Design and Computational Optimization of a Decoupled 2-DOF Monolithic Mechanism

This paper presents the mechanical design, computational optimization, and experimentation of a decoupled 2-DOF monolithic mechanism. In the mechanical design, statically indeterminate leaf parallelograms provide the decoupling effect, and the displacement of the piezoelectric actuator (PEA) is amplified with a statically indeterminate lever mechanism. In a piezo-driven mechanism, the contact interface between the PEA and the mechanism is a major cause of the discrepancies between the estimated and measured characteristics. However, no explicit and reliable model is available to estimate the contact stiffness. In this paper, a computational optimization based on the response surface methodology is performed and the influence of the contact interface is taken into consideration by adding adequate safety margin to the design objectives. Ultimately, a prototype is manufactured and experimentally investigated for its characteristics and performances. Experimental results show that the developed mechanism has a workspace range in excess of 82 mu m x 82 mu m with a first natural frequency of 423 Hz (with a 53.4-g load mass). The cross-axis coupling ratio is experimentally measured to be below 1%, indicating excellent decoupling performances.