Noise-Resistant Incremental Position Sensor Circuit
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Solution Overview
Problem
Intermittently operating incremental position sensors are susceptible to electromagnetic interference (EMI), particularly impulse noise, which can cause position loss and are difficult to detect and correct, leading to inaccurate measurements.
Innovation Solution
A method and circuit design that determines noise influence on measurement signals, generates corrective signals when noise exceeds a threshold, and replaces scheduled measurements with corrective ones until noise is below the threshold or a maximum number of attempts is reached, using noise canceling means to improve immunity to EMI.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the drive signal is increased to decrease noise influence, then noise immunity is improved, but power consumption increases
Solution Approach 1:
The patent implements dynamic adjustment of the drive signal amplitude based on detected noise levels. The system continuously monitors noise at circuit nodes and adaptively increases or decreases the drive signal amplitude accordingly, allowing optimal noise immunity with minimal power consumption under normal conditions while providing enhanced protection during noisy periods.
Solution Approach 2:
The system changes the amplitude parameter of the drive signal dynamically in response to noise conditions. By monitoring noise thresholds and adjusting the drive signal amplitude parameter, the system achieves variable noise immunity without constant high power consumption, resolving the contradiction between reliability and energy use.
2Use of energy by moving object
If pulsed measurements are used to reduce power consumption, then energy efficiency is improved, but susceptibility to impulse noise increases
Solution Approach 1:
The patent incorporates a feedback mechanism that monitors noise levels at circuit nodes during pulsed measurements and triggers corrective actions when noise exceeds thresholds. This feedback loop allows the system to maintain low power consumption through pulsed operation while detecting and correcting noise-corrupted measurements, thus reducing susceptibility to impulse noise.
Solution Approach 2:
The system performs preliminary noise detection before final position determination. By monitoring circuit nodes for noise influence ahead of time and identifying corrupted measurements, the system can take preliminary corrective actions such as requesting re-measurements, preventing noise from affecting the final position output while maintaining efficient pulsed operation.
3Measurement precision
If corrective measurements are performed repeatedly to overcome noise, then measurement accuracy is improved, but measurement time increases
Solution Approach 1:
The patent applies partial corrective action by performing corrective measurements only when noise thresholds are exceeded, rather than continuously. The system uses noise monitoring to determine when corrective measurements are necessary, avoiding unnecessary re-measurements and thus minimizing time loss while maintaining position accuracy when needed.
Solution Approach 2:
The system performs preliminary noise detection to identify when corrective measurements are needed before executing them. This preliminary action allows the system to minimize the number of corrective measurements by only performing them when actually necessary, reducing time loss while ensuring accuracy when noise is present.
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
Enhances the immunity of incremental position sensors to electromagnetic interference, reducing the impact of noise on position measurements and preventing position loss by effectively correcting noise-corrupted data, thereby ensuring accurate incremental position detection.
Implementation Method 1
These sensors are inductive and operate by pulsed drive coils coupled via a spatially periodic scale to sense coils
Data Source
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AI summary
A method of operating an intermittently measuring or pulsed incremental position sensor, and a position sensor that has noise detecting circuitry activated during each measurement, triggering corrective measurements as long as the influence of noise is detected. Corrective measurements immediately follow and replace a noise-influenced measurement well before the next scheduled measurement. Noise can be detected as a differential amplifier's common-mode input signal, thus clearly separating the influence of noise from the sensor's differential input signal.