Modelling and control of two cooperating underwater vehicles with on -board manipulators
Abstract
Two cooperating Autonomous Underwater Vehicles (AUVs), each equipped with a robotic arm on-board, can be advantageously used to perform underwater transportation tasks and to manipulate underwater objects such as pipelines, cables and mines. In this research, the modelling and control problem is studied for two Underwater Vehicle Manipulator (UVM) mechanisms holding a rigid object. The rigidbody equations of motion for each UVM mechanism are derived in the world coordinate frame using the Lagrange's formulation. Then, the hydrodynamic effects, such as the added mass, drag and buoyancy as well as the forces due to the motions of the surrounding fluid are incorporated into the resulting equations of motion. Aforementioned hydrodynamic terms cannot be neglected because of the relatively high density of the medium (sea water) in which the system operates. Moreover, the kinematic and dynamic coupling terms due to the load are studied and included in the dynamical model. A reduced-order model whose formulation is due to the kinematic constraints is proposed for the control law design. The dynamical model both in the full and the reduced-order space contains parameter uncertainties such as the added mass and drag coefficients. An adaptive controller with parameter estimation is formulated in the reduced-order space. The controller design is based on the Lyapunov theory and guarantees the asymptotic stability of the states both in the reduced and full-order space. The applicability of the mathematical model and the adaptive controller are tested by computer simulations.
Degree
Ph.D.
Advisors
Koivo, Purdue University.
Subject Area
Ocean engineering|Electrical engineering
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