CHEN 4601 Lecture 42: 2015_11_13 Lecture

• School: UMN
• Department: Chemical Engineering
• Course: CHEN 4601
• Professor: Prodromos Daoutidious

Document Summary

Recall the main idea: disturbances set point controller process output. Change the input to counter this effect (act before they affect the output) Key requirement: all disturbances are measurable, the model predicting their effect is perfect. Disturbances that cannot be measured on-line (enzyme concentrations, moisture, impurities, ) Disturbances that cannot be included in a model (ex: valve sticking, pump failure) All models are idealizations of reality --> there is always modeling error. -> feedforward and feedback are used together (can"t only rely on feedforwardfeedback gives robustness) -> today: focus on feedforward problem; monday: focus on feedforward/feedback. Feedforward controller final control element process output variable manipulated input. Chen4601_processcontrol page 1 can turn this into block diagram. Gff minus b/c trying to counter effects of signal. In what follows, i will focus on this forming, dropping the primes. Next: gff, gsp = ? to have i) stability ii) zero offset iii) ise optimality: stability --> gff, gsp need to be stable.