Abstract
Supercavitation is a hydrodynamic phenomenon in which an underwater body is almost entirely inside the cavity wall. Since the density of the gas is much lower than that of water, skin friction drag can be reduced considerably. We develop controllers to control a supercavitating vehicle, which is a high-speed vehicle with a cavitator at its nose. We designed controllers based on impulsive inputs, which are used to change the pitch of the vehicle slightly. This slight pitch change is desirable, since a large pitch change can lead to instability of the vehicle due to large planing force. Moreover, our impulsive controllers are robust to disturbances. In practice, the vehicle consumed its fuel to move forward. This fuel consumption led to changing parameters of the vehicle, such as mass. To handle this changing system, we used fuzzy impulsive controllers. We ran simulations to verify the effectiveness of our controllers.
Highlights
Supercavitation is a hydrodynamic phenomenon in which an underwater body is almost entirely inside the cavity wall
As far as we know, this paper is novel in developing control laws for a supercavitating vehicle, which can handle changing systems
This paper developed robust control laws to control depth and roll of a supercavitating vehicle
Summary
Supercavitation is a hydrodynamic phenomenon in which an underwater body is almost entirely inside the cavity wall (a layer of gas bubbles). The authors of Reference [5] presented a dynamic model that captures the physics of a supercavitating vehicle with a disk cavitator. Considering the case where the full cavity is developed, we present control laws to control depth and roll of the vehicle. Consider the case where the vehicle follows a target depth under our impulsive control laws. Inspired by fuzzy control methods in References [21,22,23], this paper introduces an adaptive fuzzy method to reduce the fluctuation of the vehicle, as it follows the target depth. As far as we know, this paper is novel in developing control laws for a supercavitating vehicle, which can handle changing systems. Our contributions are summarized as follows: we first develop realistic simulation models, considering varying cavitation numbers, vehicle depth, environmental disturbance, and fuel consumption.
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