Absolute Encoder Position Detection with Reliability-Based Correction
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Solution Overview
Problem
Conventional absolute encoders face reliability issues due to variations in two-phase sine wave signal amplitude or offset, leading to inaccurate position detection, especially when peak values are required for correction, which can't be calculated during normal operation without changing the object's position.
Innovation Solution
A position detecting apparatus with a signal detecting unit, correction unit, and reliability calculating unit that adjusts correction values based on signal reliability, allowing for continuous accurate position detection without the need for feedback circuits or object position changes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If an offset correcting circuit with feedback is used to correct encoder offset, then the reliability of the absolute position signal is improved, but the device complexity and cost increase due to additional feedback circuit components
Solution Approach 1:
The patent extracts the essential correction function from complex feedback circuits and implements it through a simplified calculation-based approach. The correction unit calculates correction values based on signal characteristics (amplitude, offset) without requiring additional feedback circuitry, thereby maintaining reliability while reducing device complexity
Solution Approach 2:
The patent replaces the mechanical/electrical feedback circuit system with a computational system. Instead of using physical feedback components to correct offset, the invention uses calculation units that process signal data and apply correction algorithms, substituting hardware complexity with software-based correction
2Reliability
If correction values are calculated based on peak signal values, then the reliability of position detection is improved, but the ease of operation deteriorates because the object position must be changed to obtain peak values
Solution Approach 1:
The patent performs preliminary calculation of correction values using signal characteristics that are available during normal operation. By calculating correction values based on amplitude and offset parameters that can be obtained without position changes, the system prepares correction data in advance, eliminating the need to move the object to peak positions
Solution Approach 2:
The patent implements dynamic correction value calculation that adapts to changing signal conditions during normal operation. The correction unit continuously updates correction values based on real-time signal characteristics, allowing the system to maintain accuracy without requiring the object to be positioned at specific peak locations
3Measurement precision
If the position of the object is changed to obtain peak signal values for correction, then the accuracy of correction values is improved, but the productivity decreases due to additional position changes required
Solution Approach 1:
The patent enables continuous position detection without interruption for correction value acquisition. The correction unit calculates correction values using signal parameters available during normal detection operations, eliminating the need to stop or reposition the object, thereby maintaining continuous productive operation while ensuring accurate correction
Data Source
AI summary
A position detecting apparatus includes a signal detecting unit that detects a plurality of periodic signals, a correction unit configured to correct the plurality of periodic signals using a correction value to generate a plurality of correction signals, a first calculating unit configured to generate a plurality of displacement signals based on the plurality of correction signals and to calculate the position based on the plurality of displacement signals, a second calculating unit configured to calculate a reliability based on the plurality of displacement signals, and a correction value adjusting unit configured to adjust the correction value based on the reliability. The second calculating unit calculates a first reliability corresponding to a first correction value and a second reliability corresponding to a second correction value, and changes the first correction value to the second correction value when the second reliability is higher than the first reliability.