The Simplex architecture for safe online control system upgrades

We describe the Simplex architecture, a real-time software technology which supports the safe, reliable introduction of control system upgrades while the system is running. We introduce its basic structure in control systems, discuss its fault-tolerance feature, and investigate the control issues when the technology is employed. Application of the Simplex architecture is demonstrated for a plasma-enhanced chemical vapor deposition (PECVD) system, a standard process in semiconductor manufacturing. We conclude the paper with a discussion of the potential impact that the Simplex architecture can make on future control applications.