5.1.   INTRODUCTION

Complex dynamic systems such as aircraft, power systems, and telecommunications
networks present major challenges to control systems designers. Both
the military and civilian sectors of our economy are demanding new and
highly sophisticated capabilities from these systems that traditional controls
technology is not offering. Among these capabilities are the following:

• Adaptability/Dynamic Reconfigurability. Large-scale engineered systems
  must have the ability to quickly and gracefully react to a changing
  environment or to changes in their own configuration without compromising
  their operational integrity. Extreme performance dynamic
  systems must be able to support online switching of algorithmic components
  and rapid redirection of the interconnections among them, as well
  as changing the priorities at which information is flowing. This ability is
  particularly useful for hybrid control systems.
• Plug-and-Play Extensibility. New advances are continually being made in
  control algorithm design, communications and sensor technology, and
  high-performance hardware platforms. To take full advantage of these
  innovations as they become available, we must be able to insert new
  technology into the system architecture without redesigning the components
  already in the system.
• Interoperability. Today’s control systems operate in distributed, heterogeneous
  environments; that is, the software components may be running on
  different processors, using different programming languages, hardware
  platforms, and network protocols, often over wireless links. Real-time
  communication must be provided among these distributed components
  while satisfying stringent constraints on bandwidth, response time, and
  reliability.
• Openness. Reconfigurability and component interchangeability require
  software architectures that are flexible and that support tools and
  algorithms from a variety of sources and domains. This requires a shift
  away from traditional control system implementation, which tends to be
  built with a particular application in mind and which makes rigid,
  limiting assumptions about the types of technology that will be used.
  The development of control systems across applications involves much
  duplication of effort; there are tremendous opportunities for reuse that
  are currently not being exploited. A shift to open architectures is
  essential for addressing this problem.