2,074 research outputs found
Automotive Inductive Position Sensor
Inductive angular position sensors (IAPS) are widely used for high accuracy and low cost angular position sensing in harsh automotive environments, such as suspension height sensor and throttle body position sensor. These sensors ensure high resolution and long lifetime due to their contactless sensing mode and their simple structure. Furthermore, they are suitable for wider application areas. For instance, they can be miniaturized to fit into a compact packaging space, or be adopted to measure the relative angle of multiple rotating targets for the purposes of torque sensing. In this work, a detailed SIMULINK model of an IAPS is first proposed in order to study and characterize the sensor performance. The model is validated by finite element analysis and circuit simulation, which provides a powerful design tool for sensor performance analysis. The sensor error introduced by geometry imperfection is thoroughly investigated for two-phase and three-phase configurations, and a corresponding correction method to improve the accuracy is proposed. A design optimization method based on the response surface methodology is also developed and used in the sensor development. Three types of sensors are developed to demonstrate the inductive sensor technology. The first type is the miniaturized inductive sensor. To compensate for the weak signal strength and the reduced quality (Q) factor due to the scaling down effect, a resonant rotor is developed for this type of sensor. This sensor is fabricated by using the electrodeposition technique. The prototype shows an 8mm diameter sensor can function well at 1.5mm air gap. The second type is a steering torque sensor, which is designed to detect the relative torsional angle of a rotating torsional shaft. It demonstrates the mutual coupling of multiple inductive sensors. By selecting a proper layout and compensation algorithm, the torque sensor can achieve 0.1 degree accuracy. The third type is a passive inductive sensor, which is designed to reduce power consumption and electromagnetic emissions. The realization and excellent performance of these three types of sensors have shown the robustness of the inductive sensor technology and its potential applications. The research conducted in this dissertation is expected to improve understanding of the performance analysis of IAPS and provide useful guidelines for the design and performance optimization of inductive sensors
MEASUREMENT AND MODELING OF HUMIDITY SENSORS
Humidity measurement has been increasingly important in many industries and process control applications. This thesis research focus mainly on humidity sensor calibration and characterization. The humidity sensor instrumentation is briefly described. The testing infrastructure was designed for sensor data acquisition, in order to compensate the humidity sensor’s temperature coefficient, temperature chambers using Peltier elements are used to achieve easy-controllable stable temperatures. The sensor characterization falls into a multivariate interpolation problem. Neuron networks is tried for non-linear data fitting, but in the circumstance of limited training data, an innovative algorithm was developed to utilize shape preserving polynomials in multiple planes in this kind of multivariate interpolation problems
Experimental Tests of Particle Flow Calorimetry
Precision physics at future colliders requires highly granular calorimeters
to support the Particle Flow Approach for event reconstruction. This article
presents a review of about 10 - 15 years of R\&D, mainly conducted within the
CALICE collaboration, for this novel type of detector. The performance of large
scale prototypes in beam tests validate the technical concept of particle flow
calorimeters. The comparison of test beam data with simulation, of e.g.\
hadronic showers, supports full detector studies and gives deeper insight into
the structure of hadronic cascades than was possible previously.Comment: 55 pages, 83 figures, to appear in Reviews of Modern physic
Developing of a device for measuring the areal distribution of the forces in the contact zone of foot and underground for the use in leg prostheses
The presented work demonstrates the process of designing a cheap, low cost three axis
force sensor. Further it describes its integration in an array of multiple sensors to measure
the distribution of forces acting on the sole of a prosthetic foot. The focus will be on
easy manufacturing and common materials since the sensor will be integrated in a low
cost prosthesis for lower limp amputees. Using the knowledge from bio mechanics and
some basic assumptions for the later use, requirements for the project are derived. After
a presentation of some state of the art sensor principles, suitable concepts are collected.
Than, the concepts are compared using a comparison table to find the one the fits the requirements
the best. A very compelling concept using barometers casted in silicone rubber
is tested using a simple prototype to try out whether it is a good candidate or not. The
tests show that the concept is capable of measuring forces but due to its disadvantageous
susceptibility for temperature changes it is rejected for the further development process.
