Development of hybrid MEMS devices has demonstrated a need for automatic microassembly strategies. Visual servoing techniques have shown great promise as a control strategy capable of sub-micron precision while compensating for many of the problems that exist in the micro domain, including thermal expansion of assembly devices and imprecisely modeled and calibrated sensors and actuators. This project develops rules for micropart design to aid in device assemblability with visual servoing techniques by ensuring that the microparts can be easily tracked and controlled using vision feedback. A criterion is presented that estimates part trackability based on the visual appearance of the part. This criterion is then used to microfabricate features to improve part trackability and hence, the assemblability of the device. The criterion considers the feature appearance when the part lies out of the optical systems's depth-of-field. A Fourier optics based approach is used to simulate the visual appearance of microparts represented by CAD models using high resolution optical systems. This simulation is used to automatically design microfabricated features on microparts. These features are used to estimate the tracking accuracy of the MEMS parts to subpixel levels using interpolation techniques in optical flow based tracking. This allows MEMS parts to be assembled with sub-micron precisions using visual servoing strategies. Results demonstrating the capabilities of our design-for- microassembly rules using visual servoing microassembly strategies are presented.

The assembly of complex microsystems consisting of several single components (i.e. hybrid microsystems) is a difficult task that is seen to be a real challenge for the robotics research community. It is necessary to conceive flexible, highly precise and fast microassembly devices and methods. In this paper, the development of a microrobot-based microassembly station is presented. Mobile piezoelectric microrobots with dimensions of some cm³ and with at least 5 DOF can perform various manipulations either under a light microscope or within the vacuum chamber of a scanning electron microscope. The control system of the microassembly station is described. The main attention is given to a vision-based sensor system for automatic robot control and a re-configurable parallel computer array enabling the station to work in real-time.

This paper addresses the localization problem in mobile robotics and microrobotics, which is necessary to be resolved for closed loop identification and control. An original method is developed which uses the image of a specific pattern and a signal processing method based on wavelet transforms. The pattern is made of two calibrated networks of straight lines perpendicular with respect to each other and which constitutes a reference phase excursion. With an adapted processing technique, a straight line equation is computed for each network characterizing its position as well as its orientation with a high accuracy. The intersection of those two perpendicular lines defines the mobile robot position and heading whose movement is studied. That technique leads to promising results: sub- micrometer accuracy in the position measurement.

New sensor technologies with the sensitivity and specificity capable of detecting biological and chemical agents at low concentration are of increasing importance for many environmental monitoring applications. We propose a potentially new class of microsensors that exploits the mechanical dynamics of a micrometer-sized particle held in a 3D optical force trap formed by a focused laser beam. Modulation of the laser trapping power axially perturbs the microparticle from its equilibrium position and permits measurement of the mechanical compliance transfer function (force input, displacement output) characterizing the particle micromechanical dynamics. In a mechanically homogeneous and isotropic environment, the particle motion is readily modeled as a forced harmonic oscillator; however, physico-chemical interactions between the particle and its surroundings impose external forces that modify the compliance transfer function. Our preliminary measurements indicate < 10 ppm changes in mass of a trapped microparticle can be detected with this method, suggesting possible applications as a chemical/biological sensor or for solubility measurements of microparticles.

The rapid development of reproductive biology has created a need for quantifying penetration forces during artificial fertilization. It has been demonstrated that the success of such procedures heavily depends on the mechanics of penetration of the egg's zona and membrane. To quantify the forces during intracytoplasmic injections we have developed a MEMS based force sensor. Deep RIE and fusion bonding are used to fabricate a variable capacitance type sensor. It is designed to measure the penetration force during intracytoplasmic injection of egg cells as well as other applications in the 1 - 500 micrometers N force range. The sensor measures tri-axial forces using a system of flexible beams subjected to bending and torsion. The process is relatively simple and allows for easy modification of the force range. A penetration pipette tip is attached to the sensor body using a low temperature bonding technique. Calibration, sensitivity and initial experimental data is provided.

This paper compares several methods of flip chip assembly suitable for complex high-density micro-systems and discusses the advantages and disadvantages of each, based on our results in eight years of flip chip development and production. Flip chip advantages over other chip interconnection methods include smaller size, better electrical performance, and greater ruggedness. Many new methods of flip chip assembly have become available as alternatives to the venerable solder bump flip chip technology. These newer methods offer finer pitch connections, lower temperature processing, and more design flexibility than the older solder bump approach. In particular, the stud bump/adhesive flip chip method allows assemblies starting from individual die, rather than requiring full wafers. This singulated chip approach is more economical, faster to implement and modify, and avoids the `known good die' problems inherent in wafer-based flip chip processes. Stud bump flip chip, as described here, permits easy prototyping and micro-scale breadboarding during development, and rapid transition to production.

