New low-cost approach detects building deformations with extreme real-time accuracy


Researchers have applied their new camera-based method to measure building deformations to track very small movements of the adaptive frame of a prototype building 9 meters high. Courtesy: Flavio Guerra, University of Stuttgart.

A new method for measuring the deformation of buildings based on the camera allows you to detect small displacements from a distance of 10 meters. The method can be useful for the continuous detection of rapid deformations in high-rise buildings, bridges and other large structures in order to adapt these structures to external influences.


"Our new approach to detection construction deformations can be used for continuous monitoring of movements. For bridges, measured strains can be used to counter external loads such as a truck crossing the bridge, thereby increasing the life of the bridge, said Flavio Guerra of the University of Stuttgart, a member of the research team. in real time, it can be used to alert any new deformations– which may cause cracks – have been discovered. "

Researchers led by Tobias Heist describe new technology in Optical Society (OSA) Applied optics, The study was carried out as part of a project whose purpose is to develop the technology necessary to create buildings adapted to environmental conditions, such as sunlight, air temperature, wind and earthquakes.

“One day, we may have light buildings that change shape in response to complex wind forces and can remain motionless during an earthquake,” Guerra said. “This type of adaptation requires an extremely accurate measurement of the deformation of the building so that you can evaluate the current state of the building and predict the direction of its movement.”

Vision Based Method

The new method involves mounting the camera on a tripod at a small distance from the front of the building and attaching small emitters to the building. The camera then determines whether the light sources are moving relative to each other. A computer generated hologram is used to create multiple copies of each image of a light source on image sensor, Averaging the movement of several copies of the laser spot helps to reduce measurement errors such as noise, and gives measurement errors below the hundredth of a pixel. Using multiple cameras would improve this accuracy even further and allow large structures,

Although fiber-optic sensors can be used to monitor the condition of structures, they must be installed during the construction of a building. new cameraa based system can be connected after construction and uses equipment that is cheaper than fiber-optic systems.

“The multipoint measurement method we used is based on a relatively simple method developed for controlling coordinate measuring machines,” Guerra said. “Nevertheless, we first applied the multi-point method to large objects in the open air at environmental conditions in real time."

Researchers note that most camera control systems illuminate an object, in this case a building, and then display it with a camera. They went the other way, attaching emitters to the building and directing the light directly to the camera. This setting allows faster and more accurate measurements because camera gets more light coloured,

Adaptive prototype structure monitoring

The researchers used their new method to track very small movements of the adaptive frame of a prototype building 9 meters high. Their measurements were in good agreement with the data of the vibrometer and strain gauge obtained for the prototype.

Further, the researchers plan to use the system to measure movement in real buildings. They also plan to make the software more reliable and redundant so that it is reliable for continuous measurement 24 hours a day.


Researchers combine lasers and terahertz waves in a camera that sees “invisible” details


Additional Information:
Flavio Guerra et al. Accurate measurement of building deformation using holographic multipoint replication, Applied optics (2020). DOI: 10.1364 / AO.385594

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citation:
New low-cost approach detects building deformations with extreme accuracy in real time (2020, March 16)
restored March 16, 2020
from https://phys.org/news/2020-03-low-cost-approach-deformations-extreme-precision.html

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