Closed loop testing of a suspension based piezoelectric microactuator

This paper extends the demonstrated dual-stage servo bandwidth capabilities of a suspension based piezoelectric microactuator from simulation to actual laser based closed loop testing. A dual-stage zero dB crossover frequency on the open loop transfer function (i.e. servo bandwidth) of 2000 Hz was demonstrated using laser feedback. The stability of the controller was evaluated for different levels of suspension first torsion off-track gain. Charge control was shown to have up to 8 degrees of phase margin advantage over voltage control.