Performance comparison of different Smith Predictor controller structures

Öz

Industrial processes have significant time delays due to their long-time constants and the inclusion of integrators. This can lead to undesirable conditions such as high overshoot, oscillation, and instability. The Smith Predictor, developed by O. J. M. Smith, is an effective controller structure for controlling processes with time delays. This study compares the performance of four different Smith Predictor structures previously presented in the literature. To ensure the comparisons are objective, the controller parameters for all predictor models were determined using a Genetic Algorithm (GA)-based optimization method under the same optimization settings. Three different long-time-delay systems were considered in the study: the first is a fourth-order system with no roots at the origin, the second is a fifth-order system with one root at the origin and the others discrete, and the third is a second-order, two-pole system containing a pole at the origin. Based on the findings, the Smith Predictor structure was determined to offer the best control performance among the four structures examined for time-delay systems.

Anahtar Kelimeler

• Smith predictictor
• time-delay systems
• genetic algorithm optimization

Farklı Smith Öngörücü kontrolör yapılarının performans karşılaştırması

Öz

Endüstriyel süreçler, geniş zaman sabiteleri ve entegratör içermeleri nedeniyle ciddi zaman gecikmesine sahiptirler. Bu ise yüksek aşım oranı, salınım ve kararsızlık gibi istenmeyen durumları ortaya çıkarabilmektedir. O. J. M. Smith tarafından geliştirilen Smith Öngörücüsü, zaman gecikmesi içeren proseslerin kontrolünde etkili bir kontrolör yapısıdır. Bu çalışmada, daha önce literatürde sunulmuş dört farklı Smith Öngörücüsü yapısının performansları karşılaştırılmaktadır. Karşılaştırmaların nesnel olabilmesi için tüm öngörücü modellerinde kontrolör parametreleri, Genetik Algoritma (GA) temelli optimizasyon yöntemi ile aynı optimizasyon ayarları altında belirlenmiştir. Çalışmada üç farklı uzun zaman gecikmeli sistem dikkate alınmıştır: İlkinde dördüncü dereceden ve orijinde kök bulundurmayan bir sistem, ikincisinde beşinci dereceden, bir kökü orijinde ve diğerleri ayrık olan bir sistem, üçüncüsünde ise ikinci dereceden, orijinde bir kutup içeren iki kutuplu bir sistem ele alınmaktadır. Elde edilen bulgular ile zaman gecikmeli sistemler için incelenen dört yapıdan en iyi kontrol performansını sunan Smith Öngörücüsü yapısı belirlenmiştir.

Anahtar Kelimeler

• Smith öngörücü
• zaman gecikmeli sistemler
• genetik algoritma optimizasyonu

Kaynakça

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