Displacement Amplification Mechanism Research Articles

Experimental evaluation of force and amplification factor of three different variants of flexure based micro displacement amplification mechanism

Microelectromechanical System (MEMS) based complaint displacement amplification mechanism capable of producing different displacement amplification factors in three different configurations is designed and experimented. Microprobe system having an acupuncture needle and high-resolution camera has been used to measure displacements, forces and stiffness of the designed mechanism. Configuration 1 gives amplification factor 7.6 with natural frequency of 222.13 kHz. Configuration 2 amplifies displacement 16 times with natural frequency of 258.62 kHz. Amplification factor of 16.14 and natural frequency of 215.51 kHz is achieved with 3rd configuration. Modal analyses of all the three configurations of the mechanism match well with the experimental values. The mechanism is analytically modeled and simulated using Finite Element Method techniques and fabricated using commercially available fabrication process PolyMUMPs. Kinematic sensitivity and performance analysis of the proposed mechanism is carried out to predict the behavior of mechanism with respect to different geometric parameters. The results show that with increasing angle of flexure, amplification factor decreases, and it becomes constant at angles higher than 6° with increasing input displacement. It further shows a significant change in amplification factor with increasing length but after 600 μm the change in amplification factor becomes insignificant. Analyses results demonstrate the viability of mechanism as a displacement amplification mechanism. A good agreement is found between numerical and experimental results. This amplification mechanism can be used independently or integrated with any conventional actuation as well as sensing mechanism in a microsystem where amplified displacement is desired for improved sensitivity and performance.

柔顺桥式位移放大机构的非线性建模与优化

柔顺桥式位移放大机构的非线性建模与优化

Topological design of compliant orthogonal displacement amplification mechanism under the unidirectional input force

The orthogonal displacement amplification mechanism is used to output and amplify the displacement perpendicular to the direction of the input force, and its configuration often uses a typical bridge-type. However, the bridge-type amplifier to achieve orthogonal shift conversion must enter the bidirectional symmetric input forces, otherwise the output will produce parasitic displacement. In view of this problem, the topology optimization method is used to find the new configuration of the displacement amplification mechanism, so that it can still realize the orthogonal displacement transformation under the unidirectional input force condition. Based on the solid isotropic material with penalization (SIMP) topological description method, the ratio of output and input displacements is maximized as the objective function, the ratio of parasitic displacement and output displacement as one of constraint functions, and the topological optimization mathematical model of the compliant orthogonal displacement amplifier is established under the unidirectional input force. The sensitivity information of the objective and constraint functions is deduced by the adjoint matrix method, and the optimization problem is solved by the method of moving asymptotes (MMA). The topology optimization results of orthogonal displacement amplifier are given through numerical examples, and the effect of spring stiffness on the topology optimization result is also discussed. Finally, the parasitic motions of the displacement amplification mechanism obtained from topology optimization and the bridge-type amplification mechanism are compared through the finite element analysis and experiment. Finite element simulation and experiment confirm the correctness and validity of the proposed method.

Kinematic sensitivity analysis of a novel micro-mechanism for displacement amplification

This research article presents the design and analysis of a displacement amplification mechanism based on a microelectromechanical system (MEMS). The mechanism, compared to generic displacement mechanisms, is smaller and capable of amplifying input displacement by a factor of 6.8. Finite element analysis (FEA) is performed with commercial software Intellisuite using the extended finite element method (XFEM) technique to verify the analytical results from mathematical models. Kinematic response and kinematic sensitivity analysis of the amplification mechanism are computationally carried out to predict the effect of different geometric parameters on the performance of the proposed mechanism. The analysis predicts that length and angle of flexure are the two key geometric parameters significantly affecting the amplification factor (AF), with length having a direct relationship and angle of flexure having an inverse relationship. A significant increase in the AF is seen for a flexure length up to 550 μm and angle below 5°. Based on the sensitivity analysis, the design is optimized, and geometric parameters are finalized. Modal analysis and dynamic simulations, including direct-integration transient and steady-state modal analysis, are performed on the mechanism under the application of 25 g. The mechanism can be integrated with any conventional actuating mechanism in a microsystem where the amplification of a small displacement at the output is desired.

