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# 45

AUTOMATION

1- Automated systems have probably been the most important applications of the development of data processing in the last decades. These systems enable planes to land when there is no visiblity, they can be found in cars (ABS technology) etc, and their applications in our everyday life are getting innumerable. However production plants have been using automation as a means to improve reliability, efficiency and productivity. This has been particularly obvious in the car industry where automated production lines have become a common feature. For instance, it is estimated that 90% of G.M. Corporation's investments are in computer-controlled machines and experts predict that, by 1995 (*), over 60% of automobile assembly will be done by automated machines - including robots.

2 - Basically automation consists in transferring decision-taking from an operator to an automatic system which is capable of adjusting to events as production is going on. A simple unit is composed of three elements :
-sensing devices whose job is to measure the required parameters: these devices may be gauges, photo-electric cells, thermocouples, sensors, etc. This information is usually transformed into electronic output signals. (A device that changes signals of one type into another is called a transducer; the potentiometer is one example.)
-The output signals are fed into a computer which compares them with the orignal signal and decides whether or not production adjustment is necessary.
-The decisions of the computer are carried out by means of actuators i.e. pneumatic, hydraulic, mechanical or electrical systems such as valves, motors and resistors.

3 - FEEDBACK

The central element of an automated system is feedback. If unexpected inputs (=disturbances) affect the controllded system, they cause unwanted effects, consequently the output signals are different from those which were expected. These are fed back and compared with the desired input: the difference is the system error, or the error signal, which is then added to the initial command, thus generating a new actuating signal.

Fig.1 - In this closed-loop system, the various data which have been obtained at different stages of production can modify the orders given by the original program.

4 - BINARY LOGIC

Binary logic is to be found at the centre of every automated circuit, as it enables the system to decide whether, for instance, the output signal is similar to the input: as a matter of fact, the solution to an automation problem is found by logically expressing the relations which exist between two situations: the output data to be controlled (pressure, temperature, voltage, etc) and the input variables.

Binary logic rests on a very simple idea : a signal is or is not the same as another, a statement is true or not, current passes or not. Thus logic functions are of course used in microelectronics where they constitute the basis of integrated circuits. However these functions can be used in a conventional electrical circuit or even a pneumatic system.

J.C. Viel

(*) This text was written in 1989.

COMPREHENSION

1 - What has data processing enabled firms to develop in recent years ? Why are industries interested in automation ? What part is being (and will be) reserved to automation at G.M. Corp ?

2 - Fill in with words from the text :
Decisions are taken by ... and not by ... : when there is a problem, the machine ... by itself to production which never stops. In a basic system, ... parameters are obtained by means of ... and transformed into electrical signals by ... . After a ... has analyzed these signals, it sends out new input signals to the controlled system . Devices such as valves, motors and resistors can be classified as ... .

3 - Right or wrong ?
Feedback means that ...
-input data are fed into a computer
-output variables directly affect the actuators
-any disturbance is taken into account -the error signal is used as an actuating signal -output data are analyzed in order to adjust the input signal

4 - Right or wrong ?
Binary logic :
-automation could hardly (=… à peine) exist without it
-thanks to it, it's possible to know whether a system is operating properly
-logic functions imply that variables can take two values at the same time

LANGUAGE STUDY

1- Use the following words to make significant sentences:
by means of - reliability - efficiency - a feature - to be worth - to require - a device - to feed ... into - to actuate

2- In the text, find the preposition that goes with:
to consist ... - to compare ... - to feed ... - to transfer ... - to adjust .... - to transform ... - to add ... - different ... - the solution ... a problem

3- Compound adjectives
The solution (to an automation problem) must be expressed logically --> there is a logically-expressed solution (to an automation problem)
Transform as in the example above
-the system is controlled by a computer
-a valve which is remotely controlled
-designing which is made (=aided) by a computer -a device which transmits pressure
-a system that locks automatically -a machine that is actuated by pneumatic power
-a relay which has a high speed -a system operated by air -a relay which is directly connected
-actuators are systems for adjusting the production process

4- Comparisons

Fig.2 - A pneumatic OR logic unit	Fig.3- A pneumatic AND logic unit

Use SIMILAR TO - EQUAL TO - INFERIOR TO - SUPERIOR TO - EQUIVALENT TO - DIFFERENT FROM - SAME ...AS - largER / MORE powerful THAN, and write a few sentences of the following model: When pressure in A is inferior to pressure in B, the valve is pressed to the left and signal B reaches outlet E without escaping through inlet A. (Note: we say 'inlet A, outlet E' and NOT 'the inlet A, the outlet B')

5- Logic gates :
As shown here, they are electronic switches that allow current to pass (or not) when definite conditions are fulfilled. (note the phrase : to fulfill a condition)

Fig.4 Gate 1	Fig.5 Gate 2

What would you call gate 1 and gate 2?
(Complete) In Figure 5, A and B are normally - ... switches R is a ........... switch

Complete the following truth tables

a - Explain the results : use IF - WHEN - THEN - AS A RESULT- CONSEQUENTLY - TO TRIGGER (= déclencher) etc. and the present tense.

b - Use the same sentences with IF - ON CONDITION THAT - UNLESS and change the tenses as in the examples :
If A or B WAS on then the lamp WOULD light up
If A or B HAD BEEN switched on then the lamp WOULD HAVE LIGHTED up.

6- Consider the following diagram

Describe how the circuit operates
a- Fill up the blanks : If ... you A, the coil in R is ... with 24V DC, and as a result R is .... . When (it is) triggered, R closes contact R1 which is mounted ... with (or to) A and contact R2 which ... M.
b- Continue the description. What happens if A is switched off ? If B is opened ?

7 - Explain the possible moves of the truck

Fig.7

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