1,804 research outputs found
A dependable AMR sensor system for automotive applications
The increasing replacement of mechanical parts by x-by-wire systems in automotive applications allows improving driver safety. These systems demand highly dependable sensors that ensure their functionality despite the harsh operating conditions. This means that the sensors should be capable of working continuously despite catastrophic faults and keeping the performance over time. An anisotropic magnetoresistance (AMR) sensor is a magnetic sensor commonly used for angle measurements in cars. It is affected by catastrophic faults and performance degradation due to undesired parameters included at the sensor outputs. Until now, physical redundancy is often used to handle catastrophic faults. For the performance, compensation factors for the undesired parameter, such as offset voltage, are estimated at the start of the sensor life. Although the undesired parameters drift due to aging effects, the sensor performance remains within the allowed tolerant band. However, this tolerant band will decrease in the future because the dependability requirements are continuously increasing. Therefore, it is necessary to consider strategies to guarantee the sensor performance over time. This paper proposes a system to improve the sensor dependability using analytical redundancy for catastrophic faults but also with self-x properties to maintain the sensor performance over time. Results indicate a dependability improvement in terms of reliability, with a reduction of 50% in the rate of uncovered failures. The safety requirement ASIL level D is satisfied, and with regard to maintainability, the sensor performance is maintained over time
A dependable anisotropic magnetoresistance sensor system for automotive applications
The increasing usage of electronic systems in automotive applications aims to enhance passenger safety as well as the performance of the cars. In modern vehicles, the mechanical and hydraulic systems traditionally used have been replaced by X-by-wire systems in which the functions are performed by electronic components. However, the components required should be reliable, have a high-performance, low-cost and capable of operating for a long time in a highly dependable manner despite the harsh operating conditions in automotive applications. Dependability represents the reliance that a user justifiably poses on the service offered by a system, being this especially important in safety-critical applications in which a failure can constitute a threat to people or the environment. An Anisotropic Magnetoresistance (AMR) sensor is a type of magnetic sensor often used for angle measurements in cars. This sensor is affected by performance degradation and catastrophic faults that in principle cause the sensor to stop working suddenly. Therefore, the sensor dependability should be improved in order to guarantee that it will satisfy the continuous increasing dependability as well as accuracy requirements demanded by automotive applications. This research proposes an AMR sensor system that includes a fault-tolerant approach to handle catastrophic faults and self-X properties to maintain the performance of the sensor during its lifetime. Additionally, an interface with the IEEE 1687 standard has been considered, so the sensor is able to communicate with other components of the system in which it is integrated
Angular Position Sensor Based on Anisotropic Magnetoresistive and Anomalous Nernst Effect
Magnetic position sensors find extensive applications in various industrial
sectors and consumer products. However, measuring angles in the full range of
0{\deg} to 360{\deg} in a wide field range using a single magnetic sensor
remains a challenge. Here, we propose a magnetic position sensor based on a
single Wheatstone bridge structure made from a single ferromagnetic layer. By
measuring the anisotropic magnetoresistance (AMR) signal from the bridge and
two sets of anomalous Nernst effect (ANE) signals from the transverse ports on
two perpendicular Wheatstone bridge arms concurrently, we show that it is
possible to achieve 0{\deg} to 360{\deg} angle detection using a single bridge
sensor. The combined use of AMR and ANE signals allows to achieve a mean angle
error in the range of 0.51{\deg} to 1.05{\deg} within a field range of 100 Oe
to 10,000 Oe.Comment: 12 pages, 10 figure
Magnetic sensors and gradiometers for detection of objects
Disertační práce popisuje vývoj nových detekčních zařízení s anizotropními magnetorezistoryThis thesis describes development of innovative sensor systems based on anisotropi
Low-Cost Throttle-By-Wire-System Architecture For Two-Wheeler Vehicles
This paper investigates the performance of a low-cost Throttle-by-Wire-System
(TbWS) for two-wheeler applications. Its consisting of an AMR throttle position
sensor and a position controlled stepper motor driven throttle valve actuator.
The decentralized throttle position sensor is operating contactless and
acquires redundant data. Throttle valve actuation is realized through a
position controlled stepper motor, sensing its position feedback by Hall
effect. Using a PI-controller the stepper motors position is precisely set.
