Introduction and motivation
Control

Control is one of the simplest ways to control. This ensures startup of one or more devices. These devices can only be turned on or off, or perform a sequence of operations. Diagram of regulation control is shown in Figure 1.1

Fig. 1.1: Basic scheme for control

Controlled system is a machine which is controlled by the control system. For imagine is possible to show the following example. System control circular saw and actuator switch power. Power switch, an actuator, a circular saw, controlled system put into operation. Turn off the circuit breaker is made out of service.

Another example might be a set of belt conveyors that are logically connected. Activating this equipment, a gradual lowering of all conveyors. The first to put into operation the conveyor, which is in the direction of material flow last. When will be in normal operation (steady state) the previous conveyor is running. In this way, against the flow of conveyed material, there are all conveyors in operation. Shutdown may be gradual so that the first is off the conveyor, which was put into operation last. Other conveyors are being shut down at intervals. Length of the time interval between the impulse to turn off and the actual individual must ensure emptying conveyor belts from this material. Thus are gradually shut down all conveyors, gradually in the direction of material flow.

Control is possible according to type divided into several groups:

- Local
- Remote
- Automatic
- Software

Local control is used in simple machines and equipment. In particular, it is possible to see him in household appliances and power tools.

The remote control is very common in the manufacturing process, where there is more control of machines or equipment from a central control room operator or habitat. Very often it is a combination of local and remote machines using the switch. This method is applied especially in the partial repair of machinery.

Automatic control is such that when actuated member is featured / shut to / from the operation other than human impulses. As an example, the automatic pumping of water from the sump. Sensor measuring water level provides an impetus to start or stop the pump.

Program control is applied to the set of machines. For example, when you run big power units is necessary to provide lubrication and cooling machines triggered during service and sometime after weaning. Should this not happen, the machine would be damaged. So the command to start the machine are first put into operation the pump lubricating oil. After reaching the required oil pressure is put into the pump ensures coolant circulation. After meeting these two requirements, the main drive is put into operation. An example of a similar startup file device for household appliances can be automatic washing machine.

Control can show more detail, as shown in Figure 1.2 Controlled system as the pump that drives the electric motor (actuator). Connection to the power supply provides power switch, which is controlled locally or remotely (control).

Fig. 1.2: Detailed control scheme