Modelling and Analysis of Characteristics of a Piezoelectric-Actuated Micro-/Nano Compliant Platform Using Bond Graph Approach.

The piezoelectric-actuated flexure-based compliant platform is commonly adopted in many fields of micro and nanotechnology. In this paper, bond graph modeling, and kinematic and dynamic characteristics of a piezoelectric-actuated micro-/nano compliant platform system are investigated. During modeling, the bond graph model of the piezoelectric actuator (PZT) is derived by considering both the electrical domain and the mechanical domain. Considering the compliances of flexure hinges and elastic linkages, as well as the input ends, the bond graph model for the bridge-type displacement amplification mechanism in the compliant platform is established by combining pseudo-rigid-body (PRB) model theory and elastic beam theory. Based on the interactions between the PZT subsystem and compliant platform subsystem, the kinematic performance of the proposed compliant platform system is evaluated through both computer simulations and experimental tests. Furthermore, the frequency responses, dynamic responses and load capacity of the compliant platform system are studied. This paper explores a new modeling method for a piezoelectric-actuated compliant platform system, which can provide an effective solution when analyzing the micro-/nano system.

Design, analysis and validation of the bridge-type displacement amplification mechanism with circular-axis leaf-type flexure hinges for micro-grasping system

For stable and flexible manipulation, realizing parallel grasping and large output stroke simultaneously has become a key issue in the researches on micro-grasping system. The typical solution is to use compliant orthogonal displacement amplification mechanism (such as bridge-type mechanism), in which the flexure hinges are generally axial load-dominated, whereas the deflection of traditional straight-axis flexure hinges is not related to the axial load under small deflection assumption. In this study, a bridge-type mechanism with circular-axis leaf-type (CALT) flexure hinges is designed, analyzed and validated. Through modeling the generalized displacements of CALT flexure hinge, the positive direction of its axis in the bridge-type mechanism is designed. The precise models of load relations for the CALT flexure hinges in the bridge-type DAM are established, and the multi-objective parametric optimization is further given. Small deflection-based static FEA results verify the generalized displacements’ models of CALT flexure hinge as well as the parametric optimization result. Compared with the corresponding bridge-type mechanism with the largest output displacement in the traditional researches, the output displacement of optimal result is improved effectively. For the design validation, the optimal design result is further applied to construct a piezoelectric-driven microgripper, which grasps parallelly and enlarges the output stroke simultaneously.

Design and analysis of novel micro displacement amplification mechanism actuated by chevron shaped thermal actuators

This paper presents design and analysis of microelectromechanical system (MEMS) based displacement amplification mechanism actuated using thermal actuators with enhanced performance. The proposed model consists of chevron shaped thermal actuators, an amplification mechanism capable of amplifying displacement 20 times and an electrostatic comb drives for sensing displacements. When voltage is applied to thermal chevrons, displacement is produced which is then amplified 20 times. Steady state static thermal electrical analysis is performed under variable resistivity and voltage bias of 2 V. In-plane reaction forces of magnitude 194.2 and 150.91 µN along X and Y-axis, respectively, thus producing displacement of 0.11 and 2.22 µm along X and Y-axis, respectively. Time domain simulations of device are carried with constant electrical resistivity, variable voltage and convective boundary conditions. Modal analysis of the mechanism is carried out to predict the natural frequencies and associated mode shapes of mechanism during free vibrations. The desired mode is at frequency of 286.160 kHz. Dynamic simulations including direct integration-transient, transient modal and steady state modal analysis are performed on the device for time span of 0.0006 s, under application of 25 g and frequency range of 200–300 kHz. Simulation results prove the viability of the mechanism as an amplification device with enhanced voltage–stroke ratio.

