Position Measurement System Timestamp Synchronization
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Solution Overview
Problem
Current positioning systems using GNSS and IMU face challenges in achieving high accuracy due to delays in processing and data propagation, especially when combining absolute and relative positioning means, which affects real-time performance and accuracy in autonomous vehicles and similar applications.
Innovation Solution
A position measurement system that includes an absolute positioning unit, a relative positioning unit, and a positioning computation unit, where each unit attaches time stamps to their respective measurement results and outputs them, allowing for synchronized and timely processing to improve accuracy and reduce delays in composite positioning.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If GNSS positioning is used for absolute position measurement, then positioning coverage is improved, but positioning accuracy in moving direction deteriorates due to computation delay
Solution Approach 1:
The system attaches time stamps to measurement results at the moment they are obtained, and the positioning computation unit uses these time stamps to determine the latest available data for computation. This preliminary timestamping action allows the system to always use the most recent measurement data, reducing the effective computation delay and improving positioning accuracy in the moving direction while maintaining GNSS positioning coverage.
2Reliability
If composite positioning computation is performed using Kalman filter with multiple positioning means, then positioning reliability is improved, but real-time performance deteriorates due to data output cycle differences
Solution Approach 1:
Each positioning measuring unit attaches a time stamp to its measurement result at the moment of measurement. The positioning computation unit then selects the latest measurement result from each positioning means based on these time stamps, ensuring that the most recent data is used in the Kalman filter computation. This preliminary timestamping enables the system to maintain high positioning reliability through composite positioning while improving real-time performance by eliminating delays from data output cycle differences.
3Reliability
If multiple positioning means are combined for composite positioning, then positioning reliability is improved, but positioning accuracy deteriorates due to processing delay and data propagation delay
Solution Approach 1:
The system attaches time stamps to measurement results from multiple positioning means at the moment they are obtained. The positioning computation unit uses these time stamps to identify and select the latest measurement results from each positioning means for composite positioning computation. This preliminary timestamping action ensures that the most recent data from all positioning means is used, improving positioning accuracy by reducing the impact of processing delays and data propagation delays while maintaining the reliability benefits of composite positioning.
4Measurement precision
If positioning computation is performed using latest measurement results, then positioning accuracy in moving direction is improved, but data synchronization complexity increases
Solution Approach 1:
The system introduces time stamps as an intermediary element that is attached to each measurement result. These time stamps serve as a simple synchronization mechanism that allows the positioning computation unit to easily identify and select the latest measurement results from multiple positioning means without requiring complex data synchronization protocols. This intermediary timestamping approach improves positioning accuracy in the moving direction while keeping data synchronization complexity manageable.
Data Source
AI summary
A position measurement system includes one or more computers each including a memory and a processor configured to measure an absolute position of a mobile object, attach a first time stamp to an absolute position measurement result, and output the absolute position measurement result with the first time stamp; measure a relative displacement of the mobile object, attach a second time stamp to a relative displacement measurement result, and output the relative displacement measurement result with the second time stamp; and execute positioning computation for calculating the absolute position of the mobile object based on the absolute position measurement result with the first time stamp and the relative displacement measurement result with the second time stamp, attach a third time stamp to a positioning computation result, and output the positioning computation result with the third time stamp.