FEEDBACK – 21049

Feedback is a means by which a closed-loop system regulates itself. Feedback is used extensively in robotics.

An example of feedback can be found in a simple thermostat mecha- nism, connected to a heating/cooling unit. Suppose the thermostat is set for 20 degrees Celsius (20°C). If the temperature rises much above 20°C, a signal is sent to the heating/cooling unit, telling it to cool the air in the room. If the temperature falls much below 20°C, a signal tells the unit to heat the room. This process is illustrated in the block diagram.

In a system that uses feedback to stabilize itself, there must be some leeway between the opposing functions. In the case of the thermostatically controlled heating/cooling system, if both thresholds are set for exactly 20°C, the system will constantly and rapidly cycle back and forth between heating and cooling. A typical range might be 18 to 22°C. The leeway should, however, not be too wide.