Performance Analysis of Microelectromechanical System Based Displacement Amplification Mechanism

Design and analysis of microelectromechanical system based displacement amplification mechanism (MDAM) using analytical and finite element method is presented in this paper. The mechanism consists of side masses, microflexures, and microhinges with one end constrained and the other free. The MDAM acts as a displacement amplification device in a direction perpendicular to the applied displacement direction. The mechanism is modeled and analyzed using the Kane’s approach for solving kinematics, which is then used with Castigliano’s approach to develop a modified kinetic model. Modal and dynamic analyses of the mechanism are carried out to predict the natural frequencies and behavior of mechanism under application of dynamic loads. The extended finite element method (XFEM-using commercial software IntelliSuite®) is used for validation of mathematical models developed. Kinematic sensitivity and performance analysis of the proposed mechanism is carried out to predict the behavior of MDAM. Analyses results demonstrate the viability of mechanism as a displacement amplification device. An amplification factor of 10 is achieved. Effect of different performance parameters like width, length, angle, and thickness of flexures upon the output force and displacement is also part of this research work. Results predicted by analytical model and numerical simulations were found to be in close agreement. The MDAM can be used independently or in combination with other compliant mechanisms to amplify displacements. This amplification mechanism can be integrated with any conventional actuation as well as sensing mechanism in a microsystem where amplified displacement is desired for improved sensitivity and performance.

Musclelike joint mechanism driven by dielectric elastomer actuator for robotic applications

The purpose of this study is to develop an artificial muscle actuator suitable for robotic applications, and to demonstrate the feasibility of applying this actuator to an arm mechanism, and controlling it delicately and smoothly like a human being. To accomplish this, we perform the procedures that integrate the soft actuator, called the single body dielectric elastomer actuator, which is very flexible and capable of high speed operation, and the displacement amplification mechanism called the sliding filament joint mechanism, which mimics the sliding filament model of human muscles. In this paper, we describe the characteristics and control method of the actuation system that consists of actuator, mechanism, and embedded controller, and show the experimental results of the closed-loop position and static stiffness control of the robotic arm application. Finally, based on the results, we evaluate the performance of this application.

High-frequency performance for a spiral-shaped piezoelectric bimorph

Piezoelectric cantilever is suitable as an actuator for micro-flapping-wing aircraft. Higher resonant frequency brings about stronger flight energy, and the flight amplitude can be compensated by displacement–amplification mechanism, such as lever. To obtain a higher resonant frequency, straight piezoelectric bimorph was rolled into spiral-shaped piezoelectric bimorph with identical effective length in this study, which is verified in COMSOL simulations. Simulation results show that compared with the straight piezoelectric bimorph, the spiral-shaped piezoelectric bimorph with two turns has higher inherent frequencies (from 204.79 Hz to 504.84 Hz in terms of axial oscillation mode, and from 319.77 Hz to 704.48 Hz in terms of tangential torsional mode). The spiral-shaped piezoelectric bimorph is fabricated by a precise laser cutting process and consists of two turns with effective length of 60 mm, width of 2.5 mm, and thickness of 1.6 mm, respectively. With the excitation voltage of 100 Vpp applying an electric field across the thickness of the bimorph, the tip displacement of the actuator in the axial oscillation and tangential torsional modes are 85 [Formula: see text]m and 15 [Formula: see text]m, respectively.

Enhanced thermal expansion by micro-displacement amplifying mechanical metamaterial

ABSTRACTIt is important to achieve materials with large coefficient of thermal expansion in science and engineering applications. In this paper, we propose an experimentally-validated metamaterial approach to amplify the thermal expansion of materials based on the guiding principles of flexible hinges and displacement amplification mechanism. The thermal expansion property of the designed metamaterial is demonstrated by simulation and experiment with a temperature increase of 245 K for the two-dimensional sample. Both experimental and simulation results display amplified thermal expansion property of the metamaterial. The effective coefficient of thermal expansion of the metamaterials is demonstrated to be dependent on the size parameters of the structure, which means by appropriately tailoring these parameters, the thermal expansion of materials could be amplified with different amplification factor. This work provides an important method to control the thermal expansion coefficient of materials and could be applied in various industry domain.

