Vicon Optical Motion Capture Finds Use In Seismic Research

Tue 1st Oct 2002 | News


Vicon, the leading developer of optical motion capture systems, announced that the University of California-Irvine (UCI) is pioneering the use of a Vicon system within the field of earthquake engineering to more accurately evaluate the effects of strong ground motions on structures. In a ground-shaking new approach being tested by researchers in the civil engineering and computer engineering departments, UCI is using a six-camera Vicon system and dozens of ultra low-mass markers to track the motion of structures generated by the school's bi-axial shake table. The breakthrough application, which introduces Vicon's optical sensing technology as an alternative method for measuring earthquake-induced motions, allows a denser array of measurements to be obtained at a high degree of precision.

"Perhaps the most challenging problem faced in earthquake engineering research is that traditional motion sensors must be physically attached to a structure and require cumbersome cabling, configurations and substantial set-up time," said Assistant Professor Tara Hutchinson, Department of Civil & Environmental Engineering at UCI. "Conventional sensors, or transducers, also add substantial weight and can therefore change the response characteristics of the system. Using an image-based system in this context is highly advantageous because it requires very little physical contact with the structure-of-interest, is high speed and high resolution and does not introduce additional mass or otherwise modify the properties of the structure."

In its recent experiments, UCI used four high-resolution motion capture cameras to track reflective markers discreetly positioned on a scale model five-story steel frame structure. The structure was mounted on UCI's shake table, where it was subjected to different motions from the 1985 Mexico City and the 1995 Kobe earthquakes. "The resulting set of data collected using the visual transducers provides a window into the structure's potential range of motion, such as its yaw, pitch or roll along three positional degrees of freedom," said Assistant Professor Falko Kuester. Using digital signal processing algorithms, the UCI researchers compared inter-story drift and floor level velocities and accelerations to those measured using more conventional sensors (peizometric accelerometers and LVDT positional transducers). Results from this exploratory study show that the non-intrusive approach is extremely promising in terms of its ability to accurately capture the data necessary for characterizing global seismic response.

In addition to realizing more precise results more effectively, UCI is also benefiting from the ability to design experiments that track a greater number of objects and object types. In new tests at UCI, Vicon cameras and markers are being used to better predict how the interior contents of expensive laboratory environments such as biological or chemical laboratories might be displaced during an earthquake. This study is funded by the Pacific Earthquake Engineering Research (PEER) Center, one of National Science Foundation's three earthquake engineering research centers.

"UCI is demonstrating that high-resolution Vicon cameras and markers can be utilized not only to improve the way in which laboratory and field experiments are conducted, but also to literally take the weight out of the equation to generate more true-to-form results. We are pleased to be helping the university innovate in a field that has a dramatic impact on so many regions of the globe."

A discussion of UCI's recent research was presented at the International Conference on Advances and Challenges in Earthquake Engineering Research (ICANCEER) in Hong Kong in August (Hutchinson and Kuester, 2002).

About Vicon 460
Vicon 460 is a precision 3D measurement and tracking solution that can be used to collect positional information of both human subjects and inanimate objects in real time. Supporting award-winning Vicon video cameras with up to 1.3 megapixels and frame rates up to 1000 Hz, Vicon 460, a six-channel entry-level version of the larger capacity 24-camera Vicon 624, enables the user to easily measure the 3D locations of markers with sub-millimeter positional accuracy. As with all Vicon products, the system allows actors or subjects to move unrestricted by wires, cumbersome suits or large body markers. Vicon solutions are used by industry leaders including Industrial Light + Magic, Pratt & Whitney, Sony Computer Entertainment Corp., BMW, International Truck, and hundreds of others.

About Vicon
Vicon Motion Systems is a subsidiary of OMG plc (LSE: OMG) with global headquarters in Oxford, UK, and US headquarters in Lake Forest, CA. OMG subsidiary 2d3 Ltd. produces innovative visual geometry software deriving 3D data from moving images. Since 1984, Vicon has been providing professionals with the latest tools to accurately capture the subtleties of three-dimensional human motion for research, medicine, sport, engineering, game development, broadcast and film. For more information about Vicon, or to view a comprehensive list of worldwide distributors, visit www.vicon.com or contact +44 (0) 1865-261800 in the UK or (949) 472-9140 in the US.


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