Exploration for novel uses of air muscles as hydraulic muscles for underwater actuator

Since a dextrous robotic arm has been designed for use on land and in space, further development could be its use underwater for performing delicate tasks, just like a human hand, for operations such as picking up small or irregular size objects. Hitherto there has been no report on studies on modelling and control of rubber artificial muscles in hydraulic mode. The feasibility of developing these actuators using water as the articulating medium for underwater robots was therefore investigated by studying the properties of the hydraulic rubber muscle actuator. The rubber muscles used in the present tests were developed by the Shadowtrade Robot Co. Ltd. for installing in dextrous robotic arms. The objectives of this study were, thus, first, to define the kinematics of the hydraulic muscle. A test set up was designed to obtained contraction, force and response time values based on reference of a model defined for the rubber muscle when used in air. Second, to compare the performance of the rubber muscle in air and underwater using the test set up and thus third, to obtain a modelling of the hydraulic rubber muscle which was derived from that of the air rubber muscle.