Application for aerogenerator of vibration control device with displacement amplification mechanism

Application for aerogenerator of vibration control device with displacement amplification mechanism

Design, modeling and testing of a novel flexure-based displacement amplification mechanism

This paper presents a novel flexure-based displacement amplification mechanism to increase the effective actuation stroke of piezoelectric actuator. The proposed mechanism consists of two L-shape lever-type mechanism and one bridge-type mechanism. The flexure hinges in this mechanism are all loaded in tension and bending, which can solve the potential buckling problems. The symmetrical distribution of the L-shape lever mechanisms can avoid the bending moments and lateral forces at the driving end to protect the piezoelectric actuator. An analytical model based on the stiffness matrix method for the calculations of displacement amplification ratio, input stiffness and natural frequency of the mechanism is constructed and optimal design is performed under certain constraints. The finite element analysis results are then given to validate the design model and a prototype of the amplification mechanism is fabricated for performances tests. The results of static and dynamic tests show that the proposed mechanism is capable of travel range of 288.3μm with motion resolution of 50nm, and the working resonance frequencies of the mechanism without and with the actuator mounted are 155Hz and 178Hz, respectively. The finite element analysis and the experimental results show that good static and dynamic performances are achieved, which verifies the effectiveness of the proposed mechanism.

Nonlinear analysis and optimal design of a novel piezoelectric-driven compliant microgripper

In a piezoelectric-driven microgripper, obtaining parallel grasping and enlarging grasping stroke are important. This paper presents the nonlinear analysis and optimal design of a novel orthogonal displacement amplification mechanism (DAM)-based piezoelectric-driven microgripper without using traditional bridge-type mechanism or multi-stages DAM, which realizes parallel grasping and displacement amplification simultaneously in compact configuration and benefits further miniaturization. The structural design of proposed microgripper is given, in which a novel orthogonal DAM is used as the intermediate mechanism. The geometrical nonlinearity analysis of novel orthogonal DAM is conducted, including the finite difference-based analysis, the variance-based global sensitivity analysis and the correlation analysis. Based on the nonlinear analysis results, a static constraint restricting the large deflection geometrical nonlinearity degree is established. An optimal design framework of the proposed microgripper is further formulated, which maximizes the grasping movements with considering the property of piezoelectric stack actuator, the nonlinear geometric constraints, the established static constraints as well as the dynamic constraint. A design example verifies the optimal design framework, which can reduce the negative effect of large deflection nonlinearity on the orthogonal movement transformation without requiring specific experience. Experimental tests are used to verify the parallel grasping and the displacement amplification of microgripper.

電磁吸引力を用いたアクチュエータにおける変位拡大率と動作時間の関係の実験的検証

Displacement amplified electromagnetic actuators are developed for efficient use of the electromagnetic attractive force by applying displacement amplification mechanisms. Although these actuators are expected to realize faster drive than actuators directly using the electromagnetic attractive force without displacement amplification, both theoretical and experimental verifications have not been conducted yet in detail. This paper introduces an experimental verification of the effect of amplification ratio to the actuation time. A measurement system for the experimental verification was developed. The results of the experiment showed that application of displace amplification to the electromagnetic attractive force reduces the actuation time under the adequate conditions.

A novel microgripper hybrid driven by a piezoelectric stack actuator and piezoelectric cantilever actuators.

For the piezo-driven microgripper, one issue is to enlarge the grasping stroke and realize parallel grasping movement in the compact design. Piezoelectric stack actuator (PSA) and piezoelectric cantilever actuator (PCA) are two kinds of typical piezoelectric actuators. In this study, a novel microgripper hybrid driven by a PSA and two PCAs is proposed, which can be a better solution for the issue, compared with the previous microgripper using PSA-driven multi-stages displacement amplification mechanism (DAM) or using longer and narrower PCAs. A compact one-stage orthogonal DAM is proposed for the PSA in the microgripper, which can enlarge the grasping stroke and realize parallel grasping movement. The proposed orthogonal DAM is a triangulation amplification-based mechanism with undetermined structural parameters. Bidirectional symmetric input forces/displacements are not required in the proposed design. The number of the undetermined parameters and the solution principle are analyzed. Finite element analysis is used to verify the proposed DAM. The gripper arms are designed as two PCAs, for which the grasping and parasitic movements of the free end are modeled. Piezoelectric-static coupling finite element analysis is used to verify the models. The PCAs-driven grasping with considerable parasitic movement can be used in the coarse positioning. The integration of the hybrid-driven microgripper is presented, and its performances are presented and verified by experiments.

