Motion Control Analysis of Hydrofoil-Based Autonomous Surface Vehicle: An Integrated Approach Utilizing Moving-Mass-Actuated Stabilizer and Variable RPM Propeller Modeled with Computational Fluid Dynamics and Auto-Control Algorithm

Abstract

Hydrofoil-based Surface Vehicles (HSVs) have garnered significant attention for their potential to achieve high speeds, low hydrodynamic resistance, and reduced energy consumption. This efficiency is primarily due to the vehicle���s hull being elevated above the waterline, leaving only the hydrofoils and propeller submerged to generate the necessary lift force to counterbalance the vehicle���s weight at operational speeds. This study aims to extend these advantages by developing an autonomous control system, thereby enhancing the operational capabilities of these vehicles. This dissertation dedicates to overcoming the inherent stability challenges in the in-house developed hydrofoil-based Autonomous Surface Vehicle (HASV). This battery-powered HASV leverages hydrofoil to lift its superstructure above the water, significantly decreasing drag and improving efficiency at cruising speeds. However, the design, which incorporates a single mast connecting the superstructure to the substructure, introduces notable stability issues. These challenges primarily arise from nonlinear flow loading on the hydrofoil substructure and external environmental factors such as ocean waves and currents. This complexity necessitates the development of an effective control system. In response to these challenges, the study introduces an innovative control system utilizing the Proportional-Integral-Derivative (PID) algorithm to regulate the HASV���s pitch, roll, and heave stability. It includes a novel moving-mass-actuated (MMA) stabilizer in conjunction with an adjustable revolutions-per-minute (rpm) propeller. The MMA stabilizer enables dynamic adjustment of the HASV���s center of gravity, enhancing control over pitch and roll movements. Simultaneously, the propeller���s rpm is continuously modulated to manage thrust, thereby adjusting the lift force generated by the HASV substructure, which is crucial for controlling heave motion stability. Previous research on HASV stability control primarily relied on either physical model testing or mathematical modeling. While physical model testing is comprehensive, it is often prohibitively expensive and time-consuming. In contrast, mathematical models, though efficient, require significant simplifications, frequently failing to fully capture complex physical processes, especially those with strong free surface effects. Given the HASV���s limited stability and pronounced free surface effects, there is an urgent need for a more effective and practical approach to investigate and optimize the PID control system. Addressing this need, the study proposes a more accurate Unsteady Reynolds-Averaged Navier-Stokes (URANS) CFD-based control investigation approach. This approach integrates a PID controller into the URANS CFD model, combining the detailed analysis capabilities of CFD with the precision of PID control. This integration ensures that the performance of the proposed control system can be precisely investigated and optimized under different diverse operational scenarios. This study first starts with the CFD-based hydrodynamic performance analysis of a 2D dual hydrofoils with different configuration and generated a dataset, the dataset is then used to train an Artificial Neural Network (ANN) in order to use the ANN to interpolate within the interesting range and generate a finer resolution results. This analysis helps to have a basic understanding of how the wing and tail can interact with each other and laying the ground for the design of the submerged portion (substructure) of the HASV. Later, this study continues with a scaled-down experimental setup and procedure designed to test the hydrodynamic characteristics of the HASV���s substructure. This experimental study resulted in an understanding of the drag and lift behavior of the substructure, which is be used in the validation of the 3D CFD model. Then, this study continues to use the validated 3D CFD model as a tool to apply the CFD-based control investigation approach, mentioned above, to optimize the performance of the PID controller for regulating the HASV���s roll, pitch and heave motion. Then the effectiveness of the optimized control system on these three DOFs is tested using the CFD-based control investigation approach under different loading scenarios (calm water and waves)