Servomechanism, Regulator and Process Control

by S. K. Bhattacharya

 

Servomechanism is an automatic control system in which the controlled variable value is forced to follow the variations of reference value, instead of regulating a variable value to “set point”. Take, for example, an industrial robot arm. It is also called tracking control system.

Regulator is a feedback control system in which controlled variable is maintained at a constant value in spite of external load on the plant. The reference input or command signal although adjustable, is held constant for long period of time. The primary task is then to maintain the output and the desired value in the presence of disturbances. Examples are regulation of steam supply in steam engine by fly-balls governor, thermostat control of home-heating systems, regulation of the voltage of an alternator, frequency controller and speed controller and so on.

Process control refers to control of such parameters as level, flow, pressure, temperature and acidity of process variables. A particular parameter has only one desired value. The control system is required to ensure that the process output is maintained at the desired level in spite of external disturbances which affect the process.

Bhattacharya, S. K. Control Systems Engineering. – Pearson Education India, 2009. – 550 p. (P. 6).

 

8.                Translate the word combinations with Participles:

 

a) Participle I Active and Passive

The receiving station; the following problem; the leading branch of industry; a growing interest; the age of “thinking machines”; the increasing pressure;interacting variables

The engineers discussing the design; the equipment being installed in…; scientists contributing to the development of this theory; magnetic field formingelectromagnetic waves; inventors improving the device; the experiment being carried out; the engineer operating with high frequency modulator; the systemsimproving productivity

When discussing the design…; when using the controllers…; demonstrating the possibility of…; speaking about the law…

Being founded (=when founded) in 2010…; being examined (=while examined)…; being heated (=when heated)…; being supplied (=though supplied)

with the necessary equipment…; the experiment being carried out…

 

 

b) Participle II Passive

The received messages; the transmitted news; the used device; the invented machine; the improved design; the controlled variable; the transmitted binary signal; the desired value

         The polymer found during the experiment…; signals transmitted over very long cables…; the design discussed yesterday…; the model developed the speed; techniques based on…; the effect caused by

          When transported gasses are compressed…; when discussed the design was…; if heated to 100 °C water…; though discovered the mistake had no…

 

c)     Perfect Participle Active and Passive

Having created the theory of…; having made improvements in the device; having transmitted the message they were…; having summed up the information the computer…; having achieved the success

Having been used for a long time the device…; having been repaired the machine operated …; having been tested the motor…

 

9.                Translate into English paying attention to the forms of Participle:

a) Силы, действующие на тело…; компьютеры, выполняющие миллионы операций в секунду…; методы, улучшающие исследовательскую работу…; эксперимент, который  проводится в …; рабочие, устанавливающие новое оборудование…; инженеры, использующие новые достижения…; поверхность, отражающая свет…; увеличивающееся напряжение; метод, который применяется в настоящее время…

Работая над проблемой…/при работе над проблемой…; сравнивая системы…/при сравнении систем…; производя новые конструкции; применяяновые методы; увеличивая скорость; устанавливая новое оборудование /когда они устанавливали новое оборудование…; проводя эксперимент /при проведении эксперимента…/когда они проводили эксперимент…

Так как этот вопрос рассматривается на…; хотя мотор был проверен…; когда новую модель завершат, она будет…; так как это устройствоиспользуется в этом эксперименте, оно будет…; проблемы, которые обсуждаются в настоящее время,…

b) Усовершенствованные механизмы…; полученные результаты…; переданные (передаваемые) сигналы…; хорошо оснащенная лаборатория…

 Результаты, полученные в этом эксперименте…; проблема, решенная успешно…; метод, разработанный этим ученым…; лаборатория,оборудованная новейшей аппаратурой…; материалы, рекомендованные для…

Если воду нагреть до…; как упомянуто выше…; как видно из статьи…; хотя машину и починили…; если мотор не проверен…

 

c) Получив новую информацию…/после того, как они получили новую информацию…; решив важную проблему…/после того, как он решилважную проблему…; сравнив силы, инженер определит…/когда/после того, как инженер сравнит силы, он определит…

После того, как двигатель отремонтировали, он…; после того, как необходимая информация была получена…

