1. First we will talk about automated machines.

■An automated machine is a device that is designed to carry out a function that can not be modified.

1.2.Robots:

■ Automated machine used mainly in industry

■It can be reprogrammed; it's functions can be modified by changing of program.

■It can detect stimuli and react to it carrying out an action.

2.Control Systems 

It is a set of elements created to allow the automatization of a process.

It is formed by:

■A sensor: It can detect stimuli like presence

■Controller: It is the element that makes the effector work

■Mechanism: Transforms the effector's action into one suitable solving the problem  

■ Input: information that the system receives.

 ■ Output:  The system's response.

-Types of control systems:

-Open loop: Systems that don't take into account the state of the output.

-Closed loop:There is feedback between the output and the input.

Examples:

-Open loop:                                                                              -Closed loop:

3. Everyday control systems

 3.1 The cistern: An appliance that stores water normally used to flush the toilet, or to autofeed the animals.

It has two processes:

-Emptying: The process in which the water is released carrying out its function.

-Filling up: When he toilet has emptied, the cover returns to its original position and water enters in the cistern.

1: High cover.  2: Low cover  3: Ballcock  4: Piston  

 4.Electromechanical control systems

-This are systems that need a human that activates and for example, lights up if someone pushes a switch.

They activate the components of one appliance in a specific moment with an apropiated prolongation.

One example of this devices are cams:

4.1.Types of cams

-Pear-shaped cam: It's the simplest rotation it just activates the circuit once.

-Ratchet: It's on constant movement creating an intermitent effect.

-Multiple ratchet cam: It's the most complex type of cam. It's on constant movement and in each rotation it activates the system more than once.

-Limit switches: The following diagram shows how filling a water tank can be controlled. The pump moves liquid from one container to another.

When the tank is full, a device desactivates the pump and the liquid stops flowing.

This switch is called a limit switch.

There are two types:

-Relays: Relays are also electromechanicasl controls.

5. Electronic control systems:

Control systems are able to carry out increasingly complex operations.

Many of these sytems consist of just electronic elements.

5.1.Transistors as control systems.

When we want to detect one physical parameter with the purpose of carrying out an action we can use circuits with transistors.

-The physical parameter could be, for example pressure.

-The response could be to switch on an alarm.

Sensors are devices that detect the physical parameter.

-Basic control circuits using transistors

Using transistors we can control the components of an automated system that needs more power, i.e relays and motors.

5.1.1.Control of a relay

When we connect positive and negative energy to the circuit, then push the switch, the relay activates, and the energy flows trough the motor, and the circuit works.

5.1.2.Control of a motor

In this circuit the sensor is the LDR. That means that depending on the ammount of light the circuit will work or not.

If there is a lot of light the resistance decreases and the transistor gets energy on the base closing the circuit and making the motor work, the diode works as a protector. Also if the screw of the potentiometer is rotated the resistance of the potentiometer changes, varying the intensity of the motor.