Compliant Micropositioning Stage Research Articles

Large stroke electromagnetic redundant actuated six degrees-of-freedom parallel compliant micropositioning stage

In this paper, a novel large stroke six degrees-of-freedom (6-DOF) electromagnetic redundant actuated micropositioning stage is proposed. The 6-DOF stage adopts a configuration that is composed of eight parallel driving branch chains. Each branch chain is driven by a voice coil motor and incorporates a parallelogram flexure mechanism and a decoupling mechanism for guidance and decoupling. The positioning stage is symmetrically arranged and possesses the advantages of simple structure and easy assembly. As a result, assembly errors are significantly reduced and positioning accuracy is enhanced. The decoupling mechanism uses a large stroke flexible ball joint that increases the motion range of the positioning stage and decouples the coupled motion, thereby enhancing the stability and accuracy of the stage. To evaluate the performance of the stage, static and dynamic analytical models of the 6-DOF stage are derived based on the compliance matrix method and the Lagrangian dynamic modeling method. Additionally, the accuracy of the analytical models and the static and dynamic performances of the positioning stage are verified through finite element analysis (FEA) and experimental testing. The experimental results demonstrate that the stage realizes a workspace of 2.06 mm × 2.02 mm × 3.1 mm × 23.4 mrad × 23.1 mrad × 14.9 mrad. Finally, to verify the tracking performance trajectory of the 6-DOF positioning stage, tracking experiments are performed using a controller that combines a proportional-integral controller and a notch filter.

Design of a Compliant Vertical Micropositioning Stage Based on Lamina Emergent Mechanisms

This article presents the design and development of a novel compliant vertical micropositioning stage (VMS) with a millimeter stroke and compact profile. The concept design of the stage is inspired by lamina emergent mechanisms. The overall mechanism is fabricated using a plate-like material, which can realize an out-of-plane motion vertical to the mechanism plane. The proposed architectural design guarantees the advantages of the center platform in terms of millimeter stroke, high compactness, and low displacement coupling ratio. Analytical models of the stiffness and resonant frequency of the stage are established by resorting to pseudorigid-body model and Lagrangian equations. They are validated by conducting simulation study with finite element analysis. For performance testing, a prototype stage driven by a voice coil motor is fabricated. Experimental results indicate that the stage (size: 100 mm × 100 mm × 5 mm) delivers a working stroke of 5.58 mm, displacement coupling ratio of 0.31%, and resolution of 0.71 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$\mu$</tex-math></inline-formula> m. It exhibits more geometric advantages over existing piezoelectric-actuated vertical stages. In addition, it has superior vertical compactness, linearity, and simplicity compared to a planar mechanism with vertical input and vertical output. The concept design proposed in this article provides a new solution for the design and development of compliant VMS.

Voice coil motor-driven multi-DOF compliant parallel micropositioning stage based on a large range beam-based spherical hinge and fully symmetrical layout

With the recent rapid developments in the field of precision engineering, demand for the large range multi-degrees-of-freedom (DOF) micropositioning stage has increased significantly. In this paper, to solve the problems of small motion range, local stress concentration, and low motion accuracy caused by the parasitic motion of the traditional flexure hinge in the multi-DOF micropositioning stage, we first propose a type of large-range beam-based flexure spherical hinge (BFSH). Subsequently, based on the proposed BFSH, a large range 3-DOF θxθyz spatial micropositioning stage driven by the voice coil motor is designed employing parallel branch chains and a fully symmetrical layout. This arrangement realizes theoretical motion decoupling in structural design. Furthermore, we use the geometric method to derive kinematic equations of the moving platform, which are used as the decoupling matrix of the control loop. Based on the compliance matrix method and Lagrange’s method, the compliance matrix model of the BFSH, the 3-DOF micropositioning stage, and the stage dynamic model are determined respectively. Additionally, finite element analysis and experimental tests are conducted to verify the accuracy of the analytical model and assess the static and dynamic performance of the designed 3-DOF stage. Moreover, a fractional order phase advanced proportional integral controller is designed for closed-loop control to track the sinusoidal trajectory and spherical trajectory. The results reveal that the stage can achieve the desired large workspace of ± 21.5 mrad × ± 20.3 mrad × ± 3.23 mm, as well as excellent decoupling and trajectory tracking performance.

