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CONTROL SYSTEMS | ||||||||||
V. Ryan © 2003 - 2009 | ||||||||||
PDF FILE - CLICK HERE FOR PRINTABLE WORKSHEET BASED ON EXERCISE BELOW (CLOSED SYSTEMS) | ||||||||||
CLOSED SYSTEMS: When designing a control system it is good practice to consider it as a
number of stages. For example; |
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The temperature is constantly monitored and this is called feedback. As long as the sensor works, the computer processes and the printer prints out - feed back is taking place. | ||||||||||
OPEN SYSTEMS | ||||||||||
PDF FILE - CLICK HERE FOR PRINTABLE WORKSHEET BASED ON OPEN SYSTEMS | ||||||||||
A system that does not have feedback is an open
system. An open system normally works once and then stops. A good
example is seen below. A digital camera is used to take a photograph, it
is transferred to the computer where processing of the picture takes
place and finally a printout is produced. This is a closed system
because there is no feedback and no attempt is made to improve the
picture. The person taking the picture decides to improve the final printout, using graphics software. He prints out the photograph several times and alters the photo with the software. Is the system still an open system or has it now changed to a closed system with feedback? |
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When drawing a systems diagram the boxes are labelled and there is no need to draw pictures representing each stage. However, when attempting course work, adding drawings helps present the diagram in a more graphical way. The open systems diagram shown below represents use of a digital camera which is shown graphically above. | ||||||||||
QUESTION: | ||||||||||
Draw a systems diagrams to represent a closed system of your choice and an open system. | ||||||||||
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