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Article
Publication date: 29 July 2014

Xin Ye, Jun Gao, Zhijing Zhang, Chao Shao and Guangyuan Shao

The purpose of this paper is to propose a sub-pixel calibration method for a microassembly system with coaxial alignment function (MSCA) because traditional sub-pixel…

Abstract

Purpose

The purpose of this paper is to propose a sub-pixel calibration method for a microassembly system with coaxial alignment function (MSCA) because traditional sub-pixel calibration approaches cannot be used in this system.

Design/methodology/approach

The in-house microassembly system comprises a six degrees of freedom (6-DOF) large motion serial robot with microgrippers, a hexapod 6-DOF precision alignment worktable and a vision system whose optical axis of the microscope is parallel with the horizontal plane. A prism with special coating is fixed in front of the objective lens; thus, two parts’ Figures, namely the images of target and base part, can be acquired simultaneously. The relative discrepancy between the two parts can be calculated from image plane coordinate instead of calculating space transformation matrix. Therefore, the traditional calibration method cannot be applied in this microassembly system. An improved calibration method including the check corner detection solves the distortion coefficient conversely. This new way can detect the corner at sub-pixel accuracy. The experiment proves that the assembly accuracy of the coaxial microassembly system which has been calibrated by the new method can reach micrometer level.

Findings

The calibration results indicate that solving the distortion conversely could improve the assembly accuracy of MSCA.

Originality/value

The paper provides certain calibration methodological guidelines for devices with 2 dimensions or 2.5 dimensions, such as microelectromechanical systems devices, using MSCA.

Details

Assembly Automation, vol. 34 no. 3
Type: Research Article
ISSN: 0144-5154

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Article
Publication date: 16 March 2015

Xin Ye, Jun Gao, Zhijing Zhang, Chao Shao and Pan Liu

The purpose of this paper is to design and develop 14-degree of freedom (DOF) robotic micromanipulator with which LIGA devices and axle hole part can be both manipulated…

Abstract

Purpose

The purpose of this paper is to design and develop 14-degree of freedom (DOF) robotic micromanipulator with which LIGA devices and axle hole part can be both manipulated and assembled.

Design/methodology/approach

The in-house robotic microassembly system is composed of a 6-DOF large motion serial robot with microgrippers, a hexapod six-DOF precision alignment worktable and a vision system whose optical axis of the microscope is parallel with the horizontal plane. A prism with special coating is fixed in front of the objective lens, thus, two-part figures can be acquired simultaneously by the microscope with 1.67 to 9.26 micron optical resolution. The relative discrepancy between the two parts can be calculated from image plane coordinate instead of calculating the space transformation matrix. A modified microgripper was designed to clamp meso-scale parts and its effectiveness was confirmed experimentally. Through the use of the other vision system, the insert action can be successfully manipulated. A laser ranger finder was integrated in this micro-assembly system to measure the assembly result.

Findings

A new 14-DOF robotic micromanipulator, including eight axes automatically and six axes manually, has been developed for the assembly of LIGA meso-scale flat parts and axle hole parts. The microassembly system with coaxial alignment function (MSCA) system is able to concurrently manipulate all eight axes automatically and six axes manually.

Originality/value

The robotic microassembly is applied in the assembly of meso-scale parts. The new capabilities of the MSCA will allow for the assembly of microsystems more efficiently and more precisely.

Details

Industrial Robot: An International Journal, vol. 42 no. 2
Type: Research Article
ISSN: 0143-991X

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Article
Publication date: 3 August 2010

Luca Bruzzone and Giorgio Bozzini

The purpose of this paper is to report research which led to the realization of a robot for miniaturized assembly endowed with high‐accuracy and high‐operative flexibility.

Abstract

Purpose

The purpose of this paper is to report research which led to the realization of a robot for miniaturized assembly endowed with high‐accuracy and high‐operative flexibility.

Design/methodology/approach

The proposed solution is a microassembly system composed of a Cartesian parallel robot with flexure revolute joints and a modular gripper with metamorphic fingertips, capable of adapting their shape to different micro‐objects. The fingertips are realized by electro‐discharge machining from a sheet of superelastic alloy. Thanks to its modularity, the gripper can be arranged with two opposite fingers or three fingers placed at 120°. The fingers are actuated by a piezoelectric linear motor with nanometric accuracy.

Findings

The experimental results on the prototype are very interesting. The measured positioning accuracy of the linear motors is 0.5 μm; the end‐effector positioning accuracy is lower, due to the non‐perfect kinematics and hysteresis of the flexure joints; however, these effects can be compensated by the direct measurement of the end effector position or by visual feedback. The metamorphic design of the fingertips remarkably increases the grasping force; moreover, the grasping is more stable and reliable.

Practical implications

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

Originality/value

The combination of Cartesian parallel kinematics, cog‐free linear motors and superelastic flexure revolute joints allows one to obtain high‐positioning accuracy; the metamorphic fingertips enhance the grasping effectiveness and flexibility.

