Pipeline mandrel positioning control system

摘要

A method and apparatus is provided for automated control and positioning of a mandrel within a pipe during bending operations. Position detection is accomplished by means of a low frequency electromagnetic signal transmission from a coil placed in close proximity parallel to the pipe outer surface. This signal is detected by a pair of orthogonal receiving coils mounted on the mandrel in close proximity to the pipe inner surface. The phases of the received signals with respect to the transmitted signal and the ratio of the amplitudes of the two received signals is used to estimate the relative position of the transmitter and the receivers. Control of the mandrel along with transmission of reference phase information is accomplished via a high frequency direct sequence spread spectrum radio link between a computer console outside the pipe mounted on the bender and a computer unit mounted inside the pipe on the mandrel.