Optimal design of a compliant mechanism with circular notch flexure hinges

This paper presents an optimal design of a compliant mechanism with circular notch flexure hinges as well as a performance evaluation of a two-axes ultra-precision stage using the compliant mechanism. The compliant mechanism consists of two double-symmetric four-link mechanisms for two translational motions. As the circular notch flexure hinge can produce rotation as well as axial translation via its deformation, the double symmetric four-link mechanism can translate along one direction in a small range. In the optimal design, a composite global design index based on Min-Max principle is applied for the design of the compliant mechanism with circular notch flexure hinges owing to its simplicity and compactness. The designed compliant mechanism, piezoelectric elements for actuation, and capacitance-type displacement sensors for position measurement are assembled into an ultra-precision stage. The experimental results show that the stage implemented by the compliant mechanism will be applicable to two-axes ultra-precision positioning systems such as the fine positioning table of coarse-fine positioning systems, ultra-precision machining centres, wafer stages, and scanners for atomic force microscopy (AFM).