London Lecture David Clarke Prof. Research into validation at Oxford was inspired by a 'successful' experiment in the self-tuning control of a large chemical batch reactor that went wrong. An undetected fault led to near-disaster and major loss of production.
Economic considerations dictate a layered approach to the problem.
A SEVA device does not simply detect internal faults but attempts, where possible, to correct their effect on the transmitted data. Examples of flow, dissolved-oxygen, and temperature sensors show how Oxford's SEVA devices handle faults. It is shown how a PI loop can respond to degraded sensor data and how the measurement of an auxiliary variable can smoothly and optimally take over plant control when the primary sensor starts to fail. Moreover MPC enables the reconfiguration of control loops based on detected instrument faults. The interplay of SEVA, MPC and control theory is discussed to demonstrate that it is the interaction between layers of the control hierarchy that offers the greatest potential benefit.