Wireless communication with mobile inspection robots while submerged inside oil storage tanks

Data acquisition during storage tank inspection is one of the most important aspects for petrochemical storage tank owners. Mobile inspection robots designed to enter inside a storage tank without taking the tank out of service are required to enter through manholes on the roof of the tank with openings as small as 300-millimetre diameter. These robots are controlled via an umbilical cable which supplies power to the robot, sends and receives signals to control robot motion, and transfers inspection data acquired by non-destructive testing (NDT) sensors back to NDT inspectors. It is important to localize a robot inside the tank so that NDT data indicating a defect such as corrosion pitting in tank floors or weld cracks can be mapped for subsequent monitoring and repair. Wireless communication with the robot for NDT data acquisition and localization would enable the minimization of umbilical size and its effective management which is important when a small mobile robot is supplied with a very long umbilical. This paper presents results of a study to develop a wireless communication system that uses radio frequency (RF) signals with low power (