102 research outputs found
Workshop on "Robotic assembly of 3D MEMS".
Proceedings of a workshop proposed in IEEE IROS'2007.The increase of MEMS' functionalities often requires the integration of various technologies used for mechanical, optical and electronic subsystems in order to achieve a unique system. These different technologies have usually process incompatibilities and the whole microsystem can not be obtained monolithically and then requires microassembly steps. Microassembly of MEMS based on micrometric components is one of the most promising approaches to achieve high-performance MEMS. Moreover, microassembly also permits to develop suitable MEMS packaging as well as 3D components although microfabrication technologies are usually able to create 2D and "2.5D" components. The study of microassembly methods is consequently a high stake for MEMS technologies growth. Two approaches are currently developped for microassembly: self-assembly and robotic microassembly. In the first one, the assembly is highly parallel but the efficiency and the flexibility still stay low. The robotic approach has the potential to reach precise and reliable assembly with high flexibility. The proposed workshop focuses on this second approach and will take a bearing of the corresponding microrobotic issues. Beyond the microfabrication technologies, performing MEMS microassembly requires, micromanipulation strategies, microworld dynamics and attachment technologies. The design and the fabrication of the microrobot end-effectors as well as the assembled micro-parts require the use of microfabrication technologies. Moreover new micromanipulation strategies are necessary to handle and position micro-parts with sufficiently high accuracy during assembly. The dynamic behaviour of micrometric objects has also to be studied and controlled. Finally, after positioning the micro-part, attachment technologies are necessary
Factors of Micromanipulation Accuracy and Learning
Micromanipulation refers to the manipulation under a microscope in order to
perform delicate procedures. It is difficult for humans to manipulate objects
accurately under a microscope due to tremor and imperfect perception, limiting
performance. This project seeks to understand factors affecting accuracy in
micromanipulation, and to propose strategies for learning improving accuracy.
Psychomotor experiments were conducted using computer-controlled setups to
determine how various feedback modalities and learning methods can influence
micromanipulation performance. In a first experiment, static and motion accuracy
of surgeons, medical students and non-medical students under different
magniification levels and grip force settings were compared. A second experiment
investigated whether the non-dominant hand placed close to the target can contribute
to accurate pointing of the dominant hand. A third experiment tested a
training strategy for micromanipulation using unstable dynamics to magnify motion
error, a strategy shown to be decreasing deviation in large arm movements.
Two virtual reality (VR) modules were then developed to train needle grasping
and needle insertion tasks, two primitive tasks in a microsurgery suturing
procedure. The modules provided the trainee with a visual display in stereoscopic
view and information on their grip, tool position and angles. Using the
VR module, a study examining effects of visual cues was conducted to train tool
orientation. Results from these studies suggested that it is possible to learn and
improve accuracy in micromanipulation using appropriate sensorimotor feedback
and training
Design of a Cyber Physical Framework for the Assembly of Micro Devices
Micro Devices Assembly (MDA) is an emerging domain with a significant economic potential. Existing methods for assembly of micro devices are tedious and costly. For this reason, it is important to develop a collaborative framework for the field of MDA. In this thesis, a Cyber Physical Framework (CPF) is proposed to support a collaborative approach using software and physical resources for rapid assembly of micro devices in a distributed environment. CPF adopts the cloud computing principles to improve the Quality of Experience (QoE) of users accessing the simulation videos and physical assembly videos. The cloud computing principle enables the distributed engineers/users to access the cyber physical resources from various locations.Computer Science Departmen
Automated Micromanipulation of Micro Objects
In recent years, research efforts in the development of Micro Electro Mechanical Systems, (MEMS) including microactuators and micromanipulators, have attracted a great deal of attention. The development of microfabrication techniques has resulted in substantial progress in the miniaturization of devices such as electronic circuits. However, the research in MEMS still lags behind in terms of the development of reliable tools for post-fabrication processes and the precise and dexterous manipulation of individual micro size objects.
Current micromanipulation mechanisms are prone to high costs, a large footprint, and poor dexterity and are labour intensive. To overcome such, the research in this thesis is focused on the utilization of microactuators in micromanipulation. Microactuators are compliant structures. They undergo substantial deflection during micromanipulation due to the considerable surface micro forces. Their dominance in governing micromanipulation is so compelling that their effects should be considered in designing microactuators and microsensors.
In this thesis, the characterization of the surface micro forces and automated micromanipulation are investigated. An inexpensive experimental setup is proposed as a platform to replace Atomic Force Microscopy (AFM) for analyzing the force characterization of micro scale components. The relationship between the magnitudes of the surface micro forces and the parameters such as the velocity of the pushing process, relative humidity, temperature, hydrophilicity of the substrate, and surface area are empirically examined.
In addition, a precision automated micromanipulation system is realized. A class of artificial neural networks (NN) is devised to estimate the unmodelled micro forces during the controlled pushing of micro size object along a desired path. Then, a nonlinear controller is developed for the controlled pushing of the micro objects to guarantee the stability of the closed loop system in the Lyapunov sense. To validate the performance of the proposed controller, an experimental setup is designed.
The application of the proposed controller is extended to precisely push several micro objects, each with different characteristics in terms of the surface micro forces governing the manipulation process. The proposed adaptive controller is capable of learning to adjust its weights effectively when the surface micro forces change under varying conditions. By using the controller, a fully automated sequential positioning of three micro objects on a flat substrate is performed. The results are compared with those of the identical sequential pushing by using a conventional linear controller.
The results suggest that artificial NNs are a promising tool for the design of adaptive controllers to accurately perform the automated manipulation of multiple objects in the microscopic scale for microassembly
Design, characterisation and testing of SU8 polymer based electrothermal microgrippers
Microassembly systems are designed to combine micro-component parts with high
accuracy. These micro-components are fabricated using different manufacturing
processes in sizes of several micrometers. This technology is essential to produce
miniaturised devices and equipment, especially those built from parts requiring different
fabrication procedures. The most important task in microassembly systems is the
manipulator, which should have the ability to handle and control micro-particles.
Different techniques have been developed to carry out this task depending on the
application, required accuracy, and cost. In this thesis, the most common methods are
identified and briefly presented, and some advantages and disadvantages are outlined.
A microgripper is the most important device utilized to handle micro-objects with
high accuracy. However, it is a device that can be used only in sequential microassembly
techniques. It has the potential to become the most important tool in the field of micro-robotics, research and development, and assembly of parts with custom requirements.
Different actuation mechanisms are employed to design microgrippers such as
electromagnetic force, electrostatic force, piezoelectric effect, and electrothermal
expansions. Also, different materials are used to fabricate these microgrippers, for
example metals, silicon, and polymers such as SU-8.
To investigate the limitation and disadvantages of the conventional SU-8
electrothermal based microgrippers, different devices designed and fabricated at IMT,
Romania, were studied. The results of these tests showed a small end-effector
displacement and short cycling on/off (lifetime). In addition, the actuator part of these
microgrippers was deformed after each operation, which results in reduced displacement
and inconsistent openings at off state every time it was operated in a power ON/OFF
cycle. One of these limitations was caused by the existence of conductors in arms of the
end-effectors. These conductor designs have two disadvantages: firstly, it raises
temperature in the arms and causing an expansion in the opposite direction of the desired
displacement. Secondly, since the conductors pass through the hinges, they should be
designed wide enough to reduce the conductor resistance as much as possible. Therefore,
the wider the hinges are, the higher the in-plane stiffness and the less out of plane
deflection. As a result, it increases the reaction force of the arm reducing the effect of
deformation. Based on these limitations a new actuatorstructure of L-shape was proposed to reduce
the effects of these drawbacks. This actuator has no conductor in the hinges or the arms
of the end-effectors which reduce limitation on the hinge width. . In addition, a further
development of this actuator was proposed to increase the stiffness of the actuator by
doubling its thickness compared with the other parts of the griper. The results of this
actuator proved the improvement in performance and reduction of the actuator
deformation.
This new actuator structure was used to design several different microgrippers with
large displacement and suitable for a wide range of applications. Demonstrations of the
capabilities of the microgrippers to be used in microassembly are presented.
In addition, a novel tri-directional microactuator is proposed in this thesis. This
actuator’s end-effector is capable of displacements in three different directions. This
actuator was used with the other designs to develop a novel three-arm (three fingers)
multidirectional microgripper.
To study the microgripper displacement as a function to the heater temperature, the
TCR of the conductor layer of each device was measured. Because different
configurations of conductor layers were studied, a significant effect of the metal layer
structure on TCR was discovered. The TCR value of gold film is reduced significantly
by adding the chromium layers below and about it which were used to improve the
adhesion between the gold film and the SU layers.
In this thesis, a new method based on a robotic system was developed to characterise
these microgrippers and to study the steady state, dynamic response, and reliability
(lifetime cycling on/off). An electronic interface was developed and integrated to the
robotic system to control and drive the microgrippers. This new system was necessary to
carry out automated testing of the microgrippers with accurate and reliable results.
Four different new groups of microgrippers were designed and studied. The first
group was indirectly actuated using an L-Shaped actuator and two different actuator
widths. The initial opening was 120 μm for both designs. The maximum displacement
was about 140 μm for both designs. However, the actuator in the wider heater width
showed more stable behavior during the cycling and the dynamic tests.
The second group was based on direct actuation approach using the L-Shaped
actuator. There were eight different designs based on this method with different heater
conductor shape, actuator width, and arm thickness. The initial opening was 100 μm and there were different displacements for the eight designs. The study of these microgrippers
proved that the actuator stiffness has a significant effect on the microgripper
displacement. In addition, the shape of the heater conductor has less effect. The largest
displacement achieved using this method of design was about 70 μm.
The third group was designed for dual mode operation and has three different designs.
The initial openings were 90 μm and 250 μm. The displacement was about 170 μm in
both modes. The last microgripper design was a tri-arm design for multi-mode operation.
The lifetime study of SU8 based microgrippers in this thesis was the first time such
an investigation was carried out. The results of IMT designs showed that the larger is the
displacement the less stable is the gripper design because of the high rection force acting
on the actuators. The L-shape based microgrippers had better performance and they did
not break after more than 400 cycles. In addition, the studies of static displacement and
dynamic response of different designed microgripper proved that better performance of
the proposed actuator can be obtained by using double thickness for the actuator as
compared to the arm thickness
International Workshop on MicroFactories (IWMF 2012): 17th-20th June 2012 Tampere Hall Tampere, Finland
This Workshop provides a forum for researchers and practitioners in industry working on the diverse issues of micro and desktop factories, as well as technologies and processes applicable for micro and desktop factories. Micro and desktop factories decrease the need of factory floor space, and reduce energy consumption and improve material and resource utilization thus strongly supporting the new sustainable manufacturing paradigm. They can be seen also as a proper solution to point-of-need manufacturing of customized and personalized products near the point of need
Micromanipulation-force feedback pushing
In micromanipulation applications, it is often desirable to position and orient polygonal micro-objects lying on a planar surface. Pushing micro-objects using point contact provides more flexibility and less complexity compared to pick and place operation. Due to the fact that in micro-world surface forces are much more dominant than inertial forces and these forces are distributed unevenly, pushing through the center of mass of the micro-object will not yield a pure translational motion. In order to translate a micro-object, the line of pushing should pass through the center of friction. Moreover, due to unexpected nature of the frictional forces between the micro-object and substrate, the maximum force applied to the micro-object needs to be limited to prevent any damage either to the probe or micro-object. In this dissertation, a semi-autonomous manipulation scheme is proposed to push microobjects with human assistance using a custom built tele-micromanipulation setup to achieve pure translational motion. The pushing operation can be divided into two concurrent processes: In one process human operator who acts as an impedance controller to switch between force-position controllers and alters the velocity of the pusher while in contact with the micro-object through scaled bilateral teleoperation with force feedback. In the other process, the desired line of pushing for the micro-object is determined continuously so that it always passes through the varying center of friction. Visual feedback procedures are adopted to align the resultant velocity vector at the contact point to pass through the center of friction in order to achieve pure translational motion of the micro-object. Experimental results are demonstrated to prove the effectiveness of the proposed controller along with nanometer scale position control, nano-Newton range force sensing, scaled bilateral teleoperation with force feedback
Cyber physical approach and framework for micro devices assembly
The emergence of Cyber Physical Systems (CPS) and Internet-of-Things (IoT) based principles and technologies holds the potential to facilitate global collaboration in various fields of engineering. Micro Devices Assembly (MDA) is an emerging domain involving the assembly of micron sized objects and devices. In this dissertation, the focus of the research is the design of a Cyber Physical approach for the assembly of micro devices. A collaborative framework comprising of cyber and physical components linked using the Internet has been developed to accomplish a targeted set of MDA life cycle activities which include assembly planning, path planning, Virtual Reality (VR) based assembly analysis, command generation and physical assembly. Genetic algorithm and modified insertion algorithm based methods have been proposed to support assembly planning activities. Advanced VR based environments have been designed to support assembly analysis where plans can be proposed, compared and validated. The potential of next generation Global Environment for Network Innovation (GENI) networking technologies has also been explored to support distributed collaborations involving VR-based environments. The feasibility of the cyber physical approach has been demonstrated by implementing the cyber physical components which collaborate to assemble micro designs. The case studies conducted underscore the ability of the developed Cyber Physical approach and framework to support distributed collaborative activities for MDA process contexts
Modeling, simulation and control of microrobots for the microfactory.
Future assembly technologies will involve higher levels of automation in order to satisfy increased microscale or nanoscale precision requirements. Traditionally, assembly using a top-down robotic approach has been well-studied and applied to the microelectronics and MEMS industries, but less so in nanotechnology. With the boom of nanotechnology since the 1990s, newly designed products with new materials, coatings, and nanoparticles are gradually entering everyone’s lives, while the industry has grown into a billion-dollar volume worldwide. Traditionally, nanotechnology products are assembled using bottom-up methods, such as self-assembly, rather than top-down robotic assembly. This is due to considerations of volume handling of large quantities of components, and the high cost associated with top-down manipulation requiring precision. However, bottom-up manufacturing methods have certain limitations, such as components needing to have predefined shapes and surface coatings, and the number of assembly components being limited to very few. For example, in the case of self-assembly of nano-cubes with an origami design, post-assembly manipulation of cubes in large quantities and cost-efficiency is still challenging. In this thesis, we envision a new paradigm for nanoscale assembly, realized with the help of a wafer-scale microfactory containing large numbers of MEMS microrobots. These robots will work together to enhance the throughput of the factory, while their cost will be reduced when compared to conventional nanopositioners. To fulfill the microfactory vision, numerous challenges related to design, power, control, and nanoscale task completion by these microrobots must be overcome. In this work, we study two classes of microrobots for the microfactory: stationary microrobots and mobile microrobots. For the stationary microrobots in our microfactory application, we have designed and modeled two different types of microrobots, the AFAM (Articulated Four Axes Microrobot) and the SolarPede. The AFAM is a millimeter-size robotic arm working as a nanomanipulator for nanoparticles with four degrees of freedom, while the SolarPede is a light-powered centimeter-size robotic conveyor in the microfactory. For mobile microrobots, we have introduced the world’s first laser-driven micrometer-size locomotor in dry environments, called ChevBot to prove the concept of the motion mechanism. The ChevBot is fabricated using MEMS technology in the cleanroom, following a microassembly step. We showed that it can perform locomotion with pulsed laser energy on a dry surface. Based on the knowledge gained with the ChevBot, we refined tits fabrication process to remove the assembly step and increase its reliability. We designed and fabricated a steerable microrobot, the SerpenBot, in order to achieve controllable behavior with the guidance of a laser beam. Through modeling and experimental study of the characteristics of this type of microrobot, we proposed and validated a new type of deep learning controller, the PID-Bayes neural network controller. The experiments showed that the SerpenBot can achieve closed-loop autonomous operation on a dry substrate
Visual Servoing
The goal of this book is to introduce the visional application by excellent researchers in the world currently and offer the knowledge that can also be applied to another field widely. This book collects the main studies about machine vision currently in the world, and has a powerful persuasion in the applications employed in the machine vision. The contents, which demonstrate that the machine vision theory, are realized in different field. For the beginner, it is easy to understand the development in the vision servoing. For engineer, professor and researcher, they can study and learn the chapters, and then employ another application method
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