Title

Computer Control Software
Quick revise

This is the use of a computer to monitor and control an external process. Input sensors are used by the computer to monitor the various parts of a process that it is controlling. Before any process can be controlled by a computer a control program must be written by a human to tell the computer what to do.

This video explains about Computer control and data logging

Analogue and digital signals
  • A sensor can send two types of signal to a computer – digital and analogue.
  • Digital signals can only have two values: on (or true) and off (or false).
  • Analogue signals can have any value.
  • To process analogue signals the computer needs an analogue-to- digital converter.

analogue and digital signals

Feedback
  • Feedback control systems use the values of their output signals to affect the value of their input signals.
  • This is useful when a certain set of conditions needs to be constantly maintained.
  • Output signals make changes to the conditions outside which will affect its input signals.

Feedback

Sensors

Many different types which can each measure some physical quantity outside the computer such as:

  • Temperature;
  • Pressure;
  • Light;
  • Water and moisture levels;
  • Relative humidity;
  • Movement and wind speed.

Sensors detect analogue data which is converted into digital data before it is sent to the computer

Actuators
  • Many control systems need to control devices that can move such as a motor in a greenhouse to open or close a window.
  • A device called an actuator is used to generate signals that can make devices move.
Microprocessors

These are used to control automatic machines by following pre-programmed sets of instructions called control programs.

Found around the home in for example:

  • Video recorders;
  • Camcorders;
  • Hi-fi systems;
  • Microwave ovens;
  • Dishwashers;
  • Burglar alarms
Robots

Used in hundreds of applications e.g.

  • Assembling and spray-painting cars
  • Maintaining overhead power cables
  • Testing blood samples

They all have the same basic hardware components:

  • sensors which are used to monitor changes in physical conditions such as speed and position;
  • a microprocessor to process the information received from sensors;
  • actuators to produce movement or turn external devices like switches on or off

Advantages of robots

  • They can work in environments that are hazardous to humans, such as in outer space, underwater or in radioactive environments
  • They can perform repetitive and boring tasks without needing to stop for a break
  • The quality of their work is always the same because they never get bored or have an off-day
  • They can work to a greater level of accuracy than humans
  • They can work 24 hours a day, seven days a week, resulting in increased productivity

The main disadvantage of robots is that they are expensive to buy and install

An introduction to robotics

This video looks at Robots which can carry out boring work efficiently, accurately and without breaks, such as in car manufacture. The automation involved has advanced hugely since the production line was first introduced by Henry Ford. Robots can also be used in situations which are too dangerous for people. A robot to measure radiation at Chernobyl is shown.

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