According to High precision parts customization Experience ， Machining of mechanical parts The error sources of the inductive micrometer are as follows ：

　　１、 The nonlinear error of inductance measurement principle

　　 Because displacement and output voltage and inductance are nonlinear ， The measurement circuit is also nonlinear ， Therefore ， Machining of mechanical parts In order to reduce the nonlinear error ， Differential structure and limited measuring range are often used 。 For example ， Machining of mechanical parts Manufactor For variable air gap measurement range 1/5～1/10 Air gap length of ， Solenoid 1/3～1/10 Coil length of ， The increase of coil length is beneficial to the expansion of linear range ， However, special attention should be paid to the uniformity of magnetic conducting material and winding and the machining accuracy of coil framework 。 Symmetry shall be ensured for differential structure ， Reasonable selection of armature length and coil pitch ， This should be obtained through experiments 。

　　２、 Zero position error of micrometer

　　 The bridge output shall be zero when the armature is in the middle position ， However, due to the asymmetry of geometric and electrical parameters of the two coils in the mechanism 、 Zero position error caused by inconsistency and other reasons 。 Too much zero voltage will saturate the amplifier ahead of time ， Make the servo motor heating and cause the system control failure 。 It is required to measure and select parameters of main parts during assembly ， Stability treatment of magnetic materials in processing 。

　　３、 Temperature error

　　 The change of the temperature of the micrometer will cause zero drift ， Its linearity and phase will change Temperature error 。 Change of dimension of mechanism parts caused by temperature change 、 The change of resistivity of materials will change the coil impedance ， Destroy the original balance ， Permeability of magnetic material caused by temperature change 、 Change of material medium ， Change of output inductance and parasitic capacitance 。 Therefore ， The magnetic material selection in the mechanism can meet the magnetic requirements ， We should also pay attention to the selection and matching of linear expansion coefficient 。

　　４、 Power fluctuation

　　 Will cause output signal fluctuation ， Power fluctuation It will change the magnetic induction strength and permeability of iron core and cause the change of magnetic resistance ， Therefore Stay Machining of mechanical parts In ， Power supply should be stabilized 。 The fluctuation of power frequency will cause the change of inductive reactance ， Differential operation can be used to compensate for its influence ， The selected magnetic material should match the frequency change 。