Variable Reluctance Sensor Interface Pre-Processing Circuit
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Solution Overview
Problem
Variable reluctance sensors (VRSs) face inaccuracies in determining the angular position and speed of rotating objects due to synchronous and asynchronous noise, dynamic signal variations, and mechanical tolerances, leading to erroneous transitions in the detect signal pulse.
Innovation Solution
A VRS interface with a pre-processing circuit, such as a peak and hold circuit or RC filter, is implemented to modify the VRS signal and prevent it from dropping below a threshold value, reducing erroneous transitions and improving signal accuracy by generating a clean detect signal pulse.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a VRS is used to measure angular position and speed, then position and speed information can be obtained, but synchronous and asynchronous noise causes erroneous transitions in the detect signal
Solution Approach 1:
The patent applies preliminary action by implementing a pre-processing circuit that modifies the VRS signal before it reaches the comparators. The pre-processing circuit proactively prevents the signal from dropping below threshold values that would cause erroneous transitions, thereby eliminating noise-induced errors before they can affect measurement accuracy.
2Reliability
If the VRS signal is directly processed without pre-processing, then the device complexity is low, but erroneous transitions occur due to signal dropping below threshold values
Solution Approach 1:
The patent introduces an intermediary pre-processing circuit between the VRS signal source and the comparator. This intermediary circuit modifies the signal characteristics to prevent erroneous transitions while maintaining overall system simplicity. The pre-processing circuit acts as a mediator that conditions the signal without requiring complex processing downstream.
3Ease of manufacture
If mechanical tolerances and signal variations are present, then manufacturing is easier and adaptability is higher, but measurement precision deteriorates due to erroneous detect signal transitions
Solution Approach 1:
The patent applies preliminary anti-action by using the pre-processing circuit to counteract the effects of mechanical tolerances and signal variations before they can cause measurement errors. The circuit proactively prevents signal drops below critical threshold values, thereby compensating for manufacturing variations and maintaining measurement precision despite ease of manufacture considerations.
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
The solution enhances the accuracy of position and speed determinations, providing improved noise immunity and reducing false detections, thus improving the performance of devices using VRSs.
Implementation Method 1
each tooth passing by the VRS changes the magnetic flux which is converted to an electrical voltage induced in the coil
Data Source
AI summary
The embodiments described herein can provide a variable reluctance sensor (VRS) interface that may reduce the probability of erroneous transitions in a resulting generated detect signal. As such, the VRS interface can improve the accuracy of position and/or motion determinations, and thus can improve the performance of a wide variety of devices that use variable reluctance sensors. To facilitate this, the VRS interface includes a pre-processing circuit configured to modify a VRS signal to prevent the modified VRS signal from dropping below a threshold value and generating erroneous transitions in the detect signal pulse between leading and lagging edges of a tooth. In one embodiment the pre-processing circuit comprises a peak and hold circuit. In another embodiment the pre-processing circuit comprises a resistor-capacitor circuit. In either case the pre-processing circuit can prevent erroneous transitions in the detect signal and thus may improve the performance and accuracy of the system.