Variable proportional-integral-resonant (PIR) control of actuators with harmonic disturbances

Harmonic disturbances in servo applications, in particular rotating actuators, are common and lead to a non-smooth motion with ripples. A novel variable proportional-integral-resonant (PIR) control which combines a PI and PR regulation is proposed. The main PIR control feature is its ability to track both dc and ac quantities at the same time. The design and analysis of the closed control loop are performed in frequency-domain via the open loop characteristics. The control gain boundaries due to the time delays are addressed. The experimental evaluation of compensating two first harmonics at different reference velocities discloses the variable PIR control as superior in comparison to the underlying optimal PI one.