The transient performance of servomechanisms with derivative and integral control

THE utility of servomechanisms in their many applications depends on the speed, stability, and accuracy of their responses. These three characteristics, or the lack of them, may be observed in the responses of a servomechanism to test inputs. The error, which is the difference between the input and the output of the device, is used to actuate the control in a direction which tends to remove the error. In order to achieve the best performance under both transient and equilibrium conditions, it often has been found expedient to employ, as an additional correction signal, either the derivative or the time integral of the error, or both. The servomechanism is then said to have derivative and/or integral control. The present paper reports an investigation of the transient performance of low-order, linear servomechanisms with derivative and integral control.