7.1.1 – 7.1.5 – Centralized Control Systems

7.1.1 – Discuss a range of control systems

A control system is one or more devices that guide other devices or systems.

We need control systems for many things such as:

  • Heating or air con at home
  • Automatic doors
  • Washing Machines
  • GPS and Sat Nav

Washing Machines!

Washing machines can contain many different sensors such as:

  • Water-level
  • Water Temperature
  • Load sizes
  • Buttons for the user interface (Yes buttons are pressure sensors!)

7.1.2 – Outline the uses of microprocessors and sensor input in control systems

Sensors

  • Sound
  • Motion
  • Humidity
  • Heat
  • Pressure
  • Temperature

What makes a good sensor?

Accuracy

Is the reading from the sensor accurate?

Range

A temperature sensor is no good if it is to determine the temperature of a freezer if it does not register below freezing point

Resolution

Determines the smallest increment. A sensor that can determine increments of .1 Degree could give readings as 17.2 or 7.5 whereas a sensor that increments by one degree would give 17 or 18 only

Microprocessors

A micro processor is as the name suggests. A Very small processor that contains most if not all of a CPU on a single chip or circuit.

7.1.3 – Evaluate different input devices for the collection of data in specified situations

To be completed

7.1.4 -Explain the relationship between a sensor, the processor and an output transducer

Transducers

Transducers convert from one form to another such as analogue to digital or digital to analogue

Analogue needs to be converted to digital so the processor can read it

Digital is converted to analogue so it can be output

Actuators

“An actuator is the mechanism by which a control system acts upon an environment. The control system can be simple (a fixed mechanical or electronic system), software-based (e.g. a printer driver, robot control system), a human, or any other input.”

An Actuator takes the signal and converts it into movement such as the opening of an automatic door.

An actuator could also be a transducer if it converts the signal type (A-D or D-A)

To be completed

7.1.5 – Describe the role of feedback in a control system

Open Loop Vs Closed Loop Systems

An open loop control system acts completely on the basis of input and the output has no effect on the control action.

closed loop control system considers the current output and alters it to the desired condition. The control action in these systems is based on the output.