Sensor Synchronization Using Extrapolation to Resolve Latency
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Solution Overview
Problem
Existing sensor synchronization methods face challenges in achieving precise, equidistant sensor values and times due to latency and dead time issues, which affect the accuracy and efficiency of measurements, particularly in continuous measurement systems like laser scanners used for 3D point cloud creation.
Innovation Solution
A synchronization method where a master sensor independently acquires values, and slave sensors synchronize their measurements using a synchronization signal derived from the master sensor's values through extrapolation, decoupling the synchronization from the master sensor's latency and dead time, allowing for precise, equidistant sensor values and times with lower accuracy demands.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Extent of automation
If simultaneous trigger signal is sent to all sensors, then data acquisition is initiated at the same time, but measurements are not captured at a single point in time due to time delays
Solution Approach 1:
The system sends compensation offsets to slave sensors in advance before the actual measurement trigger. These offsets pre-correct for the known propagation delays, allowing all sensors to capture measurements that are effectively synchronized to the same reference time point despite the physical timing differences in signal transmission.
Solution Approach 2:
The master sensor determines propagation delays by comparing its own measurements with those from slave sensors, then feeds back compensation values to the slave sensors. This closed-loop feedback mechanism continuously optimizes the synchronization by adjusting for measured timing differences.
2Measurement precision
If synchronization signal is sent with time offset to match delay times, then measurement synchronization is achieved, but additional effort is required and delay times must be known
Solution Approach 1:
The master sensor automatically determines the propagation delays by analyzing the time differences between its own measurements and slave sensor measurements. The system self-calibrates without requiring external intervention or pre-known delay values, reducing the complexity of setup and configuration.
Solution Approach 2:
The system performs delay determination and compensation offset calculation in advance during an initialization phase, so that during actual measurement operations, the synchronization is achieved automatically without requiring real-time complex calculations or manual adjustment.
3Productivity
If sensors are clocked at different intervals, then individual sensor dead times are accommodated, but subsequent measurements may not be synchronized and waiting periods occur
Solution Approach 1:
The system dynamically adjusts the clocking intervals of slave sensors based on their individual dead times and performance characteristics. Rather than using fixed intervals, the synchronization system adapts the timing parameters in real-time to optimize both productivity and synchronization accuracy for continuous measurements.
4Measurement precision
If extrapolation or interpolation is used to provide sensor values at constant time intervals, then equidistant sensor values are achieved, but unpredictable discontinuities exist between distance values
Solution Approach 1:
The system replaces the mechanical scanning approach (physically moving the laser beam in fixed angular steps) with a calculated timing approach. By using the determined propagation delays and compensation offsets, the system calculates the exact moments when measurements were effectively taken, allowing for accurate time-stamping and synchronization without requiring physically equidistant measurement points.
Data Source
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Figure 1c~1d
Figure 2
AI summary
The method involves providing extrapolation rule and extrapolated time associated with intended value of a master sensor to be predetermined on basis of the extrapolation rule. A first synchronization signal is transmitted to a slave sensor when the extrapolated time occurs and delay time different from the extrapolated time in a temporally defined manner occurs. Recording of slave sensor value is triggered by a first synchronization signal. The intended value and the slave sensor value are provided as connected value tuple. An independent claim is also included for a sensor measuring system.