Design, Fabrication and Control of Spherobot: A Spherical Mobile Robot

In the literature, Spherobot refers to a mobile robot with a spherical exo-skeleton and a propulsion mechanism that uses unbalance masses in a tetrahedral arrangement. A modified design of Spherobot, that is better suited to fabrication, is presented in this paper. The modified propulsion mechanism and other components of the design are discussed in detail to highlight the challenges of fabrication. An adaptive estimation and control algorithm used for position control of the unbalance masses and a steering algorithm used for motion control of Spherobot are also discussed. Experimental results of the Spherobot navigating a hallway with bends is presented.     

Parylene surface-micromachined membranes for sensor applications

This paper reports the design, fabrication process, and testing results of Parylene surface-micromachined membranes with integrated strain gauges or thermal resistors made of thin film metals. The membrane is suspended above the substrate. This paper demonstrates the feasibility of sensor applications with a force (tactile) sensor and a fluid shear stress sensor.     

Micromechanical force sensors based on SU-8 resist

This paper presents an innovative approach to develop highly sensitive 3D force sensors. In order to increase the probing sensitivity by using a material with low Young’s Modulus, a novel force sensor design based on SU-8 polymer is realized. Therefore, a low cost fabrication process is developed accompanied by design studies and an estimation of mechanical properties of the deforming elements. This paper will present the fabrication process as well as a distinguishing set of test results, analytical results, and simulations on the characterization of the presented SU-8 force sensor. The novel SU-8 design consists of an SU-8 boss-membrane with integrated piezoresistive elements. The SU-8 membranes are structured using photolithography. The SU-8 micromechanical structures are characterized to determine film stresses, bending stiffness, displacement of the stylus, and breaking points. Included in these tests are measurement of the stress behavior at different process steps and simulation of stress distribution in the membrane at different directions of loading. In addition a comparative analytical investigation of the structures is carried out particularly with regard to the displacement of the stylus.     

An Adaptive Approach for the Segmentation and the TV-Filtering in the Optic Flow Estimation

We consider a variational model for the joint total variation filtering (TV) and the segmentation in the optic flow estimation. The model is based on a functional with a spatially varying regularization parameter to solve such an ill-posed problem. We present an adaptive approach based on a posteriori error indicators which allows us to select locally the optimal values of the diffusion coefficient in the functional. We show that the adaptive process applied to the linear part of the functional (with respect to the optic flow variable) fulfills the segmentation objective. Moreover, this adaptive approach provides an approximation of the Mumford–Shah functional in the sense of the \(\Gamma \)-convergence of a family of discrete energies. The simultaneous filtering and segmentation are achieved within this approach with accuracy and a reduced number of degrees of freedom, which improves each task to obtain a reliable optic flow estimation. We present some numerical simulations to show the performances of the method for the segmentation and the simultaneous segmentation-filtering.     

Design of bossed silicon membranes for high sensitivity microphone applications

This paper deals with the design optimization of new high sensitivity microphones in silicon on insulator (SOI) technology for gas sensing applications. A novel geometry of bossed silicon membranes used as mechanical transducer has been studied by finite element modelling. Device fabrication is achieved from SOI substrates through deep backside anisotropic etching and shallow front side reactive ion etching to define a bossed sensing membrane with two reinforced areas. Thus, the influence of thin film stresses on the device performance is largely decreased. Polysilicon gauges are located on the reinforced areas to get a better linearity in pressure.     

Smart adaptive optic systems using spatial light modulators

Many factors contribute to the aberrations induced in an optical system. Atmospheric turbulence between the object and the imaging system, physical or thermal perturbations in optical elements degrade the system's point spread function, and misaligned optics are the primary sources of aberrations that affect image quality. The design of a nonconventional real-time adaptive optic system using a micro-mirror device for wavefront correction is presented. The unconventional compensated imaging system presented offers advantages in speed, cost, power consumption, and weight. A pulsed-coupled neural network is used to as a preprocessor to enhance the performance of the wavefront sensor for low-light applications. Modeling results that characterize the system performance are presented.     

Design,fabrication and characterization of a piezoelectrically actuated bidirectional polymer micropump

We present the design, fabrication and characterization of a new, piezoelectrically actuated fully polymeric three chamber peristaltic micropump. An optimized bimorph bending actuator has been designed to deform the polymer membranes in an optimal and most-efficient way. The piezoelectric actuators of the micropump are driven with actuation voltages of ±260 V. The pump has a total size of 46 × 18 × 4 mm, is produced by hot embossing and is assembled in a very simple way. The presented design is able to pump water with a flow rate of 4.8 ml/min and achieves a maximum back pressure of app. 200 mBar.     

