Civil Engineering

In the construction industry of Japan, the number of laborers, particularly experienced laborers, is decreasing by decreasing birthrate and aging population. Also, the number of death in the construction industry is one-third of the number in all industries. To resolve the above problems, autonomous construction systems have been researched by various companies and research institutes. In this research, we aim at the realization of autonomous surface compression work by vibration roller with environment-installed sensors. Our approach is to install plural LiDARs (Light Detection and Ranging) in the work field and estimate the position of vibration roller. In this paper, we propose a position estimation method based on the environment-installed LiDARs, path planning for a vibration roller, and path tracking control of it. Furthermore, we conducted indoor experiments to confirm the proposed system using the original 1/10 vibration roller model and outdoor experiments to confirm the accuracy of the position estimation method in real-time using an actual vibration roller. (Ref: Robotics Symposia 2019: http://k-nagatani.org/pdf/2020-RS-KZN-online.pdf (Japanese))

 

 

A robotization method by retrofitting a robot to conventional construction machines is introduced to lower the introduction barrier for regional construction companies. The target machine is a six-wheeled dump truck. A conventional Global Navigation Satellite System (GNSS)-based path tracking method was implemented on it. Also, to ensure safety during operation, an emergency stop function was installed on the dump truck with three-dimensional Light Detection and Ranging (3D LiDAR). Based on the initial experiments, the authors concluded that even the retrofitted conventional dump truck could perform basic functions for autonomous driving, such as path tracking and emergency stop.

 

At disaster sites, the use of Micro Unmanned Aerial Vehicles (MUAVs) is expected for human safety. One application is to support first-phase emergency restoration work conducted by teleoperated construction machines. Recently, to extend the operation time of a MUAV, we proposed a power-feeding tethered MUAV to provide an overhead view of the site to operators. For autonomous flight of the MUAV, we propose a position estimation method by observing the slacked tether instead of using the Global Positioning System (GPS), vision sensors, or a laser rangefinder. The tether shape is assumed to be a catenary curve that can be estimated by measuring the tether's length, tension, and outlet direction. Some indoor experimental results proved the feasibility of the proposed method, as shown in this movie clip.

 

When sediment disasters occur, unmanned construction machines are useful for emergency rehabilitation from the point of view of worker’s safety. However, in case of initial response, operators feel difficulty because of a lack of visual information caused by no moving camera vehicles. In order to add a third party’s point of view, we developed a power-feeding helipad for tethered multi-rotor UAV mounting on an unmanned construction machine. The helipad controls the tension of the tether for adjustment of its feeding length. In this movie-clip, we introduce our helipad, and show an initial field test.