||In 2012, the Abyss Twisted-pair Imaging System (ATIS) was built by the National Yat-sen University for gas hydrate investigation off southwest Taiwan. After several deep-towed operations, we found that the battery life of the ATIS is a bit short for its video storage and recording capacity. In addition, we found that, on the ATIS, the capabilities of adding optional sensors, sizing objects, obstacle avoidance, and heading adjustment are absent. Therefore, in this study, a new vehicle ATIS II was developed to extend battery life and to allow for providing the capabilities of adding optional sensors, sizing objects, obstacle avoidance, and heading adjustment. On the issue of increasing battery life, the ATIS was originally equipped with the lithium ion batteries which can provide power for as long as 2.5 hours. Considering the cost of the battery, the ATIS II adopted the Absorbent Glass Mat (AGM) batteries as the power source.|
By the use of the AGM batteries, the ATIS II can sustain the operation for 5 hours that is the average recording storage time for the ATIS video system. For adding optional sensors on the ATIS II, a junction box was designed to provide a simple, compact and low cost solution to the problem of accessing optional sensor data inputs. For object scaling, a parallel laser system was incorporated into the imaging system of the ATIS II. Two parallel lasers separated by a known distance (30 cm) are projected onto the seafloor object. When a video is taken, the laser projections on the target provide a scale bar that can be used to measure the size of objects in the image. As for obstacle avoidance, it is extremely important to always know whether there is obstacle in the way or not while towing an underwater vehicle. Therefore, a scanning sonar was integrated into the ATIS II for detecting the obstacle during the tows. Considering the issue of heading adjustment, a fixed fin was mounted on the ATIS for stabilizing the
vehicle in yaw motion while towing the ATIS. However, the heading of the ATIS can be difficult to maintain on the course direction when environmental forces act on the vehicle in an unpredictable manner. When the vehicle heading deviates from the course direction, heading adjustment is needed for better quality of seafloor video observation. Therefore, an adjustable fin was designed for the ATIS II so that the fin angle can be altered to maintain the vehicle’s heading on the towing direction. Based on the improvement designs mentioned above, the water proof housings for batteries and electronics are redesigned. As well, a new frame for ATIS II are designed for optimum placement of electronic housings, junction box, the imaging system, sensors, and the adjustable fin.