A novel piezoelectric actuated 2-DOF joint for underwater manipulator: design, simulation, and experimental investigation

For some underwater applications that need lightweight manipulator and fine operation, a novel piezoelectric actuated underwater mechanical manipulator two-degrees-of-freedom (2-DoF) joint was proposed and investigated in this study. The joint is composed of two unit arm sections orthogonally connected by connecting components. The inverse piezoelectric effect of the piezoelectric actuator on the unit arm section generates friction as a driving force in the contact area of the two unit arm sections, which can realize the 2-DoF rotation of the unit arm section. Due to the compatibility of the piezoelectric actuated method with the water environment, the manipulator joint adopts a simpler and more compact open structure, which does not require additional complicated waterproof sealing devices, and has the advantages of smaller size and lightweight. In addition, because the piezoelectric actuated method directly drives the unit arm section through the friction contact interface, it can achieve micro-displacement, so that the joint has the advantage of fine work. First of all, a 2-DoF joint prototype was designed, and corresponding simulations were performed to verify its working principle. Then a prototype of the proposed manipulator joint was made, its size is 125 mm × 25 mm × 25 mm and weighs 35.6 g, and experimental investigation was carried out. Finally, the experimental results show that the joint prototype can achieve motion in the air and underwater. The water environment will have a certain influence on the optimal working frequency and output performance of the joint. The proposed joint has potential application prospects in some microminiaturization and fine manipulation occasions. (paper)