Data-driven fractional order feedback and model-less feedforward control of a XY reluctance-actuated micropositioning stage.

This paper proposes a compound data-driven control method to solve the problems of low damping resonance, different dynamic properties, and hysteresis in the large-range compliant micropositioning stage driven by a Maxwell reluctance actuator. First, in order to verify the proposed control algorithm, a reluctance-actuated, XY compliant micropositioning stage is constructed according to the principle of operation of a reluctance actuator. Second, in order to eliminate the influence of complex dynamics on the controller design, a fractional order proportional-integral feedback controller is designed using a data iterative feedback turning algorithm. Third, the finite impulse response feedforward filter is optimized using experimental data, and the on-line inverse estimation of the system frequency response function and its iterative feedforward compensation are carried out to further eliminate the influence of light damping resonance. Finally, the proposed control method is used for tracking the experiment and compared with other methods. The experimental results show that the proposed control method can better meet the requirements of high precision, fast speed, and strong anti-interference ability for large stroke micro/nanopositioning and tracking.

A novel compliant XY micro-positioning stage using bridge-type displacement amplifier embedded with Scott-Russell mechanism

This paper presents a new bridge-type compliant displacement amplifier embedded with Scott-Russell mechanism. Based on this design, a novel compliant XY micro-positioning stage is also designed, analyzed and tested to illustrate the advantages of the proposed amplifier. The main feature of the new amplifier is to employ Scott-Russell mechanism to replace one arm of the compound bridge-type mechanism, aiming to improve its lateral stiffness and the natural frequency in the working direction. The compliant XY micro-positioning stage is driven by two novel bridge-type amplifiers with orthogonal distribution. Double parallelogram guide mechanisms are added at the output ends of the bridge-type mechanisms to further lower the parasitic movements of the XY stage. Then, an analytical model based on the stiffness matrix transfer method is established for the static and dynamic characteristics of stage, which are also verified by performing finite element analysis. Finally, an experimental prototype is manufactured and its static and dynamic performances are tested. The test results demonstrate that the stage can realize a workspace of 181.0 μm × 179.5 μm with motion resolution of 20 nm and a maximum coupling error of 1.07%. The natural frequencies of XY stage along the working direction are 178 Hz and 248 Hz respectively when the PZTs are not installed or installed. Additionally, the trajectory tracking performance of the stage is also preliminarily evaluated. All of the results obtained from the analytical model, finite element analysis and experimental tests verify the effectiveness of the novel bridge-type displacement amplifier and the compliant XY micro-positioning stage.

Fractional order zero phase error tracking control of a novel decoupled 2-DOF compliant micro-positioning stage

This study focuses on a piezo-actuated two-degrees-of-freedom (2-DOF) decoupled compliant micro-positioning stage driven by a novel compound bridge-type amplification mechanism embedded with Scott-Russell mechanism. According to the system identification, the transfer functions of two working directions are obtained. Both of the measured dynamic cross couplings between them are also lower than −40 dB, demonstrating that the single-input-single-output control strategy can be adopted reasonably. Based on the identified frequency response, a fractional order proportional-integral (FOPI) controller is designed for the 2-DOF compliant micro-positioning stage. Compared with the integer order proportional-integral (IOPI) controller using same parameters, the amplitude error of the FOPI controller is 2% lower than that of IOPI controller. Additionally, a fractional order zero phase error controller (FOZPETC) is designed by obtaining the inverse of the fractional order closed-loop system in a large frequency range. And the gain of the corrected control system is 1 in a wide frequency band to eliminate the phase error in the close-loop control system. Finally, using the compound control strategy of FOZPETC+FOPI, a series of trajectory tracking tests are carried out on the proposed novel 2-DOF compliant micro-positioning stage. All the experimental results prove that the designed controller can achieve good positioning and tracking performance of the micro-positioning stage, and confirm the effectiveness of the compound control strategy of FOZPETC+FOPI.

