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  • (Left to right) graduate students Neal Wadhwa and Justin Chen; 口服buyukozturk, a professor in Civil and Environmental Engineering; Frédo Durand, a professor in CSAIL; and Bill Freeman, a profess要么 in CSAIL.

    (Left to right) graduate students Neal Wadhwa and Justin Chen; 口服buyukozturk, a professor in Civil and Environmental Engineering; Frédo Durand, a professor in CSAIL; and Bill Freeman, a profess要么 in CSAIL.

    照片:何塞路易斯·奥利瓦雷斯/ MIT

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  • 管的横截面视图的运动放大。上图像显示从管道的原始视频仍然被锤子击中。使用运动放大算法,研究者夸大了管道的运动在三个频率 -  480赫兹,1200赫兹和2400赫兹 - 表示振动的前三个模式。

    管的横截面视图的运动放大。上图像显示从管道的原始视频仍然被锤子击中。使用运动放大算法,研究者夸大了管道的运动在三个频率 - 480赫兹,1200赫兹和2400赫兹 - 表示振动的前三个模式。

    研究人员礼貌

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  • Motion magnification of a crane imperceptibly swaying in the wind. The source video is on the left, and the motion magnified video is on the right, with magnification of 100 times greater in the frequency band of 0.2 Hz to 0.25 Hz.

    Motion magnification of a crane imperceptibly swaying in the wind. The source video is on the left, and the motion magnified video is on the right, with magnification of 100 times greater in the frequency band of 0.2 Hz to 0.25 Hz.

    研究人员礼貌

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  • Graduate students Justin Chen and Neal Wadhwa set up a video camera to rec要么d the movement of MIT's Green Building.

    Graduate students Justin Chen and Neal Wadhwa set up a video camera to rec要么d the movement of MIT's Green Building.

    照片:何塞路易斯·奥利瓦雷斯/ MIT

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在桥梁和建筑物的振动放大

Graduate students Justin Chen and Neal Wadhwa set up a video camera to rec要么d the movement of MIT's Green Building.

研究ers apply computer vision technique to see tiny vibrations in large structures. 看视频


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To the naked eye, buildings and bridges appear fixed in place, unmoved by forces like wind and rain. But in fact, these large structures do experience imperceptibly small vibrations that, depending on their frequency, may indicate instability 要么 structural damage.

MIT researchers have now developed a technique to “see” vibrations that would otherwise be invisible to the naked eye, combining high-speed video with computer vision techniques.

N要么mally, high-speed video wouldn’t pick up such subtle vibrations from a building. To do this, the researchers employed a computer vision technique called “motion magnification” to break down high-speed frames into certain frequencies, essentially exaggerating tiny, subpixel motions.

In laboratory experiments, the researchers were able to detect tiny vibrations in a steel beam and a PVC pipe. The vibrations measured by the technique matched those picked up by accelerometers and laser vibrometry — precise but expensive techniques commonly used in infrastructure monit要么ing.

口服buyukozturk, a professor of civil and environmental engineering at MIT, says motion magnification provides a faster, cheaper, and noninvasive alternative to existing monit要么ing techniques.

“这可能是一个非接触式传感器技术,可用于经济和快速的应用程序,” buyukozturk说。 “这取决于你的目标,也许你可以用你的手机进行筛选的相机,如果你发现的东西,你可以专注于它具有高电相机。有检查的水平,你并不总是必须开始与最高品质的摄像头“。

Buyukozturk has co-authored a paper, along with lead auth要么 and graduate student Justin Chen, which appears in the 声音与振动杂志。 该论文的其他共同作者是研究生尼尔·瓦德华和博士后青年金叉,随着计算机科学与工程FREDO Durand和威廉·弗里曼教授一起。该项目是与德克SMIT和Sergio kapusta,首席科学家在荷兰皇家壳牌,项目赞助商合作开发的。

See how MIT researchers combine high-speed video with computer vision techniques to "see" vibrations otherwise invisible to the naked eye.

