Sensor Timestamp Estimation via Register Oversampling
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Solution Overview
Problem
Microcontroller units (MCUs) in vehicles lack the ability to determine the exact timestamp of sensor register updates from sensors like accelerometers, due to lack of access to the sensor's internal timestamp data, leading to integration errors in acceleration profiles.
Innovation Solution
The system observes sensor data at a sampling frequency different from the sensor update frequency, generates an observed sequence to identify updates, estimates the sensor update frequency and phase, and determines a timestamp for register updates based on these estimates.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the MCU samples sensor data at a different frequency than the sensor update frequency, then the MCU can operate independently without accessing sensor internal timestamp data, but the exact timestamp of sensor register updates cannot be determined
Solution Approach 1:
The system uses feedback by continuously monitoring the sensor register for value changes and using these change detections to infer timestamp information. The MCU samples the register at its own frequency and uses the pattern of detected changes to estimate when updates occurred, creating a feedback loop that compensates for the frequency mismatch.
Solution Approach 2:
The sensor register acts as an intermediary between the sensor's internal timestamp mechanism and the MCU. Instead of directly accessing timestamp data, the MCU uses the register contents and their changes as an intermediate signal to infer timing information through analysis of update patterns.
2Measurement precision
If the MCU samples at the sensor update frequency, then exact timestamp determination is possible, but the system requires access to sensor internal timestamp data and cannot operate independently
Solution Approach 1:
The invention extracts only the necessary information (register value changes) from the sensor system without requiring access to the internal timestamp mechanism. By taking out just the observable update pattern from the register, the MCU can determine timestamps independently without the complexity of synchronized access to sensor internal state.
3Productivity
If the MCU samples sensor data at a higher frequency than the sensor update frequency, then more update events can be detected, but integration errors in acceleration profiles increase due to inability to determine exact update times
Solution Approach 1:
The system performs preliminary analysis of the update pattern by collecting multiple samples and detecting change events before performing integration. By preliminarily identifying when updates occurred through change detection, the system prepares accurate timing information in advance, enabling reliable integration even with higher sampling rates.
Data Source
AI summary
Systems and methods for estimating sensor timestamps by oversampling are provided. One example method involves observing, at a sampling frequency, sensor data from a register of a sensor. The sensor updates the register with sensor data at as sensor update frequency. The sampling frequency is different from the sensor update frequency. The method also involves generating, based on the sensor update frequency and the sampling frequency, an observed sequence representing the sensor data. The observed sequence indicates whether the register is observed to be updated or not updated. The method also involves estimating, from the observed sequence, the sensor update frequency and a sensor update phase. The method also involves determining, based on the sensor update frequency as estimated and the sensor update phase as estimated, a timestamp corresponding to an update of the register.