SUMMARY - On November 13th the prototype Maverick robot was demonstrated at the Mobil Oil refinery in Paulsboro, New Jersey which was attended by representatives from the U.S. Department of Energy, Exxon, Mobil, General Electric, Thermo-Electron, and other representatives of industry. The demonstration was the culmination of nine months of intensive efforts, which stunned industry specialists by the brevity of the time involved to develop a nearly commercial working robot and deployment system.
MOBIL - PAULSBORO, NEW JERSEY
The test site location revealed several operational issues that will have to be coordinated in the future. Access to the base of the tanks is physically restricted by piping runs and the berms surrounding the tanks. The cabling running from the control trailer to the robot will need to be extended significantly. A longer cable will be needed to reach the exterior tank shell base for those tanks that have restricted access. The submergible cable length will need to be increased as well to allow inspections of the larger tanks. To deploy the robot, a cherry-picker was used to lift the 155-pound robot and the tripod from the ground up onto the tank top. This and a "Hot Work Permit" will be required to gain access to the work site. The operation of the tripod and winch were satisfactory and issues of covering the tank hatch after insertion and personnel breathing apparatus were discussed with safety personnel. In addition to these issues, a set of 2-way radios were used during the week which proved invaluable to coordinate operations between the ground and the tank top.
The first day of testing leading up to the demonstration required changes to the vehicle. Within the first ten feet of movement, the drive mechanisms began to jam and the vehicle was pulled out of the tank. The magnetic wheels had picked up almost 3/4 of an inch thick of metal shavings, rust, and pieces of welding rod off the tank bottom held together by a black substance, increasing the wheel diameter and jamming the mechanism. The magnetic wheels were removed and replaced with nonmagnetic wheels after fitting them with a toothed rubber tread. Traction was an issue due to the large rivets protruding upward from the tank floor plate seams, which was the reason for fitting the vehicle with the magnetic wheels. The new wheels performed well. An electrical noise problem was encountered also, but it was due to a loose electrical connector and was corrected quickly.
The tank bottom was covered with a heavy layer of material, consisting of metal filings and rust held together in clumps by a black tacky oil residue. The sludge partially blocked the ultrasonic probes from getting thickness readings on the tank bottom and was stirred up while driving, reducing visibility to a couple of inches. A narrow broom attachment was fitted to the front of the vehicle to clear a section of the tank floor prior to scanning it by driving back and forth across the section. It worked well for prepping the floor for inspection, but had the effect of kicking up so much material that the cameras were completely obscured.
The sonar-based tracking system was the last subsystem to be tested within the tank. Due to a high amount of ringing, the acoustics in the tank were very poor and the system was initially unable to operate. The equipment designer was flown out overnight from California to troubleshoot the system after all of the appropriate tests had been performed and had failed to bring the system up. The acoustics required modifications to the software and alternative settings out of the normal ranges to correct the problem, and the system was up for the demonstration operating from two baseline stations. Testing was conducted to see if the sonar transducers could hear and transmit through the tank wall, since deployment into the tank's interior proved to be rather difficult. The tests proved the system could operate from the exterior of the tank, which will greatly simplify operations and certification of the subsystem.
All of the equipment and systems was operating properly on the day of the demonstration. Throughout the week, all of the problems that cropped up were corrected on site using the spares and tools which were brought along to the demonstration. This fact impressed the Mobil personnel supporting the test. As the word spread, inspection personnel from the refinery dropped by just to get a look at the equipment to see the future of their profession.
The complete Maverick deployment system was evaluated for operational modifications. The control trailer was pulled a total of 5,300 miles, testing all packing, including computers and instrumentation, against road vibration. At the test site, the control trailer and consoles provided for a professional presentation. The robot vehicle was compact, streamlined and rugged. The cabling was clean and kept to a minimum. The personnel operating the equipment were prepared.