Precision X-Y robotic object handling using a dual GMR bridge sensor

A dual integrated GMR bridge sensor, which is able to simultaneously detect x and y components of an external magnetic field, was demonstrated, and applied to the precision robotic placement of objects. Two orthogonal GMR bridges are used, biased by two sets of integrated Co/sub 78/Pt/sub 22/ film permanent magnets with different coercivities (1230 Oe and 522 Oe, respectively). The field sensitivity is 0.35 mV/(V/spl times/Oe) in each field direction. For the positioning application, an absolute accuracy of 10 /spl mu/m in x-direction has been achieved over more than 1900 cycles which is insensitive to sensor offsets and thermal drifts.