Wireless sensing and vibration control of civil structures

2007

This study presents a partially-decentralized control scheme for wireless control of large civil structures. Reducing the seismic response of a structure reduces the likelihood of significant damage to the structure or its occupants. The cost of implementing such a system is reduced by employing wireless sensors, thus avoiding the prohibitive cost of installing cable-based systems. Wireless sensors with embedded computational abilities capable of sensing and actuation can perform structural control tasks without a central computer. A wireless sensor network is developed composed of wireless sensors employing identical static Kalman estimators. The wireless sensors command actuators with LQR derived state-feedback control forces based on state vectors locally calculated from embedded Kalman estimators. Each unit compares the estimated state values to their local measured state data; in the case where the estimate error exceeds a predefined threshold, replaces the estimated value with the measured value and transmits the update to the entire wireless sensor network. By strategically transmitting only some of the measured data, this scheme reduces demand on the limited wireless bandwidth and energy resources associated with wireless sensor networks. Numerical simulation results using this scheme are presented as well as experimental results for a half-scale 3-story steel structure with magnetorheological (MR) dampers controlling each floor.

2012

All praise is for ALLAH (SWT), the most compassionate, the most merciful. May peace and blessings be upon prophet Mohammed (PBUH), his family and companions. I thank almighty ALLAH (SWT) for giving me the knowledge and patience to complete this work. My deep and heartfelt gratitude and appreciation to my parents who have always sacrificed their own welfare for mine, and to whom I can only offer my unending love. It is only thanks to their prayers and blessings that I was able to complete this work. Thanks to all my family members whose love, support, encouragement and belief in me have been invaluable. Special thanks to my wife for her patience and support of me during my study period. Prof. Magdi S. Mahmoud, for his consistent help, guidance and attention that he devoted throughout the course of this work. His valuable suggestions and useful discussions made this work interesting to me. His support and words of encouragement gave a new life to my efforts in hard times. Without his help and valuable directions, this work would have never seen the light of the day. Thanks are also due to my thesis committee members Prof. Fouad Al-Sunni, Prof.

Proceedings of the 2011 American Control Conference, 2011

This paper studies a time-delayed decentralized structural control strategy that aims to minimize the H 2 norm of the closed-loop system. In a decentralized control system, control decisions are made based on data acquired from sensors located in the vicinity of a control device. Due to the non-convexity nature of the optimization problem caused by a decentralized architecture, controller design for decentralized systems remains a major challenge. In this work, a homotopy method is employed to gradually transform a centralized controller into multiple decentralized controllers. Linear matrix inequality (LMI) constraints are adopted in the homotopic transformation to ensure closed-loop control performance. In addition, multiple decentralized control architectures are implemented with a network of wireless sensing and control nodes. The sensor network allows simultaneous operation of multiple wireless subnets. Both the theoretical development and system implementation support the information overlapping between decentralized subnets. For validation, the wireless sensing and control system is installed on a six-story laboratory steel structure controlled by magnetorheological (MR) dampers. Shake-table experiments are conducted to demonstrate the performance of the wireless decentralized control strategies.

2008

Recent years have seen growing interest in applying wireless sensing and embedded computing technologies for structural health monitoring and control. The incorporation of these new technologies greatly reduces system cost by eliminating expensive lengthy cables, and enables highly flexible system architectures. Previous research has demonstrated the feasibility of decentralized wireless structural control through numerical simulations and preliminary laboratory experiments with a three-story structure. This paper describes latest laboratory experiments that are designed to further evaluate the performance of decentralized wireless structural control using a six-story structure. Commanded by wireless sensors and controllers, semi-active magnetorheological (MR) dampers are installed between neighboring floors for applying real-time feedback control forces. Multiple centralized/decentralized feedback control architectures have been investigated in the experiments, in combination with different sampling frequencies. The experiments offer valuable insight in applying decentralized wireless control to larger-scale civil structures.

2011

This paper studies a time-delayed decentralized structural control strategy that aims to minimize the H2 norm of the closed-loop system. In a decentralized control system, control decisions are made based on data acquired from sensors located in the vicinity of a control device. Due to the non-convexity nature of the optimization problem caused by a decentralized architecture, controller design for decentralized systems remains a major challenge. In this work, a homotopy method is employed to gradually transform a centralized controller into multiple decentralized controllers. Linear matrix inequality (LMI) constraints are adopted in the homotopic transformation to ensure closed-loop control performance. In addition, multiple decentralized control architectures are implemented with a network of wireless sensing and control nodes. The sensor network allows simultaneous operation of multiple wireless subnets. Both the theoretical development and system implementation support the information overlapping between decentralized subnets. For validation, the wireless sensing and control system is installed on a six-story laboratory steel structure controlled by magnetorheological (MR) dampers. Shake-table experiments are conducted to demonstrate the performance of the wireless decentralized control strategies.

