機械システムの振れ抑制のための正確なモデル予測制御

The thesis proposes a control scheme based on an explicit model predictive control (EMPC) for suppressing fluctuation in time responses of mechanical systems. The control objective is not only to achieve robust tracking performance and rejecting disturbances, but also to suppress the fluctuation of the mechanism. Two kinds of fluctuation systems are considered in this thesis, i.e., torsional fluctuation system which a measured output contains an outlier and active magnetic micromanipulator which the operating point changes, or holding angle changes. The torsional fluctuation system can be represented by two-mass system which typically consists of a driving motor and load, both of which connect through a flexible shaft. Consequently, there is the difference between the motor and load speed, which results in the torsional fluctuation inevitably. In addition, the measured output, the motor speed, contains an outlier. The requirement of the high speed servo operation, tracking the desired motor speed, has to carefully design. The robust EMPC is proposed in order to achieve not only good tracking performance and load-change effect rejection, but also low torsional fluctuation whereas the measurement noise contains outliers. The control structure is based fundamentally on the combination of EMPC and an estimator where the well-known Kalman filter is replaced by the estimator to deal with the outlier phenomena. The effectiveness of the proposed method is compared with a PID control scheme by means of the simulation validations. The active magnetic micromanipulator having two dimensional degree of freedom that is able to move along x and y-axis in micro scale. The proposed micromanipulator\u27s structure consists of two decoupling links, namely the top and bottom link are able to move along the x and y-axis, independently. Each link has identically parallel leaf spring mechanisms. For a steering force, the combination of permanent magnets and electric coils is utilized as double driving. The hybrid control scheme is proposed which is a combination between EMPC and PID controllers. The PID controller is suitable for handling the holding angle changes, or the initial displacements. The EMPC controller provides an excellent tracking performance. The control objectives are to achieve the robust tracking performance and to suppress the fluctuation of the flexible structure. Root mean square error is less than 4μm whereas the active magnetic micromanipulator held by the user\u27s hand. The experimental results obtained indicate the effectiveness of the hybrid control. The results in this thesis reveal the effectiveness of both control schemes, robust EMPC and hybrid control, for suppressing the fluctuation in mechanical systems. For the torsional fluctuation system which the measured output contains an outlier, the results also show combining different norms. For the active magnetic micromanipulator, the results also show combining two controllers to handle the nonlinear system collectively. The contributions of the hybrid control enable a user to accomplish tracking reference tasks beyond human dexterity with the active magnetic micromanipulator.電気通信大学201

Workshop on "Control issues in the micro / nano - world".

International audienceDuring the last decade, the need of systems with micro/nanometers accuracy and fast dynamics has been growing rapidly. Such systems occur in applications including 1) micromanipulation of biological cells, 2) micrassembly of MEMS/MOEMS, 3) micro/nanosensors for environmental monitoring, 4) nanometer resolution imaging and metrology (AFM and SEM). The scale and requirement of such systems present a number of challenges to the control system design that will be addressed in this workshop. Working in the micro/nano-world involves displacements from nanometers to tens of microns. Because of this precision requirement, environmental conditions such as temperature, humidity, vibration, could generate noise and disturbance that are in the same range as the displacements of interest. The so-called smart materials, e.g., piezoceramics, magnetostrictive, shape memory, electroactive polymer, have been used for actuation or sensing in the micro/nano-world. They allow high resolution positioning as compared to hinges based systems. However, these materials exhibit hysteresis nonlinearity, and in the case of piezoelectric materials, drifts (called creep) in response to constant inputs In the case of oscillating micro/nano-structures (cantilever, tube), these nonlinearities and vibrations strongly decrease their performances. Many MEMS and NEMS applications involve gripping, feeding, or sorting, operations, where sensor feedback is necessary for their execution. Sensors that are readily available, e.g., interferometer, triangulation laser, and machine vision, are bulky and expensive. Sensors that are compact in size and convenient for packaging, e.g., strain gage, piezoceramic charge sensor, etc., have limited performance or robustness. To account for these difficulties, new control oriented techniques are emerging, such as[d the combination of two or more ‘packageable' sensors , the use of feedforward control technique which does not require sensors, and the use of robust controllers which account the sensor characteristics. The aim of this workshop is to provide a forum for specialists to present and overview the different approaches of control system design for the micro/nano-world and to initiate collaborations and joint projects

