Omnidirectional Speed-and-Direction Sensor With 3D Hall Sensing
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Solution Overview
Problem
Existing rotational speed and direction sensors for commercial vehicles require axial displacement capability and accurate measurement, while existing solutions are computationally complex and consume memory, particularly with Hall sensors.
Innovation Solution
A magnetic field sensor using three linearly independent Hall sensors with orthogonal normal vectors, generating two differential signals for direction detection, and a combined signal for speed determination, housed in a stable configuration with flux guide plates, allowing accurate measurements despite positional changes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If three magnetic field measuring elements are used for independent speed and direction measurement, then measurement capability is improved, but calculation complexity and memory consumption increase
Solution Approach 1:
The patent extracts and utilizes the z-component of the magnetic field vector as an additional independent measurement channel. By combining this extracted component with two differential signals from Hall sensors, the system achieves three independent measurement channels without requiring three separate complex sensor arrangements, thereby reducing calculation complexity while maintaining measurement precision.
Solution Approach 2:
The patent makes the magnetic field measuring elements radially isotropic through the use of a specific tensor structure, allowing the same sensor configuration to provide three independent measurement channels for both speed and direction measurement. This multi-functional approach eliminates the need for separate sensor arrangements for different measurement purposes.
2Measurement precision
If active sensors are fixed in position to determine exact rotational direction, then measurement accuracy is improved, but adaptability to axial displacement is reduced
Solution Approach 1:
The patent transitions from planar 2D magnetic field sensing to 3D sensing by incorporating measurement of the z-component perpendicular to the sensor chip plane. This dimensional extension creates a radially isotropic measurement capability that maintains accuracy regardless of axial displacement, as the three-component vector measurement can resolve rotational direction from any axial position.
Solution Approach 2:
The patent changes the measurement parameters by utilizing the full three-dimensional magnetic field vector rather than only in-plane components. By measuring Bx, By, and Bz components and processing them through specific tensor operations, the system achieves parameter invariance to axial displacement while maintaining rotational direction determination accuracy.
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
Reduces computing time and increases accuracy by using two differential signals for direction detection, enabling quick calculation of rotational speed and direction, and provides stability and temperature compensation.
Implementation Method 1
Hall sensors in particular are used for this, which measure the magnetic field emanating from a rotating object at three points
Data Source
AI summary
A magnetic-field (MF) sensor, including: a chip having first, second and third MF measuring-elements (ME) to output first, second and third MF signals, amplitudes of which are proportional to a MF emanating from a rotating-object (RO), in which directions of the normal vectors of the MF MEs are linearly independent; a signal acquisition unit to determine first/second differential-signals (DS), in which the first DS is based on a difference between the MF signals of the first and second MF MEs, and in which the second DS is based on a difference between the MF signals of the first/third MF MEs, and in which the signal acquisition unit is configured to determine a combined signal from the MF signal of the first MF ME and the first/second DS; and an evaluation unit to generate an output signal, which contains a speed and direction of motion of the RO.