Hysteresis Compensated Force Sensor Using Dual-Frequency Excitation
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Solution Overview
Problem
Magnetic field-based force sensing technologies face significant challenges in accurately measuring forces due to hysteresis effects, which can result in signal deviations exceeding ±2.5%, making it difficult to obtain reliable measurements, especially in applications requiring high precision.
Innovation Solution
A sensor device that employs alternating current signals of different frequencies and amplitudes to generate magnetic fields, allowing for the evaluation of sensing signals and determination of correction values to compensate for hysteresis-related deviations, thereby eliminating hysteresis effects from measured signals.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If magnetic field-based force sensing is used to measure forces applied to ferromagnetic objects, then force measurement capability is provided, but hysteresis effects cause signal deviations exceeding ±2.5% that reduce measurement precision
Solution Approach 1:
The patent applies periodic alternating current signals at two different frequencies to the magnetic field generating element. By using periodic excitation signals with different frequencies (first frequency and second frequency), the system can distinguish between hysteresis-related signals and true force signals through frequency-based separation, thereby eliminating hysteresis effects from the measurement
Solution Approach 2:
The patent changes the frequency parameter of the driving signal to resolve the hysteresis problem. By measuring at two different frequencies and comparing the results, the system can identify and compensate for hysteresis effects, which manifest differently at different frequencies, thus improving measurement precision
2Measurement precision
If alternating current signals of different frequencies are used to generate magnetic fields for hysteresis compensation, then measurement precision is improved, but device complexity increases due to additional driving and evaluation requirements
Solution Approach 1:
The magnetic field generating element serves multiple functions: it generates magnetic fields at the first frequency for hysteresis compensation measurement and at the second frequency for true force measurement. This multi-functionality reduces the need for separate excitation sources, thereby limiting the increase in device complexity while achieving improved measurement precision
3Measurement precision
If hysteresis compensation is implemented using multiple frequency signals, then signal accuracy is improved, but measurement time increases due to multiple signal cycles required
Solution Approach 1:
The system performs preliminary measurement at the first frequency to capture hysteresis effects before the actual force measurement at the second frequency. By preparing the magnetic field state in advance and using the first frequency measurement to characterize hysteresis, the system can then compensate for these effects in the second measurement, achieving accurate results without excessive time loss
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
This approach enables real-time compensation for unwanted signal hysteresis, providing more accurate force measurements by distinguishing between hysteresis-induced signals and true force signals, even in ferromagnetic materials with significant hysteresis, thus improving the precision and reliability of force sensing.
Implementation Method 1
a magnetic field generating element (50) being adapted for generating a magnetic field in order to generate a magnetic flux in an object (2) to be sensed
Implementation Method 2
a first magnetic field sensing element (10) being adapted to sense a magnetic field depending on a variation of the generated magnetic flux in said object (2) to be sensed
Implementation Method 3
Hysteresis is a known phenomenon in ferromagnetic materials like iron (Fe), nickel (Ni), cobalt (Co) and their alloys. It is the inability of the material to return back to its original state when an external force or magnetic field previously applied to it is removed
Data Source
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AI summary
Sensor device for measuring forces applied to an object to be sensed with the sensor (1) having a magnetic field generating element (50), a magnetic field sensing element (10), a driving unit (200) being adapted to drive the magnetic field generating element (50) with a first and second driving signal having a first and second frequency, and an evaluation unit (300), the sensor being able of compensating a hysteresis of the object to be sensed.