Development of the power distribution system and communications hub for an underwater remotely operated vehicle

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dc.contributor.advisorMarais, Stephenen_ZA
dc.contributor.authorDe Smidt, Rogeren_ZA
dc.date.accessioned2015-07-01T08:57:16Z
dc.date.available2015-07-01T08:57:16Z
dc.date.issued2014en_ZA
dc.descriptionIncludes bibliographical references.en_ZA
dc.description.abstractThis report details the research, design, development and testing of the third generation underwater remotely operated vehicle (ROV) produced by the University of Cape Town’s Robotics and Agents Research Laboratory (RARL). The ROV was designed and built in response to a request from the Department of Zoology for an ROV to aid their oceanic research. The two generations that had gone before this ROV had provided the research group with good experience, but a new vehicle was required that would offer a more robust research tool for the zoologists and a more versatile platform for future development within the RARL. ROV System Together with project partner Thomas Knight, a new ROV design was developed that was based on the open frame designs commonly used on commercially available ROVs. The ROV was to be propelled by five individual thruster modules and carried four high-powered LED light modules to provide lighting for the ROV’s forward and aft video cameras. In order to navigate the ROV a sonar unit was also incorporated on board. In order to provide power and communications from the surface station to each of the modules on board the ROV, distribution systems for each were required. As the project progressed, it became clear that these distribution systems were critical to the reliability and versatility of the vehicle and became the focus of the author’s scope. The report starts with a description of the design process that resulted in the decision to design a new ROV and then a brief description is provided of the ROV systems incorporated in the final design. The detailed design of the power and communications distribution systems is then presented using a bottom-up design approach, starting with the distribution of power and communications on board the ROV. Brief descriptions of the major components in these systems follow below. Electronics Pod The Electronics Pod (E-Pod) was designed to distribute power to each module on the ROV at the required voltages and currents, and to distribute serial communications to each module over an RS- 485 multi-drop network. The E-Pod incorporated two microcontrollers that were used to control the switching of power to each of the modules and were also connected on the RS-485 communications network. This RS-485 network was connected to the surface via an optical fibre link in the ROV’s tether, and the two converters required to establish this link were also housed in the E-Pod. Video feeds from the on-board cameras were fed into an encoder in the E-Pod and transmitted to the surface controller also via the fibre link. The power required by the E-Pod was drawn from the Power Pod on the ROV, which is described below. Power Pod The Power Pod was designed to convert the 400 VDC supply from the tether into 5 V, 12 V, 15 V and 48 V, which were required by the E-Pod. A total of 1.66kW was to be supplied to the E-Pod so compact, high-power DC-DC converters were integrated into the design of custom-made printed circuit boards (PCBs) in order to provide the required power. Currents sensors, temperature sensors and voltage level sensors were incorporated in the Power Pod circuitry. A microcontroller in the Power Pod was used to read all of the sensors and communicate the values to the surface controller via the E-Pod. Subsea Junction Box Because the ROV’s tether contained copper cores for power transmission and optical fibres for communications transmission, a very expensive hybrid subsea connector was required if it was to plug directly into the Power Pod or E-Pod. A junction box was therefore designed in which the copper cores of tether were separated from the optical fibres. The copper cores were fed to the Power Pod and the optical fibres to the E-Pod. The junction box was filled with oil and pressure compensated to reduce the risk of water ingress. Surface Power Supply Unit Including power losses in the distribution system, 2kW of power was required to be supplied to the tether. A surface power supply unit (PSU) was designed with an isolated, ungrounded 400 VDC power supply, which ran off a standard 230 V, 16 A mains supply. Start and emergency-stop switches were provided on the PSU enclosure, as well as a lockable isolator. The PSU incorporated an Ethernet network switch and fibre optic media converter to provide the link necessary between the tether and the laptop running the user interface and sonar software.en_ZA
dc.identifier.apacitationDe Smidt, R. (2014). <i>Development of the power distribution system and communications hub for an underwater remotely operated vehicle</i>. (Thesis). University of Cape Town ,Faculty of Engineering & the Built Environment ,Department of Mechanical Engineering. Retrieved from http://hdl.handle.net/11427/13229en_ZA
dc.identifier.chicagocitationDe Smidt, Roger. <i>"Development of the power distribution system and communications hub for an underwater remotely operated vehicle."</i> Thesis., University of Cape Town ,Faculty of Engineering & the Built Environment ,Department of Mechanical Engineering, 2014. http://hdl.handle.net/11427/13229en_ZA
dc.identifier.citationDe Smidt, R. 2014. Development of the power distribution system and communications hub for an underwater remotely operated vehicle. University of Cape Town.en_ZA
