Displacement Calculation Device Correcting Multi-Period Errors
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Solution Overview
Problem
Conventional displacement calculation methods are inadequate in correcting errors with periods greater than one period of displacement detection signals, as they fail to account for changes due to pitching, rolling, yawing, scale distortion, and noise, leading to persistent interpolation errors.
Innovation Solution
A displacement calculation device and method that analyze amplitude, center position, and phase differences between displacement detection signals and a reference signal to calculate both short-period and long-period displacement errors, allowing for precise correction of displacement data.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional interpolation correction methods are used, then interpolation errors within one period can be corrected, but errors with periods greater than one period (due to pitching, rolling, yawing, scale distortion) cannot be corrected
Solution Approach 1:
The invention segments the error correction process into multiple independent correction mechanisms: one for interpolation errors within one period, and another for errors with periods greater than one period. By dividing the correction task into separate segments, the system can address different error types without interference, thereby improving both measurement precision and adaptability to various error periods
Solution Approach 2:
The invention introduces dynamic correction by continuously monitoring and adjusting for errors with varying periods. Instead of using a fixed correction table, the system dynamically calculates correction values based on real-time detection of Lissajous waveform distortions, enabling adaptation to changing error conditions such as stage movement and scale distortion
2Reliability
If the Lissajous waveform shape changes with a period greater than one period, then conventional one-period correction methods fail to converge, but the invention enables correction by analyzing multi-period characteristics
Solution Approach 1:
The invention implements feedback by continuously analyzing the Lissajous waveform and detecting changes in its shape and period. The system uses this feedback information to adjust correction values in real-time, ensuring convergence even when errors have periods greater than one period. This feedback mechanism improves reliability while managing complexity through intelligent adaptation
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The solution effectively corrects displacement errors with periods equal to or greater than one period of the displacement detection signals, converging correction residuals and improving accuracy by accounting for errors caused by stage movement, scale distortion, and noise.
Implementation Method 1
In a magnetic encoder, a magnetic force that varies in accordance with displacement of a magnetic scale is detected by a magnetic sensor
Implementation Method 2
interference signals that vary in intensity in accordance with displacement of a diffraction grating scale or the like are received by light receiving elements of a displacement detection sensor and subjected to photoelectric conversion
Data Source
AI summary
A displacement calculation device 30 calculates a displacement based on two or more displacement detection signals differing in phase. The displacement calculating device 30 includes a detected displacement calculation unit 32 calculating a detected displacement based on the displacement detection signals, a signal analysis unit 33 calculating an amplitude error, a vibration center error, and a phase error between the displacement detection signals and a reference signal, a periodic displacement error calculation unit 34 calculating a periodic displacement error and a period of the displacement error based on the errors calculated by the signal analysis unit 33, and a displacement correction unit 35 correcting the detected displacement calculated by the detected displacement calculation unit 32, based on the displacement error and its period calculated by the periodic displacement error calculation unit 34, and outputting a corrected calibrated displacement.