An AUV project applied to studies on manoeuvrability of underwater vehicles

Barros, Ettore A. de; Dantas, João Lucas Dozzi; Freire, Luciano Ondir; Stoeterau, Rodrigo Lima

doi:10.1049/pbce077e_ch4

Cited by 2 publications

(3 citation statements)

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“…Relatively good estimates for the critical pressure of an unstiffened perfect cylindrical shell can be obtained using analytical formulations taken from the literature. Subsequently, some of these formulations are presented and used to estimate the order of magnitude of the critical hydrostatic pressure of an existing AUV designed by the Unmanned Vehicles Laboratory at the University of Sao Paulo (see Barros et al [38]). Five analytical formulations were selected:…”

Section: Analysis Of the Unstiffened Shellmentioning

confidence: 99%

“…Equations ( 1)-( 5) were applied to the cylindrical shell of an existing AUV (see Reference [38]) made of aluminum (5456-H111) (E = 70.3 GPa, σ y = 230 MPa, and ν = 0.33) with dimensions L = 840 mm, R = 97.175 mm, and h = 6.35 mm. The critical length calculated according to Equation ( 10), in this case, is L cr 1191 mm, so that L/L cr 0.705, i.e., the AUV length is, in fact, shorter than the critical length.…”

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confidence: 99%

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Buckling Analysis of an AUV Pressure Vessel with Sliding Stiffeners

Freitas¹,

Álvarez

Ramos

et al. 2020

JMSE

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The structure of an autonomous underwater vehicle (AUV), usually composed of a cylindrical shell, may be exposed to high hydrostatic pressures where buckling collapse occurs before yield stress failure. In conventional submarines, welded stiffeners increase the buckling resistance, however, in small AUVs, they reduce the inner space and cause residual stresses. This work presents an innovative concept for the structural design of an AUV, proposing the use of sliding stiffeners that are part of the structure used to accommodate the electronics inside it. Since the sliding stiffeners are not welded to the shell, there are no residual stresses due to welding, the AUV fabrication process is simplified, enabling a reduction of the manufacturing cost, and the inner space is available to accommodate the equipment needed for the AUV mission. Moreover, they provide a higher buckling resistance when compared to that of an unstiffened cylindrical shell. A comparative analysis of the critical buckling loads for different shell designs was carried out considering the following: (i) the unstiffened shell, (ii) the shell with ring stiffeners, and (iii) the shell with sliding stiffeners. Results evidenced that major advantages were obtained by using the latter alternative against buckling.

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Section: Analysis Of the Unstiffened Shellmentioning

confidence: 99%

mentioning

confidence: 99%

Buckling Analysis of an AUV Pressure Vessel with Sliding Stiffeners

Freitas¹,

Álvarez

Ramos

et al. 2020

JMSE

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“…The control algorithm was tested in simulations based on a modified version of the AUV Pirajuba, 13,14 seen in Figure 1, developed by the Unmanned Vehicles Laboratory at University of Sa˜o Paulo. The vehicle has an axisymmetric body with a nose and tail based on the relationship 15 and a cylindrical middle body.…”

Section: Auv Dynamic Modelmentioning

confidence: 99%

Study of autonomous underwater vehicle wave disturbance rejection in the diving plane

Dantas

Cruz

Barros

2013

Proceedings of the Institution of Mechanical Engineers, Part M:

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Autonomous underwater vehicles operating near the sea surface are subject to wave disturbances in their motion, which can affect severely the data acquisition during the vehicle motion. Bathymetric maps, for example, may suffer a big loss in quality due to such kind of disturbances that can impose oscillations in the vehicle depth and attitude. This article describes a controller structure for compensating the wave disturbances in the vertical plane for a torpedo-like autonomous underwater vehicle, based on a modified version of the linear quadratic Gaussian with loop transfer recovery control combined with a wave filter. The proposed methodology uses additional to the classic linear quadratic Gaussian with loop transfer recovery design the measurement of non-controlled states, such as the pitch rate and heave velocity, in the control action. The wave disturbances were filtered away by a shaping filter fitted to the sea spectrum, and the sensor signals were integrated by an extended Kalman filter. The proposed control methodology was tested against the classical linear quadratic Gaussian with loop transfer recovery controller in a 6-degree-of-freedom non-linear autonomous underwater vehicle simulator, producing a better performance in most demanding conditions such high wave crests. The tests also revealed the impact of the hydroplane geometry on the controller performance, which should not be underestimated by the autopilot designer.

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An AUV project applied to studies on manoeuvrability of underwater vehicles

Cited by 2 publications

References 0 publications

Buckling Analysis of an AUV Pressure Vessel with Sliding Stiffeners

Buckling Analysis of an AUV Pressure Vessel with Sliding Stiffeners

Study of autonomous underwater vehicle wave disturbance rejection in the diving plane

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