 

10.           Translate the following sentences paying attention to the forms and functions of Participles:

a)                     1. While flowing along a conductor the current heats it. 2. Being widely used in industry electrical motors are also used in our everyday life. 3. Cybernetics has developed a concern with a wide range of processes involving people as active organizers, as sharing communicators. 4. The powerful ventilatorsare being turned on, the air is being purified. 5. The installation being used is very efficient. 6. The best results were achieved with electro-ionizing laser devicesoperating on carbon dioxide. 7. Following instructions computing equipment will perform different calculations. 8. These devices working by electronic impulses perform at fantastic speed and with great precision. 9. Electronic systems are spreading widely all over the world.

b)                    1. Each new generation of computers opens up new possibilities for basic and applied research. 2. The experiment carried out resulted in the improvement of all parts of the system. 3. It required some more experiments to prove the precision of the results obtained. 4. The change in scale was measured by a number of transistors on a chip. 5. Though first developed for military purposes radar can be used in modern cars. 6. The transducer attached to each wheel changes the tire pressure accordingly. 7. It is well-known that technological progress is impossible without electronics, computers, robots, and new materials. 8. Electricity has provided mankind with the most efficient source of energy. 9. When required the data will be applied in the practical work.

c)                     1. Having designed a car radar the engineers started complex tests. 2. Having been tested the computer system was installed at a plant. 3. Having been tested under unfavorable conditions the machine was successfully put into operation. 4. Having done a given number of operations the machine stopped automatically. 5. Having been heated the substance changed its properties. 6. Having obtained the necessary data he stopped his work. 6. Having lost some of its electrons the atom becomes positively charged.

 

11.           Translate the sentences paying attention to the Absolute Participle Construction:

1) The conductor having the form of a coil, the inductance increased. 2) The rocket houses automatic and radio-controlled instruments, these instruments receiving any order the Earth may send. 3) Reduced weight and size are particularly important, miniaturization becoming the necessity in order to reach the high speed. 4) A simple component having failed, the whole system was repaired. 5) The true size of the Earth and the true distance to the moon having been calculated, Newton solved the problem of universal gravitation. He discovered the laws of motion, these laws having become the basis of practical mechanics. 6) The reflected signal having been received, the distance to the object was counted. 7) The temperature being increased, the resistivity of the semiconductor decreases.

 

 

12.           Form one sentence of each pair using the Absolute Participle Construction:

1) Man-made satellites move round the Earth. They will help to solve many problems connected with space travel.

2) Radio is the fastest way to detect an artificial satellite. It is largely used for that purpose.

3) Those new devices have already been tested. They received recognition.

4) The energy sources of the world decrease. The scientists must look for new sources of energy.

5) There are many different sources of energy. Coal is the most important of them.

6) Great progress has been achieved in rocket technique. It was possible to construct a rocket overcoming the Earth’s gravitation.

 

13.           Translate into English:

Программи́руемый логи́ческий контро́ллер (ПЛК) (англ.Programmable Logic Controller, PLC) или программируемый контроллер— электронная составляющая промышленного контроллера, специализированного (компьютеризированного) устройства, используемого для автоматизации технологических процессов. В качестве основного режима длительной работы ПЛК, зачастую в неблагоприятных условиях окружающей среды, выступает его автономное использование, без серьёзного обслуживания и практически без вмешательства человека.

Иногда на ПЛК строятся системы числового программного управления станком (ЧПУ, англ. Computer numerical control, CNC).

ПЛК являются устройствами реального времени.

В отличие от:

- микроконтроллера (однокристального компьютера), микросхемы предназначенной для управления электронными устройствами, областью применения ПЛК обычно являются автоматизированные процессы промышленного производства, в контексте производственного предприятия;

-  компьютеров, ПЛК ориентированы на работу с машинами и имеют развитый 'машинный' ввод-вывод сигналов датчиков и исполнительных механизмов в противовес возможностям компьютера, ориентированного на человека (клавиатура, мышь, монитор и т. п.);

- встраиваемых систем— ПЛК изготавливается как самостоятельное изделие, отдельно от управляемого при его помощи оборудования.

