Establishing a predictive performance indicator for real‐time hybrid simulation

Abstract

Real-time hybrid simulation (RTHS) is increasingly being recognized as a powerful cyber-physical technique that offers the opportunity for system evaluation of civil structures subject to extreme dynamic loading. Advances in this field are enabling researchers to evaluate new structural components/systems in cost-effective and efficient ways, under more realistic conditions. For RTHS, performance metric clearly needs to be developed to predict and evaluate the accuracy of various partitioning choices while incorporating the dynamics of the transfer system, and computational/communication delays. In addition, because of the dynamics of the transfer system, communication delays, and computation delays, the RTHS equilibrium force at the interface between numerical and physical substructures is subject to phase discrepancy. Thus, the transfer system dynamics must be accommodated by appropriate actuator controllers. In this paper, a new performance indicator, predictive performance indicator (PPI), is proposed to assess the sensitivity of an RTHS configuration to any phase discrepancy resulting from transfer system dynamics and computational/communication delays. The predictive performance indicator provides a structural engineer with two sets of information as follows: (i) in the absence of a reference response, what is the level of fidelity of the RTHS response? and (ii) if needed, what partitioning adjustments can be made to effectively enhance the fidelity of the response? Moreover, along with the RTHS stability switch criterion, this performance metric may be used as an acceptance criteria for conducting single-degree-of-freedom RTHS.

Experimental implementation of predictive indicators for configuring a real-time hybrid simulation

“…In this section, established stability and performance indicators are utilized to guide effective partitioning of the system with consideration of experimental errors [22,23,43]. System identification of the hydraulic actuator system is performed to model the transfer system dynamics and thus facilitate outer loop control design.…”

“…For instance, errors introduced by structural modeling, numerical integration and experimental setup [22,25]. Model idealization is present in the numerical substructure model which is built to approximate actual continuous structure.…”

“…Moreover, to support the design of an appropriate RTHS experiment, predictive stability indicators (PSI) and predictive performance indicators (PPI) have been developed. PPI and PSI were established to provide researchers with the tools to assess the impact of partitioning choices on the stability and performance of a global RTHS system [22]. They facilitate a quantitative examination of the sensitivity of an RTHS configuration to any phase discrepancy arising from time delays and lags in the system, thus assisting the researcher to design an effective experiment.…”

Real-Time Hybrid Model Testing of a Braceless Semi-Submersible Wind Turbine: Part I — The Hybrid Approach

“…New error quantification criteria were developed that could be calculated online, i.e. during the execution of a ReaTHM test [14,15]. In addition to those examples of fundamental developments, advanced methods, such as model-based control strategies [5], or stability analyses based on Delayed Differential Equations [16] were applied to new types of problems.…”

“…Another solution is to monitor the effects of such uncertainties using energy criteria at the interface between the numerical and physical substructure as suggested in [34,35,15]. Such criteria have not been used in the present project, and remain to be developed for the present application.…”