Magnetostrictive actuator with differential displacement amplification mechanism

In light of the contradiction between stroke and accuracy of current actuators, a high precision, large displacement actuator was designed. Rare earth giant magnetostrictive material was used as the driving source and the displacement differential amplification was based on a flexure hinge. A magnetic circuit and driving magnetic field was designed with the characteristics of magnetostrictive drive. The axial pre-pressure of the magnetostrictive rod was supported by a cylindrical helical spring and a displacement amplification mechanism. A new type of differential amplification device was projected by the flexible hinge. The convex desktop splint fixed displacement amplification mechanism was adopted to enlarge the magnetostrictive’s small displacement. After the actuator prototype was manufactured and the test platform was established, the output characteristics and amplification mechanism performance were analyzed. Results showed that under the condition of 0 to 4 input current, the maximum displacement was 158.4 μm and the magnification was 7.14. DOI: http://dx.doi.org/10.5755/j01.mech.22.4.16166

Design and Static Magnetic Analysis of Magnetostrictive (Tb<sub>0.3</sub>Dy<sub>0.7</sub>Fe<sub>1.95</sub>) Fuel Injector with Flexible Piston Hydraulic Displacement Amplification

This paper presents the conceptual design of fuel injector based on giant magnetostrictive material, with displacement amplification mechanism. The permissible emission level EURO norms become stricter in case of fuel injection technology of modern combustion engine. The magnetic circuit of the magnetostrictive fuel injector is analyzed using finite element method. Based on the structure and working principle of our magnetostrictive fuel injector (MFI), the properties of driving magnetic field are researched.

Compact piezoelectric tripod manipulator based on a reverse bridge-type amplification mechanism

We report a hierarchical piezoelectric tripod manipulator based on a reverse bridge-type displacement amplifier. The reverse bridge-type amplification mechanism is pre-strained by each piezo-stack actuator up to 60 μm and is cross-stacked in a series arrangement to make a compact and high-stroke manipulator having load-bearing characteristics. The designed manipulator with three degrees of freedom is compact with a height of 56.0 mm, a diameter of 48.6 mm and total weight of 115 g. It achieves a translational stroke of up to 880 μm in heaving motion and a tilting angle of up to 2.0° in rotational motion within the operating voltage and power range of the piezoelectric stack actuator. A key feature of the present design is built-in and pre-strained displacement amplification mechanisms integrated with piezoelectric stacked actuators, resulting in a compact tripod manipulator having exceptionally high stroke and load-bearing capacity.

Design, modeling and test of a novel compliant orthogonal displacement amplification mechanism for the compact micro-grasping system

In the compact micro-grasping system, the combination of precisely orthogonal movement transformation, displacement amplification and simple structure is important. The typical solution of the combination issue requires bidirectional symmetric input forces/displacements. However, under a certain driving condition, numerous actuators used in micro-manipulation only supply unidirectional input froce/displacement for the driven mechanism, which makes the typical solution infeasible. In this study, a novel compliant orthogonal displacement amplification mechanism (DAM) is proposed to solve the combination issue for numerous actuators used in micro-grasping. The proposed mechanism is a triangulation amplification-based mechanism with undetermined structural parameters. The number of the undetermined parameters and the solution principle are analyzed. The design process is presented. Finite element analysis (FEA) is used to verify the design method. The FEA results show that, for the design examples, the errors evaluating the orthogonal movement transformation are smaller than 0.56ź% and 0.15 % respectively, and the displacement amplification ratios are larger than 4.6. The orthogonal displacement amplification is realized. A precise model of the displacement amplification ratio is derived. The dynamic performances of the proposed orthogonal DAM are modeled and FEA verified. Furthermore, a microgripper utilizing the proposed mechanism is presented. The performances of the gripper, including the displacement amplification and the parallel movement of the jaws, are verified by FEA and experiments.