Mobile Agent-Based Remote Monitoring and Maintenance of Process Controller Performance

Abstract

C ontroller performance usually refers to how well a controller and the process it controls work together in a single loop. This topic is of importance to companies wishing to gain a competitive edge. This might be surprising in the light of the fact that controllers can normally provide healthful performance at a limited operating range; 80% of loops have performance problems and feedback controllers perform far less than optimally 1 . Although use of advanced model control is now widespread, Proportional-Integral-Derivative (PID) controllers are by far dominant feedback control algorithms. It's fair to say that with the amount of research effort put into control theories in the past decades, such as techniques about designing and commissioning, controllers are matured enough to handle these simple linear controllers. Therefore, what is lacking is the monitoring and maintenance of the controller after commissioning in order to keep the controller in an optimal state.There are outstanding benefits for monitoring and maintaining controller performance over the Internet: G Operators or managers can remotely monitor and adjust the plants and controllers in order to adapt to the quick change of markets; G Skilled plant managers situated in geographically diverse locations can collaborate to perform control tasks; G The software providers can remotely maintain and update their geographically distributed software products.Mobile agents are computer programs, consisting of both code and data that are able to migrate autonomously from node to node to perform computations on behalf of the user 2 . Mobile agents are beginning to be implemented into the remote monitoring and maintenance operations and have resulted in small-scale demonstrations and applications 3,4,5 . Yu et al 3 established a Problem-Oriented Multi-Agent-Based E-Service System to provide rapidly responsive services for industrial processes. Jezic et al 4 proposed a Remote Maintenance Shell (RMS) for software management in large distributed environments, which is based on the remote operations performed by cooperative mobile agents. Lovrek et al 5 developed an agent based software maintenance application. It allows software installation, modification and verification on the remote target system without suspending its regular operation.This paper investigates the integration of the mobile agent technology and the monitoring and maintenance of controller performance. A multi-agent based monitoring and maintenance system is proposed, which allows distributed access, parallel computing, remotely monitoring and maintaining the performance of geographically distributed controllers. An industrial catalytic reactor simulator with a PID controller is used as a case study to illustrate the proposed mobile agent application.The rest of this paper is organised as follows. A brief introduction to the methodology of monitoring and maintaining controller performance is given first and immediately followed by the description of the mobile agent based system. A case study i...