The adjustment of control systems for quick transient response

The time taken for correction of transient errors in linear feedback systems is examined theoretically. For any of a large class of such systems the quickest approach to complete correction is obtained when the system is adjusted to be quasi-critically damped. Furthermore, the time taken to achieve a large attenuation of an initial error is, in general, dependent on only one system parameter, termed the settling time-constant; and this is relatively easy to calculate when the system is quasi-critically damped. These results, together with other known advantages of quasi-critical damping, suggest that the latter constitutes a useful general design criterion of stability.