Redundant Sensor Signal Capture via Orthogonal Stimuli
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing fault detection mechanisms in safety-relevant systems, such as motor vehicle sensors, are inadequate for detecting gain errors and distinguishing stimulus signals from usable signals, especially when the measurement channel cannot be accurately modeled and time-related or frequency separation is not possible.
Innovation Solution
A sensor system utilizing a redundant assemblage of sensors excited by frequency-orthogonal stimulus signals, allowing for complete separation of signal and stimulus without limiting the frequency response, and enabling fault detection without a measured variable, using a processing device with mixers, stimulus filters, compensators, and redundancy reducers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If redundant sensors are used for fault detection, then reliability is improved, but measurement precision deteriorates when measured variable is zero due to undetectable gain errors
Solution Approach 1:
The patent applies preliminary action by superimposing a test signal onto the sensor signal before processing. This allows the measurement channel to be checked in advance even when no measured variable is present, enabling detection of gain errors that would otherwise be undetectable. The test signal is added to the sensor signal at the input stage, ensuring the measurement path is actively verified regardless of the measured variable value.
2Reliability
If stimulus signals are used to check measurement channels, then reliability is improved, but difficulty of detecting and measuring worsens due to inability to distinguish stimulus from usable signal
Solution Approach 1:
The patent applies periodic action by using a periodic test signal with a specific frequency that is superimposed on the sensor signal. The evaluation device then uses frequency-selective filtering to separate the periodic test signal from the usable sensor signal based on their different frequencies. This allows reliable distinction between stimulus and measurement signal without requiring complex time separation or accurate channel modeling.
3Ease of operation
If frequency separation is attempted to distinguish stimulus from signal, then ease of operation is improved, but device complexity increases due to additional filtering requirements
Solution Approach 1:
The patent uses frequency as an intermediary property to separate the test signal from the sensor signal. By assigning different frequencies to the test signal and the usable sensor signal, the evaluation device can use simple frequency-selective filters to separate them. This intermediary frequency domain separation simplifies the overall system compared to complex time-domain separation or signal modeling approaches, as it only requires basic filtering operations.
Data Source
AI summary
A sensor system for furnishing a D-dimensional measured signal encompasses at least N sensors (where D<N) sensors that have measurement directions linearly independent of one another; a stimulus source for furnishing a periodic stimulus signal for each of the sensors, the stimulus signals having mutually orthogonal frequencies; and a processing device for removing the stimulus signals from the sensor signals and for furnishing the D-dimensional measured signal.