An electromagnetic sensing technique to detect metallic objects for microtunneling system

This paper describes a new forward detection technique which detects metallic objects while underground conduits are being installed by using NTT's trenchless microtunneling system (ACEMOLE model PC10). The forward detection sensor developed here consists of one transmitting coil and two receiving coils. This technique uses electromagnetic induction to detect buried metallic objects up to 15 cm ahead. An earlier model compact signal processing unit and experimental front-end jack with a forward detection sensor could not detect objects in sideways directions. Therefore, the authors developed a new sensor that is able to detect objects in sideways directions, while also having excellent forward detection performance.