Constraint-Based Design of Parallel Kinematic XY Flexure Mechanisms

Abstract

This paper presents parallel kinematic XY flexure mechanism designs based on systematic constraint patterns that allow large ranges of motion without causing over-constraint or significant error motions. Key performance characteristics of XY mechanisms such as mobility, cross-axis coupling, parasitic errors, actuator isolation, drive stiffness, lost motion, and geometric sensitivity, are discussed. The standard double parallelogram flexure module is used as a constraint building-block and its nonlinear force-displacement characteristics are employed in analytically predicting the performance characteristics of two proposed XY flexure mechanism designs. Fundamental performance tradeoffs, including those resulting from the nonlinear load-stiffening and elastokinematic effects, in flexure mechanisms are highlighted. Comparisons between closed-form linear and nonlinear analyses are presented to emphasize the inadequacy of the former. It is shown that geometric symmetry in the constraint arrangement relaxes some of the design tradeoffs, resulting in improved performance. The nonlinear analytical predictions are validated by means of computational finite element analysis and experimental measurements.

A normalization-based approach to the mobility analysis of spatial compliant multi-beam modules

“…This reveals that we can exert two transverse forces, on the motion stage, at the symmetric centre of all beams to eliminate the parasitic bending angles. The new action position is termed as the centre of stiffness [18].…”

“…This is caused by the significant load-stiffening effect [1,18]. Under the small deflection assumption, this issue can be neglected.…”

“…A normalization technique has been employed in the modeling and design of compliant/flexural mechanisms [5,[18][19][20][21][22][23]. It has been shown that the normalization strategy can simplify equations and derivation in the analysis of compliant mechanisms.…”

“…[24] proposed a characteristic length for normalizing the Jacobin matrix of rigid-body robots. The normalization technique [5,[18][19][20][21][22][23] provides a way to deal with the above non-homogeneous issue in identifying the DOF of compliant mechanisms. In addition, in the analysis of compliant mechanisms, one can assume that all loads are in the same order of magnitude and comparable under the same dimension.…”

A Piezo-Driven Compliant Nanopositioning Stage with Large Stroke for Micro/Nano Manipulation

“…In addition, duo to a lateral displacement at the driving end of the stage increases with the increasing of the input displacement, a decoupling mechanism is needed for protect PZT from the lateral forces and bending torques. [8] Therefore, it is a challenge working to design a compliant nanopisitioning stage possessing both low cross-coupling and large stroke simultaneously.…”