Absolute Position Detection Using Elliptical Lissajous Curves
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Solution Overview
Problem
Current position detecting systems with incremental magnetic encoding rulers require time-consuming initialization and multiple sensors for absolute position detection, making them inefficient and costly.
Innovation Solution
An absolute encoder with a magnetic encoding ruler and two magnetoresistive sensors, where the sensors generate elliptical patterns based on magnetic fields to determine the absolute position without additional sensors, allowing for rapid and cost-effective detection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If incremental magnetic encoding rulers are used, then the system can detect position changes, but initialization is time-consuming
Solution Approach 1:
The magnetic encoding ruler is pre-configured with two magnetic paths having different pole widths (first pole width and second pole width) and opposite polarities. This preliminary structural arrangement enables the system to generate distinct elliptical patterns immediately upon startup, eliminating the need for time-consuming initialization procedures required by incremental systems.
2Measurement precision
If absolute encoding track with more bits is used, then absolute position detection precision is improved, but the number of sensors increases
Solution Approach 1:
Instead of increasing the number of sensors along a single dimension, the invention introduces a second magnetic path with different pole widths, adding a dimensional variation to the magnetic encoding structure. This allows two magnetoresistive sensors to generate distinct elliptical patterns that together provide absolute position information, achieving high precision without proportionally increasing sensor count.
Solution Approach 2:
The invention changes the parameter of pole width between the two magnetic paths. The first magnetic path has a first pole width while the second magnetic path has a second pole width different from the first. This parameter variation creates distinguishable elliptical patterns that enable absolute position detection with only two sensors, avoiding the need for multiple sensors required by traditional multi-bit absolute encoding.
3Measurement precision
If multiple hall sensors are used for absolute position detection, then detection accuracy is improved, but device cost increases
Solution Approach 1:
The invention changes the pole width parameter between the two magnetic paths to create distinguishable signals. By using two magnetoresistive sensors detecting different pole widths, the system achieves accurate absolute position detection through elliptical pattern analysis, replacing the need for multiple expensive hall sensors and reducing overall device cost.
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
Enables precise and rapid absolute position detection with only two magnetoresistive sensors, reducing the need for multiple hall sensors and minimizing initialization time and costs.
Implementation Method 1
a first magnetoresistive sensor disposed adjacent to the first magnetic path to detect magnetic fields of the first magnetic path and to generate a first magnetoresistive signal, and a second magnetoresistive sensor disposed adjacent to the second magnetic path to detect magnetic fields of the second magnetic path and to generate a second magnetoresistive signal
Data Source
AI summary
An absolute position detecting device and method are provided. The absolute position detecting device utilizes the incremental magnetization on a magnetic encoding ruler with two different pole widths, such that elliptical Lissajous curves may be obtained by magnetoresistive sensors. The absolute position may be obtained by determining the region of the signals on the ellipses read by the magnetoresistive sensors.