Magnetic Sensor Position Orientation Air Gap
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing contactless magnetic sensors for determining the position of moving parts with both linear and rotational movements suffer from precision issues and sensitivity to air gap variations, leading to inaccurate measurements in both rotational and translational movements.
Innovation Solution
A magnetic sensor system that measures the direction of magnetic induction in two orthogonal planes, one normal to the rotational movement and the other to the translational movement, using a radially magnetized cylinder target and Hall effect cells to determine the position and orientation of the target with improved precision and insensitivity to air gap variations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a Hall effect component is used to measure the magnetic field in three orthogonal directions, then the position and orientation of the target can be determined, but the measurement is very sensitive to air gap variations
Solution Approach 1:
The patent transitions from measuring only magnetic field amplitude to measuring both direction and amplitude of the magnetic induction vector. By adding directional measurement capability (measuring components along three orthogonal axes), the system can determine position and orientation simultaneously while becoming less sensitive to air gap variations, as the directional information provides redundancy that compensates for amplitude changes due to gap variations.
Solution Approach 2:
The patent changes the measurement parameters from solely amplitude-based detection to include directional components. By measuring the direction of the magnetic induction vector in addition to its amplitude, the system gains the ability to distinguish between changes caused by air gap variations and those caused by actual position changes, thereby improving reliability against air gap sensitivity.
2Adaptability or versatility
If multiple ferromagnetic parts are implemented to enable rotational and translational measurement, then the sensor can determine position in both movements, but bulk constraints are increased
Solution Approach 1:
The patent merges the functions of measuring both rotational and translational position into a single integrated magnetic target structure (the cylinder portion). Instead of using separate mechanisms for each measurement type, the invention combines them into one compact magnetic target that can simultaneously provide information about both rotational angle and translational position through its radially varying magnetization pattern.
Solution Approach 2:
The magnetic target is designed with multi-functionality, serving both rotational position sensing and translational position sensing purposes. The radially magnetized cylinder portion can encode both angular position (through its rotational orientation) and linear position (through its axial location), allowing a single component to perform multiple measurement functions without requiring separate dedicated structures for each function.
3Measurement precision
If probes are positioned precisely to achieve accurate measurement, then measurement precision improves, but manufacturing complexity increases
Solution Approach 1:
The magnetic target structure is designed to be self-aligning and self-referencing. The radially magnetized cylinder portion creates a magnetic field pattern that inherently provides reference information, allowing the measurement system to automatically determine position without requiring mechanically precise probe positioning. The target essentially serves itself by providing the reference framework needed for accurate measurement.
Solution Approach 2:
The patent changes from amplitude-only measurement to directional measurement, which fundamentally alters how position is determined. Instead of relying on precise geometric positioning of probes to detect amplitude changes, the system measures the direction of the magnetic induction vector, which provides inherent positional information that is less sensitive to probe positioning tolerances.
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 provides precise positioning and orientation of moving parts with reduced sensitivity to air gap variations, enhancing the accuracy of position determination in both rotational and translational movements, and is suitable for applications like motor vehicle gearboxes.
Implementation Method 1
Hall effect cells sensitive to the components of the magnetic induction along three axes normal to each other
Data Source
Figure 1~3
Figure 4~6C
Figure 7A~9B
AI summary
The invention relates to a magnetic sensor for determining the position of a part (2) that is, on the one hand, rotatably mobile following an angular course limited according to a rotary movement (R) and, on the other hand, translatably mobile according to an axis of translation (X) and following a limited linear course, said sensor comprising, on the one hand, a magnetised target (3), rigidly mounted onto the mobile part (2), in the form of a radially magnetised cylinder portion having an axis of symmetry matching the axis of translation (X) and, on the other hand, a system (5) for measuring the magnetic induction of the magnetised target in order to determine the position of the target in space. According to the invention, the system (5) measures, at a single point, the direction of magnetic induction in two orthogonal planes, one of which (P1) is normal to the rotary movement (R) and the other one of which (P2) is normal to the translation movement (X), in order to determine the position and orientation of the target.