Torque Sensor Using Four Magnetic Field Sensors to Cancel Interference
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing force and torque measurement technologies face challenges in effectively reducing the influence of magnetic interference fields using the inverse magnetostrictive effect.
Innovation Solution
The arrangement employs at least four magnetic field sensors and a circumferentially magnetized machine element with a hollow axis, where the sensors are strategically positioned to measure the axial directional component of the magnetic field caused by the inverse magnetostrictive effect, minimizing the impact of magnetic interference fields by using a combination of primary and secondary sensors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If magnetic field sensors are used to measure force/torque based on the inverse magnetostrictive effect, then measurement capability is achieved, but magnetic interference fields reduce measurement precision
Solution Approach 1:
The sensor system is segmented into multiple magnetic field sensors (at least four) positioned at different locations around the machine element. Each sensor measures the magnetic field at its specific position, and the individual measurements are combined through evaluation to determine the force or torque while canceling out interference fields. This segmentation allows the system to distinguish between signal components caused by the measured quantity and those caused by interference.
Solution Approach 2:
Multiple magnetic field measurements from different sensor positions are merged and evaluated together to produce the final measurement result. The evaluation process combines the individual sensor signals in a way that extracts the force/torque information while suppressing or eliminating the influence of magnetic interference fields that affect all sensors similarly.
2Measurement precision
If multiple magnetic field sensors are deployed to reduce interference, then measurement accuracy improves, but device complexity increases
Solution Approach 1:
The use of multiple sensors (segmentation) is justified by the need to achieve interference rejection. The sensors are strategically positioned around the machine element to capture magnetic field information from different perspectives, enabling the evaluation system to differentiate between signal and interference through spatial analysis.
Solution Approach 2:
The magnetic field sensors serve multiple functions: they detect both the magnetic field changes caused by the inverse magnetostrictive effect (useful signal) and the magnetic interference fields (disturbance). By processing the combined information from all sensors, the system simultaneously achieves force/torque measurement and interference rejection, making the multi-sensor configuration multi-functional.
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 configuration allows for a significant reduction in the influence of magnetic interference fields, enabling accurate measurement of forces and moments based on the inverse magnetostrictive effect.
Implementation Method 1
The machine element has at least one magnetization region extending circumferentially around an axis in an axial section of the machine element for magnetization formed within the machine element. The first, second, third, and fourth magnetic field sensors are each designed for individually measuring an axial directional component of a magnetic field caused by the inverse magnetostrictive effect.
Data Source
Figure 1~2
Figure 3~4
Figure 5
AI summary
An arrangement for measuring a force and/or a torque (Mt) on a machine element extending along an axial axis is disclosed. The machine element has a cavity and at least one magnetization region, extending circumferentially around the axial axis in an axial section. The arrangement further includes at least one first magnetic field sensor, a second magnetic field sensor, a third magnetic field sensor and a fourth magnetic field sensor, each of which is designed to individually measure an axial direction component of a magnetic field caused by the magnetization and also by the force or torque (Mt) and each of which lies in the axial section. At least the first magnetic sensor and the second magnetic sensor are arranged in the cavity of the machine element.