Microbead-Based Biosensing in Microfluidic Devices

Microbeads are frequently used as a solid support to capture target analytes of interest, such as proteins and nucleic acids, from a biological sample. The integration of microbeads into microfluidic systems for biological testing is an area of growing interest. Such lab-on-chip systems are designed to integrate several functions of a conventional laboratory onto a single chip. As a platform to capture targets, beads offer several advantages over planar surfaces such as large surface areas to support biological interactions (increasing sensitivity), the availability of libraries of beads of various types from many vendors, and array-based formats capable of detecting multiple targets simultaneously (multiplexing). This dissertation describes the development and characterization of microbead-based biosensing devices. A customized hot embossing technique was used to stamp an array of microwells in a thin plastic substrate where appropriately functionalized agarose microbeads were selectively placed within a conduit. Functionalized quantum dot nanoparticles were pumped through the conduit and used as a fluorescent label to monitor binding to the bead. Three-dimensional finite element simulations were carried out to model the mass transfer and binding kinetics on the beads’ surfaces and within the porous beads. The theoretical predictions were critically compared and favorably agreed with experimental observations. A novel method of bead pulsation was shown to improve binding kinetics in porous beads. In addition, the dissertation discusses other types of bead arrays and demonstrates alternative bead-based target capture and detection strategies. This work enhances our understanding of bead-based microfluidic systems and provides a design and optimization tool for developers of point-of-care, lab-on-chip devices for medical diagnosis, food and water quality inspection, and environmental monitoring

Design, Optimization, and Experimental Characterization of a Novel Magnetically Actuated Finger Micromanipulator

The ability of external magnetic fields to precisely control micromanipulator systems has received a great deal of attention from researchers in recent years due to its off-board power source. As these micromanipulators provide frictionless motion, and precise motion control, they have promising potential applications in many fields. Conversely, major drawbacks of electromagnetic micromanipulators, include a limited motion range compared to the micromanipulator volume, the inability to handle heavy payloads, and the need for a large drive unit compared to the size of the levitated object, and finally, a low ratio of the generated magnetic force to the micromanipulator weight. To overcome these limitations, we designed a novel electromagnetic finger micromanipulator that was adapted from the well-known spherical robot. The design and optimization procedures for building a three Degree of Freedoms (DOF) electromagnetic finger micromanipulator are firstly introduced. This finger micromanipulator has many potential applications, such as cell manipulation, and pick and place operations. The system consists of two main subsystems: a magnetic actuator, and an electromagnetic end-effector that is connected to the magnetic actuator by a needle. The magnetic actuator consists of four permanent magnets and four electromagnetic coils that work together to guide the micromanipulator finger in the xz plane. The electromagnetic end-effector consists of a rod shape permanent magnet that is aligned along the y axis and surrounded by an electromagnetic coil. The optimal configuration that maximizes the micromanipulator actuation force, and a closed form solution for micromanipulator magnetic actuation force are presented. The model is verified by measuring the interaction force between an electromagnet and a permanent magnet experimentally, and using Finite Element Methods (FEM) analysis. The results show an agreement between the model, the experiment, and the FEM results. The error difference between the FEM, experimental, and model data was 0.05 N. The micromanipulator can be remotely operated by transferring magnetic energy from outside, which means there is no mechanical contact between the actuator and the micromanipulator. Moreover, three control algorithms are designed in order to compute control input currents that are able to control the position of the end-effector in the x, y, and z axes. The proposed controllers are: PID controller, state-feedback controller, and adaptive controller. The experimental results show that the micromanipulator is able to track the desired trajectory with a steady-state error less than 10 µm for a payload free condition. Finally, the ability of the micromanipulator to pick-and-place unknown payloads is demonstrated. To achieve this objective, a robust model reference adaptive controller (MRAC) using the MIT rule for an adaptive mechanism to guide the micromanipulator in the workspace is implemented. The performance of the MRAC is compared with a standard PID controller and state-feedback controller. For the payload free condition, the experimental results show the ability of the micromanipulator to follow a desired motion trajectory in all control strategies with a root mean square error less than 0.2 mm. However, while there is payload variation, the PID controller response yields a non smooth motion with a large overshoot and undershoot. Similarly, the state-feedback controller suffers from variability of dynamics and disturbances due to the payload variation, which yields to non-smooth motion and large overshoot. The micromanipulator motion under the MRAC control scheme conversely follows the desired motion trajectory with the same accuracy. It is found that the micromanipulator can handle payloads up to 75 grams and it has a motion range of ∓ 15 mm in all axes

