Grasping Marine Products With Hybrid-Driven Underwater Vehicle-Manipulator System

Abstract

This article presents the comprehensive framework for a hybrid-driven underwater vehicle-manipulator system (HD-UVMS) to grasp marine products on the seabed. The purpose of the proposed hybrid-driven propulsion system is to improve the swimming ability of the HD-UVMS by using thrusters and enhance the stability of its pose adjustment mechanism via two unique long fin propulsors. The control mode for the thrusters and long fin propulsors is based on a fuzzy logic control method. Subsequently, a lightweight manipulator is developed to grasp marine products. The open–closed angle and current controls for the gripper help to avoid damaging marine products. A vision system is installed to enable the HD-UVMS to gradually approach marine products with the aid of monocular vision and grasp them with the aid of binocular vision. A detailed method for monocular passive ranging and stereo matching, in accordance with real-time metrics, is elaborated. Finally, relevant experiments are conducted in an indoor pool and under real sea condition to assess the effectiveness of the proposed framework. Note to Practitioners —The motivation behind this article is the design of an underwater vehicle-manipulator system that can grasp marine products on the real seabed and perform other underwater intervention tasks. Currently, the predominant method of fishing for marine products relies on human divers, which has disadvantages for human divers’ health due to the long periods of time spent working underwater. In order to further study the problem, this article develops a hybrid-driven underwater vehicle-manipulator system (HD-UVMS) to work in a real seabed environment. A hybrid-driven motion control framework is presented using the thrusters to achieve effective cruising and searching for marine products and long fin propulsors for the fine pose adjustment required to grasp marine products. The proposed lightweight underwater manipulator can grasp marine products on the seabed with the aid of a vision system. A series of experiments suggests that the HD-UVMS is practical and valid.