Regelung dynamischer Systeme mit stochastischer Zeitverzögerung durch ein Kommunikationsnetzwerk

Communication networks are commonly used in the automation technology for the wiring of large plant. Special designed bus systems are generally used which support a real-time capability and are usable for control purposes of dynamic systems. Actuators, sensors and control units can directly be connected by such bus systems. The integration of communication-networks for large machines is in general cheaper, reduces weight and power, easier to install and maintain and has a higher reliability in comparison to classical point-to-point connections. The bus system can be shared by different applications of such connected plants. The largest cross-linked network itself is the internet. Existing networks like the internet are used for large distance connections, because the installation of special networks might be too expensive, e.g. a transatlantic connection.

The increased data transfer rate and reaction time of communication networks enables remote control of plants through the internet. The industry shows an increasing usage of control applications through communication networks. Sensors and actuators with TCP/IP interfaces were developed, to directly integrate it into networks. By using the internet, the infrastructure is in general already available and no additional installation is necessary. But it has to be considered, that the real-time performance with control through the internet is bad and stochastical time delays appear. These delays could result in unwanted system behaviour and must be considered in the controller design.

When controlling a dynamical system over the internet it must be distinguished whether the data network is integrated in the control loop, or if it is only used for a remote system start with the possibility of editing control parameters (e.g. the desired value or some controller gain-values) where the control loop itself runs locally. If only a local control loop exists, no delay problems occur by using the network. But if the internet is integrated in the control loop, stochastical time delays appear through the network connection.

New controller designs are neccesarry for a stable control of dynamical systems with stochastically varying time delays in the control loop. The following work points out different approaches for the design of controllers for input delay systems with stochastically varying time delays. Static and adaptive control laws are considered in the further work.