OGENTS/SURVEY Automatic Survey System for Use in Shield Tunnels

We have developed an automatic survey system for use in shield tunnels, OGENTS/SURVEY™.

Obayashi Corporation has developed the OGENTS/SURVEY automatic survey system for use in shield tunnels jointly with ENZAN KOUBOU CO., LTD. (https://www.enzan-k.com/eng/index.html).
In tunnel work using the shield construction method, initiatives toward the introduction of ICT and automation are progressing rapidly, but in order to tackle the industry-wide issue that there will be a lack of skilled workers such as shield technicians and expert laborers as a consequence of the population decline, falling birthrate, and aging population forecast for the future, the development and dissemination of automation technology realizing further productivity increases is required.
Currently, Obayashi Corporation is working on the development of the shield automation system Obayashi Intelligent Shield, or OGENTS, which can be applied to all shield tunnel sites. It achieves productivity increases by saving work in shield construction overall, so we are aiming to put it to practical use as an applied technology in the shield tunnel work of the “DX measures in the infrastructure field” being promoted by the Ministry of Land, Infrastructure, Transport and Tourism.
In the system development of the Obayashi Intelligent Shield, the work pertaining to the shield construction is broadly divided into six fields, and the development of each of the individual elemental technologies and the development of the main system which integrates all of the elemental technologies and automates the overall process are carried out in parallel.

On this occasion, as the first phase of the development, we have developed the OGENTS/SURVEY automatic survey system for use in shield tunnels for "automatic survey of shields," which is one of the six fields.
In shield construction, surveys in tunnels are carried out daily in order to manage the progress and precision of the construction, and surveys of the position and attitude of the shield machines (machine surveys) have been automated previously, but the surveys of the amount of meandering of the segment in the horizontal and vertical direction (segment surveys), etc. were still carried out manually as before, so automation technology was required. Furthermore, there is a lot of work in cramped spaces, and the work of peering into the surveying instruments (target recognition work) requires a half-crouching position, etc., so there is a physical burden on the measurers, and in addition there was the issue that work hours were restricted so that there was no impact on the tunneling period for the shields.
This system remotely operates the automatic target recognition total station from a tablet for all of the four surveys necessary in shield construction (the alignment control point survey and the benchmark survey, the segment survey, the machine survey), so it is possible to implement shield construction automatically without using other surveying instruments.

The features of OGENTS/SURVEY are as follows.

1. Automatic surveys by remote operation using a tablet

   Previously, in surveys in shield tunnels, generally two people carried out the survey: the measurer who carried out the target recognition work, and an assistant. With this system, the administrator carries out the survey work by installing the target and total station necessary for the survey, and remotely operating the total station from a tablet, so the measurer and assistant are not necessary. Furthermore, the target recognition work is no longer necessary, so the physical burden on the measurer is reduced.

   

2. Handling of all surveys in tunnels, increasing productivity

   With this system, in addition to the previously automated machine survey, the alignment control point survey, benchmark survey and segment survey are also automatically carried out using one total station. Each of the survey results is transmitted to the shield tunneling management system, so the work of inputting data into records or systems locally is not required, which not only reduces the survey time by 30% but also prevents human error.

3. Maintaining of high survey precision with the self-diagnosis function and automatic calibration function

   Sometimes the precision of the automatic target recognition total station declines due to the impact of vibrations and shocks, etc. when it is used on sites, but in previous shield automatic survey systems, there were no functions which detected a decline in precision.
   With this system, we have introduced a self-diagnosis function which detects a decline in precision instantly, and by using this function together with the self-calibration function which automatically carries out instrument calibration, it is possible to maintain high precision.

   

   Note that Obayashi Corporation developed the critical technology for OGENTS/DRIVE shield autonomous driving, one field of Obayashi Intelligent Shield (OGENTS), in March 2021.