Analysis of optical linear encoders’ errors under vibration at different mounting conditions

The optical linear encoders are the preferred choice sensors for positioning machine tools’ moveable parts. Machine tools’ errors have been traditionally focused on the analysis and performance of the machine tool structure until recent works have treated the encoder itself as a source of error. Encoder error quantification has been done for several mounting conditions in static situations, but there is a lack of information regarding the performance of the encoder under dynamic solicitations. The aim of this work is to analyze the loss of accuracy of the sensor because of vibration for different mounting conditions. A finite element model of encoder has been developed and experimental results have been analyzed using this model.

► Optical linear encoders under vibrations at different mounting conditions.
► New resonances with important encoder error values to appear.
► Error influenced by yaw movements of the scanning carriage in relation to the scale.
► Error influenced by initial strains of coupling springs.
► The error can exceed several times the accuracy of the encoder.