Product quality adaptive control system for a food extruder /
Automatic twin screw extruder (TSE) control was implemented
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| Format: | Thesis Book |
| Language: | English |
| Published: |
[Place of publication not identified] :
[publisher not identified] ;
1995.
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| Subjects: | |
| Online Access: | Link to OAKTrust copy http://proxy.library.tamu.edu/login?url=http://proquest.umi.com/pqdweb?did=742163891&sid=1&Fmt=2&clientId=2945&RQT=309&VName=PQD |
| Summary: | Automatic twin screw extruder (TSE) control was implemented comparing both fixed and adaptive controllers on an APV-MPF50 TSE. Product quality attributes (PQA) were controlled using MIMO and MISO based GPC algorithms. Vision system parameters along with sensory data were correlated off-line with the PQA in search for potential control candidates. The initial system analysis and parameter correlations used steady state analysis of an RSM experimental design. Dynamic response analyses utilized both step response and pseudo random signal experiments. An on-line food-grade RTD method was illustrated using calorimetric technique. Stochastic X, ARX, and ARMAX models were developed. Model predictive controllers were developed along GPC guidelines and extended to include combination GPC-SPC methods. Models and controllers were simulated using actual process noise and implemented on-line to compare performance. Tracking performance was compared using step changes in setpoints. The reaction to typical uncontrolled disturbances was also evaluated by using corn meal of different granulation and moisture content, barrel temperature setpoint changes, and simulating screw wear via die resistance change. In all cases, all controllers performed the desired control function. The combination of SPC and GPC control principles provided the smoothest responses to regulation and tracking requests by eliminating response to noise. Adaptive control with open loop estimation improved performance slightly over the fixed ARX controller. The adaptive algorithm combined with SPC logic and supervisory logic offers the best alternative for automatic TSE extruder control. Finally, an attempt to increase the degrees of freedom for control was researched on a second extruder (Wenger TX-52 TSE). A choke valve was introduced in the die neck to explore the relationship between total die resistance and PQA. In this set of experiments, the uncontrolled disturbance was screw wear (simulated by cone screw set back). The data indicated that valve adjustment could be used successfully for compensation of screw wear and as a fine tuning control option for adjustment of work input. In this part of the research, automatic control was not implemented since the valve used was manual. |
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| Item Description: | Vita. "Major Subject: Agricultural Engineering". |
| Physical Description: | xvii, 333 leaves : illustrations ; 28 cm. Issued also on microfiche from University Microfilms Inc. |
| Bibliography: | Includes bibliographical references. |