System identification of an autonomous underwater vehicle

• Main Author: Kuek, Zheng Wei
• Other Authors: Basman Elhadidi
• Format: Final Year Project
• Language: English
• Published: Nanyang Technological University 2021
• Subjects: Engineering::Mechanical engineering::Fluid mechanics
• Online Access: https://hdl.handle.net/10356/150934
• Institution: Nanyang Technological University

Autonomous Underwater Vehicles (AUVs) are finding more applications and are widely used. To better control these vehicles, there is a need to identify the hydrodynamic characteristics using system or parameter identification. This report details the fabrication and system identification of a prototype, where all sensors and data logging are within the AUV itself for better accuracy. Two experiments were conducted to determine the hydrodynamic coefficients in yaw motion. The first experiment intended to determine the linear and quadratic damping coefficients. The steady state velocity was measured at different specified thruster settings and substituted into the equation of motion. The second experiment was intended to determine the added mass coefficient. This involved turning off thrusters when the AUV was rotating at constant angular velocity and measuring the decay in angular rate. A least squares technique was performed on the data and derived the deceleration data at specific angular velocities before being substituted into the equation of motion. With these three hydrodynamic coefficients determined, a dynamic model of the AUV was generated for yaw motion.