Angle-Error Correction Algorithm for Optical Motion Detection
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Solution Overview
Problem
Optical pointing devices face reliability issues in detecting motion on surfaces with periodic lines, which can cause misreporting of motion along one axis as motion along the other axis, especially when used on desks with wood or other periodic materials, leading to decreased accuracy in motion displacement calculations.
Innovation Solution
The 'Angle Error Correction' algorithm is implemented, which counts the total number of detected diagonals and compares it to a threshold to enable correction, discarding erroneous motion features by checking for consistent inflection types in neighboring locations along the axis and perpendicular locations, thereby improving motion detection accuracy on surfaces with periodic lines.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If standard edge direction algorithms are used for motion detection, then the device can operate on any surface, but motion detection accuracy deteriorates when used on surfaces with periodic lines (such as wood desks)
Solution Approach 1:
The algorithm applies different processing rules to different regions of the photodetector array based on local edge characteristics. By analyzing the specific pattern of positive and negative edges at each location and comparing with neighboring regions, the system adapts its motion detection behavior to local surface characteristics, thereby maintaining accuracy on periodic surfaces while preserving general versatility.
Solution Approach 2:
The system continuously monitors the detected edge patterns and uses feedback from comparing current frame edges with previous frame edges to identify periodic line artifacts. When periodic patterns are detected, the algorithm adjusts its motion calculation by discarding spurious edge inflections and relying more on consistent edge direction data, thereby correcting measurement errors in real-time.
2Difficulty of detecting and measuring
If edge inflection conditions are used to detect motion, then motion detection is enabled, but erroneous motion features are generated due to periodic surface patterns
Solution Approach 1:
The algorithm extracts and separates useful motion information from harmful periodic pattern artifacts. By identifying edge inflections that correspond to actual object motion versus those caused by periodic surface lines, the system extracts only the relevant motion signals for calculation while discarding spurious features generated by the surface pattern.
Solution Approach 2:
The system adds a temporal dimension to the analysis by comparing edge inflections across multiple successive frames. Motion features that persist consistently across frames are identified as genuine, while those that appear and disappear in sync with periodic surface patterns are rejected. This temporal filtering dimension effectively separates real motion from surface-artifact-induced false detections.
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 algorithm significantly enhances the reliability of motion detection by reducing errors caused by periodic surface features, ensuring accurate calculation of motion displacement along both axes, even on surfaces with interfering patterns like wood desks.
Implementation Method 1
an optical sensing device including a photodetector array for measuring the varying intensity pattern of a portion of a surface which is illuminated with radiation
Data Source
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AI summary
There is described a method for measuring relative motion between an illuminated portion of a surface (S) and an optical sensing device comprising a photodetector array (100), which includes a plurality of rows and columns of pixels respectively aligned along first and second axes (X, Y), the method allowing to determine a measurement of the relative motion between the optical sensing device and the illuminated portion of the surface based on a comparison of motion features extracted from light intensity patterns obtained with the photodetector array, wherein said method includes a checking process between two light intensity patterns for discarding erroneous motion features due to the surface design.