In this paper, the authors design and develop a removable and lightweight underwater manipulator system for man-portable underwater robots. The aim of the development is to enhance manipulation capabilities of man-portable underwater robots. The developed manipulator system consists of two multi-degrees of freedom manipulators and an attitude control system. The dexterity of the developed manipulators will achieve various underwater missions. In this research, the manipulator system is attached to a commercial man-portable underwater robot and the performance of the system is tested in water tanks. We demonstrate several practical applications of the developed manipulator system in a lake and a harbor.
The advantages of man-portable underwater robots are lightweight, easy-to-use, and low-cost. Man-portable underwater robots do not require any special equipment for carry and recover. They can be easily operated by one or two person(s) without special teams and can be operated from small boats. From these reasons, the operational costs and maintenance costs of man-portable underwater robots are low as compare to those of large underwater robots. Several researchers have developed lightweight and low-cost underwater robots (e.g. Csepp, 2005; Allen, Stokey, Austin, Forrester, Goldsborough, Purcell, and von Alt, 1997; Madhan, Desa, Prabhudesai, Sebastiao, Pascoal, Desa, Mascarenhas, Maurya, Navelkar, Afzulpurkar, and Khalap, 2006) for scientific researches. Several companies sell man-portable and easy-touse underwater robots (e.g. Matsushima, and Nakabayashi, 2008; SeaBotix Inc., 2010; Anderson, and Crowell, 2005; Yeo, 2007). In addition, removable and replaceable components are practical for field robots. Since such components can be attached and removed as needed, it is easy to operate when conducting fieldwork. It is also easy to maintain removable and replaceable components. Based on such a design concept, Takemura and Shiroku (2010) developed a removable one-armed manipulator that had 5 degrees of freedom (DOF) for a Remotely Operated Vehicle (ROV).