A Soft Sensor for Viscosity Control of Polymer Extrusion

Marion McAfee, Stephen Thompson

Research output: Chapter in Book/Report/Conference proceedingConference contribution

4 Citations (Scopus)


Viscosity represents a key indicator of product quality in polymer extrusion but has traditionally been difficult to measure in-process in real-time. An innovative, yet simple, solution to this problem is proposed by a Prediction-Feedback observer mechanism. A `Prediction' model based on the operating conditions generates an open-loop estimate of the melt viscosity; this estimate is used as an input to a second, `Feedback' model to predict the pressure of the system. The pressure value is compared to the actual measured melt pressure and the error used to correct the viscosity estimate. The Prediction model captures the relationship between the operating conditions and the resulting melt viscosity and as such describes the specific material behavior. The Feedback model on the other hand describes the fundamental physical relationship between viscosity and extruder pressure and is a function of the machine geometry. The resulting system yields viscosity estimates within 1% error, shows excellent disturbance rejection properties and can be directly applied to model-based control. This is of major significance to achieving higher quality and reducing waste and set-up times in the polymer extrusion industry.
Original languageEnglish
Title of host publicationProceedings of the European Control Conference 2007
PublisherInstitute of Electrical and Electronics Engineers (IEEE)
Number of pages8
ISBN (Print)978-3-9524173-8-6
Publication statusPublished - Jul 2007
EventEuropean Control Conference (ECC '07) - Kos, Greece
Duration: 02 Jul 200705 Jul 2007


ConferenceEuropean Control Conference (ECC '07)


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