Measurement Principle

The pig’s translational and rotational movements are measured with the help of accelerometers and gyroscopes, which are the main components of this inertial system. After compensating for the earth’s rotation, gravitation and other forces, it determines orientations and velocities in X, Y and Z directions. By correlating the inertial system results with the data from dippers and odometer information, the pig computes the exact orientation and position of the pipeline in three dimensions.

Known reference points are necessary to achieve sufficient accuracy of absolute measurements (in Differential GPS - DGPS - position and GPS time). For this purpose, ROSEN uses above-ground benchmarkers placed at known GPS reference points. The marker receiver is then activated by the on-board pig transmitter system. The system records the GPS time of the pig’s passage, e.g. measuring the GPS position of the trap stations and line valves generates reference points.