Networks and Precision Control - IEEE Xplore

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Jun 2, 2014 - nando Paganini, Ioannis (Yannis) Ch. Paschalidis, and A. Galup Ulsoy) and. Stephen P. Boyd's acceptance speech for the IEEE Control ...
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Networks and Precision Control

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o member of the IEEE Control Systems Society (CSS) would doubt the ubiquity and impor­ tance of networks. These networks include communication, information, transportation, electric power, sensor, chemical, biological, economic, and social. Many of these networks are big, and most are becoming bigger. For example, consider the Facebook and Google+ social networks. Facebook Digital Object Identifier 10.1109/MCS.2014.2308613 Date of publication: 12 May 2014

went from 1 million users in 2004 to 100 million users in the middle of 2008 to more than 1 billion users in late 2012 [1]. Approximately 750 million users were reported to log in daily as of December 31, 2013. Google+, a relative latecomer to social networking, went from about zero users in late 2011 to over 500 mil­ lion users by the end of 2013 [2]. The importance of control to systems with interconnected components was recognized by the CSS with its creation of IEEE Transactions on Control of Network Systems. The first feature article of this

issue of IEEE Control Systems Magazine (CSM) discusses algorithms for mea­ suring the importance of individual nodes in very large networks. More specifically, in the article “The Page­ Rank Problem, Multiagent Consensus, and Web Aggregation,” Hideaki Ishii and Roberto Tempo consider the Page­ Rank algorithm used by the Google Internet search engine to measure the relative importance of Web pages based on the hyperlink structure of the Web. Ideas from PageRank go beyond rank­ ing Web pages to rank the importance

Contributors

Hideaki Ishii.

Wen-Hong Zhu at Atigun Pass across the Brooks Range in Alaska on July 27, 2013.

Roberto Tempo in Aiguilles de Chamonix, France.

James Primbs climbing inside the dome at the Duomo in Florence, Italy, while attending the IEEE Conference on Decision and Control in December 2013.

8  IEEE CONTROL SYSTEMS MAGAZINE  »  JUNE 2014

Warren Dixon with some autonomous vehicles, including mobile wheeled robots and a quadrotor.

of other objects, such as journal articles, authors, professional athletes, and pro­ teins in biological systems. The com­ putation of Page­ Rank is challenging due to the very large size of the Web, and the dif­ ficulty is gathering and using global information about the network struc­ ture. The article describes a randomized decentral­ ized approach to allow the computations to be carried out in parallel on a large number of computers. The article also draws connec­ tions to problems studied by the systems and control community, such as the ranking of control journals, consensus in multiagent systems, and aggregation-based techniques. The second feature article, “FPGA Logic Devices for Precision Control: An Application to Large Friction Actua­ tors with Payloads” by Wen-Hong Zhu, considers the very physical problem of precision control in electromechanical systems. A field-programmable gate array (FPGA) is an integrated circuit based around a matrix of configurable logic blocks connected via programma­ ble interconnects that can be configured by the user after manufacturing, which is to what the term “field programma­ ble” refers. Modern FPGAs have large numbers of logic gates (hence the “gate array”) and RAM blocks that can be used to implement reasonably compli­ cated digital computations, and these FPGAs can easily push the 500-MHz performance barrier. The reprogram­ mability of FPGAs enables bugs to be fixed and functionality to be updated after the FPGA-containing device is manufactured, which can reduce time to market and lower nonrecurring en­ gineering costs. The article describes algorithms for using FPGAs for the precision control of actuators with large friction. Approaches for low-cost ve­ locity estimation and adaptive friction compensation are demonstrated experi­ mentally for a harmonic drive actuator with large friction, subject to a variety of payload conditions.

Although the second feature article is not on networks per se, FPGAs are re­ lated to networks. First, the logic gates and RAM blocks form a network in the FPGA. Second, FPGAs are widely used as part of the hardware in tele­ communications and net­ working. Third, FPGAs are used in smartphones and mobile Internet de­ vices, which contribute to social networks. In the “President’s Mes­ sage,” Jay Farrell discusses the impact of control tech­ nology, its hidden impact on commercial products, the outreach fund whose purpose is to bring controls to the broader community, and other topics related to the CSS. “CSS News” discusses future CSS conferences and changes in personnel within the CSS. “Member Activities” congratulates the members of the CSS who were elevated to IEEE Fellow in 2014. In “Technical Activities,” Frank Allgöwer describes the 2014 IEEE CSS Video Clip Contest and encourages submissions to arrive by the deadline of August 1. “Publication Activities” provides brief biographies for Deputy Editor-in-Chief Jonathan P. How and Associate Editors Antonella Ferrara, Yiguang Hong, and Antonio Loría, who were added to the CSM Editorial Board in 2014. “People in Control” has interviews with six IEEE Fellows (Peter H. Bauer, Yoichi Hori, Tetsuya Iwasaki, Fer­ nando Paganini, Ioannis (Yannis) Ch. Paschalidis, and A. Galup Ulsoy) and Stephen P. Boyd’s acceptance speech for the IEEE Control Systems Award that was delivered at the 2013 IEEE Conference on Decision and Control. “Focus on Education” describes a large-scale effort in India to write Scilab programs that provide solu­ tions to the examples given in a wide range of textbooks used to train con­ trol engineers. “Historical Perspec­ tives” is the second in a series of columns that commemorates the 60th anniversary of the CSS with remi­ niscences from past CSS presidents.

This issue includes recollections of Stephen Kahne, who was president in 1981. In “Bookshelf,” Warren E. Dixon reviews Optimal Adaptive Control and Differential Games by Reinforcement Learning Principles by Draguna Vrabie, Kyriakos G. Vamvoudakis, and Frank Lewis, and James A. Primbs reviews the second edition of Investment Science by David G. Luenberger. The recipi­ ents of the 2013 IEEE Control Systems Awards are summarized in the column by that name. “Conference Reports” provides summaries of three different confer­ ences held in 2013. Thomas Parisini and Roberto Tempo report on the 52nd IEEE Conference on Decision and Con­ trol that was held in Florence, Italy; Changyun Wen and Zhong-Ping Jiang report on the 25th Chinese Control and Decision Conference that was held in Guiyang, China; and Didier Theilliol and Jozef Korbicz report on the Second International Conference on Control and Fault-Tolerant Systems that was held in Nice, France. “CSS Business” contains the min­ utes of the IEEE CSS Board of Gover­ nors meeting held in Florence, Italy, in December 2013. Among the regular columns, “25 Years Ago” revisits an article by A. Galip Ulsoy and Yoram Koren on applications of adaptive control to ma­ chine tools. “Conference Calendar” lists upcoming conferences sponsored or cosponsored by the CSS. “Book An­ nouncements” provides summaries of books recently published in the control field. “On the Lighter Side” considers the topic of metrology, and “Random Inputs” considers the control of control presentations.

References [1] G. A. Fowler, “Facebook: One billion and counting,” Wall Str. J., Oct. 4, 2012. [2] M. McGee, “Google+ hits 300 million active monthly ‘in-stream’ users, 540 million across Google,” MarketingLand, Oct. 29, 2013.

Richard D. Braatz  JUNE 2014  «  IEEE CONTROL SYSTEMS MAGAZINE  9