Hydraulic Grabs are capable of placing and removing of underwater structures without hitch by divers. However, grab operators are unable to observe states of the grabs and the objects when the turbidness of water disturbs observation by TV cameras. For this reason, operators still need support and observation of divers during positioning of the grab and grasping the object. Therefore, this paper proposes a remotely controlled system that can support operators by representing the motion of the grab and the shape of the objects using sensor data and VR technology. Two types grab models are developed and experiments are carryed out. The experimental result show the validity of the proposed remotely controlled system for unclear environment.
Mechanization is necessary for safer and more efficient underwater construction work in port areas. Teleoperated underwater construction machines are under developing. The problem is that conventional TV camera system is useless in water because of turbidity. Haptic information is introduced as the aid to control construction machines substituting for visual information. Components of control technologies are visualization of haptic image, force feedback, and similar figure controller. Leveling experiment of gravel mound was carried out successfully on land with an experimental land model of underwater backhoe.
[abstFig src='/00280002/04.jpg' width=""300"" text='The experiment of recognition by acoustic video camera' ]External recognition is important for underwater machinery works. However, acquisition of external field information from optical camera images may not be possible, owing to muddiness of water caused by such work. Furthermore, in order to improve the workability of machines in the scenario of their remote operation, it is important to know the positional relation information between a target object and the end effector. To solve these problems, an acoustic video camera was developed and performance test experiments were conducted at a caisson dockyard. In the experiments, a prototype of acoustic video camera was used to measure and to recognize a target objects and an underwater construction machine. And the feasibility of monitoring for underwater construction using the acoustic videos was evaluated. As a result, it was found that despite the lower accuracy of shape recognition on account of a resolution problem, the positional relation could be recognized satisfactorily since the video images could be presented from an arbitrary viewpoint.
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