Real time hybrid simulation: from dynamic system, motion control to experimental error

Abstract

SUMMARY Real‐time hybrid simulation (RTHS) has increasingly been recognized as a powerful methodology to evaluate structural components and systems under realistic operating conditions. It is a cost effective approach compared with large scale shake table testing. Furthermore, it can maximally preserve rate dependency and nonlinear characteristics of physically tested (non)structural components. Although conceptually very attractive, challenges do exist that require comprehensive validation before RTHS should be employed to assess complicated physical phenomena. One of the most important issues that governs the stability and accuracy of an RTHS is the ability to achieve synchronization of boundary conditions between the computational and physical substructures. The objective of this study is to propose and validate an H∞ loop shaping design for actuator motion control in RTHS. Controller performance is evaluated in the laboratory using a worst‐case substructure proportioning scheme. A modular, one‐bay, one‐story steel moment resisting frame specimen is tested experimentally. Its deformation is kept within the linear range for ready comparison with the reference closed‐form solution. Both system analysis and experimental results show that the proposed H∞ strategy can significantly improve both the stability limit and test accuracy compared with several existing strategies. Another key feature of the proposed strategy is its robust performance in terms of unmodeled dynamics and uncertainties, which inevitably exist in any physical system. This feature is essential to enhance test quality for specimens with nonlinear dynamic behavior, thus ensuring the validity of the proposed approach for more complex RTHS implementations. Copyright © 2012 John Wiley & Sons, Ltd.

Modelling and control issues of dynamically substructured systems: adaptive forward prediction taken as an example

“…This is true when G TS has been specifically chosen, or a DSS controller has been used and synthesized on the basis of the exact synchronization theory [37]. Essentially, G TS has its own dynamics, and τ is more related to frequency-dependent phase characteristics, as mentioned implicitly in some DSS literature [3,8,17,23] Here, s denotes the Laplace variable, and a(s) and b(s) correspond to the denominator and numerator polynomials, respectively. The ODE model indicates phase dynamics as a result of non-ideal mechanics within G TS , for example friction, backlashes and oil density variations.…”

Real-time system support for hybrid structural simulation

“…There also has been some work on distributing computational responsibility across multiple platforms in order to get better performance. This can involve coupling a general purpose computing platform alongside specialized hardware [13,21,22] (such as a digital signal processor or the xPC Host/Target arrangement), or coupling multiple general purpose platforms [15] over a real-time network or specialized multi-computer shared memory platforms such as SCRAMnet [11]. Most closely related to our work is an earlier middleware design for real-time hybrid testing on Linux [24].…”

“…First, it is a good approximation of the types of realistic computations often used in the civil engineering RTHS community [20,22], since it is completely regular and has highly deterministic behavior. Second, our goal is not to discover efficient finite element discretizations for parallel real-time computation, rather our goal here is to parallelize existing RTHS computations that are used in practice.…”

Application of the Hybrid Simulation Method for the Full-Scale Precast Reinforced Concrete Shear Wall Structure

“…Especially, the real-time HS plays a powerful role to evaluate the rate dependent behaviors, such as magneto-rheological damper or vibration isolation system [18,[27][28][29][30][31][32][33][34][35][36]. Additionally, the Network for Earthquake Engineering Simulation (NEES), which featured 14 geographically distributed and shared-use laboratories to test modern structural system [37][38][39][40], accelerates the development of the HS platforms (OpenFresco manufactured by dSpace, and MTS (STS and FlexTest systems) National Instru ments [41], and UI-Simcor developed by the MUST-SIM facility and the MAE Center at the University of Illinois at Urbana-Champaign [42]).…”