Development of Shotcrete Robot

In recent years, concrete spraying or shotcrete work carried out at NATM method tunnel construction sites has become a social problem because the dust put into the air during work. Further, current shotcrete methods result in a large amount of rebounded concrete and dust, which raise both cost and safety concerns. Although some companies have developed shotcrete robots, all such robots must be controlled manually - and the above two problems remain. To solve these problems, we have developed a fully automatic shotcrete robot, the performance of which has been verified through actual construction work. In efficient shotcrete work, there are two requirements: (1) the distance from the nozzle to the wall must be kept constant, and (2) the nozzle must be maintained perpendicular to the wall. To do these things, our robot determines its position in the tunnel and controls the nozzle movement by a hydraulic arm with five degrees of freedom through feedback loops. This paper describes the robot’s construction, the way it located its own position, its control system, its operation, and experimental results at construction sites.