The integration of complex electronic systems onto small- scale robots requires advanced assembly methods. The NanoWalker is an example of such a robot where a large amount of electronics must be embedded in the smallest possible space. To make a space-efficient implementation, electronic chips are mounted using flip chip technology on a pre-bumped flexible printed circuit (FPC). A 3D structure is obtained by mounting the FPC vertically in a triangular fashion above a tripod built with three small piezo-actuated legs used for the walking and rotational motions. Advanced computer aided design systems are used for the design and to generate manufacturing files. Unlike other commercial products such as cellular phones, watches, pagers, cameras, and disk drives that use flip chip technology to achieve the smallest form factor, the assembly process of the NanoWalker is directly dependent on other characteristics of the system. Minimization of coupling noises through proper FPC layout and die placement within temperature constraints due to the proximity of sensitive instrument was a critical factor. The effect of vibration caused by the piezo- actuators and the weight of each die were also other important issues to consider to determine the final placement in order to maintain proper sub-atomic motion behavior.

The NanoWalker project is an attempt to explore a new approach in the development of various instruments. The idea is to build a small autonomous robot capable of nanometer range motions that will provide a standard platform for new miniaturized embedded instruments. This modular approach will allow easy expansion in instrumentation capability through the use of an arbitrary number of NanoWalkers which would perform similar or different measurement simultaneously on various samples. To do so, a fair amount of electronics must be embedded for infrared wireless communication, processing, support for the embedded instrument, and accurate control and drive capability for the piezo-actuated motion system. Miniaturization of the whole assembly is also a key characteristic to allow more robots to operate simultaneously within smaller surface areas. As such, new assembly techniques applicable to small volume production must be used to achieve the smallest possible implementation. The integration phase within the technological constraints is complicated by the fact that several factors such as the weight and weight distribution of the electronic assembly will have a direct impact on the very sensitive motion behavior of the robot. The NanoWalker is briefly described with the integration phases and the requirements that must be met by the assembly process.

The design of two piezoelectrically-actuated mesoscale robot quadrupeds is described. In each design, two piezoelectric actuators are used in conjunction with multi-degree of freedom articulated legs to create elliptical leg motions necessary for rough terrain capabilities. One design incorporates inertially-decoupled five-bar linkages for legs, while the other a two degree-of-freedom spatial linkage for each leg to achieve elliptical foot motion. The five-bar design has a footprint that measures 9 cm X 6.5 cm and weighs 51 grams, and the spatial linkage design has a footprint of 9 cm X 12 cm and weighs 29 grams. Data is presented for each design that characterizes nominal speed and typical power consumption. The ability to turn left or right is provided by shifting the input frequency to emphasize different dynamic modes in the robots.

A system of launchable miniature mobile robots with various sensors as payload is used for distributed sensing. The robots are projected to areas of interest either by a robot launcher or by a human operator using standard equipment. A wireless communication network is used to exchange information with the robots. Payloads such as a MEMS sensor for vibration detection, a microphone and an active video module are used mainly to detect humans. The video camera provides live images through a wireless video transmitter and a pan-tilt mechanism expands the effective field of view. There are strict restrictions on total volume and power consumption of the payloads due to the small size of the robot. Emerging technologies are used to address these restrictions. In this paper, we describe the use of microrobotic technologies to develop active vision modules for the mesoscale robot. A single chip CMOS video sensor is used along with a miniature lens that is approximately the size of a sugar cube. The device consumes 100 mW; about 5 times less than the power consumption of a comparable CCD camera. Miniature gearmotors 3 mm in diameter are used to drive the pan-tilt mechanism. A miniature video transmitter is used to transmit analog video signals from the camera.

In this work we point out how it is possible to develop autonomous systems starting from the interaction of simple mechanical and electronic devices and toys. Our aim is to involve students in these skills for building platforms to experiment basic concepts of artificial intelligence. By using this simple and fascinating way they achieve knowledge about the most important aspects of the subject. Besides, they are actively engaged in creating something that is meaningful to themselves or to others around them. In relation to this context we have built two simple and compact vehicles each capable of doing two different basic behaviors: the wall following (moving the vehicle at a constant distance from the wall on its left or right hand) and the obstacle avoidance (avoiding collision with obstacles during the path). As to compare vehicles two different control systems have been developed. The first system is controlled by an analogical circuit, whereas the second by a digital circuit.

