Dual-Phase Encoder Interpolation with Two-Stage Noise Reduction
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Solution Overview
Problem
Existing optical rotary encoder systems face challenges in enhancing resolution and accuracy due to noise, distortion, and phase errors in encode signals, which lead to incorrect interpolation signals and errors in position detection.
Innovation Solution
A signal processing apparatus with a first noise reduction unit to remove high-frequency noise before interpolation processing, followed by an interpolating unit for generating higher-resolution signals, and a second noise reduction unit to remove noise from the output signals, effectively addressing noise and distortion issues.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a single noise suppression circuit using analog parts is used, then high frequency noise is removed, but distortion components, phase errors, and offset errors remain
Solution Approach 1:
The noise suppression function is divided into multiple stages: a first noise suppression circuit before interpolation processing and a second noise suppression circuit after interpolation processing. Each stage targets different types of noise and errors, with the first circuit handling high frequency noise and the second circuit handling remaining distortion components, phase errors, and offset errors, thereby comprehensively improving position detection accuracy
Solution Approach 2:
The first noise suppression circuit performs preliminary noise suppression on the encode signals before they enter the interpolation processing unit. This preliminary action removes high frequency noise components in advance, preventing them from causing interpolation errors and improving the quality of signals fed into the interpolation circuit
2Measurement precision
If interpolation processing is applied to encode signals with errors, then resolution is enhanced, but interpolation signals include errors
Solution Approach 1:
Before the interpolation processing unit processes the encode signals, the first noise suppression circuit performs preliminary suppression of high frequency noise and other errors. This preliminary action ensures that the interpolation circuit receives cleaner signals, thereby enhancing angle resolution while minimizing the introduction of interpolation errors
Solution Approach 2:
The second noise suppression circuit processes the interpolation signals after they are generated, providing a feedback mechanism that removes remaining errors including distortion components, phase errors, and offset errors. This feedback approach ensures that even if some errors slip through the first stage, they are corrected in the second stage, maintaining high reliability
Data Source
AI summary
Digital signals with higher resolution are generated from dual-phase encode signals indicating phase changes of a position or an angle of a target. A signal processing apparatus for processing dual-phase encode signals indicating changes in position of a target, comprises: a first noise reduction unit configured to remove high frequency noise from each of the dual-phase encode signals before interpolation processing; an interpolating unit configured to apply interpolation processing to the dual-phase encode signals output from the first noise reduction unit to generate dual-phase encode signals with higher resolution; and a second noise reduction unit configured to remove noise from the dual-phase encode signals output from the interpolating unit.