The concepts are reevaluated and a new concept is chosen. Afterwards the design process
is described. Beginning with the mechanical design explaining the working principle. The
calculation of the dimensions is presented. After that a circuit to work with a capacitive
measurement as well as a version for resitive measurement is developed and a layout for
a prototype board using capacitive measurement is proposed. To prove the functionality,
the capacitive system is built up as a prototype. To try the measurement behavior and
to measure its repeatability a test stand is designed. It uses commercial available load
cells to conduct a reference measurement. The output of the sensor is compared to the
reference measurement. With various different test procedures the curves mapping the
measured values to the force for normal and shear force measurement are determined.
During the tests, different aspects of performance like creep behavior or hysteresis are investigated.
Also the repeatability is measured various times under different loads to make
reliable estimations of the precision of the measurement. Further on, a resistive force
sensor which could be used instead of the capacitive sensing elements is tested regarding
its curve and performance to have a comparison of the advantages and disadvantages of
either designing the future sensor with resistive or capacitive sensing elements. With both
concepts a repeatability of a few percent uncertainty can be achieved. Further on ways to
improve future versions of the sensor are described based on the experiences made during
the work with the prototype. Finally a possible way to integrate multiple sensors into a
sensing array is proposed. The design as well as possible electrics to acquire the data are
discussed. This way a solid basis for further developments of a sensing array measuring
the force distribution is given.Die vorgestellte Arbeit zeigt den Prozess der Konstruktion eines preiswerten, kostengünstigen
Dreiachs-Kraftsensors. Weiterhin wird eine Integration der Sensoren in ein Array,
zur Messung der Verteilung von Kräften auf der Fußsohle besprochen. Der Schwerpunkt
soll dabei auf einer einfachen und günstigen Herstellung, sowie der Verwendung handelsüblicher
Materialien liegen, da der Sensor in ein kostengünstiges Prothesenkonzept integriert
werden soll. Ausgehend von den Erkenntnissen der Biomechanik und einigen grundlegenden
Annahmen für die Nutzung des Sensors, werden verschiedene Anforderungen
abgeleitet. Im Folgenden wird der Stand der Technik anhand einiger aktueller Forschungsarbeiten
und Sensorprinzipien vorgestellt. Daraufhin werden geeignete Konzepte gesammelt,
die zur Entwicklung des Sensors eingesetzt werden können. Anschließend werden
die Konzepte anhand einer Vergleichstabelle verglichen, um das bestgeeignetste Konzept
zu finden. Eine sehr überzeugende Variante, bei der Barometerchips in Silikon eingegossen
werden, wird mit einem einfachen Prototyp getestet, um herauszufinden, ob es
sich um einen guten Kandidaten für die weitere Entwicklung handelt, oder nicht. Die
Versuche zeigen, dass der Prototyp in der Lage ist, Kräfte zu messen, jedoch zeigt sich
eine große Anfälligkeit für Temperaturschwankungen. Das Konzept wird deshalb nicht
weiter verfolgt. Die Konzepte werden neu bewertet und anschließend ein Neues ausgewählt.
Daraufhin wird der Entwurfsprozess beschrieben. Das Funktionsprinzip und die
Auslegung der Abmessungen werden erläutert. Anschließend wird eine Schaltung zum
Arbeiten mit einer kapazitiven Messung, sowie eine Schaltung für eine resitive Messung
entwickelt und ein Layout für eine Platine zur kapazitiven Kraftmessung vorgeschlagen.
