Laser Speckle Angle Positioning Device
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Solution Overview
Problem
Conventional high-precision absolute positioning circular gratings face challenges in manufacturing, calibration, and assembly, leading to high costs and shaft concentricity errors, limiting their precision and practicality for angle positioning.
Innovation Solution
A high-precision angle positioning device utilizing a rotary disk unit, non-deformable laser-speckles image-acquiring unit, angle calibrating unit, and storage unit, which acquires and compares laser-speckles images to calculate precise angle coordinates, overcoming the limitations of traditional circular gratings by using a low-cost and accurate method.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional high-precision absolute positioning circular gratings are used, then angle positioning accuracy is improved, but manufacturing cost and assembly complexity increase significantly
Solution Approach 1:
The patent uses laser speckle imaging to create an optical copy of the positioning surface pattern instead of requiring physical high-precision gratings. The laser speckle pattern captures the unique surface characteristics and uses image correlation to determine angular position, replacing the need for complex multi-annular grating structures and their precise assembly.
Solution Approach 2:
The patent replaces the mechanical grating structure with an optical measurement system. Instead of using physical gratings that require precise mechanical assembly on the rotary shaft, the system uses laser illumination and camera-based image capture to optically measure the angular position through speckle pattern correlation.
2Measurement precision
If conventional high-precision absolute positioning circular gratings are used, then angle positioning accuracy is improved, but manufacturing cost increases non-linearly
Solution Approach 1:
The patent replaces expensive, difficult-to-manufacture high-precision gratings with a simple rotary disk that has a unique positioning surface pattern. The positioning surface can be a simple marked disk or patterned surface that is much cheaper to manufacture than conventional high-precision gratings, while still providing high measurement precision through laser speckle correlation.
Solution Approach 2:
The laser speckle imaging system creates an optical replica of the positioning surface pattern, allowing the system to measure angular position based on pattern recognition rather than requiring the physical grating structure itself to be extremely precise. This copying approach enables the use of simpler, cheaper physical components.
3Measurement precision
If conventional high-precision absolute positioning circular gratings are used, then angle positioning accuracy is improved, but shaft concentricity errors occur during assembly
Solution Approach 1:
The laser speckle imaging system automatically compensates for assembly misalignments and shaft concentricity errors through image correlation algorithms. The system captures the speckle pattern at each angular position and compares it with reference patterns, allowing the measurement process itself to correct for mechanical imperfections in the rotary assembly.
Solution Approach 2:
The patent changes the measurement parameter from direct physical grating reading to optical pattern recognition. By using laser speckle correlation instead of mechanical grating scales, the system becomes insensitive to shaft concentricity errors and assembly misalignments, as the optical measurement can detect the true angular position of the positioning surface pattern regardless of mechanical imperfections.
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 device achieves high-precision angle positioning with reduced costs and improved accuracy, meeting the requirements of a high-precision absolute angle positioning sensor by calculating sub-coordinated angles through image comparison and storage of coordinated laser-speckles images.
Implementation Method 1
a non-deformable laser-speckles image-acquiring unit, used for emitting a coherent light to a positioning surface of the rotary disk unit, so as to acquire a non-deformable laser-speckles image of the positioning surface by receiving a reflected light coming from the positioning surface
Implementation Method 2
acquire a non-deformable laser-speckles image of the positioning surface by receiving a reflected light coming from the positioning surface
Data Source
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AI summary
The present invention proposes a high-precision angle positioning device. To complete a high-precision angle positioning operation, the high-precision angle positioning device firstly uses a non-deformable laser-speckles image-acquiring unit to acquire N non-deformable laser-speckles images from a rotary disk unit, and then defines N coordinated non-deformable laser-speckles images and N coordinated angles through an angle calibrating unit and an angle recognizing and positioning unit; therefore, after finding an i-th coordinated non-deformable laser-speckles image having the largest overlapping area with an immediate non-deformable laser-speckles image through image comparison, an immediate image plane displacement between the immediate non-deformable laser-speckles image and the i-th coordinated non-deformable laser-speckles image can be calculated for calculating immediate sub-coordinated angle of immediate non-deformable laser-speckles image, such that an immediate angle coordinate for the immediate non-deformable laser-speckles image can be calculated through an i-th coordinated angle of the i-th coordinated non-deformable laser-speckles image and the immediate sub-coordinated angle.