Design, modeling, and optimization of an underwater manipulator with four-bar mechanism and compliant linkage

Abstract

Underwater manipulators are very important for a robot to perform a specific operation in water. Conventional robot arm manipulators have been suggested for various operations but have not been suitable for repeated motion in gathering something. This paper presents a new underwater manipulator design for gathering things such as starfish on the sea floor. The manipulator is composed of a four-bar linkage to achieve repeated motion along a loop and compliant linkages to enhance the efficiency of the gathering work. Kinematic and quasi-static analyses were performed to calculate the loop path and the reaction force at the actuation point. Based on the analysis, optimal design was performed to maximize the working distance with the height difference and the reaction moments considered as constraints. A prototype was assembled to test the performance of the manipulator, and the empirical loop path was compared to simulation results.