A critical reflection on the problems, premises and prescriptions of the science of automatic control

Zhiqiang Gao

Center for Advanced Control Technologies, Cleveland State University

Beijing Institute of Technology, Dec. 26, at 3:00pm, Bldg 6, 3rd Floor Conference Room

時間：12月26日 下午3:00
地點：北理工自動化學院，北理工6號樓3層會議室
內容： 對控制科學的問題與前提的反思

      Abstract: The field of automatic control is considered the epitome of engineering science: above all it precipitated the industrial revolution that made the modern life possible; it has also become a branch of applied mathematics with the uttermost rigor. But the field has its own struggle, like all fields of engineering science, in grasping pure principles in design and in making reality-bound premises in theory. This is reflected in the persistent dichotomy of theory and practice, which has been the subject of numerous debates in the history of this field. In this lecture we reflect on some of the most fundamental problems, concepts, principles and methods in the science of automatic control. In particular, we examined the long-held premise that the problem of control is that of stability and optimality. To offer an alternative, it is argued that the problem of automatic control is, in essence, that of disturbance rejection, with the notion of disturbance generalized to symbolize the uncertainties, both internal and external to the plant. A novel, unifying concept of disturbance rejector is introduced to compliment the traditional notion of controller. The new controller-rejector pair is shown to be a powerful organizing principle in the realm of automatic control, leading to a Copernican moment where the model-centric design philosophy is replaced by the one that is control-centric in the following sense: the controller is designed for a canonical model and is fixed; the difference between the plant and the canonical model is deemed as disturbance and rejected.

      BIOGRAPHY:Prof. Zhiqiang Gao received his Ph.D. in Electrical Engineering from the University of Notre Dame in 1990 and has taught at Cleveland State University ever since. Faced with ever widening chasm between control theory and practice, Dr. Gao returned to the roots of controls by collaborating extensively with engineers at NASA and industry in solving real world problems, from which the foundation and authenticity of research were rebuilt. Collaborating with Prof. Jingqing Han, Dr. Gao worked quietly on active disturbance rejection control for over 15 years, nurturing it from its early, conceptual stage to a maturing and emerging industrial control technology. In doing so, he made an obscure idea clear and established firmly a general design principle in dealing with uncertainties in industrial settings, often with staggering improvements in performance and energy saving. Asking basic, rudimentary question in research and in teaching, Dr. Gao and his team find creative solutions in practice and vitality in education.

      About the 2016 Winter lecture series on Engineering Cybernetics:

      Cybernetics, conceived by Wiener in 1948, is a science of interrelationships, of feedback, of information and control in both biological and engineered systems. While control theory has seen ferocious growth in the form of applied mathematics, the progress on information side of cybernetics, as a symbiotic twin of control but beyond the general purpose information and communication theory, has been sorely lacking. It’s about time that the problem of information, unique in the field of automatic control, is recognized and systematically investigated. In doing so we return to the origin of Engineering Cybernetics as conceived by Prof. H.S. Tsien in 1954 and take inventory of its problems, inventions and attempts in its long history at conceptualizations. This lecture series consists of 8 lectures and it begins by revisiting the ideas of the pioneers of this field, such as Tsien, whose ideas may have faded in the modern developments but nonetheless quite relevant still in addressing contemporary issues. By revisiting the original ideas and inventions of the early pioneers we attempt to reimagine what the field of engineering cybernetics could have become as a science of information and control.

      Much has been accomplished in the field of control theory in the vein of applied mathematics. But it is not without its own challenges. Prof. John von Neumann once warned that as “mathematical discipline travels far from its empirical source, … it is beset with very grave dangers”, because “at a great distance from its empirical source, or after much ‘abstract’ inbreeding, a mathematical subject is in danger of degeneration”. Whenever this stage is reached, he suggests, “the only remedy seems to be the rejuvenating return to the source: the reinjection of more or less directly the empirical ideas”. This, he argues, is “a necessary condition to conserve the freshness and the vitality of the subject. And this is the goal of this lecture series: the reinjection of fresh and lively ideas of Engineering Cybernetics, in search of the rejuvenation of its relevance and vitality.