From Soft Mooring System to Active Positioning in Laboratory Experiments

Sauder, Thomas; Tahchiev, Galin

doi:10.1115/omae2020-19103

Cited by 3 publications

(3 citation statements)

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“…In response to the first limitation, Sauder & Tahchiev [4] developed a laboratory apparatus that enables magnifying the sensitivity of the floater response to the LF loads generated by the incoming wave by adjusting the stiffness and damping parameters of a virtual soft mooring system. This type of Cyber-Physical (CP) testing method has been introduced earlier in hydrodynamic testing, under the denomination Real-time Hybrid Model testing * [5].…”

Section: Background and Motivationmentioning

confidence: 99%

“…Here, CP testing is performed in force-control, that is, a set of actuation lines impose the virtual mooring forces to the floater, and the corresponding LF velocity and position feedback close the simulation loop. More details can be found in Section 4.1 and in [4].…”

Section: Background and Motivationmentioning

confidence: 99%

“…As presented in the work of Sauder and Tahchiev [4], and shown in Figure 2a the structure under consideration is subjected to head waves in an ocean basin and kept in position using an active positioning system. The structure in its mooring is then assimilated to a single-degree-of-freedom second-order dynamical system, and its LF motions are described by…”

Section: Description Of the Case Studymentioning

confidence: 99%

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Bayesian Experimental Design of Cyber-Physical Tests for Hydrodynamic Model Calibration

Abbiati

Sauder

2021

Volume 6: Ocean Engineering

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An application of cyber-physical testing to the empirical estimation of difference-frequency quadratic transfer functions is presented. As an alternative to today’s procedure based on hydrodynamic tests with broad-banded or realistic (e.g., JONSWAP) wave spectra, tests in bichromatic waves are considered. The laboratory setup is the one developed by Sauder & Tahchiev (2020) that enables magnifying the sensitivity of the floater response to the low-frequency wave loading by adjusting the stiffness and damping parameters of a virtual soft mooring system. Bayesian experimental design is proposed to optimize the selection of the control variables (frequencies in the bichromatic wave and properties of the virtual mooring system) for a batch of cyber-physical tests. The experimental design algorithm is based on the recent work of Huan & Marzouk (2013). In a virtual yet realistic case study using an uncertain parametric quadratic transfer function, we demonstrate how the uncertainty of its describing parameters and other calibration parameters (low-frequency added mass and hydrodynamic damping) can be reduced. Results indicate that the proposed procedure has the potential for reducing experimental cost for calibration of hydrodynamic models.

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Section: Background and Motivationmentioning

confidence: 99%

Section: Background and Motivationmentioning

confidence: 99%

Section: Description Of the Case Studymentioning

confidence: 99%

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Bayesian Experimental Design of Cyber-Physical Tests for Hydrodynamic Model Calibration

Abbiati

Sauder

2021

Volume 6: Ocean Engineering

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Empirical estimation of low-frequency nonlinear hydrodynamic loads on moored structures

Sauder

2021

Applied Ocean Research

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Optimal Actuator Placement for Real-Time Hybrid Model Testing Using Cable-Driven Parallel Robots

Ueland

Sauder

Skjetne

2021

JMSE

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In real-time hybrid model testing, complex ocean structures are emulated by fusing numerical modelling with traditional hydrodynamic model testing. This is done by partitioning the ocean structure under consideration into a numerical and a physical substructure, coupled in real time via a measurement and control interface. The numerically computed load vector is applied to the physical substructure by means of multiple actuated winches so that the resulting experimental platform becomes a type of cable-driven parallel robot. In this context, the placement of the actuated winches is important to ensure that the loads can be accurately and robustly transferred to the physical substructure. This paper addresses this problem by proposing a performance measure and an associated actuator placement procedure that enables accurate force tracking and ensures that the numerically calculated loads can be actuated throughout the testing campaign. To clarify the application of the proposed procedure, it is applied to the design of a test setup for a moored barge. Overall, the paper represents a guideline for robust and beneficial actuator placement for real-time hybrid model testing using cable-driven parallel robots for load-actuation.

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From Soft Mooring System to Active Positioning in Laboratory Experiments

Cited by 3 publications

References 0 publications

Bayesian Experimental Design of Cyber-Physical Tests for Hydrodynamic Model Calibration

Bayesian Experimental Design of Cyber-Physical Tests for Hydrodynamic Model Calibration

Empirical estimation of low-frequency nonlinear hydrodynamic loads on moored structures

Optimal Actuator Placement for Real-Time Hybrid Model Testing Using Cable-Driven Parallel Robots

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