Optical Coherence Tomography Distal Sensor Based Handheld Microsurgical Tools

Microsurgery is typically differentiated from a general surgery in that it requires a precise sub-millimeter manipulation that could only be achievable under optical magnification. For instance, microsurgeons use surgical microscopes to view surgical sites and train themselves several years to acquire surgical skills to perform the delicate procedures. However, such microsurgical approach imposes considerable physical stress and mental fatigue on the surgeons and these could be sources for surgical risks and complications. For these reasons, a variety of robotic based surgical guidance methods have been developed and studied with the hope of providing safer and more precise microsurgery. These robotic arm based systems have been developed to provide precise tool movement and to remove physiological hand tremor, which is one of the main limiting factors that prevents precise tool manipulation. In another approaches use simpler system that adds robotic functions to existing handheld surgical tools. It is a hybrid system that incorporates the advantages of conventional manual system and robot-assist system. The advantages of such hybrid handheld systems include portability, disposability, and elimination of the large robotic-assist systems in complex surgical environment. The most critical benefit of the hybrid handheld system is its ease of use since it allows surgeons to manipulate tools mostly using their hand. However due to the imprecise nature of tool control using hands, tool tracking is more critical in handheld microsurgical tool systems than that of robotic arm systems. In general, the accuracy of the tool control is largely determined by the resolution of the sensors and the actuators. Therefore, it is essential to develop a real-time high resolution sensor in order to develop a practical microsurgical tools. For this reason, a novel intuitive targeting and tracking scheme that utilizes a common-path swept source optical coherence tomography (CP-SSOCT) distal sensor was developed integrated with handheld microsurgical tools. To achieve micron-order precision control, a reliable and accurate OCT distal sensing method was developed. The method uses a prediction algorithm is necessary to compensate for the system delay associated with the computational, mechanical and electronic latencies. Due to the multi-layered structure of retina, it was also necessary to develop effective surface detection methods rather than simple peak detection. The OCT distal sensor was integrated into handheld motion-guided micro-forceps system for highly accurate depth controlled epiretinal membranectomy. A touch sensor and two motors were used in the forceps design to minimize the motion artifact induced by squeezing, and to independently control the depth guidance of the tool-tip and the grasping action. We also built a depth guided micro-injector system that enables micro-injection with precise injection depth control. For these applications, a smart motion monitoring and a guiding algorithm were developed to provide precise and intuitive freehand control. Finally, phantom and ex-vivo bovine eye experiments were performed to evaluate the performance of the proposed OCT distal sensor and validate the effectiveness of the depth-guided micro-forceps and micro-injector over the freehand performance

Force-Sensing-Based Multi-Platform Robotic Assistance for Vitreoretinal Surgery

Vitreoretinal surgery aims to treat disorders of the retina, vitreous body, and macula, such as retinal detachment, diabetic retinopathy, macular hole, epiretinal membrane and retinal vein occlusion. Challenged by several technical and human limitations, vitreoretinal practice currently ranks amongst the most demanding fields in ophthalmic surgery. Of vitreoretinal procedures, membrane peeling is the most common to be performed, over 0.5 million times annually, and among the most prone to complications. It requires an extremely delicate tissue manipulation by various micron scale maneuvers near the retina despite the physiological hand tremor of the operator. In addition, to avoid injuries, the applied forces on the retina need to be kept at a very fine level, which is often well below the tactile sensory threshold of the surgeon. Retinal vein cannulation is another demanding procedure where therapeutic agents are injected into occluded retinal veins. The feasibility of this treatment is limited due to challenges in identifying the moment of venous puncture, achieving cannulation and maintaining it throughout the drug delivery period. Recent advancements in medical robotics have significant potential to address most of the challenges in vitreoretinal practice, and therefore to prevent traumas, lessen complications, minimize intra-operative surgeon effort, maximize surgeon comfort, and promote patient safety. This dissertation presents the development of novel force-sensing tools that can easily be used on various robotic platforms, and robot control methods to produce integrated assistive surgical systems that work in partnership with surgeons against the current limitations in vitreoretinal surgery, specifically focusing on membrane peeling and vein cannulation procedures. Integrating high sensitivity force sensing into the ophthalmic instruments enables precise quantitative monitoring of applied forces. Auditory feedback based upon the measured forces can inform (and warn) the surgeon quickly during the surgery and help prevent injury due to excessive forces. Using these tools on a robotic platform can attenuate hand tremor of the surgeon, which effectively promotes tool manipulation accuracy. In addition, based upon certain force signatures, the robotic system can precisely identify critical instants, such as the venous puncture in retinal vein cannulation, and actively guide the tool towards clinical targets, compensate any involuntary motion of the surgeon, or generate additional motion that will make the surgical task easier. The experimental results using two distinct robotic platforms, the Steady-Hand Eye Robot and Micron, in combination with the force-sensing ophthalmic instruments, show significant performance improvement in artificial dry phantoms and ex vivo biological tissues

