Sea Technology

DEC 2012

The industry's recognized authority for design, engineering and application of equipment and services in the global ocean community

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Sea & Sun Marine Tech The Coastal Glider shown underwater near Greenland. to the battery mass by a drive chain, and measurement of the battery roll is affected by the use of a separate potentiometer engaged with the chain. Limit switches are also integrated into the adaptor plate to prevent damage if the roll system is overdriven. All of the drive components (BE pump, BE valve, pitch motor and roll motor) are located in the front of the glider to keep the electrically noisy equipment away from the communications equipment, navigation equipment and science equipment in the aft electronics bay. The arrangement of these components dictated a larger diameter than is found on other gliders. The outside diameter of the main hull measures 0.32 meters for compatibility with equipment for handling small-size standard torpedoes. Battery and Power System. The glider runs on a lithium battery, with all electronics designed to be powered by 18 to 32 volts DC. Power use in a glider is very irregular. The glider will go for long periods of time on the descent or ascent using very little power. Most of the motive power is used in a few seconds at the bottom infection. This type of large draw is diffcult for batteries to provide and tends to shorten battery life. For this reason, an ultracapacitor pack was installed, from which all of the main actuators are powered. This also helps to decouple the motors from the more sensitive electronic equipment. The ultracapacitors are located below the pitch, roll and internal BE components. Electronics Bay. The electronics bay comprises a dry cylindrical volume that has a 19.1-centimeter inner diameter and is 30.5 centimeters long. Approximately 80 percent of this volume (7 liters) is available for sensor integration. The remaining section is reserved for glider communications and navigation equipment. Communications and Navigation. The standard glider is equipped with three modes of communications: WiFi, Freewave and Iridium. The glider also has a GPS unit for determining location. All communications are facilitated by an antenna mounted on the aft centerline of the glider. All three communications modalities use the same interface and command structure. Wi-Fi is generally used in the shop or on the deck to communicate with the glider for uploading mission fles and downloading large data fles, or for doing routine maintenance tasks. Freewave line-of-sight communications is used when launching and retrieving the glider. Iridium monitors and controls the glider when it is out of range of other communications. The communications system allows for telemetry of engineering data via Iridium to either a server at Exocetus or a specially confgured customer server. Data includes position information and glider status, battery voltage, average power consumption and any warnings or faults. Data from the science computer is collected and stored Sea & Sun Technology DECEMBER 2012 / st 35

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