Sensor Clock Monitoring for PSI5 Oscillator Drift Detection
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Solution Overview
Problem
Current airbag systems face issues with sensor clock oscillators drifting or failing, which can disrupt signals on the PSI5 bus, leading to potential incorrect non-triggering of airbag systems and reduced safety in road traffic.
Innovation Solution
A method and device for monitoring sensor clock signals in sensor units, comparing the sensor clock signal with a reference clock signal to detect deviations, and sending error messages to the control unit if the deviation exceeds predetermined thresholds, thereby quickly identifying and addressing faulty oscillators.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If no clock monitoring is implemented, then the device complexity is low, but the reliability deteriorates due to undetected oscillator drift or failure
Solution Approach 1:
The patent implements preliminary monitoring of the sensor clock signal by continuously comparing it with a reference clock signal before the oscillator failure can disrupt PSI5 bus communication. The deviation evaluation and error counter mechanisms are activated in advance to detect drift or failure conditions, enabling early warning and maintaining system reliability without adding complex post-failure diagnostics.
2Reliability
If continuous clock monitoring is implemented, then the diagnostic coverage is improved, but the use of energy increases due to continuous comparison and evaluation operations
Solution Approach 1:
The patent employs a feedback mechanism where the sensor clock signal is continuously compared with the reference clock signal, and the deviation is evaluated against predefined thresholds. The error counter provides feedback on the accumulation of deviations, and when a threshold is exceeded, an error signal is generated. This feedback-based approach enables continuous monitoring with optimized energy consumption by only triggering error signals when actual deviations occur, rather than continuously reporting every minor fluctuation.
3Measurement precision
If clock deviation thresholds are set narrowly, then the measurement precision is improved, but the loss of time increases due to more frequent error signals from normal variations
Solution Approach 1:
The patent implements parameter changes by establishing a deviation evaluation mechanism that compares clock signal deviations against predefined threshold values. The system dynamically evaluates whether deviations exceed acceptable ranges and only generates error signals when thresholds are breached. This parameter-based approach balances measurement precision with time efficiency by filtering out normal variations and only responding to significant deviations, preventing excessive error signaling from minor clock fluctuations.
Data Source
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AI summary
The invention relates to a method for monitoring a sensor clock signal (STS) in a sensor unit (10), which is generated and output for a data transfer between the sensor unit (10) and a control unit with a predefined period duration, wherein a reference clock signal (RTS) having a predefined reference period duration is received. The invention further relates to a device (20) for carrying out the method. To this end, the sensor clock signal (STS) is compared to the reference clock signal (RTS), wherein based on the comparison, a deviation of the current period duration of the sensor clock signal (STS) from a target period duration is detected, and wherein based on the detected deviation, a counting pulse (ZI) or a reset pulse (RI) is emitted.