Aquaculture Feed Buoy Control - Part 1: System Controller

A critical part of an aquaculture operation is feeding the fish (at the right time, the right amount at the right rate) and monitoring the operation. The UNH Open Ocean Aquaculture demonstration project is working on its third and most ambitious automated, remote feeding buoy for offshore aquaculture operations. A central part of the feeders is a computer and software in the feed buoy, which controls and monitors the operations. This onboard processor has a large variety of tasks. It must start the generator in time for scheduled large power drain activities such as powering lights in the submerged fish cages to delay sexual maturation, and the feeding operations with its pumps, feed augers, feed dosers, etc. Also, the system must monitor of the status of each of these activity as they are taking place. This includes seeing that the generator started properly, that power is on the generator's power bus, and then switching it to the main system power bus. When activities such as feeding are taking place, the system must monitor the quantity of feed in the feed hopper, the rate that the feed is being delivered to the feed hose, and the pressure in the feed hose (to catch any blockages). The system also has a series of critical points that it monitors, such as any water in the buoy, the backup battery voltage, the rate of charge by any solar and wind power system and any critical problems with feeding or other activities. The system is programmed to respond to any problems, such as emergency shut down of the generator should it get too hot, the oil pressure too low, and the fuel level gets low. It will also terminate any feeding activity if the pressure in the feed hose rises indicating blockage. If water is detected in the buoy, indicating a leakage in the buoy itself or from one of the subsystems, the system sends an alert to shore as well as turns off any critical activities and making sure that all bilge pumps are active. The programmed activities are controlled by a series of files stored on compact flash in the computer. The system checks each hour to see if an activity is scheduled, then reads another control file (listed in the activities timing file) that will control the details of that activity. If it is feeding time, then it will read the feeding file specified which will tell how fast to feed, for what duration, and what sequence of pumps to use during the feeding process. By referring to different feeding control files, several feeding schedules can be run during one day, or on a weekly cycle. A feeding cycle may include putting a small amount of feed in the hose, then turning on a pump to wash it down to the fish cage, then waiting a little time for the fish to eat that food, and repeating the operation a number of times again. These systems are evolving with the third feed buoy, and lessons learned from the first two are being incorporated into the next