研究会 (2004 年 11 月 24 日)

日時: 11/24(水) 14:00〜17:00

場所: 九州工業大学天神サテライトキャンパス Kyutech プラザ
      http://www.ims.co.jp/shop/shop/11_04.html
      http://www.kyutech.ac.jp/plaza/

講演 1. Network Based Control Systems
        (Professor Tongwen Chen, University of Alberta, Edmonton, Canada)
     2. State-dependent scaling: a novel avenue to stability
        of nonlinear interconnected systems
        (Professor Hiroshi Ito, Kyushu Institute of Technology)

懇親会: TRATTORIA HANASAKI (17:30〜19:30, アクロス B2F)

参加者: Prof. Chen, 松尾(大分大), 佐藤(佐賀大),
            延山, 伊藤，市原，R.Sakthivel(伊藤研 PD), 瀬部(以上九工大)



講演概要:
1. Network Based Control Systems
        With the explosive growth in computing and networking technology, there has
        been an increasing reliance on distributed computing and process operations
        based on computer networks. As an example, the process industry is moving
        towards sensor and control systems that are accessed over networks rather
        than hardwired. In a network distributed control system, the system
        elements such as actuators, sensors, and controllers are typically spatially
        isolated from one another, operating in an asynchronous manner, and
        communicating over a wide area via both wired and wireless links. Such
        distributed digital control systems present new challenges for control
        engineers and designers because of the interactions between control and
        communication components; network imposed constraints such as
        communication delays, packet dropout, and limited bandwidth must be
        considered in control analysis and synthesis.
        In this talk, we will examine issues in networked control systems (NCS),
        survey briefly existing research results, discuss our new research on
        system identification with packet dropout (data loss) and stability analysis
        of an NCS with a simple data transmission strategy, and finally, outline
        some future research in this area.

2. State-dependent scaling: a novel avenue to stability of nonlinear
   interconnected systems
        The problems of global stability and performance of nonlinear
        interconnected systems are addressed in this talk. The state-dependent
        scaling problem is introduced as a unified mathematical formulation
        whose solutions explicitly provide Lyapunov functions proving
        stability and dissipative properties of feedback and cascade nonlinear
        systems. The purpose is to establish stability of systems having more
        general and stronger nonlinearity than systems covered by existing
        classical and modern stability criteria such as the L_2 small-gain
        theorem, the passivity theorems, the circle and Popov criteria and the
        input-to-state stable(ISS) small-gain theorem. A unique idea of
        ``state-dependent scaling of supply rates'' is introduced for
        achieving this goal. The talk explains not only the formal applicability to
        general systems, but also demonstrates the effectiveness and practical
        usefulness in establishing stability involving nonlinearities stronger
        than systems covered by existing stability theorems. Another advantage
        of the state-dependent scaling approach is that popular classical
        stability criteria and the ISS small-gain theorem can be extracted
        from a single stability criterion as special cases.