Underwater vehicle speedometry using differential pressure sensors: Preliminary results

Underwater vehicles require accurate speedometry relative to local flow conditions to perform many tasks within the aquatic environment. This paper presents preliminary results of a differential pressure sensing system using an extension of the Pitot equation capable of providing instantaneous flow speed estimation, including yaw angles from ±45°. In contrast to systems with similar configuration based on absolute pressure sensor approaches, the differential system makes use of the pressure between two points on the sensor head, reducing the number of necessary sensors by half. The theoretical system performance and physical prototype are compared using computational fluid dynamics and flow tunnel tests from 0-0.5 m/s and angles of attack up to ±45°. The proposed speedometry device has a small form factor, uses inexpensive commodity hardware, is geometrically simple, accurate (mean absolute error of 0.024 m/s) and has low power consumption (<; 10 mW for each sensor) making it suitable for a wide spectrum of underwater vehicles.