Modelling and control of a 6 DOF robot manipulator for underwater applications - aquaculture related case studies

This paper presents kinematic models and a dynamic model of a 6 degree of freedom (DOF) underwater robot manipulator for aquaculture applications. Robotics has emerged as a key enabling technology in the industrialisation of salmon aquaculture. Although this is most apparent in the sea-based production phase, there is an increasing interest in using robotic tools in the land-based phase of the production cycle where fish are reared from eggs to smolts ready for sea transfer. The model presented here is a key component in achieving this goal, as it enables simulations of robotic operations in land-based fish facilities, and also can serve as a potential component in new control system components and solutions. The model was developed based on a commercially available robotic manipulator arm designed for underwater usage deemed suitable for in-tank operations called Reach Bravo 7 (Blueprint Lab). Forward kinematics were derived using the Denavit- Hartenberg parameters, while inverse kinematics were found numerically using the Levenberg-Marquardt method. A dynamic model for the submerged manipulator combining conventional robotic manipulator theory with advanced hydrodynamics was also developed. Together these elements comprise a software suite that can function as a virtual laboratory for testing new solutions in planning, guidance, navigation and control required to use robotic manipulators for underwater operations such as tank cleaning and dead fish removal. The outcomes of this work will thus be a first step towards fully autonomous operations in commercial land-based fish holding facilities.