On the equivalence between P+DOB and set point weighted PI controllers for velocity control of servodrives under load disturbances

Improving the velocity control of servodrives is an important topic in industrial applications, especially in the presence of internal and external disturbances. To address this problem, in this work the feedback loop of a perturbed servodrive is augmented with a Disturbance Observer (DOB). The DOB uses the control signal, velocity measurements and a nominal model of the plant to estimate the disturbance. The disturbance estimate is then used to compensate for the effects of the real disturbance. Then an equivalence between the P+dob and a set point weighted Proportional-Integral controller is established. Experiments with a laboratory prototype show the effectiveness of the proposed scheme.