Development and Application of a Fire Resistive Covering Spraying Robot to Building Construction Site

Although the amount of building construction in Japan is not expected to decrease in the next few years, there has been a decrease in the number of fire resistive covering workers over the years. In this study, to overcome the shortage of construction workers, we developed a spraying robot for fire resistive covering. Optical sensors such as LiDARs and cameras may not work efficiently in dusty environments under spraying; therefore, we proposed a spraying method that would feasibly work without using them. The robot is composed of traveling, lifting, and traversing devices, and a robot arm; it can move autonomously if a map of the working area is created in advance. We carried out several experiments to obtain the optimum spraying work data for each beam size in advance. Having the optimal spraying work data for each beam size, and grasping the position error and posture of the robot, the robot can spray accurately when sensing data for spraying is not available. By registering the work data in the work list according to the stop position and beam size, the robot can automatically spray multiple beams continuously. We applied the developed robot to a building construction. After spraying, the shape of the sprayed covering was measured using a LiDAR, which verified the thickness. The specific gravity was observed to be higher than the regulation, and the quality was equivalent to that of workers. The spraying speed was approximately 80% of that of workers. In the future, the robot will have the potential of attaining the same construction speed as workers by making various improvements to it, as well as making it spray automatically.