Sensor Synchronization via Propagation Time Calibration
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Solution Overview
Problem
In complex multi-sensor systems, especially those with distributed sensors across large areas, signal propagation times are often unknown or variable, leading to inaccuracies in data fusion and potentially critical errors in object detection, such as false negatives, which can impact safety in automated vehicle systems.
Innovation Solution
A method for synchronizing environment sensors using a central processing unit, where signal propagation times are determined through an algorithmic comparison of measured variables, allowing for the assignment of corrected time stamps and improved data fusion quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If sensors are distributed across large areas in complex multi-sensor systems, then the visual range and coverage are improved, but the signal propagation times become unknown or variable, leading to inaccuracies in data fusion
Solution Approach 1:
The system performs preliminary calibration to determine signal propagation times before actual operation. During calibration, reference objects at known positions are detected by multiple sensors, and the propagation times are calculated and stored. This preliminary action enables accurate data fusion during normal operation without requiring real-time propagation time measurements.
Solution Approach 2:
The patent replaces physical time synchronization mechanisms (like NTP protocols) with an algorithmic approach. Instead of using network time synchronization, the system uses mathematical models and calibration data to calculate and compensate for propagation time differences, substituting a mechanical/synchronization system with an informational/algorithmic one.
2Measurement precision
If NTP or similar synchronization mechanisms are used, then the time synchronization is improved, but sensors with simple design cannot be synchronized, leading to unknown or variable propagation times
Solution Approach 1:
The calibration-based synchronization method is universally applicable to all sensor types, including simple sensors without NTP capabilities. The system uses a unified calibration procedure that works with any sensor that can detect reference objects, making the synchronization mechanism adaptable to diverse sensor designs and communication protocols.
3Device complexity
If signal propagation times are ignored and time stamps are assigned at arrival, then the system complexity is reduced, but the object detection accuracy deteriorates, producing false negatives
Solution Approach 1:
The system performs preliminary calibration to determine and store signal propagation times before actual operation. During normal detection, these pre-determined propagation times are used to correct time stamps, eliminating the need for complex real-time propagation time calculations while maintaining high detection accuracy and avoiding false negatives.
Data Source
AI summary
A method for synchronizing at least two environment sensors of a multi-sensor system using a central processing unit. In the method, the environment sensors acquire sensor signals that represent at least one item of environment information. The respective environment sensors generate data packets which include the respective acquired sensor signals and/or measured variables derived from the sensor signals in each case. These data packets are received by the central processing unit via a data network. Signal propagation times of the data packets for each environment sensor are ascertained using an algorithm, and a mean signal propagation time of data packets from a respective environment sensor is determined based on a content comparison of the measured variables included by the data packets with corresponding measured variables from data packets of at least one other environment sensor, and the determined mean signal propagation time is assigned to the respective environment sensor.