Daisy Chain Position Sensor with Magnetic Interference Suppression
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Solution Overview
Problem
Existing position determining units require complex circuitry for address allocation and signal evaluation, and are limited in their ability to accurately measure positions over long ranges without interference from external magnetic fields.
Innovation Solution
A position determining unit comprising a series of sensor units arranged along a path with a transducer made of ferromagnetic material, using a daisy chain configuration and magnetic field sensors to measure aggregate current, which is proportional to the transducer's position, eliminating the need for individual sensor communication and signal evaluation, and employing bias magnets to generate a parallel or perpendicular magnetic field for differential or absolute measurements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If complex circuitry for address allocation and signal evaluation is used, then position determination accuracy is improved, but device complexity increases
Solution Approach 1:
The patent extracts and eliminates the complex address allocation and signal evaluation circuitry from the system. Instead of using individual sensor communication and evaluation circuits, the invention uses a simplified approach where sensor units are arranged in a daisy chain and their collective output is processed through a single current measuring unit, thereby removing unnecessary complexity while maintaining measurement capability
Solution Approach 2:
The patent merges multiple sensor units into a single integrated measurement system. Instead of processing signals from individual sensors separately through complex address allocation circuitry, the sensor units are combined in a daisy chain configuration where their cumulative effect is measured as a single aggregate current, simplifying the overall device architecture
2Length of stationary object
If sensor units are arranged along a long path, then measurement range is improved, but susceptibility to external magnetic field interference increases
Solution Approach 1:
The patent converts the harmful effect of external magnetic fields into a beneficial measurement capability. By using differential measurement with two magnetic field sensors, the system can distinguish between changes in the bias magnetic field (caused by external fields) and changes in the sensor signal (caused by the transducer position), thereby eliminating interference while maintaining long-range measurement capability
Solution Approach 2:
The patent implements feedback through differential measurement. The second magnetic field sensor continuously monitors the bias magnetic field conditions, and this information is used to compensate for external field interference in the measurement from the first sensor, allowing the system to maintain accuracy over long paths despite environmental disturbances
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 accurate and efficient position determination over long ranges without the need for complex circuitry, suppressing external magnetic field interference and allowing for both absolute and differential measurements, suitable for applications like seat rails and fuel tank level indication.
Implementation Method 1
The transducer is movable along the path and has a first end and a length extending parallel to the path from the first end. The transducer comprises a ferromagnetic material.
Implementation Method 2
Each sensor unit has a bias magnet with a first pole and a second pole. The sensor signal is detected by means of the at least one magnetic field sensor of the measuring unit.
Implementation Method 3
The sensor signal is detected by means of the at least one magnetic field sensor of the measuring unit.
Implementation Method 4
The power consumption Isup of all switched-on sensor units contribute to an aggregate current Isum measured by means of the current measuring unit, wherein the aggregate current Isum is a multiple of the power consumption Isup and is proportional to a position of the first end of the transducer.
Data Source
AI summary
A position determining unit is provided that has a number of sensor units arranged at positions along a path, and a transducer. Each sensor unit has a carrier, a first and second supply voltage connection, a switching output, a measuring unit and a bias magnet comprising two poles. The measuring unit is arranged on the carrier and has at least one magnetic field sensor, wherein the switching output is switched into an On or Off-state as a function of a threshold value exceeding or falling short of a sensor signal. The first supply voltage connection of each sensor unit is connected to a supply voltage, wherein a first sensor unit is arranged at a beginning of the path and a last sensor unit is arranged at the end of the path. The second supply voltage connection of the first sensor unit is connected to a reference potential.