Optimal design of geometric parameters of a four-bar based manipulator for an underwater robotic platform

In this paper, we propose a starfish capturing four-bar based manipulator for an underwater robotic platform. The manipulator is composed of six links, two torsion springs, and one motor. The model is parameterized to link lengths and spring constants, and we solve kinematics and dynamics to get the trajectory of the end-effector of the manipulator. Capturing stroke, the distance while the end-effector keeps in contact to the ground, is used for the objective function to increase capturing capacity. Six lengths of the links and two torsion spring constants are used for design variables. The reaction force, the moment, and some geometric conditions are considered as inequality constraints in the optimization process. Through the optimization, the capturing stroke of the manipulator is increased by 56% comparing to the initial stroke.