Negative Feedback in Open System
A ubiquitous feature of all open systems is feedback. This is necessary for a system to maintain dynamic equilibrium despite being subjected to a variety of disturbances from its environment. An example is the bicycle rider who uses sight and balance senses to obtain feedback on position, allowing the muscular system to maintain equilibrium in the face of external influences such as gravity, wind, traffic and variations in the road surface. Outputs are measured and compared to predetermined goals.
Corrective signals are then generated to adjust the systems inputs such that the desired level of output is re-established. This is shown diagrammatically in this figure. A very simple example of such a response in an operations system would arise in the event of an influenza epidemic. The operations manager might ensure that the system maintains its output by asking the unaffected staff to work overtime. More formal feedback and control arrangements are found in budgetary control, quality control, inventory control and production control operations.