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Next Generation Automated Rebar Inspection System

Obayashi Developed Next Generation Automated Inspection System Using Open Innovation
A Future-Oriented Project at Technology Development Base in Silicon Valley, United States

Silicon Valley Ventures & Laboratory in Silicon Valley

The Next Generation Automated Inspection System was developed with the idea that digital technology will replace "the eyes of a construction manager.” The system uses an advanced Simultaneous Localization and Mapping (SLAM) technology to drastically improve the efficiency of quality inspection processes, together with a point cloud generator and Mixed Reality (MR) that are linked to Building Information Modeling (BIM). In May 2018, tests conducted at a building construction site in Japan demonstrated that this system can be used for rebar inspections, which are especially complex and time consuming among the quality inspections.

The following are the features of the next generation Automated Inspection System that was developed.

  1. The system improves the efficiency of quality inspection regardless of the skill level of the construction manager.

    Rebar inspectors check that all parts of massive rebars are assembled exactly to the drawing, including the number of rebars, pitch, diameter, length, and material. Because a typical, conventional two-dimensional drawing does not show the placement of all rebars, inspectors had to refer to general arrangement drawings for detailed specifications. This meant construction managers had to input the general arrangement drawings into their heads and rely on their intuition to catch defects in the building construction site visually.
    Rebars cannot be checked after concrete is poured into the framework, leaving no room for error. They have to be double- and triple-checked with a critical eye. Rebar inspections used to be time and work intensive, requiring construction managers to make rounds around the site all day as the work progressed, search for the right drawings for the section, and inspect it.

  2. The Automated Rebar Inspection System uses Visual SLAM technology and images from multiple cameras installed on the equipment that construction managers wear or carry.

    The image is overlaid on a BIM model showing the placement of rebars. This makes it possible to automatically identify the current location and the location of the rebars on the drawing, even in an indoor or outdoor environment where Wi-Fi or Global Navigation Satellite System (GNSS) is not available.
    Therefore, construction managers can instantly determine if the work of the section they are checking is acceptable or not, simply by checking the MR images with the actual rebars placed over the BIM model (how they should be). Construction managers no longer need to carry the drawings around. In addition, the system uses multiple cameras to analyze three-dimensional point cloud data of rebars of a particular section and determine the number of rebars, pitch, diameter, length, and the material.
    The system can truly serve as the eyes of a construction manager and also eliminate the potential for human error. Automated Rebar Inspection System is a revolutionary product that can improve the quality of rebar inspections while helping construction managers perform work more efficiently.

    Checking rebars over BIM on a tablet
    Measuring the pitch of rebars

    Field test at a building construction site

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