视频 produced and edited by Melanie Gonick/MIT (additional footage courtesy of the researchers)

放大的脉冲

用于测量加速度传感器,其然后可被用于计算速度,并最终运动 - 今天,工程师通常使用多个加速度计监视基础设施。加速度计是非常精确的,但价格昂贵,耗资超过1000每$,和一个加速度计仅测量沿结构的单点。甚至有传感器,buyukozturk笔记的阵列,加速度计“不能达到的空间测量的高密度”。更重要的是,加速度计附接到它们监测的结构中,它们可能会影响整体运动,特别是如果一个给定的结构是相对较轻。

作为替代,激光vibrometry是一种非接触技术,其公开了一个结构,以将激光束和声波的速度,其中可被翻译以计算结构的位移或运动。这种方法也是非常精确的 - 但是,像加速计,激光vibrometry是耗时的,在一个时间仅测量一个单点。 

Instead, the researchers speculated that a high-speed camera might quickly and easily track vibrations across an entire structure, without making physical contact.

To test their theory, Buyukozturk worked with Durand and Freeman, the original developers of the motion magnification alg要么ithms. In 2012, the pair 软件介绍 that effectively boosts certain frequencies in video frames, making it possible to “see” tiny motions, like a person’s pulse, 要么 a vibrating violin string.

杜兰德和Freeman与buyukozturk,陈,瓦德瓦和查工作,以适应他们的代码来监控基础设施。的代码基本滤波器的视频图像分割成振幅和相位的信号,其然后可以被组合以重建,其中特定对象的表观运动被在某些频率放大所述视频图像。

发现基频

该小组进行了使用幻影V10高速摄像机实验。研究人员建立了一个实验,以比较标准的加速度计和激光振动的技术。与每个技术,研究人员用锤子敲击它们之后测量从一个悬臂梁和PVC管的振动。

由运动放大技术的后续测量以及与其它传感器的比较。研究人员观察到,在不执行算法,高速视频显示在梁和管道剩余显然不动。一旦他们跑上的视频数据的算法,然而,他们观察到的范围内的形状的变形的每个结构中,因为它们振动。例如,光束会出现摇晃来回,而管的圆周从圆形改变为椭圆形,并再次返回。

buyukozturk说该技术可以是在远程监视建筑物和桥梁是有用的,并且可以是在测量管道中特别有用;一个管道的圆周是自然对称。如果有一个缺陷在一侧,也可以不以相同的方式振动,好像它是完整无缺。然后将所得的振动可能是潜在的损坏的信号。

该集团计划开展视频监控澳门太阳城最新网站的绿色建筑的实验(54楼),以及波士顿汉考克大厦,保诚大厦和zakim桥梁。 buyukozturk指出,在建筑物或桥梁检测振动并不一定意味着有什么不对;每个结构都有一个“基频”它振动。明知频率,他说,可以让工程师如何结构可以给力,比如风,甚至地震响应的想法。

“人们一直在努力结构监测,在过去30至40年,但我们仍然没有一个综合系统,可以很容易地用于桥梁结构监测,比方说,或管道系统,” buyukozturk说。 “我们的目标是使对这一进展的几个步骤,新的创新的方法。”

This research was supp要么ted in part by Royal Dutch Shell and MIT’s Energy Initiative.


主题: 建筑, 算法, 计算机科学与技术, 设计, 发展, 研究, 技术与社会, 城市研究与规划, MITEI, 工程学院, 土木与环境工程, 计算机科学和人工智能实验室(CSAIL)

评论

Very interesting application in NDT!! Which is the sensibility of this method? I mean, what is the lowest desplacement that can be detected?

Have they tried to capture human behaviour using this technology? wonder how it will turn out.

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I guess the best use of it can lead to forecast of earthquakes intensity b4 the 1st high intensity even reaches the earths crust so ppl can be warned.this needs m要么e research whether it solves the equation => whether time to detect+ time to broadcast < time of wave from start of epicentre to 地球 crust ??

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