CONTROL SYSTEMS

CONTROL SYSTEMS

1. Types of control systems

   • Electronic control
     • Electronic control systems use transistors to recieve an electrical signal from a sensor that detects a physical parameter, such as sunlight; which activates an actuator, such as a streetlight, depending on the value of that signal.
   • Electromechanical control
     • Limit switches can be used to control automatic system by activating or deactivating other devices.

2. Elements

   • Controller circuit
     • That carries out the action for which the automatic systen has been designed
   • Sensor
     • that detects information and measures physical paraments such as temperature or humidity
   • Actuator
     • that carries out the action for which the automatic system has been designed

3. Sensors

   • Digital sensors
     • These sensors are called digital sensors beacuse they can have two states; when they are activated and let electric current pass, and they are deactivated and behave like an open circuit
   • Analogue sensors
     • These are used to measure magnitudes in a continuous range of values. They measure temperature, light level, humidity, the distance of an object...
       • Thermistors
         • Measure temperature based on the variations in resistance of a semiconductor when the temperature increases or decrases.
       • LDR
         • They change their value according to the light intensity they receive
       • Humidity sensors
         • Consist on two metal sheets, which are very close together, whose resistance or capacity varies with the level of humidity