A discussion of the principles involved in small-scale flight is presented here. In addition, several novel mechanisms have been developed in an attempt to mechanically emulate flapping flight on the meso-scale. Wings are being developed which will exploit particular material properties to emulate the dynamic characteristics of insect wings. The flapping mechanisms developed in this paper use piezoelectric unimorph actuators integrated with compliant, solid-state flexure based mechanisms. Four and five bar linkages are used to convert the linear unimorph output into a single degree-of-freedom rotational flapping motion. Due to their capacitive nature, piezoelectric actuators generally dissipate less power than traditional actuation methods such as electromagnetic mirrors. Piezoelectric actuators possess a high power density and are capable of high force output. They are frequently used to induce structural resonances, making them suitable for use in these devices. The dynamics of these systems rely on the mechanics of flexure mechanisms, the mechanical and electrical behavior of the piezoelectric elements, and the aerodynamic interaction of the wing and the air, resulting in a complex, nonlinear problem.

This paper inquires into the exportability of the fatigue measurements made on standard test-specimen to wire electro- discharge machined flexures with thin cross sections (50 micrometers ). It describes the results of a set of fatigue measurements made on 66 circular flexible hinges machined in steel and bronze by wire electro-discharge machining. After reminding the fatigue theory and describing the theoretical model used to calculate the stresses inside the bent hinges, the paper describes the experimental setup and the measured results. The main conclusions drawn out of this work is that the admissible stresses for the tested flexures having a low surface roughness (Ra equals 0.2 micrometers ) are at least as high as the admissible stresses for standard test specimens. This indicates that fatigue data found in literature can be used to calculate the dimensions of this kind of flexures without any reduction of the safety factor.

This paper presents a high performance single arm robot configuration, based on a macro-manipulator coupled with a micro-manipulator. The system is well suited to fast and precise positioning tasks for repetitive pick and place applications in the manufacturing industry. Firstly, the paper focuses on the design of the micro-manipulator, particularly on the selection of the proper micro-actuator type and location. We show that the micro-manipulator's design with an actuator placed between endpoint and ground and with a flexible suspension system can reduce the dynamic coupling between the macro-manipulator and the micro- manipulator. The overall system performance can then be improved. We describe two different designs of compact and fast micro-manipulators composed of voice coil actuators and a monolithic flexure suspension with notch hinges. Secondly, the paper presents a control strategy that allows both correction of possible misalignments of the end-effector relative to the target and compensation of tip oscillations. The dynamic interaction is analyzed and stability is verified. Finally, experimental results demonstrate significant improvements in acceleration, endpoint accuracy and settling time achieved by the novel configuration of the macro/micro-manipulator.

The authors are developing a table top factory, which is called ` Nano Manufacturing World (NMW)', in order to make 3D micro structures for information devices or medical tools. In this paper, we demonstrate a pick-and-place task of micro objects using an electric charged tool under SEM observation, and bonding task of them using a pencil-type semiconductor laser in vacuum. In NMW, we installed the electric changed tool in its right hand, the semiconductor laser in its left hand, and micro objects on its table. As if we were in a nano-scale world, we can operate the micro tasks.

This paper deals with a work in progress concerning the development of a station for micromanipulation tasks in the air (at present not in a liquid environment). A microgripper is developed, based on piezoelectric unimorphs and bimorphs. This microgripper allows to manipulate micro-objects from several microns to several hundreds of microns in diameter. In the future the microgripper will be controlled in position and force. The first results in position control of our piezoelectric unimorph actuators show an accuracy better than 10 nm at the tip of the actuator. A low cost XY-table is also developed using SMA wires to create relative motions between the microgripper and the manipulated object. For the manipulation of smaller objects, from several hundreds of nanometers to some micrometers, a work is also in progress to develop a micromanipulation station based on an AFM microscope head connected to a simple force-feedback haptic. Moreover, based on some studied microactuators for micromanipulation, an insect-like microrobot with legs is under development. The design of legs is realized using the microactuators previously described. We are now in order to test these legs and consider the whole mechanical structure of the microrobot.