Distributed dynamic systems are large-scale systems constituted by numerous subsystems deployed in distributed manner. In many cases, there are three fundamental characteristics for these subsystems. The first characteristic is autonomy. The subsystems are usually autonomous or semiautonomous and can often exist and operate independently. The second characteristic is homogeneity. The subsystems often share similarity and play relatively equal roles. The last and most important characteristic is interactivity. The subsystems should connect to a network topology collectively, such that they are able to communicate by exchanging information or substance and cooperate with each other.

1985 24th IEEE Conference on Decision and Control, 1985

Umi t O z g u n e r E n r i q u e B a r h i e r i D e p a r t m e n t o f E l e c t r i c a l E n g i n e e r i n g T h e O h i o S t a t e U n i v e r s i t y Columbus, Ohio 43210 A b s t r a c t -Many large scale mechanical systems can be modeled i n t e r m s o f p a r t i a l d i f f e r e n t i a l e q u a t i o n s w h i c h c a n t h e n b e d i s c r e t i z e d t o g i v e w h a t may be termed "homogeneous interconnected systems" or "cellu l a r s t r u c t u r e s " . I n t h i s p a p e r we c o n s i d e r a c l a s s o f

2006

Eliminating the need for extensive wiring between sensors, actuators and a controller could reduce the cost and enhance the attractiveness of control systems for civil structures. In this study, wireless sensors are proposed for a structural control system with the wireless sensors responsible for the collection of state response data, calculation of control forces, and the issuing of command signals to actuators. While wireless sensors are attractive because of their easy installations, they are limited by the amount of bandwidth available in the wireless communication channel. To address this limitation, the on-board computational resources of wireless sensors are leveraged to alleviate the need for continued use of the wireless channel. Specifically, redundant Kalman state-estimators are encoded in each wireless sensor to estimate the state response of the structure, using only local output measurements. At each time step, the estimated state is compared to the measured system output; when the estimation error exceeds an established threshold, only then is the wireless communication channel used to broadcast updated state information to the remaining wireless sensors. This partially decentralized control method is validated using a 20-story building modeled in a simulation environment. Furthermore, an experimental study is conducted using a three story test structure in which magnetorheological dampers and wireless sensors are installed for the purpose of real-time feedback control during base excitation.

1993 American Control Conference, 1993

Quite often, in the control of physical systems, structural constraints are placed on the feedback controller. Issues of complexity, computation, ease of implementation and physical dimensions play a role in the decision to select structurally constrained controllers. This paper examines controllers which are constrained by the amount of information sharing occurring in the feedback channels. A fully decentralized controller is characterized by no sharing of information among the feedback channels. Three other types of partially decentralized controllers are characterized by the way in which the feedback channels locally share information between adjacent channels. It is shown in this paper via left and right unimodular transformations, that from the set of stabilizing decentralized controllers associated with a transformed plant operator a set of stabilizing partially decentralized controllers can be recovered. This serves to identify a potentially useful methodology for the synthesis of partially decentralized controllers by formulating the problem within a framework which can take advantage of the stable factors approach to the parameterization of the set of all stabilizing fully decentralized controllers.

2009

The benefits associated with structural control include the mitigation of undesired structural responses and reduction in the probability of damage to structural components during seismic events. Structural control systems in current use depend on extensive wired communication systems to connect sensors and actuators with a centralized controller. While wired architectures are appropriate when control systems are small, the cost and installation complexity of tethered systems increases as the control system grows large ͑i.e., defined by hundreds of nodes͒. Alternatively, wireless sensors are proposed for use in large-scale structural control systems to keep costs low and to improve system scalability. Wireless sensors are capable of collecting state data from sensors, communicating data between themselves, calculating control actions, and commanding actuators in a control system. However, bandwidth and range limitations of the wireless communication channel render traditional centralized control solutions impractical for the wireless setting. While computational abilities embedded with each wireless sensor permit fully decentralized control architectures to be implemented, strategic utilization of the wireless channel can improve the performance of the wireless control system. Toward this end, this paper presents a partially decentralized linear quadratic regulation control scheme that employs redundant state estimation as a means of minimizing the need for the communication of state data between sensors. The method is validated using numerical simulations of a seismically excited six-story building model with ideal actuators. Additional experimental validation is conducted using a full-scale physical realization of the six-story building. A wireless sensor network commanding magnetorheological dampers is shown to be effective in controlling a multistory structure using the partially decentralized control architecture proposed.