Improving methodology for multi-input-single-output control system using the Robust Bode plot

Abstract

In order to improve a robust performance in a Multi-Input-Single-Output (MISO) control system, we proposed a loop-shaping methodology with the Robust Bode (RBode) plot for the MISO system. By using the current RBode plot, we are able to improve an existing Single-Input-Single-Output(SISO) control system with visualized guidelines on an open-loop characteristic Bode plot. Our proposed method transforms the robust performance problem for the MISO system into that for the SISO system in order to employ the RBode plot. As a result, we are able to design an improved MISO control system that compensates for disturbances against perturbations of controlled objects. A case study with the magnetic-head positioning control system shows that the proposed loop-shaping method is able to improve the positioning accuracy under the external vibration by about 83%.

Keywords

• robust control
• loop shaping
• multi-input-single-output system
• hard disk drive
• positioning control