Numerical Simulation of Neural Network-Controlled Unmanned Undersea Vehicle ASHRAF S. HUSSEIN Scientific Computing Department, Faculty of Computer and Information Sciences, Ain Shams University 11566, Abbassia, Cairo EGYPT Abstract:- In this paper, the locomotion of an autonomously navigated undersea vehicle that uses vorticity control propulsion is computationally simulated. The navigation procedure employs a set of vehicle geometric and state variables to predict the needed vehicle body deformations in order to pass through a set of predefined path-points. To simulate the movement of the vehicle, a two-dimensional unsteady potential flow solver was developed based on the unsteady panel method coupled with the vehicle dynamics. The developed flow solver was validated against published computational results of unsteady flow standard test cases. Then, another set of properly planned test cases to cover the range of possible conditions were processed with the simulation and the output data was subsequently used to train a Multi-Layer Perceptron (MLP) neural network. The trained network can predict what body deflection time history is necessary for the vehicle to pass through the given path-points. Several autonomous navigation test cases are presented to show the capabilities of the present method. Key-Words:-Numerical Simulation, Unsteady Flow, Unsteady Panel Method, Unmanned Undersea Vehicle, Neural Network Control 1 Introduction In recent years, research in the propulsion and maneuvering flow mechanisms used by fish and marine mammals has demonstrated the utility of biopropulsion for undersea vehicles. Despite advances in Unmanned Undersea Vehicles (UUV) technology, little progress has been made in improving propulsive efficiency and maneuverability. Conventional UUVs employ a long slender hull with a propeller as the main propulsor and lifting surfaces that provide maneuvering control. Although several recent advanced demonstrations have been made with conventional designs, these types of vehicles are fundamentally limited in their maneuvering performance. Typically requiring several body lengths to execute a turn, these vehicles can have fatally poor performance at very low speeds. Attempts to improve low-speed performance by using cross-axis thrusters have been effective, but the net result is generally loss of useful hull volume and degraded performance at higher speeds. The flexible-hull UUV propels and maneuvers like a fish [1] using the vorticity control mechanisms employed to propel and maneuver. Fishes are most desirable as a vehicle platform; they are very streamlined, relatively rigid in the forebody, and propel with low-amplitude movements in conjunction with a high-performance hydrofoil. The present work addresses the issue of overall vehicle navigation and control with the ultimate objective being the integration of vehicle dynamics and hydrodynamics control that can be implemented to finally constitute the control center of an autonomous undersea vehicle. In earlier studies of fish motion, Lighthill [2] applied the slender body theory of hydrodynamics to transverse oscillatory motions of slender fish, resulting in the Elongated Body Theory (EBT). This study revealed the high propulsive efficiency of fish, a finding that alone renders the utilization of similar propulsive techniques in man-made vehicles a very attractive quest. To pursue this idea, several studies have been conducted on the effect of fin appendages, the dynamics of slender fish, and the propulsion mechanisms of fish motion [2]-[5]. The propulsive investigations largely concentrated on the undulatory type of propulsion. Studies included analyses of a slender wing with passive chordwise flexibility [6], two-dimensional potential flow modeling over a thin waving plate of a finite chord [7]-[10], and two- dimensional flow modeling of flow over a waving plate of finite thickness [11]. Three-dimensional models have more recently been developed [12], utilizing waving plate theory, as well as comparisons of performance coefficients between fish and underwater vehicles [13]. Researchers have addressed the problem of the thrust-producing capability of moving hydrofoils [14]-[18]. This problem simulates the type of propulsion used by fish, which primarily