Capacitive Acceleration Sensor Evaluation Circuit Parasitic Detection
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Solution Overview
Problem
Capacitive acceleration sensors are prone to malfunctions due to parasitic effects and contaminants, leading to erroneous sensor values, which can cause incorrect system reactions and compromise operational safety.
Innovation Solution
An evaluation circuit for capacitive acceleration sensors that includes a switching element to reverse the polarity of the voltage provided to one of the sensors, allowing for the detection of malfunctions and parasitic effects by comparing output signals from two identical or similar sensors, thereby identifying and adapting control processes to ensure reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If capacitive acceleration sensors are used to detect acceleration parameters, then the functionality and control capability of vehicle systems are improved, but parasitic effects and contaminants cause malfunctions and erroneous sensor values that compromise reliability
Solution Approach 1:
The patent applies parameter changes by switching the polarity of the excitation voltage applied to the capacitive acceleration sensor. By reversing the voltage polarity and measuring the sensor response, the system can detect parasitic capacitances and contaminants that cause erroneous readings. This parameter switching enables differentiation between genuine acceleration signals and interference signals, thereby maintaining sensor reliability while preserving control capability.
Solution Approach 2:
The patent implements feedback by continuously monitoring the sensor output signals and comparing them against expected values based on applied voltage polarity. When discrepancies are detected indicating parasitic effects or contaminants, the system provides feedback to adapt control processes or trigger diagnostic routines, ensuring reliable operation despite sensor imperfections.
2Device complexity
If standard evaluation circuits are used for capacitive sensors, then circuit simplicity is maintained, but parasitic capacitances and contaminants cannot be reliably detected
Solution Approach 1:
The patent introduces dynamics into the evaluation circuit by implementing a switching element that periodically reverses the voltage polarity applied to the sensor. This dynamic operation allows the circuit to distinguish between static parasitic capacitances and dynamic genuine sensor responses, enabling accurate measurement despite the presence of parasitic effects without requiring complex additional circuitry.
Solution Approach 2:
The evaluation circuit changes the electrical parameter (voltage polarity) applied to the sensor and measures the corresponding output. By analyzing the sensor response to polarity reversal, the circuit can identify parasitic capacitances and contaminants, thereby improving measurement precision while maintaining relatively simple circuit architecture.
Data Source
AI summary
An additional test operating mode for an acceleration detector including two acceleration sensors in a differentiated operating mode. For this purpose, an additional test operating mode is provided, in which the reference voltage for one acceleration sensor is inverted. By comparing the output signals of the acceleration sensors and during the test operating mode, an interference, in particular a contamination of the sensors or influences by parasitic capacitances in the sensor system may be detected.