July 2, 2021
Shimizu Corporation（President: Kazuyuki Inoue）has developed a new GNSS（Global Navigation Satellite System）positioning system to promote ICT construction in civil engineering projects. The system detects highly precise construction machinery positioning data and ground deformation on slopes, and others, in real time. A new algorithm based on RTKLIB* software was built under the guidance of Professor Nobuaki Kubo at Tokyo University of Marine Science and Technology with regard to development.
High-precision positioning systems using GNSS are being used at large-scale civil engineering sites. However, these systems need to receive positioning satellite signals from four to five pairs of the same kind of positioning satellites. In some cases, a sufficient number of satellites cannot be secured if the overhead field of view is limited. Furthermore, it is limited to applications in spacious sky condition because errors due to reflected signals and satellite placement are not allowed.
The new GNSS positioning system consists of a commercially available antenna, receiver, analyzer, and new RTK-based algorithm. It features the ability to secure the necessary number of satellites and continuously provide high-precision positioning data at elevation angles up to roughly 45 degrees, even in presence of obstacles. The algorithm was built to recognize and process the different positioning satellite frequencies transmitted in Japan and elsewhere as the same type of signal. That made development of this system possible. It enabled continuous positioning by instantaneously capturing the data from the next satellite that appears after the system had been communicating with disappears from sight, regardless of the type of satellite.
It can be customizing this algorithm that obtain real time positioning data on construction machinery and observe slope movement, even at a civil engineering site backed by a steep mountain slope. A proof-of-concept trial using this system confirmed that it achieves positioning precision nearly on par with conventional GNSS positioning systems in spacious sky condition.
Shimizu will commercialize the new GNSS positioning system and deploy it widely at construction sites, and this will contribute to widespread use of ICT in construction.
≪For Reference≫
Real-time Kinematic（RTK）Positioning Principle
Satellite positioning data containing the time of transmission from a GNSS is received by one antenna installed at an observation point. The distance between the GNSS and the observation point is obtained from the time it takes for the positioning data from each satellite to reach the observation point, and this is used to calculate the position of the observation point. To improve positioning precision, 3D coordinates（latitude, longitude, and altitude）are measured at two locations: An already determined reference point and the observation point. The positioning data received at the observation point is corrected by the difference between the 3D coordinates measured for the reference point and actual coordinates. This makes it possible to achieve centimeter-order precision in positioning. This positioning method is called RTK（Real-Time Kinematic）positioning.
*RTKLIB
An open source program for GNSS positioning developed by Tomoji Takasu（Researcher, Department of Maritime Systems Engineering, Tokyo University of Marine Science and Technology）.
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