Tree maps

Tree maps

1. Output devices controlled by control systems

   • Actuators: Devices such as motors that react to according signals given to them by computers. An actuator can be used to open a window in a greenhouse.,
   • Stepper motor: A motor that turns in a series of small steps. The control signals tell the stepper motor how many steps and in which direction it should move. You can therefore control the angle through which the motor rotates. They are found in robot arms.
   • Sirens: these are used in control systems, where alarms signals need to be sounded. Burglar alarms use sirens.
   • Heating/cooling: these are used for controlling the temperature of an environment. Central heating/air conditioning systems use heating/cooling and as the output device.
   • Lights: flood lights or flashlights are often used in control systems. E.g. as well as sounding an alarm or burglar.

2. Control system examples

   • Central heating systems: Controlled by a microprocessor that has a number of sensors attached to it. The process follows a continuing cycle: regular readings of the temperature are input, the microprocessor analyses the reaing, if the temp is too hot the heater is switched off and vice versa.
   • Burglar alarm system: often very complex and uses many sensors: passive infrared sensors detect movement in a room. Proximity sensors see when doors or windows are opened. Pressure pads sense the pressure of weight. If any senjsors are cativated signals will be sent to an alarm or bell, or directly toa police station ior guard.
   • Smart meters: measuresthe amount of energy, gas or water being used in a home. Readings are taken at regular time intervals. Readings are sent back to the head office - no need for human meter readers. Monitor when the greatest consumption of resource is taking place. Help customer efficiency in use of resource.
   • Secuirity systems: many buildings have these. They activate sirens or bells. Set off an automatic sprinkler system. Send a message automatically to the fire station.