Первые логические контроллеры появились в виде шкафов с набором соединённых между собой реле и контактов. Эта схема задавалась жёстко на этапе проектирования и не могла быть изменена далее.

Первый в мире ПЛК— MOdular DIgital CONtroller (Modicon) 084, имеющий память 4 кБ, произведен в 1968 году.

В первых ПЛК, пришедших на замену обычным логическим контроллерам, логика соединений программировалась схемой соединений LD (Ladder logic Diagram). Устройство имело тот же принцип работы, но реле и контакты (кроме входных и выходных) были виртуальными, то есть существовали в виде программы, выполняемой микроконтроллером ПЛК. Современные ПЛК являются «свободно программируемыми».

В системах управления технологическими объектами логические команды преобладают над числовыми операциями, что позволяет при сравнительной простоте микроконтроллера (шины шириной 8 или 16 бит), получить мощные системы действующие в режиме реального времени. В современных ПЛК числовые операции реализуются наравне с логическими. В то же время, в отличие от большинства процессоров компьютеров, в ПЛК обеспечивается доступ к отдельным битам памяти.

 

14.           Play “dominoes”:

Device / steam; cybernetics / management / coneshaped; detector / feedback; engine / outstanding; scientist / important; study / electrical network theory / mechanical; engineering / behavioral; response / powerful; maxim / human; regulator / control; process / computer; hardware / controlled; landing / technical; object / centrifugal; float / self-regulatory; speed governor / moving; vehicles / soft and safe; force the subject; matter / the theory of ; algorithms / transfer; machining / continuous; cycle production / prices; society / automatic; calculation / space; progress / physical; tank / knowledge; variables / reference; input / an error; contribution / interdisciplinary; path elements / magnetic; amplifiers / applied.

 

UNIT FIVE

 

Texts: Sensors and Transducers, Source, Signals, DAQ hardware, DAQ software, Алгоритмы функционирования технологических объектов, управляемыхАСУТП

Grammar: The Gerund

 

1.                Memorize the words:

To convert – преобразовывать

transducer – преобразователь; датчик

strain – напряжение; деформация

gauge – измерительный прибор

voltage – напряжение

DC- direct current – постоянный ток

resistance – сопротивление

capacitance – емкость; емкостное сопротивление

inductance – индуктивность; (само)индукция

thermocouple – термоэлемент, термопара

pressure – давление

in response to – в ответ на

stimulus – стимул; раздражитель

to respond – отвечать; реагировать

unlike- - непохожий на, не такой как

to stand alone – быть выдающимся, непревзойденным

discrete – раздельный, состоящий из разрозненных частей; дискретный

 

2.                Translate the text into Russian:

Sensors and Transducers

Simple stand-alone electronic circuits can be made to repeatedly flash a light or play a musical note, but in order for an electronic circuit or system to perform any useful task or function it needs to be able to communicate with the "real world" whether this is by reading an input signal from an "ON/OFF" switch or by activating some form of output device to illuminate a single light and to do this we use Transducers.

Transducers can be used to sense a wide range of different energy forms such as movement, electrical signals, radiant energy, thermal or magnetic energy etc., and there are many different types of both analogue and digital input and output devices available to choose from. The type of input or output transducer being used, really depends upon the type of signal or process being "Sensed" or "Controlled" but we can define a transducer as a device that converts one physical quantity into another.

Devices which perform an input function are commonly called Sensors because they "sense" a physical change in some characteristic that changes in response to some excitation, for example heat or force and covert that into an electrical signal. Devices which perform an output function are generally calledActuators and are used to control some external device, for example movement. Both sensors and actuators are collectively known as Transducers because they are used to convert energy of one kind into energy of another kind, for example, a microphone (input Sensors and Transducers and a loudspeaker (output device) converts the electrical signals back into sound waves and an example of this is given below.

Simple Input/ Output System using Sound Transducers

There are many different types of transducers available in the marketplace, and the choice of which one to use really depends upon the quantity being measured or controlled.

Input type transducers or sensors, produce a proportional output voltage or signal in response to changes in the quantity that they are measuring (the stimulus) and the type or amount of the output signal depends upon the type of sensor being used. Generally, all types of sensors can be classed as two kinds, passive andactive.