Details

Assembly Automation, vol. 30 no. 3
Type: Research Article
ISSN: 0144-5154

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Article
Publication date: 9 September 2014

Xin Ye, Chao Shao, Zhijing Zhang, Jun Gao and Yang Yu

– The purpose of this paper is to design a microgripper that can achieve nondestructive gripping of a miniaturized ultra-thin-walled cylindrical part.

Abstract

Purpose

The purpose of this paper is to design a microgripper that can achieve nondestructive gripping of a miniaturized ultra-thin-walled cylindrical part.

Design/methodology/approach

The microgripper is mainly made of an inflatable silica gel gasbag, which can minimize the damage to the part in the gripping process. This paper introduces the design principle of a flexible air-filled microgripper, which is applied in an in-house microassembly system with coaxial alignment function. Its parameters and performance specifications have been obtained by simulation, experiment demarcating. The results show that the microgripper is able to grasp an ultra-thin-walled part non-destructively.

Findings

For the microgripper, finite element simulations and experiments were carried out, and both results indicate that the microgripper can achieve nondestructive gripping of a miniaturized ultra-thin-walled cylindrical part, with good stability, great grasping force and high repeat positioning accuracy.

Originality/value

Gripping the ultra-thin-walled part may lead to deformation and destruction easily. It has been a big bottleneck hindering successful assembly. This article introduces a novel microgripper using an inflatable sac. The work is interesting from an industrial point of view for a specific category of assembly applications. It provides a theoretical guidance and technical support to design a microgripper for a miniaturized ultra-thin-walled part of different sizes.

Details

Assembly Automation, vol. 34 no. 4
Type: Research Article
ISSN: 0144-5154

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Article
Publication date: 1 February 2016

Xin Ye, Pan Liu, Zhijing Zhang, Chao Shao and Yan Li

The purpose of this paper is to analyze the sensitivity of the motion error parameters in microassembly process, thereby improving the assembly accuracy. The motion errors…

Abstract

Purpose

The purpose of this paper is to analyze the sensitivity of the motion error parameters in microassembly process, thereby improving the assembly accuracy. The motion errors of the precision motion stages directly affect the final assembly quality after the machine visual alignment.

Design/methodology/approach

This paper presents the error parameters of the in-house microassembly system with coaxial alignment function, builds the error transfer model by the multi-body system theory, analyzes the error sensitivity on the sensitive direction using the Sobol method, which was based on variance, and then gets the ones which made a great degree of influence. Before the sensitivity analyzing, parts of the error sources have been measured to obtain their distribution ranges.

Findings

The results of the sensitivity analysis by the Sobol method, which was based on variance, are coincident with the theoretical analysis. Besides, the results provide a reference for the error compensation in control process, for the selection of the precision motion stages and for the installation index of the motion stages of the assembly system with coaxial alignment.

Originality/value

This kind of error sensitivity analysis method is of great significance for improving the assembly accuracy after visual system positioning, and increasing efficiency from the initial motion stage selection to final error compensation for designers. It is suitable for general precision motion systems be of multi-degree of freedom, for the method of modeling, measuring and analyzing used in this paper are all universal and applicative.

Details

Assembly Automation, vol. 36 no. 1
Type: Research Article
ISSN: 0144-5154

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Article
Publication date: 1 September 2004

Yantao Shen, Ning Xi, King W.C. Lai and Wen J. Li

This paper presents our development of a novel force and force rate sensory system to advance applications in micromanipulation using an in situ polyvinylidene fluoride…

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Abstract

This paper presents our development of a novel force and force rate sensory system to advance applications in micromanipulation using an in situ polyvinylidene fluoride (PVDF) piezoelectric sensor. To allow close monitoring of magnitude and direction of microforces acting on microdevices during manipulation, PVDF ploymer films are used to fabricate highly sensitive 1D and 2D sensors to detect real‐time microforce and force rate information during the manipulation process. The sensory system with a resolution in the range of sub‐micronewtons can be applied effectively to develop a technology on the force‐reflection microassembly of surface MEMS structures. In addition, a tele‐micromanipulation platform, which can be used to perform tele‐microassembly of the MEMS structures and tele‐cell‐manipulation with force/haptic feedback via Internet was also built successfully.

Details

Sensor Review, vol. 24 no. 3
Type: Research Article
ISSN: 0260-2288

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Article
Publication date: 5 September 2016

Chao Shao, Xin Ye, Zhijing Zhang, Dengyu Zhou and Yuhong Liu

Micro ultra-thin tubes have important implications in aerospace, nuclear energy and other fields. In microassembly process, these parts are characterized by following…

Abstract

Purpose

Micro ultra-thin tubes have important implications in aerospace, nuclear energy and other fields. In microassembly process, these parts are characterized by following reasons: the small size can easily lead to damage when gripping, even for low intensity and the parts are mainly affected by the instability of light source, for vision-based systems, the visual information about ultra-thin tubes is difficult to gather and the contact state is hard to monitor.

