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- Comparing Feed forward and Feedback Controllers
| Business Systems
by K. Ogata A business system may consist of many groups. Each task assigned to a group will represent a dynamic element of the system. Feedback methods of reporting the accomplishments of each group must be established in such a system for proper operation. The cross-coupling between functional groups must be made a minimum in order to reduce undesirable delay times in the system. The smaller this cross-coupling, the smoother the flow of work signals and materials will be. A business system is a closed-loop system. A good design will reduce the managerial control required. Note that disturbances in this system are the lack of personnel or materials, interruption of communication, human errors, and the like. The establishment of a well-founded estimating system based on statistics is mandatory to proper management. Note that it is a well-known fact that the performance of such a system can be improved by the use of lead time, or anticipation. To apply control theory to improve the performance of such a system, we must represent the dynamic characteristic of the component groups of the system by a relatively simple set of equations. Although it is certainly a difficult problem to derive mathematical representations of the component groups, the application of optimization techniques to business systems significantly improves the performance of the business system. Ogata K. Modern Control Engineering. – 4th Ed. – New Jersey: Prentice Hall, 2002. – 964 p. (P. 5). 16. Translate the text and speak about feed forward and feedback controllers: Comparing Feed forward and Feedback Controllers by David M. Koenig The feed forward controller can act on a measured event (such as the drain value position) before it shows up as a disturbance in the process output (such as the tank level). Unfortunately, the feed forward controller has no idea how well it did. Furthermore, it is often rather difficult to measure the disturbance-causing event. Sometimes there will be many disturbance-causing events, some of which cannot be measured. Also, it is not always clear how the algorithm should react to the measured disturbance-causing event. Often, each feed forward control algorithm is a special custom application. Finally, if perchance, the feed forward control algorithm acts mistakenly on a perceived disturbance-causing event it can actually generate a more severe disturbance. The feedback controller cannot anticipate the disturbance. It can only react “after the damage has been done.” If the disturbance is relatively constant there may be a good chance that the feedback controller can slowly compensate for it and perhaps even remove it. As we will show in the next couple of pages, there are some disturbances that simply should be left alone. The feedback controller can tell how well it has been done and it can often react appropriately. Unlike the case with feed forward control algorithms, there are a few well-known, easily applied feedback control algorithms that, under appropriate conditions can deal quite effectively with disturbances. Koenig D. Practical Control Engineering: Guide for Engineers, Managers, and Practitioners. – McGraw-Hill, 2009. – 538 p. (P. 7-8). 17. Translate the text in the written form: жүктеу/скачать 464,87 Kb. Достарыңызбен бөлісу:
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