Sensor Signal Selection Circuit for Common-Mode Fault Detection
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Solution Overview
Problem
Existing redundant channel signal processing systems are ineffective in handling common mode failures where multiple sensors fail simultaneously and struggle to prevent oscillatory failures from reaching output signals, while also being limited by a small number of inputs.
Innovation Solution
A signal selection and fault detection system with four input equalization circuits and a five-input output selection circuit that calculates an equalization target signal as the average of two middle input signals, detects faulty signals, and isolates them, using a combination of static and dynamic fault detection to select a median signal from equalized inputs and a previous frame output.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If redundant sensor channels are processed, then fault detection capability is improved, but oscillatory failures can still reach the output signal
Solution Approach 1:
The patent applies dynamics by implementing a dynamic selection mechanism that adapts to different failure conditions. The system dynamically switches between different signal sources based on real-time fault detection: using the median of current readings when sensors are healthy, switching to pre-stored median values when failures are detected, and applying exponential smoothing specifically when oscillatory patterns are identified. This dynamic adaptation prevents oscillatory failures from propagating to the output while maintaining high fault detection capability.
Solution Approach 2:
The patent implements feedback through continuous monitoring of sensor readings and dynamic adjustment of the output signal based on detected failure conditions. The system feeds back information about sensor health status and oscillatory patterns to modify the signal processing approach in real-time. When oscillations are detected, the feedback mechanism activates exponential smoothing to dampen these oscillations before they reach the output, thereby preventing harmful oscillatory failures while maintaining effective fault detection.
2Device complexity
If a small number of sensor inputs are processed, then device complexity is reduced, but the system cannot process signals from a sufficient number of sensors for reliable fault detection
Solution Approach 1:
The patent applies partial action by using only the median value of the four sensor inputs rather than processing all possible combinations and relationships between sensors. This selective approach uses just enough information (the median) to achieve reliable fault detection and common mode failure handling without the excessive complexity of analyzing all sensor interactions. The median calculation provides sufficient fault detection capability while keeping the processing requirements manageable.
Solution Approach 2:
The patent implements parameter changes by transforming the four sensor inputs into a single median value parameter, and by dynamically changing the processing approach based on detected failure conditions. The system changes from processing four separate sensor signals to working with a single median parameter, significantly reducing complexity. Additionally, the system changes processing parameters dynamically - switching between different algorithms (median calculation, exponential smoothing, pre-stored value usage) based on the detected failure mode, thereby maintaining reliability across different operating conditions without requiring complex simultaneous processing.
Data Source
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AI summary
A signal selection and fault detection system is provided. The system includes four input equalization circuits (202, 204, 206, 208) each configured to receive an input signal from an associated sensor (102), wherein the input signal is indicative of a parameter measured by the associated sensor (102), and output an equalized signal based on the received input signal. The system further includes a five-input output selection circuit (210) coupled to the four input equalization circuits (202, 204, 206, 208), the five-input output selection circuit (210) configured to receive an equalized signal from each of the four input equalization circuits (202, 204, 206, 208), receive a previous frame output signal, and select an output signal from the four equalized signals and the previous frame output signal.