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Computer control

What is a computer control?

This

means that a computer is part of a control system. A computer is usually used

to run the control programme. The word computer means a processor or microchip

embedded with the equipment.

Sensors

This is a

device designed to measure some physical quantity in its environment, for

example:

·

A

heat sensor that measures the temperature in a room.

·

A

pressure sensitive mat that detects someone walking over it.

When

these sensors have taken a reading, they may send the reading straight back to

the computer or they may store it and take a set of readings overtime, later

sending the readings back to the computer as a batch. The data that goes in is

called an input, and the data produced by the sensor is called an output.

There are

many different types of sensors -

ADC

Most

sensors take analogue measurements -

this means the output changes smoothly from one value to another.

·

All

computers require digital data in order for it to be processed further. Digital

data consists of two values: 0 and 1 or On and Off.

·

The

data needs to be converted from analogue signal to digital signal in order to

be collected by the sensor and handled by the computer. Therefore, a converter

is needed that is called an Analogue-to-Digital converter or ADC (hardware).

·

This

converter is connected between the sensor that the computer's input and output

port called the user interface.

Processing

When the data has been received by

the computer, it can begin to be processed. The data will be compared against a

set of rules which have been programmed into the control system and

a decision of what to do with the data will be made; the computer only follows

what it has been programmed to do. The results will be an output of some kind -

like sending a message etc.

For

example, a central heating system set up to keep the temperature at 22 degrees:

1)

The sensor takes the temperatures of a room and sends them to the computer.

2)

The computer will then process the data to see if the readings match the

required temperature (22 degrees).

3)

If the data is found lower, the boiler will automatically turn on.

4)

If the data matches the required temperature, the boiler will be turned off.

Computer

controls

There

are two types of computer control systems:

·

Open loop system - This control only looks

at the input signal in order to decide what to do, and ignores what the output

is doing. For example, a microwave is set to cook food for 2 minutes. The

control system stops the timer after 2 minutes even though your food may not be

edible or to taste. Advantage: very simple, takes a command or value and

produces an output of some kind.

·

Feedback system - This control measures the

output and some of it is fed back (where output of a system affects input) to

the input. Advantage: more precise control. Disadvantage: complicated to make.

Computer control

What is a computer control?

This

means that a computer is part of a control system. A computer is usually used

to run the control programme. The word computer means a processor or microchip

embedded with the equipment.

Sensors

This is a

device designed to measure some physical quantity in its environment, for

example:

·

A

heat sensor that measures the temperature in a room.

·

A

pressure sensitive mat that detects someone walking over it.

When

these sensors have taken a reading, they may send the reading straight back to

the computer or they may store it and take a set of readings overtime, later

sending the readings back to the computer as a batch. The data that goes in is

called an input, and the data produced by the sensor is called an output.

There are

many different types of sensors -

ADC

Most

sensors take analogue measurements -

this means the output changes smoothly from one value to another.

·

All

computers require digital data in order for it to be processed further. Digital

data consists of two values: 0 and 1 or On and Off.

·

The

data needs to be converted from analogue signal to digital signal in order to

be collected by the sensor and handled by the computer. Therefore, a converter

is needed that is called an Analogue-to-Digital converter or ADC (hardware).

·

This

converter is connected between the sensor that the computer's input and output

port called the user interface.

Processing

When the data has been received by

the computer, it can begin to be processed. The data will be compared against a

set of rules which have been programmed into the control system and

a decision of what to do with the data will be made; the computer only follows

what it has been programmed to do. The results will be an output of some kind -

like sending a message etc.

For

example, a central heating system set up to keep the temperature at 22 degrees:

1)

The sensor takes the temperatures of a room and sends them to the computer.

2)

The computer will then process the data to see if the readings match the

required temperature (22 degrees).

3)

If the data is found lower, the boiler will automatically turn on.

4)

If the data matches the required temperature, the boiler will be turned off.

Computer

control Systems

There

are two types of computer control systems:

·

Open loop system - This control only looks

at the input signal in order to decide what to do, and ignores what the output

is doing. For example, a microwave is set to cook food for 2 minutes. The

control system stops the timer after 2 minutes even though your food may not be

edible or to taste. Advantage: very simple, takes a command or value and

produces an output of some kind.

·

Feedback system - This control measures the

output and some of it is fed back (where output of a system affects input) to

the input. Advantage: more precise control. Disadvantage: complicated to make.

Actuator

This is often part of a control system - it is a mechanical device or motor which carries out the action or decision made by the control system. They can be of any size.

For example, the lense of a digital camera that zooms in and out according to how much zoom is wanted.

Computer controls

___________________________________________________I________________________________________________ I I Advantages Disadvantages

Operates 24/7 without a break. Software for the control system is specialist and costs may be high to develop.

No need for holidays or sick days. The system will not work if the computer malfunctions .

Payments aren't needed. Power reliant (system will shut down if there is a power cut).

It cannot adapt to changes as a person would do: it will only follow what it has been

programmed to do.

Repeats actions accurate.

Can process data from sensors fast. People feel more safe if an expert is in control even if the computer is reliant enough, e.g. a

robotic surgical procedure.

Can manage hundreds of inputs at the same time.

Reliable and accurate decisions are made.

Can be used in unsafe environments.

Examples of computer controls

At home

Washing machines

Microwave cookers

Dishwashers

Video recorders

Remote control television

Central heating systems

Burglar alarm system

At work

Air conditioning systems

Lifts

Automatic doors

Factory robots

Outside the home

Traffic light systems

Car park barriers

Cars - engine management systems

Lifts

Rides at theme parks

Computer controlled lighting systems at discos and concerts

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