Design and analysis of a 3-PPP compliant parallel micro-positioning stage

Design and analysis of a 3-PPP compliant parallel micro-positioning stage

Design Analysis and Optimization of Large Range Spatial Translational Compliant Micro-positioning Stage

Design Analysis and Optimization of Large Range Spatial Translational Compliant Micro-positioning Stage

Development and Analysis for a New Compliant XY Micropositioning Stage Applied for Nanoindentation Tester System

A Compliant XY micropositioning stage is purported for situating a material sample in nanoindentation tester process. This paper aims to develop, analyze and optimize a XY compliant micropositioning stage. The working stroke of proposed XY stage is amplified by combining the four-lever and a bridge amplification mechanism. To enhance the performances of the stage, the main geometric parameters are optimized by an integration method of Taguchi method, response surface method (RSM) and genetic algorithm (GA). Firstly, static analysis and dynamic analysis are conducted by the finite element analysis in order to predict initial performances of the XY stage. Secondly, the number of experiments and the data are retrieved by combination of the finite element analysis-integrated Taguchi method. Thirdly, the effects of main design variables on the output response sensitivity are considered. Later on, mathematical model for the amplification ratio was established by the RSM. Finally, based on the mathematical equation, the GA is adopted to define the optimal design variables. The results of numerical validations are in a good agreement with the predicted results. The results depicted that the proposed hybrid approach ensures a high reliability for engineering optimization problems.

Design, Modeling, and Testing of a Novel XY Piezo-Actuated Compliant Micro-Positioning Stage.

A novel decoupled XY compliant micro-positioning stage, based on a bridge-type amplification mechanism and parallelogram mechanisms, is designed in this paper. Analytical models of the bridge-type amplification mechanism and parallelogram mechanisms are developed by Castigliano’s second theorem and a Beam constrained model. The amplification ratio, input stiffness, and output stiffness of the stage are further derived, based on the proposed model. In order to verify the theoretical analysis, the finite element method (FEM) is used for simulation and modal analysis, and the simulation results indicate that the errors of the amplification ratio, input stiffness, and output stiffness of the stage between the proposed model and the FEM results are 2.34%, 3.87%, and 2.66%, respectively. Modal analysis results show that the fundamental natural frequency is 44 Hz, and the maximum error between the theoretical model and the FEM is less than 4%, which further validates the proposed modeling method. Finally, the prototype is fabricated to test the amplification ratio, cross-coupling error, and workspace. The experimental results demonstrate that the stage has a relatively large workspace, of 346.1 μm × 357.2 μm, with corresponding amplification ratios of 5.39 in the X-axis and 5.51 in the Y-axis, while the cross-coupling error is less than 1.5%.

A high accuracy algorithm of displacement measurement for a micro-positioning stage

A high accuracy displacement measurement algorithm for a two degrees of freedom compliant precision micro-positioning stage is proposed based on the computer micro-vision technique. The algorithm consists of an integer-pixel and a subpixel matching procedure. Series of simulations are conducted to verify the proposed method. The results show that the proposed algorithm possesses the advantages of high precision and stability, the resolution can attain to 0.01 pixel theoretically. In addition, the consuming time is reduced about 6.7 times compared with the classical normalized cross correlation algorithm. To validate the practical performance of the proposed algorithm, a laser interferometer measurement system (LIMS) is built up. The experimental results demonstrate that the algorithm has better adaptability than that of the LIMS.