In-situ fabrication of an out-of-plane microlens with pre-definable focal length

Out-of-plane microlenses are an important component for integrated optics. Unlike their in-plane counterparts, the fabrication of out-of-plane microlenses is more complicated, which limits their applications. In this paper, a new technique that is capable of fabricating out-of-plane microlenses is described. The resulting lenses have pre-definable focal length and can focus light beams not only in the horizontal plane, but also in the vertical plane. The fabrication process is completely compatible with the soft lithography technique. The lens chamber with two thin polydimethylsiloxane (PDMS) membranes was designed and fabricated together with microfluidic or other components using the same UV lithography mask. The lens was then formed in an in-situ fashion. Curable polymers were injected into the lens chamber and cured while pneumatic pressure was applied to keep the PDMS membranes deformed in a quasi-spherical profile. Pneumatic pressure and membrane thickness can be adjusted to control the resulting lens focal length. With a group of lens chambers with different membrane thickness, a single pressure line can be used to fabricate microlenses with different focal lengths. Since cured polymer was used as the lens filling material, the resulting lens can be used without a pressure source. Different polymers can be selected for desirable optical properties. The simulation and experimental results have proved the feasibility of this technique and resulting lens showed good focusing ability for a divergent light beam from an on-chip multi-mode optical fiber. The small design footprint, total compatibility with soft lithography and technical versatility of this technique make it particularly useful for intergrating out-of-plane microlens into microfluidic chips, which may open new possibilities for the development of on-chip optical detection system.     

Manufacturing Bespoke Architecture

At the disposal of today??s architect is an evolving array of interoperable tools and processes that allow the fabrication of design propositions to be increasingly complex, non?Cstandard and adaptive. How are we equipped to deal with such a growing breadth of new potential, and how are the philosophies that underpin this potential being defined? This paper attempts to address what is something of a contemporary dilemma in architecture, as the constraints of industrial standardisation are relaxed. Have the roles of designers and makers changed in a way that we??ve not experienced before, and is a new approach to making architecture emerging?     

A wafer-scale membrane transfer Process for the fabrication of optical quality, large continuous membranes

This paper describes a new fabrication technique developed for the construction of large area mirror membranes via the transfer of wafer-scale continuous membranes from one substrate to another. Using this technique, wafer-scale silicon mirror membranes have been successfully transferred without the use of sacrificial layers such as adhesives or polymers. This transfer technique has also been applied to the fabrication and transfer of 1 /spl mu/m thick corrugated membrane actuators. These membrane actuators consist of several concentric-ring-type corrugations constructed within a polysilicon membrane. A typical polysilicon actuator membrane with an electrode gap of 1.5 /spl mu/m, fabricated using the wafer-scale transfer technique, shows a vertical deflection of 0.4 /spl mu/m at 55 V. The mirror membranes are constructed from single-crystal silicon, 10 cm in diameter, and have been successfully transferred in their entirety. Using a white-light interferometer, the measured average peak-to-valley surface figure error for the transferred single-crystal silicon mirror membranes is approximately 9 nm as measured over a 1 mm/sup 2/ membrane area. The wafer-scale membrane transfer technique demonstrated in this paper has the following benefits over previously reported transfer techniques: 1) No postassembly release process to remove sacrificial polymers is required. 2) The bonded interface is completely isolated from any acid, etchant, or solvent during the transfer process, ensuring a clean and uniform membrane surface. 3) Our technique is capable of transferring large, continuous membranes onto substrates.     

Biodegradable submicrometric sieves in PLLA fabricated by soft lithography

Sieves are membranes with a regular array of uniform pores that present low flow resistance. Because of such characteristics they are promising devices for filtration, separation of particles by size and drug delivery control systems. In this paper, we propose and demonstrated the use of a soft lithography process for fabrication of biodegradable sieves in PLLA (poly-l-lactide) with pores in the scale of hundred of nanometers. The fabrication process is suitable for mass production and submicrometric pore diameters can be fabricated with homogeneity of about 15%. The PLLA self sustained sieve can be integrated to PLLA capsules, compounding a drug delivery systems or implants.     

