Fault Isolation in Object Oriented Control Systems

This article addresses the problem of fault propagation between software modules in a large-scale control system with object oriented architecture. There exists a conflict between object-oriented design goals such as encapsulation and modularity, and the possibility to suppress propagating error conditions. The propagation manifests itself as many irrelevant error messages, and hence causes problems for system operators and service personnel when attempting to isolate the real fault. We propose a fault isolation scheme aimed at achieving clear and concise fault information to the operator without violating encapsulation and modularity. The approach is implemented and tested on a commercial industrial robot control system from ABB Robotics and a patent application has been filed with the swedish patent office (PRV)