Purpose

The computer controls the washing machine and its actions in the same way a personal computer performs its computing functions. It is the central processing unit that sends signals to the rest of the machine so that it operates correctly. The washing machine's microprocessor tells the washing machine what to do, based on the selections you make for your laundry, such as the wash cycle and water temperature.

Sensors

The primary triggers, or input devices, that tell the microprocessor in the washing machine that it is time to act in a certain way are sensors that detect conditions such as water level and temperature. Sensors in newer machines even sense the dampness of the clothes to determine if they need to be spun longer to remove additional water. Sensors also detect movement of the machine's drum and other associated actions. They send signals back to the washing machine's computer so that it can determine what actions the machine should take next.

Actuators

Once the washing machine has been programmed, it goes through a process of running its internal programs. When you set the cycle and load for your washer, you then push the start button. This tells the washer that it is time to use its sensors and complete the wash and rinse process. This it does by turning on and off devices that control the rest of the machine, such as the motors that spin the tub and the agitator or the water pump.

The Process

The washing machine begins to dump water into the drum or tub that you put your clothes into once you push the start button. Based on the setting, the computer will allow the water to flow to a predetermined level, at which time a sensor will tell it that the water level has been reached. It will then shut off the water and begin the agitation process. Once the timer tells the washer that it is time to stop agitating, it then begins the spin process, which finishes pulling the dirt out of the clothes and removing the dirty water from the machine. At the end of the spin cycle, the washing machine's computer then tells the machine to drain the water through the drain hose, which it does by turning on the water pump and sucking it out of the machine.