REPRESENTATION OF AN AUTONOMOUS UNDERWATER VEHICLE AND TRAJECTORY CONTROLLER DESIGN FOR IN-WATER SHIP HULL INSPECTION

Original Research Paper Received 14 July 2015 Accepted 04 August 2015 Available Online 21 August 2015 This paper presents trajectory controller for Hovering type Autonomous Underwater (HAUV) Vehicle to meet the demands of in-water ship hull inspection. Accomplishing this task can just be done by vehicle that has all special requirements like high maneuverability, precise controllability and especially, Hovering Capability. Utility of such vehicle causes increasing precision, saving time and money and less health hazard for divers. Thrusters' configuration in terms of the number of thrusters, position and the thrust direction of each thruster is presented to provide the most suitable formation in terms of less energy consumption, reduced complexity of control strategies and controlling the most degrees of freedom. In this paper, roll degree of freedom is just constrained. The controller that is demonstrated was designed based on the linear dynamic model and then applied to the non-linear model to validate the controller's practicality. This controller consists of different loops, one for horizontal plane, another for the vertical plane, both were designed in state space and the last one is PID controller which is developed to control the forward speed. In the next step, the robustness of the controller is investigated in the presence of underwater disturbance and uncertainty of the hydrodynamic coefficients. State feedback controllers have advantages such as being suitable for non-linear models, useful for MIMO system and simplicity in application development.