Page 299 - The ROV Manual - A User Guide for Remotely Operated Vehicles 2nd edition

11.1.2 Vehicle health monitoring sensors
Vehicle health monitoring sensors resolve various measures within the vehicle in order to detect any parameter that strays from its nominal value. The human analog for this would be the measur- ing of blood pressure, body temperature, heart rate, blood chemistry, and the like (versus naviga- tional parameters such as running speed/distance, speech rate, lifting weight/amount). On an ROV, such parameters are used for a series of diagnostics and alarms to warn of impending faults or dam- age to system components. Some common vehicle health monitoring sensors are as follows:
Water ingress alarm: Seawater is a conductor. To measure water ingress into an air-filled space, a simple open circuit with a small potential is placed at the low point of a pressure bottle. Should a small amount of water begin to enter the bottle, the water will eventually rise to a level that contacts both conductors, thus allowing a current to pass between them. This sets off the water ingress alarm on the pilot’s console, warning of a potentially hazardous state. A word of caution—put the water ingress sensor at the very bottom of the bottle. If it is at the top, it will fry the electronics in the bottle due to board submersion before the alarm ever sounds.
Oil temperature: Oil temperature outside of a nominal range could signal breakdown of the lubricity of the fluid (especially an over-temperature status). The vehicle or lubricant manufacturer will have further information on the normal operating temperature. Alarms may then be set once temperatures fall outside of some nominal range.
Oil pressure: Oil pressure is also a critical parameter for monitoring the health of the system. Any combination of factors could cause a loss or spike in oil pressure and elicit any number of hazardous conditions. Hydraulic circuit pressure should be carefully monitored throughout the mission. On electric vehicles, oil provides lubrication for the thrusters and motive power for the manipulators and tooling; however, it is not critical to the vehicle’s operation. On the hydraulic WCROV, oil pressure is life or death to the vehicle’s function.
Compensator oil level: On more complex vehicles (especially WCROV systems), compensator oil levels are measured and monitored with output to the pilot’s console. Typically, a minimum level is set on the system alarms so that an early warning is given to the operator that the reservoir is low before the compensator’s oil is depleted. Compensator systems are discussed further in Chapter 20.
System diagnostics: Along with the vehicle’s health monitoring sensors is a logic circuit within the CPU. This software routine constantly monitors system parameters and (theoretically) diagnoses any potential problems before they become hazardous conditions. System diagnostics also assist in resolving any system faults identified through sensor readings. These systems range from the simple to the complex depending upon the vehicle operated and the difficulty of the environment encountered.
11.2 Vehicle lighting
In this section, some theory is necessary in order to properly understand lighting specifications issued by manufacturers of lighting products. We will get into a discussion of lighting parameters before delving into the practical applications of underwater lighting technology.
11.2 Vehicle lighting 289