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This paper describes a dual-track magnetic crankshaft and camshaft position sensor configuration. It uses semiconductor sensors such as magnetoresistors to pick up the magnetic flux modulation created by a toothed wheel rotating across a permanent magnet. This sen-sor's magnetic configuration, with a complementary geometry, enhances the accuracy and repeatability of the position pulses. This is critical in obtaining the engine-velocity measurement precision necessary to detect engine misfires as mandated by the OBD-II legislation. The complementary geometry also makes for a more robust design. Finally, the concept can be used for cam-shaft position sensing, with power-on capability.

MAGNECODE uses laser surface heating to pattern permanent magnets for position sensor applications. Thermal and magnetic models provide good predictions of the geometry of the laser heated regions and the resulting spatial variations in the magnetic field. Important design factors are discussed and a comparison with other magnetic sensor technologies is given.