Speckle Motion Sensor Signal Processing for Jitter and Nyquist Limits
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Solution Overview
Problem
Speckle-based motion sensors face challenges with significant jitter noise at zero or low motion, inaccuracy near the Nyquist limit, and flyaway issues at high motion speeds, limiting their effectiveness in position sensing applications.
Innovation Solution
The implementation of a 1D and 2D comb detector array with in-phase and quadrature current signals, signal frame processing, and multiple parallel DSP pipelines to mitigate noise and improve accuracy across various motion speeds, including above the Nyquist limit.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a single signal processing procedure is used, then the device complexity is low, but the measurement precision deteriorates at different motion speeds
Solution Approach 1:
The patent implements multiple parallel DSP pipelines (first and second signal processing procedures) that dynamically process signal frames differently based on motion characteristics. The system selects between procedures based on detected motion conditions, allowing optimal processing for each speed regime without requiring a single complex universal processor.
Solution Approach 2:
The patent changes processing parameters by implementing different signal processing procedures for different motion conditions. The first procedure handles low-speed motion with different parameters than the second procedure, which handles high-speed motion near the Nyquist limit, optimizing measurement precision across the full speed range.
2Reliability
If conventional signal processing is used, then the device complexity is low, but jitter noise increases at zero or low motion
Solution Approach 1:
The patent employs dynamic signal processing where the system adapts its processing approach based on detected motion levels. At zero or low motion, the first signal processing procedure is applied to minimize jitter noise, while at higher motions the second procedure takes over, providing noise reduction across all operating conditions.
Solution Approach 2:
The patent uses feedback mechanisms where the system continuously monitors motion detection results and adjusts signal processing accordingly. The selection between first and second procedures based on detected motion conditions creates a feedback loop that optimizes noise reduction while maintaining accuracy.
3Measurement precision
If conventional signal processing is used, then the device complexity is low, but measurement accuracy deteriorates near the Nyquist limit
Solution Approach 1:
The patent implements dynamic processing where the second signal processing procedure is specifically activated when motion approaches the Nyquist limit. This procedure uses different algorithms optimized for high-speed motion, maintaining accuracy where conventional processing would fail.
Solution Approach 2:
The patent changes processing parameters by switching between different signal processing procedures based on motion speed. Near the Nyquist limit, the second procedure with parameters optimized for high-speed detection is applied, preventing accuracy deterioration that would occur with conventional processing.
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
This approach reduces jitter noise, enhances accuracy at faster motions, and allows precise measurement of speeds beyond the Nyquist limit, improving the overall performance of speckle-based motion sensors.
Implementation Method 1
The spectral coherence of the laser and the wavelength-scale irregularities in the surface create an interference pattern, known as speckle, on the surface.
Implementation Method 2
The speckle pattern is imaged onto a detector array. The offset of this pattern versus the position of the sensor is then tracked over time.
Data Source
AI summary
One embodiment relates to a method of tracking motion using a speckle-based motion sensor. A distance moved is determined by a first signal processing procedure, and a distance moved is determined by a second signal processing procedure. Selection between said distances is made based on whether the distance determined by the first signal processing procedure exceeds a predetermined threshold distance. According to a preferred embodiment, the first signal processing procedure makes a more accurate determination of distance for slower speeds, while the second signal processing procedure makes a more accurate determination of distance for higher speeds. Other embodiments, aspects and features are also disclosed.