Offset-Magnet 3D Sensing for Stray-Field-Robust Object Position Detection
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Solution Overview
Problem
Existing multiple-sensor systems for detecting the state of a tiltable and rotatable object are costly, complex, and not stray field robust, leading to reduced reliability and increased complexity.
Innovation Solution
A stray field robust magnetic sensor system comprising a magnet connected to an object with its center offset from the object's axis, and a magnetic sensor with two 3D sensing pixels at different distances from the object's tilt point and the magnet's center, enabling differential 3D sensing and robustness against stray fields.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If multiple-sensor systems are used to detect the state of a tiltable and rotatable object, then measurement precision is improved, but device complexity increases and cost increases
Solution Approach 1:
The patent combines multiple sensing functions into a single magnetic sensor system. A single magnetic sensor detects both the tilt angle (via distance variations) and rotational position (via magnetic field direction) of the object, replacing what would traditionally require multiple separate sensors. This merging approach maintains measurement precision while reducing device complexity and cost.
Solution Approach 2:
The magnetic sensor performs multiple functions simultaneously: it measures both the angular position (tilt) and rotational position of the object. The sensor system is designed to extract multiple state parameters from a single sensor unit, making it a universal solution that eliminates the need for specialized sensors for each measurement type.
2Measurement precision
If multiple-sensor systems are used to detect the state of an object, then measurement precision is improved, but reliability decreases due to stray field sensitivity
Solution Approach 1:
The patent converts the potentially harmful effect of stray magnetic fields into a beneficial feature. By using a magnet attached to the object itself as the magnetic field source, the system turns what would be external interference into the primary measurement mechanism. The magnetic sensor detects changes in the magnetic field generated by the object's own magnet, making the system inherently robust against external stray fields while maintaining high measurement precision.
3Device complexity
If a magnet is centered on the object axis, then device complexity is reduced, but measurement precision deteriorates due to reduced state separation
Solution Approach 1:
The patent deliberately introduces asymmetry in the magnet positioning. The magnet is attached to the object at an offset position rather than centered on the axis. This asymmetric placement creates distinct and well-separated magnetic field patterns for different object states (tilt and rotation), significantly improving measurement precision. The offset position ensures that each state produces a unique magnetic field signature that is easily distinguishable by the sensor.
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
The system achieves reduced complexity and cost, increased lifetime, potential for miniaturization, and robustness against temperature variations and dirt, while maintaining high reliability and reducing the need for calibration.
Implementation Method 1
a magnetic sensor to determine a state of the object with respect to the multiple degrees of freedom based on a set of magnetic field strengths of a magnetic field generated by the magnet
Data Source
AI summary
A sensor system may include an object, a magnet, and a magnetic sensor. The magnet may be connected to the object such that a center of the magnet is offset from an axis of the object. The magnetic sensor may include a first three-dimensional (3D) sensing pixel and a second 3D sensing pixel. The magnetic sensor may be arranged such that the first 3D sensing pixel and the second 3D sensing pixel are at different distances from a tilt point of the object. The magnetic sensor may be arranged such that the first 3D sensing pixel and the second 3D sensing pixel are at different distances from the center of the magnet.