Modelling of Piezoelectric Actuator (PEA) for Advanced Process Control in Chemical Mechanical Polishing (CMP)

Abstract—Lead zirconate titanate (PZT) stacks are commonly used for submicron resolution actuation, fast response times and high sensitivity. They are usually modeled as expansion generators without external load. This paper proposes an electromechanical model for a commercially available micro-piezoelectric actuator (PEA) which comprises pre-stressed PZT stacks and external amplifier flexure frame for closed loop force control. The proposed model avoids the need to measure the piezoelectric charge which is usually required in conventional electromechanical models. The mechanical part of the PEA was modeled as a linear, lumped, double mass-spring-damper system and the related parameters were experimentally identified. The PEA system was characterised under load-free and load-applied conditions, and the electromechanical coupling ratios which describe the energy transfer from the electrical domain (voltage) to the mechanical domain (endpoint displacement/force) were experimentally determined.