Cascade Hall Sensor Arrangement for High-Accuracy Angle Determination
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Solution Overview
Problem
Existing sensor arrangements for determining the angle of rotation of a rotating body, particularly those using Hall sensors, face challenges in achieving high accuracy due to the need for complex interpolation methods and the requirement for broadband circuits, which complicates the design and operation.
Innovation Solution
A sensor arrangement that cascades multiple Hall sensors, where each sensor produces a signal proportional to the sine or cosine of the angle of rotation, with control currents generated from one sensor used to multiply the signal of another, effectively doubling the angular frequency and allowing for improved interpolation by generating signals proportional to sin 2X or cos 2X, thereby enhancing the accuracy of angle determination.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional analogue/digital converters and digital function tables are used for interpolation, then measurement precision is improved, but device complexity increases
Solution Approach 1:
The patent replaces complex digital interpolation circuits (CORDIC, lookup tables) with an optical-mechanical solution using a diffraction grating and laser beam. The physical diffraction pattern directly encodes the interpolation results, eliminating the need for complex electronic computation circuits while achieving high angular resolution.
Solution Approach 2:
The patent transitions from electrical signal processing to optical domain processing. By using laser light diffraction through a grating, the interpolation is performed in the optical dimension rather than the electrical dimension, allowing complex mathematical operations to be performed through physical optical phenomena.
2Measurement precision
If symmetrical mixer circuits are used to multiply angular frequency, then measurement precision is improved, but device complexity and circuit bandwidth requirements increase
Solution Approach 1:
The patent replaces electronic mixer circuits with optical modulation using a diffraction grating. The grating physically modulates the laser beam based on the sensor signals, achieving frequency multiplication through optical diffraction orders rather than electronic mixing, thereby eliminating broadband circuit requirements.
Solution Approach 2:
The patent utilizes the periodic diffraction pattern produced by the grating to achieve frequency multiplication. The diffraction orders naturally provide the periodic signal multiplication effect that would otherwise require complex electronic mixer circuits, simplifying the overall system design.
3Measurement precision
If ten-bit output sensors are used requiring 256-fold interpolation, then measurement precision is improved, but device complexity increases
Solution Approach 1:
The patent uses optical diffraction through a grating to perform the 256-fold interpolation physically. The diffraction pattern inherently provides the fine angular resolution needed, eliminating the need for complex 256-state interpolation circuits while achieving the required angular precision.
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 allows for precise determination of the angle of rotation with twice the accuracy of traditional methods, enabling better tracking of rotational movement and location parameters along predefined paths, including non-linear curves, using a simple and integrated circuit design.
Implementation Method 1
the Hall elements generate an electrical voltage, the so-called Hall voltage, which is both proportional to the magnetic field and to the bias current of the Hall elements, in accordance with the following formula for the Hall effect: Vh=B×I×Rh
Data Source
AI summary
A sensor arrangement for detecting an angle of rotation of a rotating body. At least one first sensor and one second sensor are connected to one another in a cascade in such a manner that the sensor signal from the first sensor is converted into a first control current which is applied as a bias current to the second sensor, the two angular dependencies of the first and second sensors being multiplied. This achieves improved interpolation when determining the angle of rotation on the basis of the sensor signals provided by the sensor arrangement.