Method and apparatus for positioning a boat by monitoring the magnetic field created by current circulating in an electric circuit

• Main Author: POSSEME; GILLES
• Format: Patent
• Language: English
• Published: 04.09.1984
• Subjects: CONTROLLING; PHYSICS; REGULATING; SYSTEMS FOR CONTROLLING OR REGULATING NON-ELECTRIC VARIABLES

Device for positioning a moving body in a plane indicated by the axes OX and OY by using a magnetic field. A current i, which is the sum of a current io at frequency fo in which fo &persp& 100 Hz and a current i1 at frequency f1 in which f1 &persp& 10 kHz modulated by bursts of recurring pulses having a period To with To=1/fo flows through a conductor. The moving body carries two pairs of magnetometers supplying the components of the magnetic field hxo, hyo and hx1, hy1 with respect to axes associated with the moving body about frequencies fo and f1. A subassembly, on the basis of the values of hxo and hyo, supplies a signal U1 of frequency 2fo. A subassembly, on the basis of the signal U1, supplies two signals S1 and S2 displaced by To/2. Another subassembly supplies signals T on the basis of the values of hx1 and hy1, which are compared with the signals S1 and S2 for supplying a signal S on the basis of signal U1. Signal S makes it possible to demodulate the components hxo and hyo, which are thus obtained with their signs, determining without ambiguity the position of the moving body.