TEXT 2B. Examples of Modern Control Systems

Feedback control is a fundamental fact of modern industry and so­ciety. Driving an automobile is a pleasant task when the auto responds rapidly to the driver's commands. Many cars have power steering and brakes, which utilize hydraulic amplifiers for amplification of the force to the brakes or the steering wheel. The desired course is compared with a measurement of the actual course in order to generate a measure of the error. This measurement is obtained by visual and tactile (body movement) feedback. There is an additional feedback from the feel of the steering wheel by the hand (sensor). This feedback system is a fa­miliar version of the steering control system in an ocean liner or the flight controls in a large airplane. All these systems operate in a closed-loop sequence. The actual and the desired outputs are compared, and a measure of the difference is used to drive the power amplifier. The power amplifier causes the actuator to modulate the process in order to reduce tie error. The sequence is such that if the ship, for instance, is heading incorrectly to the right, the rudder is actuated in order to direct the ship to the left. If the output is subtracted from the input and the difference is used as the input signal to the power amplifier the system is called negative feedback control system. Feedback systems are not always negative feedback systems in nature. Economic inflation, which is evidenced by continually rising prices, is a positive feedback system.

 

A positive feedback control system adds the feedback signal to the in­put signal, and the resulting signal is used as the input to the process.

Other familiar control systems have the same basic elements. A re­frigerator has a temperature setting or desired temperature, a thermostat to measure the actual temperature and the error, and a compressor mo­tor for power amplification. Other examples in the home are the oven, the furnace and the water heater. In industry, there are speed controls, process temperature and pressure controls, position, thickness, compo­sition, and quality controls among many others.

Automation is often used for processes that were previously ope­rated by humans. When automated, the process can operate without human assistance or interference. In fact, most automated systems are capable of performing their functions with greater accuracy and preci­sion, and in less time, than humans are able to do.

TASK 13. Read and translate the following text and ask questions be­ginning "What...?", "How...?", "Where...?", "In what way...?", "Whatfor...?", "When...?"

A robot is a computer controlled machine and is a technology closely associated with automation. Industrial robotics can be defined as a particular field of automation in which the automated machine (i.e. the robot) is designed to substitute for human labour. To do this, robots possess certain human-like characteristics. Today, the most common human-like characteristic is a mechanical manipulator that is patterned somewhat after the human arm and wrist. We recognize that the auto­matic machine is well suited to some tasks, while often tasks are best carried out by humans.

Fig. 1. The work of a manual control system for regulating the level of fluid 18

TASK 14. Describe the work of a manual control system for regulating the level of fluid using Fig. 1.

TASK 15. Compose sentences with some of the words from the text "Examples of Modern Control Systems " and exchange your notebooks with your group-mates for further translation:

to obtain, to be familiar with, to compare, to cause, to reduce, human assistance, to be capable of, accuracy and precision.

TASK 16. React to the following statements and questions using the verb "to obtain ". Mind: "to obtain " means to get something by making effort (to obtain data, evidence, information, knowledge, result, de­gree). Example: - You obtained valuable information, didn't you?

- Yes, I'm glad to tell you, I succeeded in obtaining impor­tant information.

1. I hear you obtained some convincing experimental evidence to prove your hypothesis.

2. When did you obtain your degree?

3.1 suppose you obtained a lot of experience through your work. 4.1 hope the results obtained by you will help you to proceed with your work.

TASK 17. Translate the sentences using the verbs "to advise" or "to consult". Mind: you consult your scientific adviser; he advises some­thing to you.

1. Я должен посоветоваться со своим руководителем.

2. Кто посоветовал вам использовать этот метод?

3. Мой руководитель советовал мне использовать другой под­ход к решению этой проблемы.

4. Они не советовались со мной.

5. Я советую вам проверить свои данные еще раз.

TASK 18. Speak about feedback control, the desired course of an automobile, closed-loop sequence, a thermostat, water heater, indus­trial robotics, beginning with the introductory phrases: further study proves, careful research demonstrates, thorough study confirms, extensive investigations make it clear, numerous experiments suggest, detailed analysis shows.

TASK 19. Be ready to speak about any example of a modern control system.

 

TASK 20. Translate the text without a dictionary.

TEXT 2C. Automation

Automation is automatic operation and control of machinery or pro­cesses by devices, such as robots that can make and execute decisions without human intervention. The principal feature of such devices is their use of self-correcting control systems that employ feedback, i.e., they use part of their output to control their input. Once the automated process is set up, human participation in the manufacturing process in­volves little more than maintenance and repair of the equipment. In a typical automated manufacturing process, the feeding in of materials, the machine operation, the transfers from one machine to another, the final assembly, the removal, and the packing are all done automatically. In some automated manufacturing, a single robot with interchangeable tool heads performs all of the various manufacturing assignments. At various stages in the operation are inspection devices that reject sub­standard products and adjust the machinery to correct any malfunction. Since electronic computers are able to store, select, record, and present data systematically, they are widely used to direct automated systems. Automation is applied in industry to the manufacture of foodstuffs, chemicals, pharmaceuticals, and electronic equipment, and is used in steel mills, automobile plants, and coal mines. Another application is its use in the launching, aiming, and guidance of military rockets. Auto­mation has also been applied to information handling, resulting in automatically prepared bills and reports and the solution of many engi­neering problems. It offers high quality products together with great savings in costs.

A minute for rest

Originality Original thought

is a straightforward process. It's easy enough

when you know what to do. You simply combine

in appropriate doses the blatantly false

and the perfectly true.

Thrift Nobody can be lucky all the time; so when your luck deserts you in some fashion don't think you've been abandoned in your prime but rather that you are saving up your ration.

Essential Vocabulary

adaptive system - адаптивная система

add v - прибавлять, складывать

arouse v - вызывать, возбуждать

automation n - автоматизация

bituminous adj - битумный, битуминозный

control engineering - техника автоматического управления

determine v - определять

displacement n - вытеснение

easing n - облегчение, ослабление

error n - ошибка; отклонение от заданной величины

excitement п - возбуждение; интерес

expenditures п - затраты

gain п - рост, увеличение; коэффициент усиления

goal-oriented system - целевая система

inaugurate v - начинать, открывать

inflationary cost - инфляционная цена

information processing - обработка информации

labour productivity - производительность труда

learning system - обучающаяся система

lignite n - лигнит, бурый уголь

malfunction п - неисправная работа; неправильное срабатывание

momentous adj - имеющий важное значение

offset v - возмещать, компенсировать

расе п - скорость, темп

reduce v - уменьшать, сокращать

refer to v - отсылать к; ссылаться на; упоминать о

respond v - отвечать, соответствовать

robust system - робастная/устойчивая система

self-correcting system - самокорректирующаяся система

 

 

 

 

self-organizing system - самоорганизующаяся система

specified tolerance - заданный допуск

stable adj - устойчивый

subtract v — вычитать

virtually adv - в сущности, фактически

 

UNIT3

TASK 1. Read and translate the text. Be ready to give definitions to such concepts as "design ", "specification ", "tradeoff", "design gap ", "synthesis ".