Abstract: Three active vibration controller design methodologies include reduced modal control, classical H ∞ and robust H ∞ control for the high-speed flexible linkage mechanisms with piezoelectric actuators and sensors are investigated. All the formulas are based on complex mode theory but re in real field. The numerical simulation carried out on a 4-bar linkage mechanism shows that the vibration of the system is significantly suppressed with permitted actuator voltages by each of these three controllers. The reduced modal control makes it more convenient to increase the modal damp of the system than the H ∞ control does, while the robust H ∞ control avoids the spillovers due to mode truncation.

Key words: Active control, Complex mode, H ∞ control, Linkage mechanism, Vibration