Optimal Decoupled Disturbance Observers for Dual Input Single Output Systems

Abstract

The disturbance observer (DOB) has been a popular robust control approach for servo enhancement in singleinput singleoutput systems. This paper presents a new extension of the DOB idea to dualand multiinput singleoutput systems, and discusses an optimal filter design technique for the related loopshaping. The proposed decoupled disturbance observer (DDOB) provides the flexibility to use the most suitable actuators for compensating disturbances with different spectral characteristics. Such a generalization is helpful, e.g., for modern dualstage hard disk drives, where enhanced servo design is becoming more and more essential in the presence of vibration disturbances.