Design/methodology/approach

The paper presents a new method to adjust the position deviations based on contact forces during microassembly processes. Specific research is such that the assembly model was established based both on mechanic calculation and numerical simulation; the assembly task was carried out on an in-house microassembly system with coaxial alignment function (MSCA), the contact statements were controlled based on force sensor feedback signals and the model of the relationship between contact force and assembly deviations was established. Through a comparative study, the results of experiment and simulation differ by less than 11 per cent, validating the accuracy and feasibility of the method.

Findings

The model of assembly force and position deviations of micro ultra-thin tubes based on MSCA has been built. Besides, the assembly force threshold, and the assembly process parameters have been obtained.

Originality/value

The assembly process parameters obtained from experiments can be applied in the precision assembly and provide theoretical guidance and technical support to the precision assembly of the multi-scale parts.

Details

Assembly Automation, vol. 36 no. 4
Type: Research Article
ISSN: 0144-5154

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Article
Publication date: 1 September 2004

Yantao Shen, Ning Xi, King W.C. Lai and Wen J. Li

This paper presents our development of a novel Internet‐based E‐manufacturing system to advance applications in micromanipulation and microassembly using an in situ

Abstract

This paper presents our development of a novel Internet‐based E‐manufacturing system to advance applications in micromanipulation and microassembly using an in situ polyvinylidene fluoride (PVDF) piezoelectric sensor. In this system, to allow close monitoring of magnitude and direction of microforces (adhesion, surface tension, friction, and assembly forces) acting on microdevices during assembly, the PVDF polymer films are used to fabricate the highly sensitive 1D and 2D sensors, which can detect the real‐time microforce and force rate information during assembly processes. This technology has been successfully used to perform a tele‐assembly of the surface MEMS structures with force/visual feedback via Internet between USA and Hong Kong. Ultimately, this E‐manufacture system will provide a critical and major step towards the development of automated micromanufacturing processes for batch assembly of microdevices.

Details

Assembly Automation, vol. 24 no. 3
Type: Research Article
ISSN: 0144-5154

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Article
Publication date: 27 September 2011

Robert Bogue

The purpose of this paper is to review recent developments in micro‐scale assembly technologies, primarily in the context of microsystems based on three‐dimensional (3D…

Abstract

Purpose

The purpose of this paper is to review recent developments in micro‐scale assembly technologies, primarily in the context of microsystems based on three‐dimensional (3D) micro‐electromechanical systems (MEMS) and micro‐opto‐electromechanical systems (MOEMS) technologies.

Design/methodology/approach

Following a brief introduction, this paper first discusses the problems associated with the assembly of micro‐components and then considers the role of robots and self‐assembly technologies. This is followed by a brief summary and conclusion.

Findings

Experimental robotic systems have been developed and used for the assembly of a wide range of MEMS and MOEMS components. Various self‐assembly technologies offer prospects for massively parallel microassembly but have yet to achieve the success of the robotic approach. Some work has sought to combine the best feature of both approaches but as yet, no technologies have been developed that can rapidly, accurately and cost‐effectively assemble micro‐components into hybrid 3D MEMS/MOEMS devices in a true production environment.

Originality/value

This paper provides a detailed review of recent progress in the robotic and self‐assembly of micro‐components.

Details

Assembly Automation, vol. 31 no. 4
Type: Research Article
ISSN: 0144-5154

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Article
Publication date: 7 September 2015

E. Rouhani and M. J. Nategh

The purpose of this paper is to study the workspace and dexterity of a microhexapod which is a 6-degrees of freedom (DOF) parallel compliant manipulator, and also to…

Abstract

Purpose

The purpose of this paper is to study the workspace and dexterity of a microhexapod which is a 6-degrees of freedom (DOF) parallel compliant manipulator, and also to investigate its dimensional synthesis to maximize the workspace and the global dexterity index at the same time. Microassembly is so essential in the current industry for manufacturing complicated structures. Most of the micromanipulators suffer from their restricted workspace because of using flexure joints compared to the conventional ones. In addition, the controllability of micromanipulators inside the whole workspace is very vital. Thus, it is very important to select the design parameters in a way that not only maximize the workspace but also its global dexterity index.

Design/methodology/approach

Microassembly is so essential in the current industry for manufacturing complicated structures. Most of the micromanipulators suffer from their restricted workspace because of using flexure joints compared to the conventional ones. In addition, the controllability of micromanipulators inside the whole workspace is very vital. Thus, it is very important to select the design parameters in a way that not only maximize the workspace but also its global dexterity index.

Findings

It has been shown that the proposed procedure for the workspace calculation can considerably speed the required calculations. The optimization results show that a converged-diverged configuration of pods and an increase in the difference between the moving and the stationary platforms’ radii cause the global dexterity index to increase and the workspace to decrease.

Originality/value

The proposed algorithm for the workspace analysis is very important, especially when it is an objective function of an optimization problem based on the search method. In addition, using screw theory can simply construct the homogeneous Jacobian matrix. The proposed methodology can be used for any other micromanipulator.

Details

Assembly Automation, vol. 35 no. 4
Type: Research Article
ISSN: 0144-5154

Keywords

1 – 10 of 78