Abstract
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.
Highlights
Real-time hybrid model testing (ReaTHM testing) is a cyber-physical empirical method for emulating complex ocean structures that combines numerical models with traditional hydrodynamic model testing [1,2]. This is done by partitioning the ocean structure under consideration into a numerical substructure and a physical substructure that are coupled in real time through a measurement and control interface
The resulting experimental substructure becomes a type of cable-driven parallel robot (CDPR), which is a setup characterised by a mobile platform being actuated by cabled winches configured in a parallel topology [7]
We seek a procedure for placement of actuators that: (1) facilitates accurate load tracking—which is important to ensure high fidelity ReaTHM testing that accurately predicts the behaviour of the target ocean structure, and (2) ensures that the actuators can always actuate the numerically calculated loads according to specified workspace requirements—which is a prerequisite to carry out a successful ReaTHM testing campaign
Summary
Real-time hybrid model testing (ReaTHM testing) is a cyber-physical empirical method for emulating complex ocean structures that combines numerical models with traditional hydrodynamic model testing [1,2]. The cable endpoints of all connected actuators, together with the platform pose, constitute the platform configuration of a CDPR Beyond their use for ReaTHM testing, CDPRs have received considerable attention in recent decades [9,10] for diverse applications, including aerial cameras [11], manufacturing [12], agriculture [13], and ocean engineering [14]. 3. Given similar platform dimensions, the actuation system in typical CDPR applications carries larger loads than in ReaTHM testing and must be designed . We seek a procedure for placement of actuators that: (1) facilitates accurate load tracking—which is important to ensure high fidelity ReaTHM testing that accurately predicts the behaviour of the target ocean structure, and (2) ensures that the actuators can always actuate the numerically calculated loads according to specified workspace requirements—which is a prerequisite to carry out a successful ReaTHM testing campaign.
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