Torque Sensor Noise Cancellation via Switching Function
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Solution Overview
Problem
Existing torque-sensing devices face challenges in accurately measuring torque applied to a rotatable shaft in the presence of non-linear magnetic noise fields without requiring additional magnetic shielding elements and are prone to errors due to external magnetic fields, particularly near-field sources.
Innovation Solution
A torque-sensing device with a magnetoelastic torque-sensing transducer featuring two oppositely polarized magnetically conditioned regions and magnetic field sensors that can switch between common mode and differential mode operations to effectively cancel noise-induced magnetic fields, allowing the same sensors to detect both torque-induced and noise signals, thereby reducing the number of sensors needed and eliminating the need for additional shielding.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If magnetic shielding elements are added to block external magnetic fields, then measurement precision is improved, but device complexity and cost increase
Solution Approach 1:
The patent converts the harmful effect of external magnetic fields into a useful measurement signal. By using the same sensors to detect both torque-induced magnetic fields and external magnetic noise, and then applying signal processing to separate them, the system eliminates the need for physical shielding while maintaining measurement accuracy. The external magnetic fields that were previously harmful are now utilized as additional information for noise cancellation.
Solution Approach 2:
The patent replaces the mechanical/physical shielding approach with an electronic/software-based solution. Instead of using magnetic shielding materials and structures to block external fields, the system uses signal processing techniques (including switching functions and noise cancellation algorithms) to electronically remove the effects of external magnetic fields from the measurement signal.
2Measurement precision
If multiple magnetic field sensors are used to detect both torque and noise signals, then measurement precision is improved, but device complexity and space requirements increase
Solution Approach 1:
The patent makes the magnetic field sensors multi-functional by using them to detect both torque-induced magnetic fields and external magnetic noise. The same sensors that measure torque are also used to measure the ambient magnetic field conditions, eliminating the need for separate sensors dedicated to noise detection and reducing the overall space required.
Solution Approach 2:
The patent combines the torque sensing function and noise detection function into a single integrated system using the same magnetic field sensors. By merging these functions and using signal processing to separate the torque signal from the noise signal, the system reduces the number of sensors needed while maintaining the ability to accurately measure both torque and environmental magnetic conditions.
3Reliability
If additional magnetic shielding elements are added, then reliability is improved, but manufacturing cost increases
Solution Approach 1:
The patent replaces expensive magnetic shielding materials and assembly processes with more economical electronic signal processing techniques. By using software-based noise cancellation and switching functions to remove magnetic interference, the system achieves reliable measurements without the high costs associated with physical shielding implementations.
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 enables accurate torque measurement in the presence of non-linear magnetic noise fields without additional shielding, reducing the required space and cost, while effectively canceling noise-induced errors, thus improving the signal-to-noise ratio and reliability of torque sensing.
Implementation Method 1
magnetoelastic torque-sensing magnetic field transducer
Implementation Method 2
magnetic field sensors that can switch between common mode and differential mode operations
Data Source
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AI summary
A torque sensing device for measuring the torque applied to a rotatable shaft, and also measuring the magnetic field noise affecting the device. The device incorporates a switching function thereby enabling the device to operate in a common signal detection mode and a differential noise detection mode. The device is capable of determining the torque applied to the rotatable shaft based upon output signals obtained from magnetic field sensors operating in both the common signal detection mode and the differential noise detection mode. The device is capable of accurately measuring a torque induced magnetic field and is capable of canceling measurement error resulting from noise induced magnetic fields.