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In this work the control system for a gravimetric feeder with vibrant duct for polymer extrusion process has been designed. The plant considered in this paper is a blending machine that mixes up to six components: each component is measured by a dedicated vibrant duct. All components are mixed directly in the chambers of the extruder screw. The mass delivered by each meter is measured by a load cell. The control objectives are: accurate mass flow estimate on the basis of the weight; accurate mass flow regulation; minimum settling time; robustness of the controller parameters against the variation of material and structure of meter.

This paper presents a full analysis and development of a system for vibrations reduction in a kitchen hood by using piezoelectric actuators. The control system is based on a feedback controller whose action depends on a single acceleration sensor collocated with the actuator. Two different resonant control laws have been designed: the first one operates without the information of the hood motor velocity; the second one is a more sophisticated controller which exploits also the velocity information. Overall, with the information of the motor velocity the best performances are guaranteed with a reduction of 75% of the vibrations. The resonant control system without the motor velocity information provides the best compromise in terms of performances (65% of reduction) and complexity of the implemented system. Tests held in anechoic chamber have shown the influence of the reduction of vibration upon the acoustic noise.978-1-4244-4602-5/09/$25.00 ©2009 IEEE