Autonomous underwater vehicles (AUVs) have shown great promise in fulfilling surveillance, scavenging, and monitoring tasks, but can be hindered in expansive, cluttered or obstacle ridden environments. Traditional gliders and streamlined AUVs are designed for long term operational efficiency in expansive environments, but are hindered in cluttered spaces due to their shape and control authority; agile AUVs can penetrate cluttered or sensitive environments but are limited in operational endurance at large spatial scales. This paper presents the prototype testbed design, modeling, and experimental hydrodynamic drag characterization of a novel self-propelled underwater vehicle capable of actuating its shape morphology. The vehicle prototype incorporates flexible, buckled fiberglass ribs to ensure a rigid shape that can be actuated by modulating the length of the semi-major axis. Tools from generative modeling are used to represent the vehicle shape by using a single control input actuating the vehicles length-to-diameter ratio. By actuating the length and width characteristics of the vehicle’s shape to produce a desired drag profile, we derive the feasible speeds achievable by shape actuation control. Tow-tank experiments with an experimental proto-type suggest shape actuation can be used to manipulate the drag by a factor between 2.15 and 5.8 depending on the vehicle’s operating speed.
Characterization of Domain of Fixed-time Stability under Control Input Constraints
