, SROSD II can anchor itself with the help of hydraulically actuated spuds. The anchored spuds and the thrusters can provide the necessary reaction forces to counteract the excavation and environmental forces. Unlike other submersible vehicles, the SROSD II is an almost neutrally buoyant system. In this paper the general arrangement of the SROSD II, the proposed locomotion and excavation systems are discussed. A simplified model for position keeping during excavation is also presented. © 2015 IEEE.