Time delayed systems,

cooperative control,

infinite delayed systems,

nonlinear systems and control,

control of partial differential equations (PDEs),

traffic control,

multi-agent reinforcement learning

In the past years, I have been working on control and coordination of time-delayed systems. In particular, I spent much time in studying control and coordination of infinite-delayed systems. The following difficulties have been solved based on my research:

1. Developing novel and general Lyapunov theorems for nonlinear systems with infinite delays;
2. Designing low-gain based and predictor-based controllers for global and semi-global stabilization of linear systems with infinite input delays;
3. Designing controllers for cooperative control of multi-agent systems with bounded and/or infinite transmission delays.

Based on these studies, I have published 13 first-authored SCI papers, 10 of which were published in IEEE Transactions on Automatic Control and Automatica (including 4 regular papers). In 2018, my work “Consensus of linear multi-agent systems with distributed infinite transmission delays: A low gain method” entered the short list of Guan Zhao-Zhi Award (best paper award of Chinese Control Conference) in that year. My PhD thesis was awarded Outstanding Thesis Award by City University of Hong Kong. I have also been instructing other PhD students on their research in time-delayed systems. All of them have published papers in good journals of control theories, such as IEEE Transactions on Automatic Control, Automatica and IEEE Transactions on Cybernetics (including 2 TAC papers and 2 Automatica papers). I am the second author of these SCI papers.

Moreover, based on my research, my PhD supervisor and Postdoc employer Prof. FENG Gang has successfully applied two research funding with more than 1.7million HKD supported by Hong Kong Government, whose titles are given as follows:

1. Cooperative control of networked multiple dynamical systems with unbounded transmission delays and its application;
2. Distributed cooperative control of networked multiple dynamic systems with time delays and its application.

Time-delayed system has been a popular research topic of control community in the past decades with many significant results obtained. In practical systems, time delays are inherent feature and often leads to poor performance and instability. To deal with time-delayed systems, many tools and methods have been developed. However, most of these results only focus on bounded delays while infinite delays or unbounded delays are rarely considered. In practical systems, there are many scenarios where infinite delays exist or modeling of such infinite delays is needed. Typical examples include systems in the fields of biology, mechanics, social science, networked control and so on. In the 1970s, several mathematicians developed theories of functional differential equations with infinite delays. These theories covered the existence, uniqueness, continuation and continuous dependence of solutions. However, control of systems with infinite delays is still rarely considered. This is mainly because at least three challenges exist when we consider infinite-delayed systems. First, tools for the analysis and synthesis of infinite delay systems are very limited. Second, solutions to infinite delay systems are sensitive to initial conditions. Third, as no bound is available for scaling the integrals relevant to infinite delay, the analysis and synthesis of infinite delay systems are inevitably complicated and challenging. To address these challenges, we propose novel and more general Lyapunov theorems, develop new controllers and use more advanced techniques. Our works on infinite-delayed systems have greatly extended the existing theoretic results on control of time delays. And new theories, new methods and new techniques are proposed.