In this paper, a prototype robotic workcell for the parallel assembly of LIGA components is described. A Cartesian robot is used to press 386 and 485 micron diameter pins into a LIGA substrate and then place a 3-inch diameter wafer with LIGA gears onto the pins. Upward and downward looking microscopes are used to locate holes in the LIGA substrate, pins to be pressed in the holes, and gears to be placed on the pins. This vision system can locate parts within 3 microns, while the Cartesian manipulator can place the parts within 0.4 microns.

An in-pipe microrobot which moves at 10 mm/s in a pipe of 15 mm diameter without power supply wire is developed. The robot consists of a microwave energy supply device, a locomotive mechanism using a piezoelectric bimorph actuator, and a control circuit. The energy supply device consists of rectifying circuits and a compact receiving antenna. The required energy of 200 mW is supplied via microwave without wire. 14 GHz microwave is rectified into DC electric energy at a high converting efficiency of 52%. The locomotive device of multi-layered bimorph actuator is newly developed and consumes only 50 mW. The control circuit consists of a saw tooth generator and a programmable logic device, and controls the direction of the robot motion by outside light signal.

Compact fast-steering two axis-tilt mirrors are key components in astronomy, laser communications, material processing applications, imaging systems, biomedical and ophthalmologic applications. The laser scanner presented in this paper can perform a variety of functions such as tracking, beam stabilization and alignment, pointing and scanning. The small overall volume of 30 X 40 X 50 mm³ can lead to a very stable and compact system design. The fact that the steered mirror has a single point of rotation for the two tilt axes is a clear advantage for systems with scanning lenses designed for this purpose. The scanner is composed of one single mirror driven by two pairs of push-pull linear electromagnetic actuators. The suspension of the mirror is based on a cone-ball bearing with optimized friction and wear behavior. A Position Sensitive Detector integrated in the module is used for the closed loop feedback positioning. The mirror can be tilted by more than +/- 52 mrad (+/- 3 degree(s)) with an accuracy better than 50 (mu) rad. A differential resolution of the order of 5 (mu) rad and a settling time for maximum deflection of 9 ms is achieved. Due to the large active area of the mirror (30 mm X 40 mm), very small spot diameters can be reached (less than 1 micrometers ) using high quality laser beams. Therefore, the scanner can be used e.g. in high precision micro-material processing of semiconductor and sensor industry.

The use of force feedback in an assembly robot can be very useful since it allows to overcome position errors and tolerance effects that cannot be detected otherwise. In order to obtain an efficient and robust force feedback loop a system capable of measuring forces with the required accuracy must be available. In addition, the relation between the forces acting on the different parts and their deformation must be known. The rigidities of the three main components of the modelled assembly system, namely the robot arm, the force sensor and the assembled parts should be known. Unfortunately, this is not always possible. A certain amount of assumptions can be made just by knowing what stiffness is smaller in relation to the others. When force feedback is used in micro-assembly operations factors not relevant in the conventional size domain start to gain importance (and vice-versa) and must therefore be considered in the control loop. In addition a method based on dimensional analysis that allows to chose the most convenient type of force sensor in relation to the resolution, measuring range and even fabrication process is described.

This paper presents our work on modeling of micro operations. The model is based on rigid body dynamics but it also takes into consideration dominant micro world forces such as van der Waals forces and electrostatic forces, in addition to friction and rolling resistance. The operations are assumed to be performed in a dry environment. The proposed work lays ground for future development of virtual micro operation environment.

To assemble hinged MEMS structures, a probe station with visual feedback has been used. With a feedback in the visual domain only, the assembly operation is really long and tedious. This paper presents the improvements using a force sensor with sound feedback coupled with vision. The developed interface allows the user to `hear the forces'. Thereby, the time and the sensitivity of the assembly operation are improved. Using the auditory interface, the assembly time is reduced by about 50%.

When grasping microparts extremely low gripping low forces, often in the micro to nano newton range, must be applied in order to prevent parts from being damaged and to prevent them from dislodging in the gripper. This paper presents our work in developing a force controlled microgripper and microgripping strategies using optical beam deflection techniques. The optical beam deflection sensor is based on modified Atomic Force Microscope techniques and is able to resolve forces below a nanonewton. A variety of gripper fingers made from materials with different conductivity and surface roughness are analyzed theoretically and experimentally using the force sensor. These results provide insight into the mechanics of micromanipulation, and the results are used to develop microgripping strategies. A design of a microfabricated force controlled microgripper is presented along with initial experimental results in applying various gripping forces to microparts. The results demonstrate the important role gripping force plays in the grasping and release of microparts.