Closed-Loop Control of Quasi-Static Scanning PZT Micromirrors with Embedded Piezoresistive Sensing and Spurious Mode Rejection

The work presents a novel closed-loop control to improve scanning linearity in piezoelectric micromirrors with embedded Lead-Zirconate-Titanate (PZT) actuation and piezoresistive sensing. The system includes two feedback loops aimed at pushing the control bandwidth beyond the microelectromechanical system (MEMS) resonance, at damping the closed-loop quality factor, at nulling the steady-state control error and at rejecting effects of MEMS high-order modes. Overall, the strategy reduces linearity errors down to ± 0.03°, but the latter aspect is particularly challenging: management of spurious resonances is indeed shown to affect the optimal control strategy, suggesting further investigation of predictive feedback techniques.