Rotating Element Angular Position Detection Using Perforated Mask
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Solution Overview
Problem
Existing methods for determining the angular position of a rotating shaft are costly, lack precision, and are not suitable for high-speed applications due to the need for precise positioning of sensors and high manufacturing costs, and they cannot be made compact or affordable.
Innovation Solution
A method using a light source and a fixed sensor with a mask featuring a repetitive two-dimensional pattern of transparent and opaque areas, where the light beam's interaction with the sensor is processed to determine the angular position of the rotating element, allowing for high accuracy and compact design, and capable of measuring rotation quality and mechanical degradation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a ring-shaped sensor or multiple sensor arrangement is used to determine angular position, then measurement precision is improved, but device complexity and manufacturing cost increase significantly
Solution Approach 1:
The mask is divided into multiple segments with different transparency patterns (transparent, semi-transparent, opaque) arranged radially. This segmentation allows a single sensor to distinguish angular positions by detecting which segment is illuminated, eliminating the need for multiple sensors while maintaining high measurement precision.
Solution Approach 2:
A mask with specific transparency patterns is introduced as an intermediary element between the light source and the sensor. The mask converts angular position information into light transmission patterns that the sensor can detect, simplifying the overall device structure while improving measurement capability.
2Measurement precision
If precise positioning of the sensor with respect to the axis is performed, then measurement precision is improved, but manufacturing cost and positioning difficulty increase
Solution Approach 1:
The mask features asymmetric transparency patterns (e.g., different sizes or positions of transparent/semi-transparent segments) that create distinct light transmission signatures for different angular positions. This asymmetry allows the sensor to accurately determine angular position without requiring precise positioning, as the pattern itself provides the positioning reference.
Solution Approach 2:
The mask with its specific transparency patterns serves as a self-contained reference system that automatically provides positioning information. The pattern itself 'services' the positioning function, eliminating the need for external precise positioning mechanisms or calibration procedures.
3Device complexity
If a single light point is used for measurement, then device complexity is reduced, but measurement precision deteriorates
Solution Approach 1:
The mask introduces a spatial dimension with multiple segments having different transparency characteristics. By detecting which segment is illuminated at any given angle, the system achieves high measurement precision using a single light source and sensor, effectively adding informational dimensions without adding physical components.
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 provides a reliable, precise, and cost-effective method for determining angular positions with large positioning tolerances, suitable for high-speed applications, and can measure the quality of rotation and detect wear over time, offering high resolution and accuracy without the need for calibration.
Implementation Method 1
at least one light source (2) emitting a beam of light (3)... a sensor (4)... detecting the image or shadows generated by the mask (5) on the sensor (4)
Data Source
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Figure 2
Figure 3~6
AI summary
The present invention concerns a method for working out the angular position of a rotating element which is mounted in a fixed frame, consisting in using at least one light source emitting a beam of light in the direction of a fixed sensor and using computing means for processing an output signal of the sensor, characterized in that it consists in: - a) arranging the light source with respect to the rotating element and of the sensor in a way so as to induce an interaction between the beam of light and the sensor which depends on the angular position of the rotating shaft, - b) arranging on the path of the beam of light, in a fixed position with respect to the sensor, a perforated mask which presents a repetitive pattern of perforations, - c) detecting shadows generated by the mask on the sensor, - d) processing the output signal of the sensor for determining the position of the shadows on the sensor, - e) and computing the angular position of the rotating element by using the position of the shadows.