High-precision interpolation using two-phase type PLL for encoders that have distorted waveforms

The authors tried to use two-phase type PLL (phase locked loops) of non-sinusoidal waveforms to interpolate distorted waveforms of incremental encoders. In order to obtain high-precision interpolation, the authors propose an iterative method to approximate the waveforms of the encoder. This method does not require precise sinusoidal waveforms of encoders for detecting positions with high resolution and high precision. The authors discuss the proposed method and present simulation and experimental results