Experimental evaluation of a fault-tolerant plug-and-play controller

Networked control systems use the network connection to exchange data and signals. In plug-and-play control the communication of control algorithms and system models over a shared network is concerned with the intention to adjust control laws automatically after the occurrence of changes in the plant structure or in the control objectives. An application scenario is the break down of a sensor or an actuator as studied in fault-tolerant control. This paper investigates such a situation in the sense of plug-and-play control. The diagnostic task and reconfiguration task are separated and assigned to predestined computational units: an onboard unit allocated at the plant with access to the plant signal and a remote off-board unit concerning the expensive computation. The onboard diagnostic unit detects and identifies the failure at runtime and transmits the model of the faulty plant to the offboard reconfiguration unit over a shared network. Using the reconfiguration strategy of the virtual sensor and virtual actuator the reconfigured controller is automatically designed and transmitted to the control station to replace the original control algorithm. In the whole sequence no human interaction is necessary. The main contributions of this paper are the combination of a diagnosis method and a reconfiguration method to perform a completely automated sequence, the implementation of this concept and the evaluation by experiments on a thermal fluid process.