dc.identifier.ris TY - Thesis / Dissertation AU - De Smidt, Roger AB - This report details the research, design, development and testing of the third generation underwater remotely operated vehicle (ROV) produced by the University of Cape Town’s Robotics and Agents Research Laboratory (RARL). The ROV was designed and built in response to a request from the Department of Zoology for an ROV to aid their oceanic research. The two generations that had gone before this ROV had provided the research group with good experience, but a new vehicle was required that would offer a more robust research tool for the zoologists and a more versatile platform for future development within the RARL. ROV System Together with project partner Thomas Knight, a new ROV design was developed that was based on the open frame designs commonly used on commercially available ROVs. The ROV was to be propelled by five individual thruster modules and carried four high-powered LED light modules to provide lighting for the ROV’s forward and aft video cameras. In order to navigate the ROV a sonar unit was also incorporated on board. In order to provide power and communications from the surface station to each of the modules on board the ROV, distribution systems for each were required. As the project progressed, it became clear that these distribution systems were critical to the reliability and versatility of the vehicle and became the focus of the author’s scope. The report starts with a description of the design process that resulted in the decision to design a new ROV and then a brief description is provided of the ROV systems incorporated in the final design. The detailed design of the power and communications distribution systems is then presented using a bottom-up design approach, starting with the distribution of power and communications on board the ROV. Brief descriptions of the major components in these systems follow below. Electronics Pod The Electronics Pod (E-Pod) was designed to distribute power to each module on the ROV at the required voltages and currents, and to distribute serial communications to each module over an RS- 485 multi-drop network. The E-Pod incorporated two microcontrollers that were used to control the switching of power to each of the modules and were also connected on the RS-485 communications network. This RS-485 network was connected to the surface via an optical fibre link in the ROV’s tether, and the two converters required to establish this link were also housed in the E-Pod. Video feeds from the on-board cameras were fed into an encoder in the E-Pod and transmitted to the surface controller also via the fibre link. The power required by the E-Pod was drawn from the Power Pod on the ROV, which is described below. Power Pod The Power Pod was designed to convert the 400 VDC supply from the tether into 5 V, 12 V, 15 V and 48 V, which were required by the E-Pod. A total of 1.66kW was to be supplied to the E-Pod so compact, high-power DC-DC converters were integrated into the design of custom-made printed circuit boards (PCBs) in order to provide the required power. Currents sensors, temperature sensors and voltage level sensors were incorporated in the Power Pod circuitry. A microcontroller in the Power Pod was used to read all of the sensors and communicate the values to the surface controller via the E-Pod. Subsea Junction Box Because the ROV’s tether contained copper cores for power transmission and optical fibres for communications transmission, a very expensive hybrid subsea connector was required if it was to plug directly into the Power Pod or E-Pod. A junction box was therefore designed in which the copper cores of tether were separated from the optical fibres. The copper cores were fed to the Power Pod and the optical fibres to the E-Pod. The junction box was filled with oil and pressure compensated to reduce the risk of water ingress. Surface Power Supply Unit Including power losses in the distribution system, 2kW of power was required to be supplied to the tether. A surface power supply unit (PSU) was designed with an isolated, ungrounded 400 VDC power supply, which ran off a standard 230 V, 16 A mains supply. Start and emergency-stop switches were provided on the PSU enclosure, as well as a lockable isolator. The PSU incorporated an Ethernet network switch and fibre optic media converter to provide the link necessary between the tether and the laptop running the user interface and sonar software. DA - 2014 DB - OpenUCT DP - University of Cape Town LK - https://open.uct.ac.za PB - University of Cape Town PY - 2014 T1 - Development of the power distribution system and communications hub for an underwater remotely operated vehicle TI - Development of the power distribution system and communications hub for an underwater remotely operated vehicle UR - http://hdl.handle.net/11427/13229 ER - en_ZA
dc.identifier.urihttp://hdl.handle.net/11427/13229
dc.identifier.vancouvercitationDe Smidt R. Development of the power distribution system and communications hub for an underwater remotely operated vehicle. [Thesis]. University of Cape Town ,Faculty of Engineering & the Built Environment ,Department of Mechanical Engineering, 2014 [cited yyyy month dd]. Available from: http://hdl.handle.net/11427/13229en_ZA
dc.language.isoengen_ZA
dc.publisher.departmentDepartment of Mechanical Engineeringen_ZA
dc.publisher.facultyFaculty of Engineering and the Built Environment
dc.publisher.institutionUniversity of Cape Town
dc.subject.otherMechanical Engineeringen_ZA
dc.titleDevelopment of the power distribution system and communications hub for an underwater remotely operated vehicleen_ZA
dc.typeMaster Thesis
dc.type.qualificationlevelMasters
dc.type.qualificationnameMSc(Eng)en_ZA
uct.type.filetypeText
uct.type.filetypeImage
uct.type.publicationResearchen_ZA
uct.type.resourceThesisen_ZA
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