FEM-Based Study for Development of Prototype Underwater Acoustic Vector Sensor with integrated Vibration Noise Cancellation

This study investigates various design parameters for the development of an underwater Acoustic Vector Sensor (AVS) with an integrated vibration noise cancellation mechanism, aimed at enhancing the performance of AVS extensively used in marine research, underwater navigation, and military applications. AVS measures sound field information in terms of pressure and particle velocity along three orthogonal axes. The two primary types of AVS configurations exist are P-P (pressure gradient type) and P-U (hydrophone and particle velocity transducer type). The P-U type offers a higher signal-to-noise ratio and frequency-independent beam pattern, making it more suitable for various applications than P-P. However, structural vibrations from mounting platforms such as Autonomous Under-water Vehicles (AUVs) can introduce unwanted noise, affecting measurement accuracy. Therefore, to address this problem, we have proposed the development of a prototype underwater AVS incorporating integrated vibration noise cancellation. This study utilizes the COMSOL Multiphysics software for Finite Element Method (FEM) method to investigate the suitable design parameters and explore the incorporation of an inertial sensor as a secondary sensor to capture platform-induced vibrations. The inertial sensor provides a reference signal that aids in cancelling out the vibration interference from the acoustic measurements. Key objectives include acoustic isolation of the secondary sensor and optimal sensor placement across a frequency range of up to 5 kHz. Different materials—nylon, titanium, stainless steel, visco-elastic rubber, and air are analyzed for their ability to isolate desired acoustic signals to get coupled to a secondary sensor, with simulations calculating the amount of incident energy coupled to the sensor. Additionally, various materials are tested as suitable outer casing. The study presents findings on the optimal material and placement for the secondary sensor and outer casing, providing insights into optimal prototype design for vibration noise cancellation for AVS applications.