Magnetoelastic Torque Sensor Harmonic Error Cancellation
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Solution Overview
Problem
Existing magnetoelastic torque sensor assemblies face challenges in accurately measuring applied torque due to non-uniform magnetic field signals and harmonic errors caused by manufacturing processes, material microstructure, and magnetization processes.
Innovation Solution
The torque sensor assembly includes a shaft with magnetoelastic regions that generate a magnetic field in response to applied torque. A plurality of sensors circumferentially positioned around these regions generate signals indicative of the magnetic field, which include multiple harmonic components. A controller processes these signals to determine an average that cancels at least one harmonic component, allowing for accurate measurement of the applied torque.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If magnetoelastic regions are used to generate magnetic field signals in response to applied torque, then torque measurement capability is achieved, but harmonic errors and non-uniform magnetic field signals are introduced due to manufacturing processes, material microstructure, and magnetization processes
Solution Approach 1:
The torque sensor assembly divides the measurement function across multiple sensors positioned at different angular locations around the shaft. Each sensor measures the magnetic field at its specific position, and the controller processes these segmented measurements to compute the average torque signal, thereby reducing the impact of localized harmonic errors from any single sensor or magnetoelastic region.
Solution Approach 2:
The controller combines the signals from multiple sensors by computing their average. This merging of multiple measurements cancels out harmonic components that are non-uniform across the different sensor positions, while preserving the uniform torque-induced magnetic field signal that appears consistently across all sensors.
2Reliability
If multiple sensors are positioned circumferentially around the magnetoelastic regions to measure magnetic field, then harmonic error cancellation is enabled, but device complexity increases
Solution Approach 1:
The multiple sensors serve dual functions: individually, each sensor detects the magnetic field at its position, and collectively, they enable harmonic error cancellation through averaging. This multi-functionality justifies the increased number of sensors, as they provide both redundant measurement capability and error reduction functionality.
Solution Approach 2:
The system changes the spatial parameter of sensor positioning, placing sensors at specific angular intervals around the shaft. This parameter optimization ensures that the sensors are positioned to maximize the cancellation of harmonic errors while maintaining a manageable number of sensors, thus balancing reliability improvement against complexity increase.
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 solution effectively reduces magnetic errors by canceling harmonic components, resulting in improved accuracy and reliability of torque measurements in applications such as vehicle electronic power steering systems.
Implementation Method 1
The shaft includes at least one region being magnetoelastic and configured to generate a magnetic field in response to the applied torque
Data Source
AI summary
A torque sensor assembly including a shaft configured to receive an applied torque. The shaft includes at least one region being magnetoelastic and configured to generate a magnetic field in response to the applied torque. A plurality of sensors, circumferentially positioned around the at least one region, configured to generate a plurality of signals that are indicative of the magnetic field. Each of the plurality of signals includes multiple harmonic components. A controller is connected with the plurality of sensors and being configured to receive the plurality of signals and determine (i) an average of the plurality of signals in order to cancel at least one of the harmonic components of the multiple harmonic components for each of the plurality of signals, and (ii) a magnitude of the applied torque based on the average of the plurality of signals.