Design and development of a new large-stroke XY compliant micropositioning stage

This paper presents the design and development of a new flexure-based compliant XY micropositioning stage with large stroke. The parallel-kinematic XY compliant stage is designed based on the Roberts mechanisms. Pseudo-rigid-body model is developed to establish the quantitative models of the whole compliant mechanism. Finite element analysis is carried out to validate the performance of the XY stage. A prototype of the XY stage is developed for experimental investigations. Experimental results show that the stage can deliver a working range larger than 12 mm in each of the two working axes. Moreover, a feedback control using the proportional–integral–derivative control algorithm is implemented to demonstrate the positioning performance of the developed XY stage. The reported ideas can also be extended to the design and control of other micro-/nanopositioning systems.

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

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 1.3μm, which validates the effectiveness of the proposed scheme.

Design and analysis of a new compliant XY micropositioning stage based on Roberts mechanism

The demand for a compliant micropositioning stage with a large workspace and high precision is increasing. This paper presents a new design of XY micropositioning stage based on Roberts mechanism, which is a traditional linear guiding mechanism. By extending the traditional rigid-body Roberts mechanism, two kinds of new compliant guiding mechanisms are designed and a novel parallel-kinematic XY compliant guiding stage is synthesized. Pseudo-rigid-body model (PRBM) is developed to build the quantitative models of the compliant Roberts mechanisms. In addition, finite-element analysis (FEA) is carried out to validate its performance. A prototype is fabricated and tested through experimental studies. Results show that the XY stage delivers a work range larger than 12mm in each axis. Moreover, the parasitic motion of the stage in the non-working direction is less than 1.7% of the motion stroke. It indicates that the designed stage meets the requirements of a large stroke and high precision linear guiding mechanism, which demonstrates the feasibility of the proposed design ideas using the Roberts mechanism.

A novel voice coil motor-driven compliant micropositioning stage based on flexure mechanism.

This paper presents a 2-degrees of freedom flexure-based micropositioning stage with a flexible decoupling mechanism. The stage is composed of an upper planar stage and four vertical support links to improve the out-of-plane stiffness. The moving platform is driven by two voice coil motors, and thus it has the capability of large working stroke. The upper stage is connected with the base through six double parallel four-bar linkages mechanisms, which are orthogonally arranged to implement the motion decoupling in the x and y directions. The vertical support links with serially connected hook joints are utilized to guarantee good planar motion with heavy-loads. The static stiffness and the dynamic resonant frequencies are obtained based on the theoretical analyses. Finite element analysis is used to investigate the characteristics of the developed stage. Experiments are carried out to validate the established models and the performance of the developed stage. It is noted that the developed stage has the capability of translational motion stroke of 1.8 mm and 1.78 mm in working axes. The maximum coupling errors in the x and y directions are 0.65% and 0.82%, respectively, and the motion resolution is less than 200 nm. The experimental results show that the developed stage has good capability for trajectory tracking.

Design of a Large-Range Compliant Rotary Micropositioning Stage With Angle and Torque Sensing

This paper presents the design, modeling, and experimental testing of a flexure-based compliant rotary micropositioning stage with a large rotational range. The rotary stage is devised based on multistage compound radial flexures. One uniqueness lies in that it owns both a compact size and a large rotary stroke. Dominant parameters of the stage are determined based on established analytical models to cater for the requirements on rotational angle and driving torque. These models are verified by conducting finite-element analysis simulations, which also demonstrate the stage performance. A prototype rotary stage is developed using a rotary voice coil motor. A strain-gauge sensor is designed to measure both rotational angle and experienced torque of the rotary stage. The sensitivities of the two-role sensor are derived analytically and calibrated experimentally. Results show that the developed stage is capable of rotary positioning with a resolution of 20 μrad over the range of 10° under an approximately infinite fatigue-life, while keeping a compact physical size. The torque sensor exhibits a resolution of 0.128 mN-m with a measuring range of 1.23 N-m. Moreover, the reported idea can be extended to the design of multiaxis rotary stage.

