Averaging Quadrature Encoder Signals to Compensate Eccentricity
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Solution Overview
Problem
Radial arrays of encoder marks on rotating objects that are not centered on the axis of rotation introduce eccentricity errors in encoder signals, making it difficult to accurately determine the angular motion of the object.
Innovation Solution
The use of two quadrature encoding modules positioned diametrically opposed on the radial array, which transmit quadrature encoder signals with a 90-degree phase shift, allows logic to determine the angular motion by averaging component signals and generating output signals that compensate for the eccentricity error.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a radial array of encoder marks is not centered on the object's axis of rotation, then the encoder signal contains an eccentricity error, but the device complexity is reduced
Solution Approach 1:
The encoder array is divided into multiple radial arrays positioned at different radii from the rotation axis. Each radial array is sensed by separate encoding modules, allowing the system to segment the measurement task and compensate for eccentricity by analyzing the differential signals from multiple arrays
Solution Approach 2:
The patent introduces an intermediary signal processing stage that receives signals from multiple encoding modules and generates corrected position signals. This intermediary processing layer mediates between the raw encoder signals and the final position data, eliminating eccentricity errors through signal combination and analysis
2Device complexity
If a single encoding module is used, then the device complexity is reduced, but the measurement precision deteriorates due to eccentricity errors
Solution Approach 1:
Multiple encoding modules positioned at different radii are merged into a unified signal processing system. The system combines signals from all modules and uses cross-correlation and spectral analysis to extract accurate position information, achieving high measurement precision without requiring each individual module to be perfectly centered
Solution Approach 2:
The patent adds a radial dimension to the traditional single-plane encoder measurement. By positioning encoding modules at multiple different radii from the rotation axis, the system transforms a one-dimensional measurement problem into a multi-dimensional one, enabling eccentricity compensation through analysis of signals across different radial positions
Data Source
AI summary
A method for compensating for encoder wheel eccentricity includes routing encoding module signals to a signal logic module when an encoder wheel is not at slew, averaging the encoding module signals, by using the signal logic module, to form averaged signals, when the encoder wheel is at slew, and generating an output signal from the averaged signals and the encoding module signals, by using the signal logic module.