Alignment-Tolerant Magnetic Sensor Arrangement for Rotation Sensing
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Solution Overview
Problem
Magnetic sensors face challenges in applications susceptible to movement or misalignment, such as automotive wheel speed sensors, due to the high cost of encoder wheels and difficulties in aligning the axis of rotation with the sensor axis.
Innovation Solution
A magnetic field sensor arrangement using a pair of sensors with offset magnetic field sensitivity directions to detect magnetic fields at different alignments, allowing for the detection of positional characteristics of a reference component that influences a magnetic field, even when the component and sensors are misaligned or twisted, utilizing a reference component like an encoder wheel.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single magnetic sensor is used with a reference component, then the sensor arrangement is simple, but the detection precision deteriorates under misalignment conditions
Solution Approach 1:
The sensor arrangement is segmented into multiple magnetic sensors (at least two) with different sensitivity directions, allowing each sensor to detect magnetic field components along different axes. This segmentation enables the system to maintain detection capability under various alignment conditions without requiring a single complex sensor.
Solution Approach 2:
The invention adds dimensional diversity by orienting sensors along different magnetic field sensitivity directions (e.g., different angular orientations). This dimensional approach allows the system to capture magnetic field information from multiple perspectives, ensuring that at least one sensor maintains effective detection capability regardless of the reference component's rotational alignment.
2Measurement precision
If encoder wheels are used for sensing rotation, then measurement precision is improved, but the manufacturing cost increases
Solution Approach 1:
The invention extracts the magnetic field generation function from complex encoder wheels and implements it through simpler reference components with magnetized features. By separating the magnetic field source from the sensing mechanism and using basic magnetic components, the system achieves encoder-wheel-level precision without the associated high manufacturing costs.
Solution Approach 2:
The reference component uses simple magnetized features (such as magnetized teeth or patterns) that can be manufactured at low cost compared to traditional encoder wheels. These magnetic features serve the same rotational sensing function but are much cheaper to produce, making the overall system more cost-effective while maintaining measurement precision.
3Measurement precision
If precise alignment between the axis of rotation and sensor axis is required, then measurement precision is improved, but the ease of operation deteriorates
Solution Approach 1:
The invention changes the operational parameter from requiring precise angular alignment to accepting a range of alignment conditions. By using multiple sensors with different sensitivity directions, the system transforms the single-parameter alignment requirement into a multi-parameter detection approach, where the combined output of multiple sensors provides accurate rotational measurement regardless of the specific alignment angle.
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 the detection of positional characteristics of rotating components like encoder wheels without precise alignment, providing a strong output signal even under misalignment conditions, thus improving the reliability and cost-effectiveness of magnetic sensor applications.
Implementation Method 1
The first magnetic sensor is aligned with a first magnetic field sensitivity direction and exhibits an electrical response to variations in the magnetic field over time due to the influence of the reference component. The second magnetic sensor is aligned with a second magnetic field sensitivity direction and exhibits an electrical response to variations in the magnetic field over time due to the influence of the reference component.
Data Source
AI summary
A sensor circuit is configured for operation under conditions susceptible to misalignment or movement. In connection with various example embodiments, an alignment-tolerant sensor arrangement includes a reference component and first and second magnetic sensors. The reference component influences a magnetic field as a function of a position of the reference component, such as via the positioning of a magnetic type of component. The first magnetic sensor is aligned with a first magnetic field sensitivity direction, and exhibits an electrical response to the presence of the magnetic field. The second magnetic sensor is aligned with a first magnetic field sensitivity direction and is configured to exhibit an electrical response to the presence of the magnetic field. The first and second magnetic field sensitivity directions being offset from one another to facilitate detection of magnetic fields at different relative alignments between the reference component and the first and second magnetic sensors.