Rotation Angle Sensing Using Digital Quadrature Signal Processing
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Solution Overview
Problem
Existing rotation-angle detecting apparatuses face challenges in achieving both low cost and high processing speed due to the need for analog signal processing and division calculations, which are time-consuming and costly.
Innovation Solution
A rotation-angle detecting apparatus that uses a plurality of detectors to generate pairs of periodic signals with a 90-degree phase difference, converts these signals to digital using an analog-to-digital converter, and processes them with a digital signal processor, incorporating a binarization unit and counter to determine the rotation angle without requiring extensive hardware for analog signal processing or division calculations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If analog signal processing and division calculations are used to determine rotation angle, then measurement precision is improved, but device complexity and processing time increase
Solution Approach 1:
The patent replaces the mechanical/optical analog signal processing system with a digital signal processing system. Instead of using analog multipliers, adders, and subtractors to process sinusoidal signals from detectors, the invention uses a digital signal processor to perform the same calculations on digitally converted signals. This substitution eliminates the need for complex analog hardware while maintaining the ability to accurately determine rotation angle through mathematical operations.
Solution Approach 2:
The patent changes the state of the signals from analog to digital form. By converting the sinusoidal output signals from detectors into digital signals through analog-to-digital conversion, the system enables the use of digital signal processing techniques. This parameter change allows complex mathematical operations to be performed efficiently in the digital domain, reducing hardware complexity while preserving measurement precision.
2Ease of manufacture
If division calculations are performed using digital signal processing to obtain rotation angle, then manufacturing cost is reduced, but processing time increases
Solution Approach 1:
The patent performs preliminary action by converting the analog sinusoidal signals to digital signals before the main calculation process. This preliminary analog-to-digital conversion enables subsequent digital signal processing operations to be performed efficiently using standardized digital circuits and algorithms, reducing both manufacturing cost and processing time compared to performing all operations in the analog domain.
Solution Approach 2:
The patent creates a digital copy of the analog sinusoidal signals through analog-to-digital conversion. This digital copy can then be processed using efficient digital algorithms for calculating rotation angle, avoiding the need for time-consuming analog division calculations while maintaining accuracy. The digital representation allows for rapid computation using standard digital signal processing techniques.
3Measurement precision
If multiple detection units are arranged around the rotating shaft to reduce eccentricity effects, then measurement precision is improved, but device complexity increases
Solution Approach 1:
The patent merges the processing of signals from multiple detection units within a single digital signal processor. Instead of requiring separate processing circuits for each detector, the invention consolidates the signal processing functions into one digital processor that can efficiently handle inputs from multiple detectors arranged around the rotating shaft, reducing overall system complexity while maintaining the ability to compensate for eccentricity effects.
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 the cost and processing time by eliminating the need for complex hardware components and division calculations, allowing for efficient determination of rotation angles with improved accuracy.
Implementation Method 1
a light-emitting portion that emits a light beam toward the rotating disc (1) and a light-receiving portion that detects the light beam reflected from the rotating disc (1)
Data Source
AI summary
A rotation-angle detecting apparatus detects a rotation angle of a rotating disc having radial markings, includes a plurality of detectors arranged at opposite sides of the axis of rotation of the disc and facing the markings, each of the detectors operable to detect a light beam from the markings, and outputting a pair of periodic signals having a 90-degree phase difference between the members of the pair; an analog-to-digital converter arranged to convert pairs of periodic signals from the detectors into pairs of digital signals; a digital signal processor configured to process the pairs of digital signals from the analog-to-digital converter; a binarization unit arranged to binarize the pairs of periodic signals from the detectors; and a counter arranged to count the pairs of periodic signals binarized by the binarization unit. The digital signal processor determines the rotation angle of the disc based on the pairs of digital signals from the analog-to-digital converter and count results from the counter.