Modeling and experimental validation of a parallel microrobot for biomanipulation

The main purpose of this project is the development of a commercial micropositioner's (SmarPod 115.25, SmarAct GmbH) geometrical model. SmarPod is characterized by parallel kinematics and is employed for precise and accurate sample's positioning under SEM microscope, being vacuum-compatible, for various applications. Geometrical modeling represents the preliminar step to fully understand, and possibly improve, robot's closed loop behaviour in terms of task's quality precision, when enterprises does not provide sufficient documentation. The robotic system, in fact, represents in this case a "black box" from which it's possible to extract information. This step is essential in order to improve, consequently, the reliability of bio-microsystem manipulation and characterization. Disposing of a detailed microrobot's model becomes essential to deal with the typical lack of sensing at microscale, as it allows a 3D precise and adequate reconstruction, realized through proper softwares, of the manipulation set-up. The roles of Virtual Reality (VR) and of simulations, carried out, in this case, in Blender environment, are asserted as well as an essential helping tool in mycrosystem's task planning. Blender is a professional free and open-source 3D computer graphics software and it is proven to be a basic instrument to validate microrobot's model, even to simplify it in case of complex system's geometries

Liquid Metal Printing with Scanning Probe Lithography for Printed Electronics

In den letzten Jahren hat das „Internet der Dinge“ (Englisch Internet of Things, abgekürzt IoT), das auch als Internet of Everything (Deutsch frei „Internet von Allem“) bezeichnet wird, mit dem Aufkommen der „Industrie 4.0“ einen Strom innovativer und intelligenter sensorgestützter Elektronik der neuen Generation in den Alltag gebracht. Dies erfordert auch die Herstellung einer riesigen Anzahl von elektronischen Bauteilen, einschließlich Sensoren, Aktoren und anderen Komponenten. Gleichzeitig ist die herkömmliche Elektronikfertigung zu einem hochkomplexen und investitionsintensiven Prozess geworden. In dem Maße, wie die Zahl der elektronischen Bauteile und die Nachfrage nach neuen, fortschrittlicheren elektronischen Bauteilen zunimmt, steigt auch die Notwendigkeit, effizientere und nachhaltigere Wege zur Herstellung dieser Bauteile zu finden. Die gedruckte Elektronik ist ein wachsender Markt, der diese Nachfrage befriedigen und die Zukunft der Herstellung von elektronischen Geräten neu gestalten könnte. Sie erlaubt eine einfache und kostengünstige Produktion und ermöglicht die Herstellung von Geräten auf Papier- oder Kunststoffsubstraten. Für die Herstellung gibt es dabei eine Vielzahl von Methoden. Techniken auf der Grundlage der Rastersondenlithografie waren dabei schon immer Teil der gedruckten Elektronik und haben zu Innovationen in diesem Bereich geführt. Obwohl die Technologie noch jung ist und der derzeitige Stand der gedruckten Elektronik im industriellen Maßstab, wie z. B. die Herstellung kompletter integrierter Schaltkreise, stark limitiert ist, sind die potenziellen Anwendungen enorm. Im Mittelpunkt der Entwicklung gedruckter elektronischer Schaltungen steht der Druck leitfähiger und anderer funktionaler Materialien. Die meisten der derzeit verfügbaren Arbeiten haben sich dabei auf die Verwendung von Tinten auf Nanopartikelbasis konzentriert. Die Herstellungsschritte auf der Grundlage von Tinten auf Nanopartikelbasis sind komplizierte Prozesse, da sie das Ausglühen (Englisch Annealing) und weitere Nachbearbeitungsschritte umfassen, um die gedruckten Muster leitfähig zu machen. Die Verwendung von Gallium-basierten, bei/nahe Raumtemperatur flüssigen Metallen und deren direktes Schreiben für vollständig gedruckte Elektronik ist immer noch ungewöhnlich, da die Kombination aus dem Vorhandensein einer Oxidschicht, hohen Oberflächenspannungen und Viskosität ihre Handhabung erschwert. Zu diesem Zweck zielt diese Arbeit darauf