Feedforward hybrid control using foundation fieldbus: A case study of temperature control with DeltaV system

With Foundation Fieldbus (FF) technology, a control strategy can incorporate function blocks running in both host controller and field devices, which is known as hybrid control. This paper focuses on implementation of feedforward hybrid control by utilizing basic function blocks in H1 field devices and advanced function block in host controller to provide a guideline for detailed design to specify of the FF philosophy to be used in a greenfield or brownfield project for maximizing end user achievement. A laboratory-scale FF H1 segment configured and operated on the DeltaV host system for feedforward on temperature control is used as an illustrative case study to analyze three different configurations by assigning control function block into different field devices in terms of the network load for scheduled communications during segment macrocycle. Experimental results obtained from the preferred control loop with minimum scheduled traffic load verify that an improvement in disturbance response can be achieved. Using control block in field device for FF-based hybrid architecture can, therefore, be applied for creating the feedforward control with disturbance anticipation capability.