Synchronized High-Speed Vision Sensor Network for Expansion of Field of View.

Akihito Noda,Satoshi Tabata,Yuji Yamakawa,Masatoshi Ishikawa

doi:10.3390/s18041276

Akihito Noda, Satoshi Tabata + Show 2 more

Open Access

https://doi.org/10.3390/s18041276

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Abstract

We propose a 500-frames-per-second high-speed vision (HSV) sensor network that acquires frames at a timing that is precisely synchronized across the network. Multiple vision sensor nodes, individually comprising a camera and a PC, are connected via Ethernet for data transmission and for clock synchronization. A network of synchronized HSV sensors provides a significantly expanded field-of-view compared with that of each individual HSV sensor. In the proposed system, the shutter of each camera is controlled based on the clock of the PC locally provided inside the node, and the shutters are globally synchronized using the Precision Time Protocol (PTP) over the network. A theoretical analysis and experiment results indicate that the shutter trigger skew among the nodes is a few tens of microseconds at most, which is significantly smaller than the frame interval of 1000-fps-class high-speed cameras. Experimental results obtained with the proposed system comprising four nodes demonstrated the ability to capture the propagation of a small displacement along a large-scale structure.

Highlights

Synchronization of frames is an inherently important issue in stereo vision systems, including binocular and multi-view systems
If multiple frames of a moving target object were captured by multiple cameras asynchronously, this assumption would be violated because those frames would be projections of the same object but at different positions
We have proposed a 500-frames-per-second high-speed vision (HSV) sensor network that acquires each frame at a timing precisely synchronized across the network

Summary

Introduction

Synchronization of frames is an inherently important issue in stereo vision systems, including binocular and multi-view systems. Precise frame synchronization is required for accurate 3-D measurement by stereo vision systems, especially for objects moving at high speed. Without this synchronization, more complicated and costly computations would be required, and greater difficulties would be involved for real-time processing. Note that this is beneficial for 1000-fps class systems, and for 30-fps vision systems that require precise frame synchronization among a large number of cameras networked through Ethernet.

Motivation and Contribution of the Work

Frame Synchronization

Binocular Experimental System

Applications and Discussions

Findings

Conclusions