Nestor Castaneda

A holistic approach to decentralized structural damage localization using wireless sensor networks

Wireless sensor networks (WSNs) have become an increasingly compelling platform for structural health monitoring (SHM) applications, since they can be installed relatively inexpensively onto existing infrastructure. Existing approaches to SHM in WSNs typically address computing system issues or structural engineering techniques, but not both in conjunction. In this paper, we propose a holistic approach to SHM that integrates a decentralized computing architecture with the damage localization assurance criterion algorithm. In contrast to centralized approaches that require transporting large amounts of sensor data to a base station, our system pushes the execution of portions of the damage localization algorithm onto the sensor nodes, reducing communication costs by an order of magnitude in exchange for moderate additional processing on each sensor. We present a prototype implementation of this system built using the TinyOS operating system running on the Intel Imote2 sensor network platform. Experiments conducted using two different physical structures demonstrate our systems ability to accurately localize structural damage. We also demonstrate that our decentralized approach reduces latency by 64.8% and energy consumption by 69.5% compared to a typical centralized solution, achieving a projected lifetime of 191 days using three standard AAA batteries. Our work demonstrates the advantages of a holistic approach to cyber-physical systems that closely integrates the design of computing systems and physical engineering techniques.

A Holistic Approach to Decentralized Structural Damage Localization Using Wireless Sensor Networks

Wireless sensor networks (WSNs) have become an increasingly compelling platform for structural health monitoring (SHM) applications, since they can be installed relatively inexpensively onto existing infrastructure. Existing approaches to SHM in WSNs typically address computing system issues or structural engineering techniques, but not both in conjunction. In this paper, we propose a holistic approach to SHM that integrates a decentralized computing architecture with the damage localization assurance criterion algorithm. In contrast to centralized approaches that require transporting large amounts of sensor data to a base station, our system pushes the execution of portions of the damage localization algorithm onto the sensor nodes, reducing communication costs by an order of magnitude in exchange for moderate additional processing on each sensor. We present a prototype implementation of this system built using the TinyOS operating system running on the Intel Imote2 sensor network platform. Experiments conducted using two different physical structures demonstrate our systems ability to accurately localize structural damage. We also demonstrate that our decentralized approach reduces latency by 64.8% and energy consumption by 69.5% compared to a typical centralized solution, achieving a projected lifetime of 191 days using three standard AAA batteries. Our work demonstrates the advantages of a holistic approach to cyber-physical systems that closely integrates the design of computing systems and physical engineering techniques.

Large-Scale Real-Time Hybrid Simulation for Evaluation of Advanced Damping System Performance

AbstractAs magnetorheological (MR) control devices increase in scale for use in real-world civil engineering applications, sophisticated modeling and control techniques may be needed to exploit their unique characteristics. Here, a control algorithm that utilizes overdriving and backdriving current control to increase the efficacy of the control device is experimentally verified and evaluated at large scale. Real-time hybrid simulation (RTHS) is conducted to perform the verification experiments using the nees@Lehigh facility. The physical substructure of the RTHS is a 10-m tall planar steel frame equipped with a large-scale MR damper. Through RTHS, the test configuration is used to represent two code-compliant structures, and is evaluated under seismic excitation. The results from numerical simulation and RTHS are compared to verify the RTHS methodology. The global responses of the full system are used to assess the performance of each control algorithm. In each case, the reduction in peak and root mean s...

Computational Tool for Real-Time Hybrid Simulation of Seismically Excited Steel Frame Structures

AbstractReal-time hybrid simulation (RTHS) offers an economical and reliable methodology for testing integrated structural systems with rate-dependent behaviors. Within a RTHS implementation, critical components of the structural system under evaluation are physically tested, while more predictable components are replaced with computational models under a one-to-one timescale execution. As a result, RTHS implementations provide a more economical and versatile alternate approach to evaluating structural/rate-dependent systems under actual dynamic and inertial conditions, without the need for full-scale structural testing. One significant challenge in RTHS is the accurate representation of the physical complexities within the computational counterparts. For RTHS, the requirement for computational environments with reliable modeling and real-time execution capabilities is critical. Additionally, the need of a flexible environment for implementation and easy integration of such platforms with remaining RTHS c...

Experimental Validation of a Generalized Procedure for MDOF Real-Time Hybrid Simulation

AbstractReal-time hybrid simulation (RTHS) has increasingly been recognized as a powerful methodology to evaluate structural components and systems under realistic operating conditions. The concept of RTHS combines the advantages of both numerical analysis and physical laboratory testing. Furthermore, the enforced real-time execution condition enables testing of rate-dependent components. One of the most important challenges in RTHS is to achieve synchronized boundary conditions between computational and physical substructures. The level of synchronization, i.e., actuators tracking performance, largely governs RTHS test stability and accuracy. The objective of this study is to propose and validate a generalized procedure for multiple-degree-of-freedom (MDOF) RTHS. A loop-shaping H∞ robust control design strategy is proposed to control the motion of the actuators. Validation experiments are performed successfully, including the challenges of multiple actuators dynamically coupled through a continuum steel ...

A Real-Time Hybrid Testing Platform for the Evaluation of Seismic Mitigation in Building Structures

Real-time hybrid testing (RTHT) has become a promising alternative to reduce the cost and operational demands when evaluating the performance of damping systems for seismic response attenuation in building structures. While damper devices can be physically tested, buildings can be represented with computational models to avoid the expense of testing a large, integrated specimen. Therefore, reliable simulation tools are needed to accurately recreate the behavior of the computational component under real-time execution demands; also, appropriate control schemes for testing the experimental component using hydraulic actuators are required for high fidelity RTHT implementation. In this paper, a novel RTHT platform appropriate for the study and evaluation of damped buildings is presented. The main components of the platform are described, including the computational tool for performing non-linear dynamic analysis of steel frames and the advanced robust control strategy for the hydraulic actuators. Additionally, initial results of a validation experiment using a re-configurable steel moment-resisting frame are presented to demonstrate the accuracy and efficiency of the proposed RTHT framework.

Experimental validation of a scaled instrument for Real-Time Hybrid Testing

A highly reconfigurable cyber-physical Real-time Hybrid Test (RTHT) instrument is under development that is particularly suitable for Civil Engineering structural control testing applications. The instrument serves as a testbed for studying structural system behavior under dynamic loading and associated vibration mitigation control techniques. The focus of this paper is to validate the developed framework experimentally regarding both its accuracy and efficiency in conducting RTHT. A MATLAB-based nonlinear finite element simulation tool, designed to predict seismically excited non-linear building response, is used as an analytical substructure, with a magneto-rheological (MR) damper as a physical substructure. A model based control scheme is adopted to compensate for de-synchronization between substructure interfaces caused by hydraulic actuator dynamics. The RTHT is then conducted for both passive and semi-active MR damper control cases, the results of which show an excellent match between RTHT and pure numerical simulation outputs, thus demonstrating the effectiveness of the prototype instrument.