Analysis of a high-resolution optical wave-front control system

We consider the formulation and analysis of a problem of automatic control: correcting for the distortion induced in an optical wave front due to propagation through a turbulent atmosphere. It has recently been demonstrated that high-resolution optical wave-front distortion suppression can be achieved using feedback systems based on high-resolution spatial light modulators and phase-contrast techniques. We examine the modeling and analysis of such adaptive optic systems, and show that under certain conditions, the nonlinear dynamical system models obtained are gradient systems (with energy functions that also serve as Lyapunov functions). These gradient systems (employing fixed phase-contrast sensors) serve as a starting point for understanding the design of practical high-resolution wave-front correction systems, in which the phase-contrast sensor itself is subject to control.     

3D-feature-based structure design for silicon fabrication of micro devices

To make MEMS structure design in a more intuitive way, and to support the “function to 3D shape to mask” design flow, a 3D feature based structure design framework and its corresponding key enabling techniques are presented on the basis of inverse design processes and top-down design methodologies. Driven by space mapping among function and structure, the feature model and its parameters are restricted with the bond graph represented simulation model, which is constructed with functional components in simulation library at the system-level. Conforming design rules, the hierarchic feature information model is established and finally can be cascaded down to a group of 3D feature nodes, which are all silicon fabrication oriented and defined on the top of CSG/B-rep 3D solid models. Surrounding this feature information model, the 2D mask deducing and fabrication parameters extraction at the fabrication-level can be performed for manufacturability checking, design/fabrication conflict feedback and fabrication process sequence generation. Taking a micro gap-closing actuator as an example, the structure design process is demonstrated in terms of this 3D feature modeling methodology.     

面向设计制造一体化的管道预制管理信息系统

管道的制造和安装是工厂建设的重要组成部分，目前国内项目的管道设计、制造和安装过程中的信息还未有效地集成起来，针对这一问题提出了一种将管道设计和制造信息集成管理的模式．基于统一的分级管道数据模型，把管道设计过程中的各种信息和制造过程中材料管理、生产进度管理和质量控制的信息进行了统一，形成了管道布置系统的集成软件结构．利用一体化的管道预制管理系统，AEC项目的承包企业可以提升现有的流程，提高生产效率和制造的质量．该方法已经在相应的软件中得到了实现，给实际应用该软件的AEC企业带来了良好的效益．     

An adaptive vision-based autopilot for mini flying machines guidance,navigation and control

The design of reliable navigation and control systems for Unmanned Aerial Vehicles (UAVs) based only on visual cues and inertial data has many unsolved challenging problems, ranging from hardware and software development to pure control-theoretical issues. This paper addresses these issues by developing and implementing an adaptive vision-based autopilot for navigation and control of small and mini rotorcraft UAVs. The proposed autopilot includes a Visual Odometer (VO) for navigation in GPS-denied environments and a nonlinear control system for flight control and target tracking. The VO estimates the rotorcraft ego-motion by identifying and tracking visual features in the environment, using a single camera mounted on-board the vehicle. The VO has been augmented by an adaptive mechanism that fuses optic flow and inertial measurements to determine the range and to recover the 3D position and velocity of the vehicle. The adaptive VO pose estimates are then exploited by a nonlinear hierarchical controller for achieving various navigational tasks such as take-off, landing, hovering, trajectory tracking, target tracking, etc. Furthermore, the asymptotic stability of the entire closed-loop system has been established using systems in cascade and adaptive control theories. Experimental flight test data over various ranges of the flight envelope illustrate that the proposed vision-based autopilot performs well and allows a mini rotorcraft UAV to achieve autonomously advanced flight behaviours by using vision.     

Multi-volume CAD modeling for heterogeneous object design and fabrication

The current computer-aided technologies in disign and product development,the evolution of CAD modeling,and a framework of multi-volume CAD modeling system for heterogeneous object design and fabrication are presented in this paper.The multi-volume CAD modeling system is presented based on nonmanifold topological elements.Material identifications are defined as design attributes introduced along with geometric and topological information at the design stage.Extended Euler operation and reasoning Boolean operations for merging and extraction are executed according to the associated material identifications in the developed multi-volume modeling system for heterogeneous object.An application example and a pseudo-processing algorithm for prototyping of heterogeneous structure through solid free-form fabrication are also described.     

