Can Noise In The Feedback Improve The Performance Of A Control System?

In linear control systems, a feedback loop is often adopted, but this limits the bandwidth of the controlled system. Moreover, owing to the presence of noise in the feedback, which is essentially linked to the measurement of the fed-back variables, the bandwidth is reduced in order to maintain the desired performance. This short note proposes the utilization of the concept of stochastic resonance to overcome this limitation. A simple, but effective, nonlinearity is introduced in the controller leading to improved performances in terms of signal-to-noise ratio when dealing with tracking of small-amplitude signals.