Design, analysis, and experimental investigations of a 2-DOF monolithic parallel mechanism

This paper presents the design and analysis of a 2-DOF monolithic parallel mechanism for micro- and nano-manipulations. Two sets of statically indeterminate leaf parallelograms are employed to provide the decoupling effect, and the displacement of the piezoelectric actuator (PEA) is amplified with a statically indeterminate lever mechanism. Due to the static indeterminacy, the load-deflection relationship of the mechanism is nonlinear. Computational analysis is utilized to investigate the nonlinearity. Computational results reveal that the structural nonlinearities of the mechanism is negligible within the maximum driving force of the PEA. The influence of the contact interface and the load mass is also investigated through computational analyses. Ultimately, a prototype is fabricated and a laser interferometer measurement system is established to obtain the position and velocity of the prototype. A number of experiments are performed to investigate the performance of the prototype. Experimental results show that the developed prototype has achieved a workspace of 82×82 μm², a first natural frequency of 423 Hz (with a 53.4 g load mass), and a cross-axis coupling ratio below 1%.