2,312 publications from this institution
A novel distributed consensus protocol, where only causal sampled position data are used, is firstly designed for second-order linear multi-agent systems with a directed communication topology. In this context, a necessary and sufficient condition depending upon the coupling gains, sampling period, and spectrum of the Laplacian matrix, is established for achieving consensus. It is revealed that second-order consensus in such a multi-agent system cannot be reached without using past sampled position data. It is also found that a relatively small sampling period does not necessarily improve the consensus performance. Then, a delay-induced consensus protocol is proposed based on sampled position data and with the help of time delay. It is found that consensus under this designed protocol cannot be reached in the absence of time delay. More interestingly, the time delay should have both lower and upper bounds in order to achieve consensus. Finally, the effectiveness of the theoretical results is demonstrated through numerical simulations.
This chapter reviews various types of conventional and fuzzy proportional-integral-derivative (PID) controllers, and their new developments in achieving autotuning—adaptive and robust capabilities. The chapter emphasizes two types of PID controllers: fuzzy PID controllers and conventional PID controllers. Both these controllers are not exactly comparable—in fact, it is generally impossible to have exactly the same conditions for a fair comparison of these controllers. As long as the fuzzy PID controllers work for some control problems for some systems that the conventional ones can't work out or don't work out so well, they have their own merits. Comparisons are actually difficult: fuzzy PID controllers have been developed for only five years or so and hence are certainly not as mature as the conventional ones that have a more than fifty-year history. There are still many drawbacks, weak-points, and technical problems inherent with various fuzzy PID-type of controllers, which is the very challenge that calls for further effort and endeavor from the research and engineering communities.