ab, Methoden zum Drucken von Materialien, einschließlich Flüssigmetallen, zu entwickeln, die mit den verfügbaren Druckmethoden nicht oder nur schwer gedruckt werden können und diese Methoden zur Herstellung vollständig gedruckter elektronischer Bauteile zu verwenden. Weiter werden Lösungen für Probleme während des Druckprozesses untersucht, wie z. B. die Haftung der Tinte auf dem Substrat und andere abscheidungsrelevante Aspekte. Es wird auch versucht, wissenschaftliche Fragen zur Stabilität von gedruckten elektronischen Bauelementen auf Flüssigmetallbasis zu beantworten. Im Rahmen der vorliegenden Arbeit wurde eine auf Glaskapillaren basierenden Direktschreibmethode für das Drucken von Flüssigmetallen, hier Galinstan, entwickelt. Die Methode wurde auf zwei unterschiedlichen Wegen implementiert: Einmal in einer „Hochleistungsversion“, basierend auf einem angepassten Nanolithographiegerät, aber ebenfalls in einer hochflexiblen, auf Mikromanipulatoren basierenden Version. Dieser Aufbau erlaubt einen on-the-fly („im Fluge“) kapillarbasierten Druck auf einer breiten Palette von Geometrien, wie am Beispiel von vertikalen, vertieften Oberflächen sowie gestapelten 3D-Gerüsten als schwer zugängliche Oberflächen gezeigt wird. Die Arbeit erkundet den potenziellen Einsatz dieser Methode für die Herstellung von vollständig gedruckten durch Flüssigmetall ermöglichten Bauteilen, einschließlich Widerständen, Mikroheizer, p-n-Dioden und Feldeffekttransistoren. Alle diese elektronischen Bauelemente werden ausführlich charakterisiert. Die hergestellten Mikroheizerstrukturen werden für temperaturgeschaltete Mikroventile eingesetzt, um den Flüssigkeitsstrom in einem Mikrokanal zu kontrollieren. Diese Demonstration und die einfache Herstellung zeigt, dass das Konzept auch auf andere Anwendungen, wie z.B. die bedarfsgerechte Herstellung von Mikroheizern für in-situ Rasterelektronenmikroskop-Experimente, ausgeweitet werden kann. Darüber hinaus zeigt diese Arbeit, wie PMMA-Verkapselung als effektive Barriere gegen Sauerstoff und Feuchtigkeit fungiert und zusätzlich als brauchbarer mechanischer Schutz der auf Flüssigmetall basierenden gedruckten elektronischen Bauteile wirken kann. Insgesamt zeigen der alleinstehende, integrierte Herstellungsablauf und die Funktionalität der Geräte, dass das Potenzial des Flüssigmetall-Drucks in der gedruckten Elektronik viel größer ist als einzig die Verwendung zur Verbindung konventioneller elektronischer Bauteile. Neben der Entwicklung von Druckverfahren und der Herstellung elektronischer Bauteile befasst sich die Arbeit auch mit der Korrosion und der zusätzlichen Legierung von konventionellen Metallelektroden in Kontakt mit Flüssigmetallen, welche die Stabilität der Bauteil beinträchtigen könnten. Zu diesem Zweck wurde eine korrelierte Materialinteraktionsstudie von gedruckten Galinstan- und Goldelektroden durchgeführt. Durch die kombinierte Anwendung von optischer Mikroskopie, vertikaler Rasterinterferometrie, Rasterelektronenmikroskopie, Röntgenphotonenspektroskopie und Rasterkraftmikroskopie konnte der Ausbreitungsprozess von Flüssigmetalllinien auf Goldfilmen eingehend charakterisiert werden. Diese Studie zeigt eine unterschiedliche Ausbreitung der verschiedenen Komponenten des Flüssigmetalls sowie die Bildung von intermetallischen Nanostrukturen auf der umgebenden Goldfilmoberfläche. Auf der Grundlage der erhaltenen zeitabhängigen, korrelierten Charakterisierungsergebnisse wird ein Modell für den Ausbreitungsprozess vorgeschlagen, das auf dem Eindringen des Flüssigmetalls in den Goldfilm basiert. Um eine ergänzende Perspektive auf die interne Nanostruktur zu erhalten, wurde die Röntgen-Nanotomographie eingesetzt, um die Verteilung von Gold, Galinstan und intermetallischen Phasen in einem in das Flüssigmetall getauchten Golddraht zu untersuchen. Schlussendlich werden Langzeitmessungen des Widerstands an Flüssigmetallleitungen, die Goldelektroden verbinden, durchgeführt, was dazu beiträgt, die Auswirkungen von Materialwechselwirkungen auf elektronische Anwendungen zu bewerten