Ultrasound barrier microsystem for object detection based onmicromachined transducer elements

This work reports on the fabrication, characterization, and encapsulation of micromachined membrane resonators for ultrasound generation and detection. Based on the encapsulated 1×1-mm membrane resonators, an ultrasound barrier microsystem for short-distance object detection including the necessary driving circuitry has been developed. Using the ultrasound principle, the barrier microsystem is able to detect, e.g., optically transparent objects. The membrane resonators are fabricated using an industrial silicon technology compatible with bipolar integrated circuit (IC) technology in combination with a postprocessing etching step. Because of the compatibility with IC fabrication technology, the membranes feature electrothermal excitation and piezoresistive detection of transverse vibrations. For the generation of ultrasound, membranes, which exhibit a slight initial buckling due to fabrication-induced compressive stresses, are best suited. At the fundamental resonance frequency f=87 kHz, maximum sound-pressure amplitudes up to 0.25 Pa can be achieved at 50-mm distance. With the piezoresistors arranged in a Wheatstone bridge, a sensitivity for the detection of sound at the resonance S_sound=2 μV/mPa (for an applied bias voltage of 5 V) is obtained. To protect the membranes from the environment, they are covered by a metal cap with a periodic grid of holes and a thin, porous membrane. With this encapsulation approach, the generated sound pressure in forward direction is only slightly lowered, while the total beam angle (≈80°) of the generated sound field is distinctly reduced     

基于自适应多尺度模板匹配的视盘检测方法

针对视盘检测易受光照和弱对比度影响的问题,提出了一种全新的视盘检测方法用于有效地定位和分割视盘.首先,采用预处理技术校正不均匀的光照和提高弱的对比度.然后,利用交替序列滤波和区域极大值技术提取一系列的视盘关键点.再次,利用提出的自适应多尺度模板匹配方法,计算每一个视盘关键点的相关系数,并将最大相关系数值所对应的关键点视为视盘中心.最后,基于获得的视盘中心,提取包含该中心位置的感兴趣区域,并在此基础上,利用Canny边缘检测算子和霍夫变换技术,实现视盘边缘的有效估计.该算法在DRIVE、DIRATEDB0、DIRATEDB1和ROC四个公共数据库上进行了测试,实验结果表明,提出算法的性能明显地优于现有方法.     

MEMS design and modelling based on resonant gate transistor for cochlear biomimetical application

The electromechanical behaviour and frequency response of the human cochlear have been described to be mimicked using an array of resonant gate transistors (RGT). Presented in this paper are the mathematical model, geometrical analysis and novel design of RGT, employed for the physical model development of the cochlea. In an array of RGTs, the aluminium bridge gate structures with length of 0.57–1.62 mm transduce the sound input signal into mechanical vibrations at audible frequency range of 1–8 kHz. The channels underneath the bridge gates transduce the mechanical vibrations into small signal drain currents with reasonable estimated sensitivity of 4–17 nA/Pa. The gain amplification and resonant frequency reduction of RGT with respect to the voltage applied onto the bridge gate structure highlight the adaptive characteristics of a human cochlear. The proposed modelling approach can aid the fabrication design of RGT for cochlear model.

     

An adaptive sliding mode controller design to cope with unmatched uncertainties and disturbance in a MEMS voltage reference source

Tunable micro-electro-mechanical systems (MEMS) capacitors as the fundamental parts are embedded in MEMS AC voltage reference sources (VRS). Being concerned with the accuracy of the output voltage in the reference sources, it gets important to address uncertainties in the physical parameters of the MEMS capacitor. The uncertainties have the great inevitable potentiality of bringing about output voltage perturbation. The output deterioration is more remarkable when the uncertainties are accompanied by disturbance and noise. Manufacturers have been making great attempts to make the MEMS adjustable capacitor with desired rigorous physical characteristics. They have also tried to mitigate physical parameter veracity. However, ambiguity in the values of the parameters inescapably occurs in fabrication procedures since the micro-machining process might itself suffer from uncertainties. Employing a proportional integral (PI) adaptive sliding mode controller (ASMC), both terms of matched and unmatched uncertainties as well as the disturbance, are addressed in this work for the MEMS AC VRS so that a strict voltage is stabilized while the system is simultaneously subjected into uncertainties and exogenous disturbance. Cross-talk, some inertial forces, and electrostatic coercions may appear as matched and unmatched disturbances. Alteration in stiffness and damping coefficients might also take place as matched uncertainties due to variations in the fabrication process or even working environment. The simulation results in the paper are persuasive and the controller design has shown a satisfactory tracking performance.