Active sensors require some form of external power to operate, called an excitation signal which is used by the sensor to produce the output signal. Active sensors are self-generating devices because their own properties change in response to an external effect and produce an output voltage, for example, 1 to 10v DC or an output current such as 4 to 20mA DC. For example, a strain gauge is a pressure-sensitive resistor. It does not generate any electrical signal, but by passing a current through it (excitation signal), its resistance can be measured by detecting variations in the current and/or voltage across it relating these changes to the amount of strain or force.

Unlike the active sensor, a passive sensor does not need any additional energy source and directly generates an electric signal in response to an external stimulus. For example, a thermocouple or photodiode. Passive sensors are direct sensors which change their physical properties, such as resistance, capacitance or inductance etc. As well as analogue sensors, Digital Sensors produce a discrete output representing a binary number or digit such as a logic level "0" or a logic level "1".

Analogue Sensors produce a continuous output signal or voltage which is generally proportional to the quantity being measured. Physical quantities such as Temperature, Speed, Pressure, Displacement, Strain etc. are all analogue quantities as they tend to be continuous in nature. For example, the temperature of a liquid can be measured using a thermometer or thermocouple which continuously responds to temperature changes as the liquid is heated up or cooled down.

 

3.                Translate the word combinations:

To convert energy of one kind into energy of another kind; unlike the active sensor; a pressure-sensitive resistor; physical properties; the amount of strain; an external stimulus; excitation signal; an output function; a wide range of different energy forms; a single light.

 

4.                Arrange the following words in pairs of antonyms:

a number of                             on the other hand

out-of-date                              regarding

result in                                   some

regardless                                up-to-date

on the one hand                       result from

 

5.                Define the parts of speech of the following words; translate them into Russian:

To differ – different – indifferent – difference; long – length – to lengthen; to apply – application – applicable – appliance; efficient – inefficient – efficiency; to divide – division – divisible – indivisible; to vary – variety – various – variable – invariable; to transform – transformer – transformation; to convert – converter – conversion – convertible; machine – to machine – machinery – machinable

 

 

6.                Form the gerund choosing the following verbs:

To convert; to create; to utilize; to move; to run

1)                The idea of (использования) the energy of oceans is not new, but tidal stations are still few. 2) Recently scientists have succeeded in (создать) a few kinds of generators for (превращения) heat directly into light. 3) This machine tool is capable of (работать) at very high speeds. 4) In fact, (превращение) conventional kinds of fuels into electricity is not economic enough. 5) Upon being heated the molecules begin (двигаться) very rapidly.

 

7.                Translate into Russian paying attention to the function and the form of gerund:

1) These pieces of metal can’t be used in the process without being hammered into thin sheets. 2) The investigator mentioned his having tested this material for strength. 3) Strengthening metals means reinforcing them with artificial fibers. 4) Their being reinforced with artificial fibers makes them more corrosion resistant. 5) Without having improved the properties of this alloy we couldn’t use it in the production process. 6) Using atomic fuel for the production of electricity is one of the most promising sources of energy. 7) Atomic fuel has great possibilities. Its being used for the direct production of electricity is one of the most promising. 8) Much effort is being given to find the most efficient means of generating electricity. 9) After the young scientist’s report having been discussed at the conference it was published in a scientific journal. 10) Sometimes we speak of applying a still broader definition of communication including the influence of one mechanism upon another mechanism. 11) Our having mastered a foreign language helps us in our work.

 

8.                Define the group of subject:

1) Testing engines should be carried out on a special stand.

2) The increasing pressure was measured precisely.

3) The metals to be strengthened are subjected to special operations.

4) The pressure increased was measured precisely.

5) To operate new flexible line became possible thanks to computers.

 

9.                Define the group of the predicate:

1) Scientists are doing their best to find more efficient ways of utilizing solar energy.

2) The task of the computer is to operate the whole line properly.

3) When transported gases are compressed into strong cylinders.

4) While discussing the design the engineers suggested a few improvements.

 

10.           Translate the texts into Russian without a dictionary and write down  the main idea of each following texts: