A Microfactory is a set of cooperating micro-machines dedicated to the production of Microsystems in small to medium quantities. This paper describes the Microfactory concept currently developed at the Institut de Systemes Robotiques (ISR). A state of the art in this domain is presented. Several novel designs on micro-positioning systems are discussed. Emphasis is put on piezo-actuators with nanometer resolution and large workspaces (few cm³). Finally, our vision for the future trends in the field of Microfactory is briefly introduced.

The assembly of a miniature linear actuator is described. The actuator consists of a base plate including the stator, a runner and guides on both sides of the runner. Stator, runner and guides are micro machined, using silicon as base material. The overall dimensions of the complete actuator are approximately 9 mm x 3 mm. A parallel robot with 4-DOF and a resolution of less than 1 (mu) m is used to assemble the actuator. The robots high accuracy is reached as a result of the parallel structure of the robot in combination with linear piezo drives. In addition, an integrated vision system allows the exact positioning of the robot relative to a previously teached position. The accuracy of the vision system is about 0.25(mu) m. Communication between the robot and the vision system takes place over a high-speed RS-422 serial link. As a first assembly step the guides, which are 8 mm long and 700 (mu) m wide, have to be mounted onto the base plate, right and left to the runners track. A special focus is laid on the exact maintenance of distance and parallelism of the guides, which is assured by the vision system. If the gap between the guides is too wide, the runner can tilt above the z- axis, which causes the actuator not to work. The opposite, a too small gap, causes the runner to be stuck between the guides. The guides are handled by a SMA-actuated miniature gripper. To keep the guides in place they are fixed by droplets of glue, whic are dispensed by a micro dispenser.

This paper reports on an experimentally microassembly workcell developed for efficient and reliable 3D assembly of large numbers of micromachined thin metal parts into DRIE² etched holes in 8 inch silicon wafers. The major objective is to integrate techniques of microgripper design, microscopic imaging and high precision motion control to build a prototype system for industrial applications. The workcell consists of a multiple-view imaging system, a 4 DOF micromanipulator with high resolution rotation control, a large working space 4 DOF precision positioning system, a flexible microgripper, and control software system. A piezoelectric force sensing unit was integrated with the manipulator system to enhance pickup reliability. Each of these components is presented with analysis of design issues and related experimental results. Operations are partially guided by a human operator through a graphical user interface (GUI). This system provides a highly flexible testbed for wafer-level 3D microassembly.

The assembly of gear systems with the size of a pin head is almost beyond the bound of human tactile skills. The magic formula for series fabrication of this hybrid micro systems is the automation of the assembly process. As a contribution, this paper presents and discusses three different assembly methods comprising specifically developed tools for different types of planetary gears with outer diameters of 1.9 mm. Because of the huge importance for the complete micro assembly process, particular attention will be dedicated to the feeding and magazining of the micro gear components. Starting with metallic gear wheels as bulk good, an extremely miniaturized gear system of the Wolfram type has been automatically assembled by employing the strategy of tolerance compensation movement. As a key component, a modular tong gripper with specifically adapted gripping jaws produced by LIGA technology has been used. Further detailed investigations were spend on handling and assembly of micro injection moulded gear wheels made of POM for a three state planetary gear system. One strategy, following the idea of in situ observation, focuses on the intensive use of electronic pattern recognition. Alternatively, an unusual method based on a novel plastic wafer magazine will be discussed in detail. Hereby the exact position and orientation of injection moulded micro components will be presented from the manufacturing process up to the final micro assembly procedure. By simplifying the moulding of the micro gears as well as their handling, storing and assembly, this method has the potential to revolutionize the series fabrication of products with dimensions in the microscopic range in general.

Microcomponents can be manufactured not only by silicon technologies, bu talso by many other technologies, e.g. precision engineering, laser ablation, microelectrodischarge, RIE and by the LIGA process. In this paper, the state of the art of the LIGA technology and its industrial applications are presented, which have been developed in recent years at the Forschungszentrum Karlsruhe. Related technologies are described as well. This includes the use of a sacrificial layer and an alternative process technology for the fabrication of mold inserts using conventional UV-lithography with the negative resist SU-8. With respect to applications of the LIGA technology, a brief introduction to their specific fabrication processes and their functionality is presented. These are microspectrometers, optical fiber connectors, cycloid gear systems, optical heterodyne receivers and micro-mechanical gyroscopes.

This paper will present a virtual environment for operations in the micro world. Virtual reality is a very important tool in task and assembly planning of micro assembly. This virtual environment presented in this paper is based on our micro operation model that takes into account rigid body dynamics, contact forces, friction forces, and available knowledge of van der Walls forces, electrostatic forces. This work lays ground for further development of micro operation techniques and micro assembly planning.

Stick and Skip Actuators (SSA) are particularly well adapted to micro- robotics. A simple design, a very high intrinsic resolution (a few nanometers) and a high rigidity make them especially interesting in high precision micro-manipulations. Moreover, a smart design allows to combine the guiding and actuating function. The mechanical interface between the piezo-elements and the guiding mechanisms in an important point of the stick and slip actuators. The design of this interface and the choice of the material are very important. Both aspects have an impact on the rigidity, which has an influence on the behavior of the actuator. They have also an incidence onf the reliability (lifetime) because the design gives the contact condition and the material the wear resistance. In addition, a loading system allowing to keep the mechanical contact at this interface has a direct effect on the contact pressure. In order to confirm the performance of SSA, prototypes have been developed at the ISR. Their designs have bene made for application in optical microscopy, for manipulators in industrial assembly of micro- engineering products, for micro-factory, chemical and bio-engineering equipment for research or routine tasks, such as testing, screening etc. This paper presents a short description of several SSA made by the IRS and describes the parameters characterizing the stick and slip motion and the mechanical interface.

Electrostatic forces are omnipresent in everyday life, sometimes a nuisance, such as hairs sticking to the comb, but also a valuable asset in a few technical processes, e.g. the Xerox copy process. Usage of electrostatic forces was so far confined to handling of nanoparticles or biological cells. This paper outlines the development of a device for feeding of Millimeter sized polymer parts by means of electrostatic forces. Starting from a brief assessment of the phenomena that generate electrostatic forces, rules for the design of an electrostatic conveyor are derived. A description of a first prototype is followed by a presentation of the results of the experiments. The paper terminates with a conclusion, that gives perspectives of future work.

The NanoWalker project aims at developing a new type of miniature wireless autonomous robot capable of performing tasks at the molecular and atomic scales. To do so, the robot must be capable to position itself within the maximum range of the embedded instrument by using a new type of relatively fast locomotion system capable of sub-micrometer step sizes. To prevent excessive traveling delays due to the critical requirement of small step sizes, relatively fast motions have been achieved through several thousand steps executed per second and operation at resonance frequency. Furthermore, step sizes larger than the maximum bending amplitude of the piezo-legs have been achieved with jumps initiated by extremely fast onboard computer controlled angular accelerations of the legs form known parameters such as mass, moment of inertia, and coefficient of friction, just to name a few. This locomotion system is based on three piezo-actuated legs formed as a pyramid with the apex pointing upward. Although this structure is relatively simple, its kinematic behavior becomes extremely sensitive to many variables that must be well understood. Such understanding is critical for the embedded computer system responsible for controlling the three legs. In this paper, an introduction with the fundamental principles behind this new actuation system is presented.

The track density of hard disk drives had been increasing of 30%/year in these last years. The increase in bandwidth is limited by the presence of mechanical resonance modes and other nonlinear in the voice coil motor (VCM) actuators. One approach to overcoming the problem is by using a dual-stage servo mechanism. Dual stage actuator systems composed of a micro actuator and a conventional actuator (VCM)-macro actuator may enable such high track densities to be attained. In this paper, a novel piezoelectric microactuator was successfully designed and mounted on the suspension in hard disk drives. The microactuator is based on the deformation in piezoelectric effect, and drives the head suspension assembly. The paper describes the structure of macro/micro actuators, its principles of operation and mechanical characteristics. The actuators system in hard disk has a high bandwidth, simple structure, and low cost.

This paper presents a computer-vision based position controller for a highly non-linear parallel piezohydraulic micromanipulator: in addition to its non-linear kinematics the micromanipulator experiences hysteresis and drive induced by piezoelectric actuators. The controller consists of a decoupling matrix that provides the decoupled translations (xyz) in the task frame and three Single Input Single Output (SISO) PI controllers for the translations. Position measurement is performed by a vision system that determines the x and y coordinates of the end- effector using a modified Hierarchical Chamfer Matching Algoritm (HCMA) and the z position using a depth-from-defocus method. Experiments show that the proposed controller is capable of serving the parallel micromanipulator with a sub-micron accuracy at a sampling rate of 18 Hz.

Semi-autonomous and fully autonomous assembly and manipulation of micro- objects is a complex process. As part of the MINIMAN micro-robot project, a vision subsystem is required which can recognise and track objects both under an optical microscope and within a scanning electron microscope. This subsystem is required as part of a more complex system for assembling and manipulating micro-objects. The two different operating environments provide many challenges when building a generic vision system due to the vast differences in the quality of the images. This paper provides a detailed description of this new vision system, together with a discussion and analysis of its flexibility and extensibility. Recent results of the system's ability to recognise rigid objects robust to camera noise and object occlusions are given, and the adaptability of the system to recognising biological objects is discussed. Finally, an overview is provided of the communication strategy between the vision subsystem and the micro-robot control system.

The development of a three-legged miniature robot, such as the NanoWalker, capable of taking steps in the micrometer and sub-micrometer range and equipped with instruments such as scanning, tunneling microsope (STM) tip, requires an adequate positioning system. In order to make use of these instruments, positioning the robot becomes one of the most critical issues. For atomic scale operations within a relatively large workspace, no traditional positioning systems were adequate for this type of robotic environment. The proposed atomic scale positioning system relies on three positioning levels where at each level, the resolution improves from 10 micrometers down to a few picometers while the circular positioning area decreases from 0,5 meter down to 200 nanometers in diameter. While the last two levels are STM- based positioning techniques, the first level with the largest positioning area is based on optical techniques. The paper describes the final set-up for implementing the first positioning level that incorporates a lateral effect photodiode to make measurements of the robot's position by detecting infrared signals emitted by the robot. Using a lens to project the robot's workspace onto the photodiode we are able to achieve of a resolution of a few micrometers in the central region of a typical 0.5-meter workspace. Due mainly to loss of signal at the edges of the workspace,the resolution of the system decreases as we near the edges.

In the scanning electron microscope (SEM), specially designed microrobots can act as a flexible assembly facility for prototype microsystems, as probing devices for in-situ tests in various applications or just as a helpful teleoperated tool for the SEM operator when examining a few samples. Several flexible microrobots of this kind have been developed and tested. Driven by piezoactuators, these few cubic centimeters small mobile robots perform manipulations with a precision of up to 20 nm and transport the gripped objects at speeds of up to 3 cm/s. New microrobot prototypes being employed in the SEM are described in this paper. The SEM's vacuum chamber has been equipped with various elements to enable the robots to operate. In order ot use the SEM image for automatic real-time control of the robots, the SEM's electron beam is actively controlled by a PC. The latter submits the images to the robots' control computer s ystem. For obtaining three- dimensional information in real time, a triangulation method with the luminescent spot of the SEM's electron beam is being investigated. Finally, the strategies of a micro force sensing and control methods required for handling techniques with two robots are discussed.

The NanoWalker is a miniature autonomous wireless robot under development. The robot is designed to accomplish complex tasks at the molecular and atomic scales. One concern is the total mass of the robot. With all the components including the mechanical structure and the complex electronic system necessary to embed the required functionality of throughput for such tasks, the mass of such a robot is estimated to be in the range of 100-200 grams depending on tradeoffs in the final design. With such a mass and limitations on the maximum voltage and current outputs that can be generated in a small form factor to deflect the piezo-ceramic legs with high-precision, a preliminary evaluation and experimentation phase of the motion behavior is essential prior to completing the final desing. It is shown both theoretically and experimentally that adequate motions are possible under such high normal forces. This was achieved through a new walking strategy referred to here as the push-slip method. The method uses the high normal forces combined with the resulting coefficient of friction between the termination of each leg and the walking surface to create initial opposite forces to the bending forces of each leg. These opposite forces, bounded by the maximum static force of friction, can be used for pushing or slipping through additional torque if the bending forces are applied reciprocal or in the direction of intended motions respectively. With the right parameters combined with tight and proper synchronizations of the legs, very effective motions can be achieved.

The NanoRunner is designed to be primarily used as an experimental wireless robot in order ot quickly test and validate several hardware/software issues and ideas prior to being implemented on the more expensive and complex wireless instrumented NanoWalker robot. As such, the NanoRunner, Like the NanoWalker is based on three piezo- actuated legs forming a pyramid with the apex pointing upward. Unlike the NanoWlaker, the NanoRunner has much simpler embedded electronics and is not capable of an accuracy and computational throughput comparable to the NanoWalker. Because of its lighter weight, it can move or run much faster. Furthermore, the NanoRunner does not have a fast infrared communication infrastructure for downloading executable code. Instead the NanoRunner is first pre-programmed with a specific behavior suitable for the tasks to be performed. Nonetheless, the NanoRunner has all the required electronics to be fully autonomous while performing its experimentation tasks. Although not as sophisticated as the NanoWalker, the NanoRunner offers a smaller and simpler robot implementation for less demanding tasks. Another major motivation for the NanoRunner is to validate various ideas in order to decrease the overall size of the robot. The size is critical since our goal is to allow more robots to work within the same area. In this paper, the NanoRunner is described. Aspects such as construction, assembly, and the method used for downloading executable code in order to pre-program the robot's behavior are also covered.

The increasing tendency of products towards miniaturization makes the substitution of conventional hinges to flexure hinges necessary, since they can be manufactured almost arbitrarily small. On account of their multiple advantages like no backlash, no slip-stick-effects and no friction, their application is especially reasonable in high-precision robots for micro assembly. Particular pseudo-elastic shape memory alloys offer themselves as material for flexure hinges. Since flexible joints gain their mobility exclusively via the elastic deformation of matter, the attainable angle of rotation is strongly limited when using conventional metallic materials with approximately 0.4% maximal elastic strain. Using pseudo- elastic materials, with up to 15% elastic strain, this serious disadvantage of flexure hinges can be avoided. A further problem of flexible joints is their kinetic behavior since they do not behave exactly like conventional rotational joints. In order to examine the kinematics of the hinges an experimental set-up was developed whereby good compliance with theoretical computed values could be achieved. A three (+1) degree of freedom parallel robot with integrated flexure hinges is investigated showing its kinematic deviations to its rigid body model. The data of the kinematic model of the flexible joint can then be implemented into the control of this complaint mechanism in order to gain not only a higher repeatability but also a good absolute accuracy over the entire working space.

It is well known that one of the major limitations in achieving small form factors in wireless electronic systems is the power source. This particularly holds true for a new class of miniature wireless robots such as the NanoWalker where complex and power-demanding electronics and computation must be embedded to support complex tasks at the molecular and atomic scales while providing very high throughputs in a fully autonomous manner. It is estimated that in a worst case, up to 15 Watts of continuous power may be required per robot. This power consumption comes mainly from the embedded 48 MIPS digital signal processing (DPS) and memory system, the drive and control electronics for the piezo- ceramic legs, the scanning tunneling microscope (STM) based control and instrumentation sub-system capable of 200,000 high-resolution readings/s, and the 4 Mb/s infrared (IR) communication interface. With these specifications coupled with the requirement to control the motion of the robot in the nanometer and micrometer ranges with several thousand steps/s, migrating some of the control functions to an external computer and exchanging data through the wireless communication channel is not an option because of additional latencies well beyond the short and highly predictable response periods required by the robots. To complicate the problem, the power delivery system must accommodate a large range of voltages between the electronics and the power amplifiers driving the piezo-ceramic legs. A solution based on continuous power delivery through a special walking surface with intermittent contacts with the robots during motion is described.

We propose the optical multi-transmission system using pyroelectric and optical piezoelectric element as the transmitter for the transmission system of micromechanical system We apply the PLZT element to the proposed system as a transmitter. The PLZT element generates the electric charge based on the change of temperature and density of the irradiation of ultraviolet ray. We developed the energy supply system using the pyroelectric effect, and the information transmission system using the optical piezoelectric effect, but that system only shows the. We show the numerical model of the transmission system using the PLZT element and the simulation results of the transmitting the photo energy and information source to the electric function. Then, the experimental results explains the performance of the developed transmission sy stem and the ability of the proposed system.