Timestamp Assignment for Sensor Data Packets
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Solution Overview
Problem
Existing methods for assigning time stamps to sensor data in vehicles are prone to errors due to unpredictable transmission delays and outliers, leading to inaccurate timestamping, especially when sensors measure ahead of their normal cycle, causing all subsequent timestamps to be set too early.
Innovation Solution
A method that determines a second anchor time by analyzing a group of data packets' arrival times and time differences to identify and exclude outliers, ensuring accurate timestamping by considering negative time differences that are not outliers, thereby avoiding premature anchor time settings.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the arrival time of sensor data is assigned as timestamp, then the timestamp can be determined simply, but the timestamp becomes inaccurate due to transmission delays and jitter
Solution Approach 1:
The patent applies preliminary action by establishing a reference timestamp (anchor point) before processing individual data packets. The system determines a reference timestamp based on the earliest arrival time, then uses this pre-established reference to calculate timestamps for all subsequent packets through addition of transmission delays, avoiding the need to determine each timestamp independently and reducing overall complexity while improving accuracy
Solution Approach 2:
The patent introduces an intermediary element - the reference timestamp (anchor point) - that mediates between the raw arrival times and the final accurate timestamps. This reference timestamp serves as a stable baseline that absorbs the variability of transmission delays, allowing individual packet timestamps to be calculated relative to this stable reference rather than absolute arrival times
2Ease of operation
If the earliest arrival time is used as anchor point, then timestamp determination is straightforward, but outliers cause all subsequent timestamps to be set too early
Solution Approach 1:
The patent implements feedback by continuously monitoring arrival times and using them to adjust the reference timestamp determination. The system evaluates multiple arrival times and uses feedback from their distribution pattern to identify and exclude outliers, then establishes the reference timestamp based on the cleaned data, ensuring robustness while maintaining operational simplicity
Solution Approach 2:
The system performs preliminary filtering and analysis of arrival times before establishing the reference timestamp. By pre-identifying and excluding outliers from the dataset used to determine the anchor point, the system ensures that the reference timestamp is not corrupted by premature measurements, while still maintaining a straightforward selection process based on the earliest valid arrival time
Data Source
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AI summary
Disclosed is a method for assigning a time stamp to a specific data packet which, just like a group of received data packets, is received by a cyclically operating sensor, said specific data packet especially being part of the group of received data packets. The disclosed method comprises the following steps: determining the time of arrival of each data packet of the group of received data packets; assigning a time stamp to each data packet of the group of data packets on the basis of a first reference point in time; determining the time difference between the determined time of arrival and the assigned time stamp for each data packet of the group of data packets (group of time differences); determining the time differences from among the group of time differences, for the data packets of which it has been determined that the time of arrival preceded the respective assigned time stamp (negative time differences); determining the negative time differences that are not to be classified as outliers; determining a second reference point in time taking into account the negative time differences that are not to be classified as outliers; assigning a time stamp to the specific data packet on the basis of the second reference point in time.