The Field Robotics Center (FRC) at Carnegie Mellon University is developing a mobile robot to inspect interiors of fuel storage tanks, both above-ground (AST) and under-ground (UGST). Neptune inspects tanks for visible deterioration, using a video camera and inspects for wall and floor corrosion, using add-on sensors, as part of its standard capabilities. The system includes a self-contained portable unit, which attaches to storage tanks. This unit deploys a small, reconfigurable robot, driven by dual magnetic tracks, carrying a camera and lights, navigation system, ultrasonic testing (UT) sensors, or other sensing probes. The robot's reconfigurable design allows it to fit through large tank openings (20" O.D.) using a parallel-crawler configuration. The robot is be tethered and relies on a purge/pressurization scheme for operation in explosive environments. The robot is propelled using electro-magnetic tracks, enabling the entire inside surface of a tank to be surveyed, whether the tank is full or empty. Magnetic force keeps the robot attached to the inside tank surfaces (fully accounting for its weight). Thus, the inside of the tank can be surveyed using a series of planned passes. By adding an accurate acoustic positioning system, it will be possible to monitor corrosive processes over time within the tank. In partially empty tanks or in tanks containing highly viscous fluids, an acoustic positioning system, relying on sound transmission and triangulation through the steel-walls, can be deployed. The robot is completely sealed so that it can operate safely inside of any fuel tank, regardless of fuel-level. Its small size makes it easy to transport and usable on a wide variety of tank sizes and shapes. Computer control and graphic interfaces to display robot position and tank corrosion status will be possible. It is envisioned that one person will be able to operate this system. Because the system is enclosed and pressurized, operation will be safe. Through careful design, proper component selection, and adherence to NEC Class I - Div. I and all applicable NFPA, UL/FM, OSHA, NESC, and API standards, it will be possible to ensure safe operation in Group D environments. The project is jointly funded by the US Army Corps of Engineers and Ebasco Services, Inc., with the Corps' US Army Construction Engineering Research Laboratories managing the research. The government sponsor is interested in seeing its many tanks inspected by this system. The industrial partner plans to offer this technology as a nationwide service. Both sponsors are contributing navigation and UT-sensing technologies and software to the overall system. The development program calls for a finished prototype by the spring of 1994. Certification of the system, through an organization such as Factory Mutual Research Corp. (FM) or Underwriters Laboratories (UL), will allow field-testing in US Army and commercial tank-farms across the US by the summer of 1994.
