Development of an actuation system based on water jet propulsion for a slim long-reach robot

Most of the long-reach inspection devices developed so far have a limitation in the reduction of their diameter when their length is increased. This limitation is due to the technology used to provide the actuation to the system. The use of water-jet as propulsion source is promising to be a solution for this problem. Currently different devices use water-jet as propulsion. However, none of these systems have been designed for small-scale nor have a straightforward control. Therefore, in this paper, we discuss the development of a long-reach water-jet probe aimed to be used in Fukushima Daiichi Nuclear Power Plant. The main elements that define this probe are three high-pressure pumps at the base, three hoses whose water flow is controlled for maneuvering the device, an Inertial Measurement Unit to acquire the attitude of the tip, and a joystick that allows the user the control of the whole device. Moreover, its design allows it to move in different kind of environments and generate three-dimensional motion. Besides the experimentation developed to characterize its behavior, the system was tested in different environments; such as on the ground, in the air and inside the water; showing the best control in aquatic environments.