H.Y. Hu – författare

The last decade has witnessed an increasing interest towards the dynamics and control of nonlinear engineering systems from the scientists engaged in nonlinear dynamics and the control engineers.

The last decade has witnessed an increasing interest towards the dynamics and control of nonlinear engineering systems from the scientists engaged in nonlinear dynamics and the control engineers. Both groups of people have recognized the importance of interaction between nonlinear dynamics and robust control during their efforts to improve the dynamic performance of engineering systems with uncertainty, which comes from either the random excitations, such as wind and earthquake, or the modelling errors of real systems including their sensors, controllers and actuators. The dynamics and control of nonlinear systems with uncertainty, therefore, is a vital interdisciplinary topic related to both stochastic systems and deterministic systems. This volume contains the papers presented at the IUTAM Symposium on Dynamics and Control of Nonlinear Systems with Uncertainty, which was sponsored by the International Union of Theoretical and Applied Mechanics (IUTAM) and held at Nanjing University of Aeronautics and Astronautics, China, 18-22 September, 2006. The aim of the symposium was to bringing together the scientists to discuss the advances in dynamics and control of nonlinear systems, especially those with uncertainties in either system modeling or excitation. The scientific committee, appointed by the Bureau of IUTAM, includes the following members: F. L. Chernousko, Moscow, Russia E. Kreuzer, Hamburg, Germany (Co-Chairman) H. Y. Hu, Nanjing, China (Chairman) A. H. Nayfeh, Blacksburg, USA G. Rega, Rome, Italy W. Schiehlen, Stuttgart, Germany (IUTAM representative) K. Sobczyk, Warsaw, Poland G. Stepan, Budapest, Hungary H. Troger, Wien, Austria ix x Preface

The time delays in controllers and actuators can either deteriorate or improve the dynamic performance of a controlled mechanical system. Thus, it is desirable to gain an insight into the effect of time delays on the dynamics of a practical system in its design phase. This monograph represents the recent advances in system modeling, analysis of stability, robust stability and bifurcation by using some new mathematical tools such as generalized Sturm criterion and Dixon's resultant elimination of polynomials. The theoretical results are demonstrated through a number of examples of active vehicle chassis, structure control, as well as the control of chaos of mechanical systems.

The time delays in controllers and actuators can either deteriorate or improve the dynamic performance of a controlled mechanical system. Thus, it is desirable to gain an insight into the effect of time delays on the dynamics of a practical system in its design phase. This monograph represents the recent advances in system modeling, analysis of stability, robust stability and bifurcation by using some new mathematical tools such as generalized Sturm criterion and Dixon's resultant elimination of polynomials. The theoretical results are demonstrated through a number of examples of active vehicle chassis, structure control, as well as the control of chaos of mechanical systems.

Recent years have witnessed a rapid development of active control of various mechanical systems. With increasingly strict requirements for control speed and system performance, the unavoidable time delays in both controllers and actuators have become a serious problem. For instance, all digital controllers, analogue anti­ aliasing and reconstruction filters exhibit a certain time delay during operation, and the hydraulic actuators and human being interaction usually show even more significant time delays. These time delays, albeit very short in most cases, often deteriorate the control performance or even cause the instability of the system, be­ cause the actuators may feed energy at the moment when the system does not need it. Thus, the effect of time delays on the system performance has drawn much at­ tention in the design of robots, active vehicle suspensions, active tendons for tall buildings, as well as the controlled vibro-impact systems. On the other hand, the properly designed delay control may improve the performance of dynamic sys­ tems. For instance, the delayed state feedback has found its applications to the design of dynamic absorbers, the linearization of nonlinear systems, the control of chaotic oscillators, etc. Most controlled mechanical systems with time delays can be modeled as the dynamic systems described by a set of ordinary differential equations with time delays.