Page 625 - The ROV Manual - A User Guide for Remotely Operated Vehicles 2nd edition

individual manufacturer’s maintenance schedule is meticulously followed. A sample maintenance schedule is provided below in “Operational forms” (Section 22.2.5).
22.2.2 Basics of ROV troubleshooting
22.2.2.1 Basics of an ROV system
There is not much “high technology” in designing, manufacturing, and producing an ROV system. Every year, the Marine Advanced Technology Education Center (MATE) hosts an ROV competi- tion for high school and college students who put together their own operational ROV system. Educators in British Columbia have put forth a book on how to build an ROV in a garage out of hardware store parts (Bohm and Jensen, 1997). The difficulty is in producing a commercially viable and reliable system that can take the abuse of fieldwork and produce results.
The basic parts of a free-swimming, OCROV system follow:
• Submersible
• Tools and sensors
• Tether
• Power supply
• Controller
• Viewing device
Essentially, an ROV is a camera generating a video signal mounted in a waterproof housing with electric motors attached to a cable. Practically all of the vehicles use common consumer industry standard commercial off-the-shelf (COTS) components.
There are a few items on the system that require computer processing power, including the sonar, the acoustic positioning system, some instrument packages, controls to run the motor driver boards or manipulator, and telemetry from the submersible to the surface. Practically all of these are located on “easily changeable” printed circuit boards. The only real nonelectronic challenge for an ROV technician is working with the O-rings, seals, and tight machining tolerances needed to complete a waterproof seal on the submersible. A simplified schematic of an ROV submersible control system is shown in Figure 22.10.
From these basics (with the use of manufacturer-supplied schematics and drawings), one should be capable of performing basic troubleshooting in the field to complete the mission requirements.
22.2.2.2 The troubleshooting process
Effective and efficient troubleshooting requires gathering clues and applying deductive reasoning to isolate the problem. Once the problem is isolated, one can analyze, test, and substitute good compo- nents for suspected bad ones to find the particular part that has failed.
The use of general test equipment (such as a digital multimeter) or special test equipment (such as an NTSC pattern generator and an oscilloscope) can speed the analysis, but for many failures, deductive reasoning can suffice. Once it is determined whether the problem is electronic or mechanical, deductive analysis changes to intelligent trial-and-error replacement. Reducing the number of suspected components to just a few and then using intelligent substitution are the fastest ways to identify the faulty device.
22.2 Servicing and troubleshooting 625