Dexterous Underwater Robot Hand: HEU Hand II

Manipulator is the most important part for underwater flexible robot manipulation, and the grasping and manipulating capability is an important indication for intelligent robot. But current generation underwater robots generally employ the claw-like end effectors without sensing or controlling of the contact forces, which is simple and easy to control, but not able to perform complex operations. In this paper, a non-anthropomorphic underwater robot hand called HEU Hand II is presented, which is a modified version of HEU Hand I. The modular approach is adopted to design the hand, which have three identical fingers. Each finger has 3 joints with 3-DOF (degree of freedom), and two axes of the joints near the palm cross orthogonally at one point, as is the case in the human hand. The HEU Hand II can be equipped with 6-axis force/ torque sensor at each fingertip and position sensor in every joint. The characteristics of the hand, transmission mechanism, corrosion prevention and seal, sensor system, and control system are described and discussed. Moreover, the controller for the hand force tracking is designed based on PBNNIC (position-based neural network impedance control) scheme. The HEU Hand II has much improvements relatively to HEU Hand I, thus it is capable of grasping a wide variety of objects of different shapes, sizes and weights. The work area of the underwater robot can expand when HEU Hand II cooperates with the robot arm. It can be applied widely in the field of exploiting the resources under the sea