Search results

Generally, the motion range of the micro scale operation is within several hundreds of microns, and the conventional joints cannot satisfy the requirements due to manufacturing and assembling errors, hysteresis and backlash in the joints. The paper aims to discuss these issues.

The following issues should be considered: a micromanipulation stage should be designed using a small-dimensional scale driven by the small size of piezoelectric actuator and the components can be replaced due to fatigue failure caused by repeated cyclic loading. This paper proposes a modular design of a flexure-based 2-DOF precision stage made using aluminum (T6-7075) material and Acrylonitrile Butadiene Styrene plastic material. The piezoelectric actuator is adopted to drive the stage for the fast response and large output force. To compensate the stroke of piezoelectric actuator, a bridge-type amplifier is designed with optimized structure.

The simulation results validate the advantages of modular positioning stage fabricated by two different materials.

The stage can be used in micro scale precision’s applications. If it will be used in nanoscale precision, then some sensors in nanoscale of measurement should be used.

The designed stage can be used in biomedical engineering, such as cell injection testing, etc.

The designed stage will be used in micro/nanoengineering field, such as micro/nanomanufacturing or assembly, manipulation of cell, etc., which will push forward high technology to a higher level.

Two kinds of materials have been selected to make the positioning stage, which are seldomly found in literature on compliant mechanism field. A modular design concept is proposed for the positioning stage design.

Micromanipulation has enabled numerous technological breakthroughs in recent years, from advances in biotechnology to microcomponent assembly. Micromotion devices commonly use piezoelectric actuators (PZT) together with compliant mechanisms to provide fine motions with position resolution in the nanometre or even sub‐nanometre range. Many multiple degree of freedom (DOF) micromotion stages have parallel structures due to better stiffness and accuracy than serial structures. This paper presents the development of a three‐DOF compliant micromotion stage with flexure hinges and parallel structure for applications requiring motions in micrometres. The derivation of a simple linear kinematic model of the compliant mechanism is presented and simulation results before and after calibration are compared with results from finite element (FE) modeling and experiments. The position control system, which uses an experimentally determined constant‐Jacobian, and its performance are also presented and discussed.

Compliant mechanism has been receiving a great interest in precision engineering. However, analytical methods involving their behavior analysis is still a challenge because there are unclear kinematic behaviors. Especially, design optimization for compliant mechanisms becomes an important task when the problem is more and more complex. Therefore, the purpose of this study is to design a new hybrid computational method. The hybridized method is an integration of statistics, numerical method, computational intelligence and optimization.

A tensural bistable compliant mechanism is used to clarify the efficiency of the developed method. A pseudo model of the mechanism is designed and simulations are planned to retrieve the data sets. Main contributions of design variables are analyzed by analysis of variance to initialize several new populations. Next, objective functions are transformed into the desirability, which are inputs of the fuzzy inference system (FIS). The FIS modeling is aimed to initialize a single-combined objective function (SCOF). Subsequently, adaptive neuro-fuzzy inference system is developed to modeling a relation of the main geometrical parameters and the SCOF. Finally, the SCOF is maximized by lightning attachment procedure optimization algorithm to yield a global optimality.

The results prove that the present method is better than a combination of fuzzy logic and Taguchi. The present method is also superior to other algorithms by conducting non-parameter tests. The proposed computational method is a usefully systematic method that can be applied to compliant mechanisms with complex structures and multiple-constrained optimization problems.

The novelty of this work is to make a new approach by combining statistical techniques, numerical method, computational intelligence and metaheuristic algorithm. The feasibility of the method is capable of solving a multi-objective optimization problem for compliant mechanisms with nonlinear complexity.

High precision robots are often used for complex assembly or positioning tasks. One way to achieve high motion precision is to design mechanical systems based on flexure joints. Flexure joints (or flexures) utilize the elastic properties of matter, which brings avoidance of dry friction. Nanometer scale motions are then possible, without wear, mechanical play or particle emission. Leading to high performance systems in terms of dynamics, parallel kinematics are useful for high precision robot design. Two research projects are presented in this paper. The first one has already led to the realization of a micro electro‐discharge machine (μ‐EDM), and the second one’s goal is to generate a family of compact ultra‐high precision manipulators.

Aims to discuss how a Cartesian parallel robot with flexure revolute joints can effectively perform miniaturized assembly tasks.

The results of the test and validation phase of a Cartesian parallel robot designed for miniaturized assembly are shown. The workspace volume is a cube with 30 mm side and the target accuracy is 1 μm. Each of the three robot legs has a prismatic‐planar architecture, with a cog‐free linear motor and a planar joint realized using ten superelastic flexure revolute joints. Flexure joints are adopted in order to avoid stick‐slip phenomena and reach high positioning accuracy; their patented construction is relatively low‐cost and allows a quick replacement in case of fatigue failure.

The tests on the prototype are very encouraging: the measured positioning accuracy of the linear motors is ±0.5 μm; on the other hand, the effects of unwanted rotations of flexure joints and hysteresis of the superelastic material are not negligible and must be properly compensated for in order to fully exploit the potential performance of the machine.

The introduction of this robotic architecture can fulfil the needs of a wide range of industrial miniaturized assembly applications, thanks to its accurate positioning in a relatively large workspace. The cost of the machine is low thanks to its extreme modularity.

The combination of Cartesian parallel kinematics, cog‐free linear motors and superelastic flexure revolute joints allows one to obtain very good positioning performance.

