Improvement of the sensing signal in geometry PIG caliper system

Summary form only given. The caliper system in geometry PIG is used to detect the dents, wrinkles and buckles of the underground gas pipe. In the caliper system, the displacement of the mechanical finger assembled with a rolling arm is measured with the magnetic field. So, the sensitivity of the caliper system mainly depends on the magnetic field of the permanent magnet. In this research, the structure of the permanent magnet, back yoke and pinhole positions are optimized. hi newly designed caliper system, the magnitude of the sensing signal is increased up to 309%.