Zum Nachweis der Funktionalität wird das kapazitive System als Prototyp aufgebaut. Um
das Messverhalten zu testen und seine Wiederholbarkeit nachzuweisen, wird ein Prüfstand
entworfen. Zur Durchführung einer Referenzmessung werden handelsübliche Wägezellen
verwendet. Der Ausgang des Sensors wird mit der Referenzmessung verglichen. Mit verschiedenen
Prüfverfahren werden die Kurven bestimmt, die die Messwerte der Normalund
Querkraft zuordnen. Während des Tests werden verschiedene Leistungsaspekte wie
Kriechverhalten oder Hysterese untersucht. Auch die Wiederholbarkeit wird mehrmals
unter verschiedenen Belastungen gemessen, um zuverlässige Schätzungen der Genauigkeit
der Messung vorzunehmen. Weiterhin wird ein resistiver Kraftsensor, der anstelle der
kapazitiven Sensorelemente verwendet werden könnte, hinsichtlich seiner Kurve und Leistung
getestet, um einen Vergleich der Vor- und Nachteile der Konstruktion des zukünftigen
Sensors mit resistiven oder kapazitiven Sensorelementen zu erhalten. Mit beiden
Konzepten kann eine gute Wiederholgenauigkeit mit nur wenigen Prozent Unsicherheit erreicht werden. Weiterhin werden Möglichkeiten zur Verbesserung der zukünftigen Version
des Sensors auf Grundlage der gesammelten Erfahrungen beschrieben. Schließlich wird
ein möglicher Weg zur Integration mehrerer Sensoren in eine Sensoranordnung vorgeschlagen.
Das Design, sowie die mögliche Elektrik zur Erfassung der Daten werden diskutiert.
Damit wird eine solide Grundlage für die Weiterentwicklung einer Sensoranordnung zur
Messung der Kraftverteilung geschaffen.Tesi
Functional-Material-Based Touch Interfaces for Multidimensional Sensing for Interactive Displays: A Review
Multidimensional sensing is a highly desired attribute for allowing human-machine interfaces (HMIs) to perceive various types of information from both users and the environment, thus enabling the advancement of various smart electronics/applications, e.g., smartphones and smart cities. Conventional multidimensional sensing is achieved through the integration of multiple discrete sensors, which introduces issues such as high energy consumption and high circuit complexity. These disadvantages have motivated the widespread use of functional materials for detecting various stimuli at low cost with low power requirements. This work presents an overview of simply structured touch interfaces for multidimensional (x-y location, force and temperature) sensing enabled by piezoelectric, piezoresistive, triboelectric, pyroelectric and thermoelectric materials. For each technology, the mechanism of operation, state-of-the-art designs, merits, and drawbacks are investigated. At the end of the article, the author discusses the challenges limiting the successful applications of functional materials in commercial touch interfaces and corresponding development trends
Design and Characterization of Tri-axis Soft Inductive Tactile Sensors
Tactile sensors are essential for robotic systems to safely and effectively interact with the environment and humans. In particular, tri-axis tactile sensors are crucial for dexterous robotic manipulations by providing shear force, slip or contact angle information. The Soft Inductive Tactile Sensor (SITS) is a new type of tactile sensor that measures inductance variations caused by eddy-current effect. In this paper, we present a soft tri-axis tactile sensor using the configuration of four planar coils and a single conductive film with hyperelastic material in between them. The working principle is explained and design methods are outlined. A 3D finite element model was developed to characterize the tri-axis SITS and to optimize the target design through parameter study. Prototypes were fabricated, characterized and calibrated, and a force measurement resolution of 0.3 mN is achieved in each axis. Demonstrations show that the sensor can clearly measure light touch (a few mN normal force) and shear force pulses (10 to 30 mN) produced by a serrated leaf when it is moved across the sensor surface. The presented sensor is low cost, high performance, robust, durable, and easily customizable for a variety of robotic and healthcare applications
A Multi-Modal Sensing Glove for Human Manual-Interaction Studies
We present an integrated sensing glove that combines two of the most visionary wearable sensing technologies to provide both hand posture sensing and tactile pressure sensing in a unique, lightweight, and stretchable device. Namely, hand posture reconstruction employs Knitted Piezoresistive Fabrics that allows us to measure bending. From only five of these sensors (one for each finger) the full hand pose of a 19 degrees of freedom (DOF) hand model is reconstructed leveraging optimal sensor placement and estimation techniques. To this end, we exploit a-priori information of synergistic coordination patterns in grasping tasks. Tactile sensing employs a piezoresistive fabric allowing us to measure normal forces in more than 50 taxels spread over the palmar surface of the glove. We describe both sensing technologies, report on the software integration of both modalities, and describe a preliminary evaluation experiment analyzing hand postures and force patterns during grasping. Results of the reconstruction are promising and encourage us to push further our approach with potential applications in neuroscience, virtual reality, robotics and tele-operation
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