Rotational Angle Computation Using Orthogonal Hall Plates
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Solution Overview
Problem
Rotational-angle sensors with orthogonally arranged Hall measuring plates face challenges in accurately computing the angle of rotation due to offset voltages, non-linear relationships between magnetic field strength and measured voltage, and sensitivity differences between the plates, leading to errors in angle computation.
Innovation Solution
A method involving the measurement of Hall voltage values at two time points, computation of nominal average values, and use of derivatives to correct for errors, specifically using the equation α=tan-1(VHZ(t=0.5) - ΔVHXΔα / VHX(t=0.5) + ΔVHZΔα, which reduces errors caused by offset voltages and gain errors, and eliminates phase errors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If Hall voltage values are measured and processed using conventional methods, then the computation is simple, but the angle computation accuracy deteriorates due to offset voltages, non-linear relationships, and sensitivity differences
Solution Approach 1:
The method performs preliminary measurements at two different time points (t=0 and t=1) to capture the system state before and after rotation. By measuring Hall voltage values at both time points and computing their differences, the method eliminates offset voltages and compensates for non-linearities before the final angle computation, thereby improving accuracy without requiring complex real-time processing
Solution Approach 2:
The method uses the measured Hall voltage values from both time points to compute corrected angle values through a feedback mechanism. The computed angle difference feeds back into the calculation to adjust for sensitivity differences and non-linear relationships, continuously improving the accuracy of the angle computation based on actual measured deviations
2Measurement precision
If measurements are taken at two different time points, then error reduction is improved, but the measurement time increases
Solution Approach 1:
The method employs periodic measurement action by taking measurements at two distinct time points (t=0 and t=1) separated by a defined time interval. This periodic sampling approach allows the system to capture rotational changes while enabling error compensation through comparison, achieving improved precision with minimal time loss by using just two measurement cycles
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 method effectively reduces errors and provides accurate computation of the angle of rotation, achieving results close to ideal values even in the presence of errors such as offset and gain errors, with minimal deviation from the actual angle.
Implementation Method 1
a first Hall measuring plate (20) and a second Hall measuring plate (30) which are arranged substantially orthogonally to each other
Data Source
AI summary
A method and apparatus for computing the angle (α) of rotation of a rotational-angle sensor apparatus (10) with a first Hall measuring plate (20) and a second Hall measuring plate (30) which are arranged orthogonally to each other.