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There is an increasing demand to achieve manipulating operations in nanometric precision and a macro-range (over a millimeter) simultaneously. In principle, it is possible to satisfy both requirements in a compact size taking advantages of flexure-based mechanisms, whereas limitations such as the parasitic rotation, cross-axis coupling, saturation may adversely affect the motion quality in nanometric level practically. Here, we propose a novel design methodology to actively prevent parasitic rotation of XY compliant mechanisms. Further, by means of design synthesis and real-time motion control, the prototype of manipulator is fabricated, which enables large motion range (±3 mm) along each actuation axis. Experimental results demonstrate a travel range of 2 mm × 2 mm with high linearity, small cross-axis coupling (< 0.4%), and low parasitic rotation (< 6.9 μ rad over 0.5 mm × 0.5 mm motion range). Moreover, the high natural frequency (~ 60 Hz) of the manipulator facilitates it to achieve high-precision motion with tracking error < 80 nm (20 Hz sinusoids). The experimental results of the proposed nano-manipulator outperform most of the existing ones. [Display omitted] • A large range compliant XY nano-manipulator of active parasitic rotation rejection. • By design of axial force passing through stiffness center, the manipulator does not have parasitic rotation in principle. • High natural frequency facilitates mm stroke and nanometric tracking error as well as micro-radian parasitic rotation. [ABSTRACT FROM AUTHOR]

Abstract Nonuniform web tension has a great negative effect on product quality of roll-to-roll printed electronics. In this paper, a roller posture adjustment device with remote-center-of-motion (RCM) characteristic is proposed to guarantee web tension uniformity. The device combines a high-stiffness spherical air bearing (SAB) and a multi-degree-of-freedom flexure-based mechanism. The nonuniform web tension in lateral direction can be divided into an equivalent force and two equivalent moments. The equivalent moments are caused by the nonuniformity of the web tension. By adjusting the roller angle around y and z -axes, the equivalent moments can be eliminated to guarantee the web tension uniformity. The multi-DOF flexure-based mechanism is composed of a linear mechanism, a rotary mechanism and a 3-DOF off-plane mechanism. Besides, the RCM characteristic of the proposed device is realized to eliminate extra parasitic movement when the roller posture is changed. Based on pseudo-rigid-body model (PRBM) method, the theoretical analysis is conducted to evaluate the kinematics, stiffness and dynamics of the device. Moreover, the parameter optimization is conducted to maximize the first two resonance frequencies of the system. After that, finite element analysis is conducted to validate the established models. Finally, a prototype of the proposed device is fabricated performance verification. The experimental results show that the proposed device has a workspace of 10.22 mrad and 8.16 mrad about two working axes with center shifts of the RCM point less than 0.75%, which demonstrate the superior property of the proposed device. Highlights • A roller posture adjustment device with remote-center-of-motion (RCM) characteristic is proposed to eliminate nonuniform web tension in lateral direction for roll-to-roll printed electronics. • The proposed device combines a high-stiffness spherical air bearing with a multi-DOF flexure-based mechanism for heavy load and precision positioning. • The proposed stage can reach a workspace of 10.22 mrad × 8.16 mrad about two axes. • Pseudo-rigid-body-model (PRBM) method is utilized to conduct theoretical analysis and dimensional optimization and finite element analysis (FEA) validation are conducted. • A prototype of the proposed roller posture adjustment device is fabricated to test the performance of it. [ABSTRACT FROM AUTHOR]

Abstract: This paper presents the dynamic modelling and performance evaluation methodologies of a flexure-base mechanism for ultra-precision grinding operation. The mechanical design of the mechanism is briefly described. A piezoelectric actuator is utilized to drive the moving platform. A flexure-based structure is utilized to guide the moving platform and to provide preload for the piezoelectric actuator. By simplifying the Hertzian contact as a linear spring and damping component, a bilinear dynamic model is developed to investigate the dynamic characteristics of the flexure-based mechanism. Based on the established model, the separation phenomenon between the moving platform and the piezoelectric actuator is analyzed. The influences of the control voltage and the preload stiffness on the maximum overshoot are extensively investigated. The slope and cycloidal command signals are utilized to reduce and/or avoid the overshoot of such flexure-based mechanism for rapid positioning. The effects of the rising time of the command signals on the maximum overshoot and the settling time are also explored. Experiments are performed to verify the established dynamic model and the performance of the developed flexure-based mechanism. [Copyright &y& Elsevier]

Abstract: This paper presents the methodology for modeling and control of a high precision flexure-based mechanism for ultra-precision turning operation. A high performance piezoelectric actuator is used to driven the flexure-based mechanism. A parallel flexure hinge mechanism is utilized to guide the moving platform and to preload the piezoelectric actuator. A high resolution capacitive sensor is used to measure the displacement of the flexure-based mechanism for closed-loop control. With consideration of the driving circuit, the dynamic model of the flexure-based mechanism has been established. The effect of the driving circuit on the dynamic response of the precision mechanism is investigated. Experimental tests have been carried out to verify the established model and the performance of the flexure-based mechanism. [Copyright &y& Elsevier]