Ing. Holger Steeb, Dr.-Ing. Fehmi Cirak, Prof. Dr.-Ing. Ekkehard Ramm, University of Stuttgart, Department of Civil Engineering, Institute of Structural ...

Zeitschrift für angewandte mathematik und mechanik

A review of recent studies on non-resonant piezoelectric actuators

\n Flexure-based compliant mechanisms are becoming increasingly promising in precision engineering, robotics, and other applications due to the excellent advantages of no friction, no backlash, no wear, and minimal requirement of assembly. Because compliant mechanisms have inherent coupling of kinematic-mechanical behaviors with large deflections and/or complex serial-parallel configurations, the kinetostatic and dynamic analyses are challenging in comparison to their rigid-body counterparts. To address these challenges, a variety of techniques have been reported in a growing stream of publications. This paper surveys and compares the conceptual ideas, key advances, and applicable scopes, and open problems of the state-of-the-art kinetostatic and dynamic modeling methods for compliant mechanisms in terms of small and large deflections. Future challenges are discussed and new opportunities for extended study are highlighted as well. The presented review provides a guide on how to select suitable modeling approaches for those engaged in the field of compliant mechanisms.

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Kinetostatic and Dynamic Modeling of Flexure-Based Compliant Mechanisms: A Survey

A review on control strategies for compensation of hysteresis and creep on piezoelectric actuators based micro systems

A nonresonant-type piezoelectric motor with a precise driving ability was proposed. The operating principle of the proposed motor is different from the previous nonresonant piezoelectric motors using either the clamping and feeding mechanism (inchworm mechanism) or the inertia drive mechanism. An oblique linear motion formed by the hybrid of two bending motions of a sandwich transducer was used to push the runner step-by-step. Two square-wave voltages were applied to the horizontal and vertical PZT elements to obtain the desired oblique linear motion. The mechanism of the proposed piezoelectric motor was illustrated in detail. Then, transient analyses were performed by ANSYS software to simulate the motion trajectory and to find the response characteristics of the motor. Finally, a prototype was fabricated to verify the mechanism and to test the mechanical output characteristics of the proposed motor. Under the input square-wave voltages of 500 V $_{\text{p-p}}$ , the prototype achieved a step displacement of 5.96 μm, a maximum no-load velocity of 59.64 μm/s, and a maximum thrust of 30 N. This paper provides a new mechanism for the design of a nonresonant piezoelectric motor with long stroke and precise driving ability.

Development of a Nonresonant Piezoelectric Motor With Nanometer Resolution Driving Ability

This paper presents a novel piezo-driven linear-rotary inchworm actuator with a large motion range and high resolution. Such an actuator will be indispensable in precision positioning. The proposed actuator consists of four flexure modules driven by four piezoelectric actuators, namely, two clamping modules to alternately hold the actuator shaft, one linear driving module and one rotary driving module to provide the driving force and torque, respectively. Its mechanical performance is analyzed in detail and the working principle is also described. A prototype of the linear-rotary actuator is fabricated, with which a series of experiments are carried out. The experimental results show that the actuator can achieve high resolution of 0.049 μm and 10.3 μrad, the maximum velocities of 1450 μm/s and 34,270 μrad/s, and the maximum output force of 11.8 N and maximum output torque of 73.5 N mm for the linear and rotary motions, respectively.

A novel piezo-driven linear-rotary inchworm actuator

A compliant dual-axis gripper with integrated position and force sensing

Micro-/nanomanipulator with remote-center-of-motion (RCM) plays a key role in precision out-of-plane aligning since it can eliminate the harmful lateral displacement generated at the output platform. This paper presents the design, modeling and test of a novel piezo-driven 2-degree-of-freedom (2-DOF) flexure-based micropositioning stage with RCM characteristic. The stage is articulated from a 3-legged parallel kinematic configuration, where the 2-DOF RCM is ensured by three improved parallelogram RCM modules (PRMs). Flexure-hinge based structures and piezoelectric stack actuators (PSAs) are adopted in the design in view of their superiorities in precision positioning applications. The analytical models predicting kinematics, stiffness, and workspace of the stage have been established and evaluated by finite element analysis (FEA). A prototype of the stage is fabricated, with which a series of experiments are carried out. The experimental results indicate that the developed RCM stage can achieve a workspace of 1030 micro-rad × 920 micro-rad (μrad) about its two working axes with a resolution of 1 μrad. Besides, the maximum center shift of the RCM point tested by an optical microscope is observed to be less than 1.3 μm, which validates the effectiveness of the proposed scheme.

A piezo-driven 2-DOF compliant micropositioning stage with remote center of motion

In this paper, a new flexure-based micropositioning stage (FMPS) is proposed to achieve decoupled XY translational motions and large travel ranges. The stage consists of four independent kinematic chains, each comprising two flexure-beam prismatic joints. The mechanism with such a special topological structure enables the motions of the platform strictly along XY axes and minimizes the parasitic rotation in theta axis. The kinematics and dynamics analysis of the mechanism are conducted to evaluate the performance of the mechanism in terms of travel range, parasitic motions, linearity, as well as natural frequency. According to the developed models, a parameter optimization of the mechanism is performed under the condition of the maximum travel range. The finite element simulation is carried out to examine the mechanical performance and the theoretical models. The experimental results show that the proposed FMPS possesses a workspace of 600 × 600 μm2, a relative coupling error of 0.6%, and the natural frequencies of 209.7 Hz and 212.4 Hz for the first two modes.

A decoupled 2-DOF flexure-based micropositioning stage with large travel ranges

This paper presents the concept design of a large-range compliant remote center of motion (RCM) stage with input/output decoupling. The developed RCM stage can achieve 2-degree-of-freedom (2-DOF) rotation motion without generating extra lateral displacement in precision parallel alignment process. The RCM characteristic is realized based on parallelogram-based RCM module (PRM). The proposed stage is featured with input/output decoupling based on the novel designed structure. The input decoupling is realized by the employ of two up-down stacked arranged input stages. The output decoupling is realized by the orthogonal arrangement of two 1-DOF RCM stages combining the wire flexure hinges. The rectangular flexure hinge and the voice coil motor (VCM) are utilized to generate large-range rotation motion considering their large compliance and large stroke, respectively. The design, theoretical analysis and experimental test of the stage are presented. Based on pseudo-rigid-body-model (PRBM) method and compliance matrix method, the theoretical analysis is conducted to evaluate the kinematics, statics, dynamics and workspace of the RCM stage. Besides, finite element analysis (FEA) is conducted to validate the established models and an experimental system of the stage is set up for performance tests. The experimental results show that the proposed RCM stage can achieve a workspace of 14.4 mrad × 16.6 mrad in its two working directions with a resolution of 15.1 μrad. Moreover, the maximum coupling output angles about the two axes is less than 0.1 mrad and 0.16 mrad, which demonstrate the decoupling property of the developed stage.

Wenjie Chen

Papers

A novel piezo-driven linear-rotary inchworm actuator

A compliant dual-axis gripper with integrated position and force sensing

A piezo-driven 2-DOF compliant micropositioning stage with remote center of motion

A decoupled 2-DOF flexure-based micropositioning stage with large travel ranges

A large-range compliant remote center of motion stage with input/output decoupling