The purpose of this paper is to present a design and verification through experiments of teleoperation of the 3 degrees‐of‐freedom micromanipulation system (MMS), in laboratory conditions.

The MMS is constructed from piezoelectric actuators sited in a flexure hinge mechanism. The nonlinearity, especially hysteresis, due to a voltage steering scheme is compensated for, via a second‐order Dahl friction model. A simple mechanical model is then constructed to capture the behavior of the MMS. Redundant force feedback sensors are applied to the MMS in order to achieve flexible operation via the so‐called fault‐tolerancing mechanism. Finally, a teleoperation scheme based on passivity formalism is proposed to achieve a stable teleoperation system.

The hysteresis curve due to voltage steering can be minimized. The fault‐tolerancing concept using redundant sensors for comfortable use of the MMS has been successfully performed. The teleoperated MMS via a commercially available PHANToM^® has been conducted under ineligible telecommunication channel delay.

The details of design, modelling and experimentations of the teleoperation of the MMS should promote the applicability of similar systems in the future.

This paper aims to improve the kinematic modeling accuracy of a spatial three-degrees-of-freedom compliant micro-motion parallel mechanism by proposing a modified modeling method based on the structural matrix method (SMM).

This paper analyzes the problem that the torsional compliance equation of the circular notched hinge is no longer applicable because it is subject to bilateral restrained torsion. The torsional compliance equation is modified by introducing the relative length coefficient. The input coupling effect, which is often neglected, is considered in kinematic modeling. The symbolic expression of the input coupling matrix is obtained. Theory, simulation and experimentation are presented to show the validity of the proposed kinematic model.

The results show that the proposed kinematics model can improve the modeling accuracy by comparing the theoretical, finite element method (FEM) and experimental method.

This work provides a feasible scheme for CMPM kinematics modeling. It can be better applied to the optimization design based on the kinematic model in the future.

This study aims to address the issue of high-precision measurement of AC electric field. An electro-optical sensor with high sensitivity is proposed for this purpose.

The proposed sensor combines electromagnetic induction and fiber Bragg grating (FBG) sensing techniques. It is composed of a sensing probe, a piece or stack of piezoelectric ceramics (PZT) and an FBG. A signal processing circuit is designed to rectify and amplify the induced voltage. The processed signal is applied to the PZT and the deformation of PZT is detected by FBG. Theoretical calculation and simulation are conducted to verify the working principle of the probe. The sensor prototype is fabricated and its performance is tested.

The results of this study show that the sensor has good linearity and repeatability. The sensor sensitivity is 0.061 pm/Vm⁻¹ in the range from 250 to 17,500 V/m, enabling a measurement resolution of electric field strength of 16.3 V/m. The PZT stack is used to enhance the sensor sensitivity and the resolution can be improved up to 3.15 V/m.

A flexure hinge lever mechanism is used to amplify the deformation of PZT for further enhancement of sensitivity. The results show that the proposed sensor has high sensitivity and can be used for the accurate measurement of an electric field. The proposed sensor could have potential use for electric field measurement in the power industry.

Aims to research the possibilities of using piezoelectric technology to improve accuracy and other characteristics of parallel servo grippers.

The paper presents in detail two different kinds of developed two‐fingered servo grippers based on piezoelectric technology with parallel moving mechanics. The first gripper is based on standing wave ultrasonic motors. The other gripper is a traditional gripper, the characteristics of which have been improved with integrated piezoelectric stack actuators. Both servo grippers have been tested and the test results and experiences are introduced in the paper.

It is possible to improve the accuracy and characteristics of a parallel servo gripper with piezoelectric technology.

In the future it is necessary to concentrate on the mechanical design of gripper bodies and the fingers. Grasping force feedback signal should be even more linear and noiseless.

Piezoelectric stack actuator's limited displacement is a problem in many practical applications when elastic or rough surface parts are handled. When integrated piezoelectric stacks are used with servo grippers, it is very important to focus on gripper's mechanical design and especially on the mechanical rigidity for getting the best possible results.

Further developed versions of these servo grippers can be used in high accuracy industry applications instead of traditional servo gripper technologies.

To provide an overview of how the solid‐to‐solid contact force equation in MSC.ADAMS can be used to reduce contact model development, minimize the probability of introducing an error and reduce simulation run time by citing the example of the International Space Station (ISS).Design/methodology/approach – In early 2000, a redesign of the ISS required a more thorough representation of the contacting geometry. The MSC.ADAMS solid to solid contact force statement became available in time to solve this problem. This allowed simulation of the segment to segment attachment, including various combinations of contact feature misalignment.Findings – A structural failure of a “Zip” nut during qualification testing resulted in a NASA request for a force balance on the nut housing, internal nut segments and bolt. Using MSC.ADAMS solid to solid contact simulation, the desired force balance was obtained. The analysis showed the coarse guide to fine guide handoff did not bind and fine guide seating engaged, allowing the four motorized bolts to connect the segment‐to‐segment interface.Originality/value – MSC.ADAMS solid to solid contact algorithms decreased simulation time, allowing this very complicated contact problem to be completed in less than 30 min. Using CAD model solid geometry greatly reduced model development time. Solid to solid contact simulation eliminated the need for tedious derivation vector algebra contact equations and greatly advanced the level of geometric complexity that could be modeled as contacting interfaces. This also minimizes the probably of errors.