This diagram presents what is known as a closed-loop feedback control system, a concept which is found in areas such as biology, economics, engineering and electronics.
Let’s consider a more accessible example: adjusting the temperature of a shower to be just right, which can include a fair amount of back-and-forth, especially if it is unfamiliar. The input to the system R(s), on the left, is a reference signal, the desired temperature. On the right is the actual temperature Y(s). The left hand box represents the controller C(s), which turns the tap to a certain angle based on the difference between the desired and actual states (Y(s) - R(s)). The right hand box represents the plant G(s), the physical set of pipes and heaters which deliver the water.
Many of us have a limited exposure to the act of receiving constructive feedback, let alone giving it. When we receive it, it is usually in the context of an annual performance review at work, too infrequent to make meaningful adjustments to one’s actions, and encased in the fear of a negative report.
Feedback must be frequent and direct to be effective. This card reminds us that it can help to correct deviations from where we want to be. It is an essential part of a closed-loop system, which continually adapts to perturbations in the environment. If feedback is too infrequent, the deviation between actual and desired states can be so great that the level of effort required to close the gap can exceed our capability, or at least feel unduly hard.
Watch another fun example of a feedback control system: a toaster.
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