Automatic system components

We now use the term automation for specific techniques combined to operate automatically in a complete system. These techniques are possible because of electronic devices, most of which have come into use in the last thirty years. They include program, action, sensing or feedback, decision, and control elements as components of a complete system.

The program elements determine what the system does and the step-by-step manner in which it works to produce the desired result. A program is a step-by-step sequence that breaks a task into its individual parts. Some steps in an industrial automation program direct other parts of the system when and how to carry out their jobs.

The action elements are those which do the actual work. They may carry or convey materials to specific places at specific times or they may perform operations on the materials. The term mechanical handling device is also used for the action elements.

Perhaps the most important part of an automated system is sensing or feedback. Sensing devices automatically check on parts of the manufacturing process such as the thickness of a sheet of steel or paper. This is called feedback because the instruments return or feed back this information to the central system control.

The decision element is used to compare what is going on in the system with what should be going on; it receives information from the sensing devices and makes decisions necessary to maintain the system correctly. If some action is necessary the decision element can give instructions or commands to the system.

The control element consists o f devices to carry out the commands of the decision element. They may be many kinds of devices: valves that open or close, switches that control the flow of electricity, or regulators that change the voltage in various machines; they make the necessary corrections or adjustments to keep the system in conform­ity with its program.

VIII. Прочтите еще раз текст и письменно ответьте на во­просы.

1. What are some elements of an automated system? What makes them possible?

2. What is a program? What does it do in an automated system?

3. Name two terms used to describe the elements which do the actual work.

4. What are some jobs these elements may do?

5. What are some of the things sensing devices do?

6. How do sensing devices act on the information they receive?

7. What is the func­tion of the decision element? What can it do?

8. What does the control element consist of? What can these devices do? What is their purpose?

Вариант 4

I. Перепишите следующие предложения, определите в каждом из них видовременную форму и залог глагола ска­зуемого. Переведите предложения на русский язык.

1. She sat still as a statue while he was playing the sonata.

2. They came to Europe where their mother had been educated and stayed three years.

3. Probably she knew that whatever happened she would not give her away.

4. Then my attention was caught by the noise coming from behind the fence.

5. She almost felt that she was being mocked at.

II. Перепишите следующие предложения и переведите их, учитывая разные значения слов "it, that, one, as, for. "

1. One must choose a profession one likes.

2. It is a book for and about children.

3. As you have worked all night, you must have a rest.

4. This poem is not so good as that written by you last year.

5. You must close the window for it is rather cold.