AMOSIN - the measuring principle

® Primary windings Secondary windings The measuring systems function on the principle of a transformer with a moving reluctance core. The mutual inductance of the primary and secondary windings of a transformer changes in accordance with the relative position of the core.
® Micro-coilstructure Sensor substrate Measuring scale = 1000 µm) of variable reluctance has been etched using photo-lithographic techniques.
SINCOSSINCOS The system consists primarily of a planar coil and a Measuring scale (Fig.1). The coil structure, with a number of winding elements (individual main elements with primary and secondary SIN/COS coils) aligned in the direction of measurement, is implemented on a substrate using micro-multi-layer technology. The measuring scale is a stainless-steel ring onto which a highly precise graduations (e.g.
® The relative angular movement in the direction of measurement between the sensor structure (in the scanning head) and the Measuring scale(measuring flange) periodically changes the mutual inductance of the individual coils, generating two sinusoidal signals with a 90° phase difference (SIN and COS). The extremely accurate signal, and its immunity to environmental influences, has the effect that, after conditioning of the signal in the evaluation electronics (Fig. 2), deviations of no more than 0.1% from the ideal sinusoidal form (harmonic content) remains. This allows high interpolation factors (further levels of sub-dividing ) to be carried out in the course of signal digitisation. This can either be done in the measuring system itself, or in the subsequent electronics (CNC etc.).An important feature of the prin-ciple of operation is that using the
AMOSIN - MEASURING PRINCIPLE(Fig. 1) AMOSIN procedure does not give rise to any measurement hystere- sis (machine backlash error). In contrast to magnetic systems, the high-frequency alternating field suppresses any hysteresis in the material.The evaluation electronics con-ditions the sensor signals and interpolates them continuously, without using strobe times, ex- ploiting a novel circuit principle. It then supplies the measurement information at the output through differential interfaces and line- drivers, either as a sinusoidal signal or as a square wave signal.
® EEPROMconfigurationdata Power supply unit Analogoutput~ 1 VppEncoderoutput RS 422 ASIC signal conditioning + evaluation Compensation signals (See the signal diagram on Page 26) Sensor unit Electronic evaluationstage In addition to the periodic quad- rature signals (A, B and their inverted) a reference signal is output for the determination of absolute position. This signal is generated from individual marks integrated into the measuring ring, and does not require any additional parts.
Measuring scale AMOSINMEASURING SYSTEM(Fig. 2) (See the description of the reference signal on Page 26.)

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