A large-range compliant micropositioning stage with remote-center-of-motion characteristic for parallel alignment

Micro-/nanopositioning stage with remote-center-of-motion (RCM) plays a key role in precision out-of-plane aligning since it can eliminate harmful lateral displacement generated at the output platform. This paper presents the design, modeling and test of a novel large-range flexure-based micropositioning stage with RCM characteristic. The stage is composed of an outer RCM guiding mechanism and a inner output-stiffness enhanced lever amplifier (OELA). The outer RCM guiding mechanism is constructed by a symmetric double parallelogram mechanism which can guide the stage to perform a RCM movement with high rotational precision. The inner OELA is designed to amplify the output displacement of the adopted piezoelectric stack actuator (PSA). Compared with conventional lever amplifier, the proposed OELA possesses twice the output stiffness, which makes it more appropriate for actuating the outer mechanism and therefore, a large rotational range can be obtained. Based on the pseudo-rigid-body-model (PRBM) method, the analytical models predicting kinematics, statics, and dynamics of the RCM stage have been established. Besides, the dimensional optimization is conducted in order to maximize the first resonance frequency of the stage. After that, finite element analysis is carried out to validate the established models and the prototype of the stage is fabricated for performance tests. The experimental results show that the developed RCM stage has a rotational range of 6.96 mrad while the maximum center shift of the RCM point is as low as $$9.2\,{\upmu } \text {m}$$9.2μm, which validate the effectiveness of the proposed scheme.

A Survey on Recent Development of Large-Stroke Compliant Micropositioning Stage

Compliant micropositioning mechanism plays an important role in precise positioning and alignment applications. Unlike conventional guiding mechanism, compliant mechanism delivers motion through the deformation of flexible components. As a result, the movement of flexible mechanism is continuous and the structure is more compact, which makes it a hot research topic in the field of precision machine design. As the increase of demands for micropositioning stage providing large motion range and high precision, this paper conducts a state-of-the-art survey on recent development on large-stoke compliant microopsitioning stages. First, a basic introduction of the compliant micropositioning stage is presented. The type synthesis and mechanism structure design of the flexible component are reported, which are the decisive factors determining the stage performance. Then, the design method of flexure hinge is introduced. Afterwards, the development of large-stroke compliant mechanism in recent years is reviewed, and a comparison study of several typical large-stroke compliant micropositioning stage is carried out. The existing issues and future work on the large-stroke compliant micropositioning stage are summarized.

A novel compliant micropositioning stage with dual ranges and resolutions

Dual-range stages are demanded in precision positioning applications that call for fine resolution in a smaller motion range and coarse resolution in a larger range. Traditional dual-range stages are realized using two actuators, which complicates the mechanism and control design procedures. This paper presents the design and testing of a novel dual-range, dual-resolution precision positioning stage driven by a single linear actuator. The stage structure is devised with leaf flexures to achieve a large stroke. Strain sensors are employed to provide different resolutions in the two motion ranges. To quantify the design of the motion ranges and fine/coarse resolution ratio, analytical models are established and verified through finite element analysis simulations. A proof-of-concept prototype is fabricated for experimental investigations and the experimental results validate the effectiveness of the proposed design. The reported ideas can also be extended to the design of multi-axis micropositioning stages.

Design and implementation of a novel rotary micropositioning system driven by linear voice coil motor

Limited-angle rotary micropositioning stages are required in precision engineering applications where an ultrahigh-precision rotational motion within a restricted range is needed. This paper presents the design, fabrication, and control of a compliant rotary micropositioning stage dedicated to the said applications. To tackle the challenge of achieving both a large rotational range and a compact size, a new idea of multi-stage compound radial flexure is proposed. A compact rotary stage is devised to deliver an over 10° rotational range while possessing a negligible magnitude of center shift. The stage is driven by a linear voice coil motor and its output motion is measured by laser displacement sensors. Analytical models are derived to facilitate the parametric design, which is validated by conducting finite element analysis. The actuation and sensing issues are addressed to guarantee the stage performance. A prototype is fabricated and a proportional-integral-derivative control is implemented to achieve a precise positioning. Experimental results demonstrate a resolution of 2 μrad over 10° rotational range as well as a low level of center shift of the rotary micropositioning system.