Sensor and actuator units are transceiving data by a CAN bus. Furthermore,
failsafe functions, plausibility checks, calibration algorithms and energy
saving modes have been implemented. Both modules have been evaluated within a
Hardware-in-the-Loop test environment in terms of reliability and
measurement/positioning performance before the TbWS was integrated in a Peugeot
Kisbee 50 4T (Euro 5/injected). Finally, the sensor unit comes with a
measurement deviation of less then 0.16% whereas the actuator unit can approach
throttle valve positions with a deviation of less then 0.37%. The actuators
settling time does not exceed 0.13s while stable, step-loss free and noiseless
operation
Integrated Sensor System for Condition Monitoring of Electromechanical Cylinders
In this work, a sensor system mechanically integrated in an electromechanical cylinder is presented with the goal of measuring relevant quantities for condition monitoring. The system monitors those parts of the cylinder which are mainly affected by wear processes, i.e., spindle drive and ball bearings. Primarily low-cost MEMS sensors, e.g., for acceleration/vibration, IR emission, and position, are integrated on specially designed ring PCBs which are mounted at the front of the spindle ball screw nut allowing, e.g., the detection of spindle defects
Noncontact Operation-State Monitoring Technology Based on Magnetic-Field Sensing for Overhead High-Voltage Transmission Lines
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Operation-State Monitoring and Energization-Status Identification for Underground Power Cables by Magnetic Field Sensing
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Eddy current angular position sensor for automotive
Programa doutoral em Líderes para Indústrias TecnológicasOs sensores angulares usados em aplicações automóveis, requerem uma boa resolução, fiabilidade, baixa
manutenção, baixo custo de produção e capacidade de trabalhar sob condições adversas. Devido a estes
requisitos, os sensores mais utilizados são os magnéticos, indutivos e magneto-indutivos. Outro fator
crítico é a dimensão do sensor, quanto mais reduzido e compacto, maior é o número de aplicações em
que pode ser aplicado. No caso dos sensores magneto-indutivos e indutivos, uma forma de reduzir o
seu tamanho é através do uso de a bobines planares impressas em placas de circuito impresso (PCB).
Estas, para além de mais compactas, conseguem também reduzir os custos de produção, otimizar a
repetibilidade e assemblagem, e permitir que o seu desenho seja facilmente adaptado às suas aplicações.
No desenvolvimento de sensores indutivos, obter a indutância das bobinas, que funcionam como elemento
transdutor, é essencial e desafiador no caso de bobinas planas. Atualmente, há duas abordagens
no estado da arte: fórmulas de aproximação (para geometrias regulares), e simulações de modelos de elementos
finitos (FEM). As simulações são demoradas e recorrem a ferramentas de software dispendiosas
e que exigem muitos recursos computacionais. Esta tese tem como objetivo desenvolver uma ferramenta
de cálculo analítico para obter a indutância de bobinas planas genéricas, reduzindo o tempo de desenvolvimento.
A ferramenta possibilita ainda o cálculo da interferência que um alvo planar condutivo tem
na indutância da bobine, tornando assim possível obter a resposta de um sensor indutivo baseado em
eddy currents durante a sua fase de desenvolvimento.
Esta tese, além de detalhar o desenvolvimento da ferramenta mencionada, também descreve todos os
processos de validação implementados, através de simulações FEM e testes experimentais. A metodologia
proposta foi aplicada com sucesso no desenvolvimento de um sensor de posição angular automotivo
baseado em eddy currrents. Foi possível comprovar que a precisão da ferramenta desenvolvida está de
acordo com as metodologias usualmente utilizadas, com a vantagem de ser mais rápida e económica.Angular sensors used in automotive applications require good precision, reliability, low maintenance, low
production costs and the ability to work in harsh conditions. Due to these requirements, magnetic, inductive
and magneto-inductive sensors are preferred and are used in current generations of automotive
angular position sensors. The size of the sensors is another relevant factor in the development of new
solutions. The smaller and more compact, the larger the number of applications in which they can be
applied. In the case of magneto-inductive and inductive sensors, one way to reduce their size is to use
planar coils printed on printed circuit boards (PCBs). These, in addition to occupy a smaller volume when
compared to solenoids, also reduce production costs and optimize repeatability and simplify assembly.
When developing inductive sensors, knowing the required inductance value of its coils is essential and
this task can be challenging in the case of planar coils. Currently, two approaches are used to calculate
the inductances of planar coils. When the coils have regular geometry approximation formulas are used,
configuring some parameters. When they have irregular geometry or a more accurate result is desired,
simulations using finite element methods (FEM) are chosen. These simulations have the disadvantage
of being time-consuming, requiring expensive software applications and a huge computing resources. In
view of the budget and the reduction of development time, this thesis provides an analytical calculation
tool for the inductance of generic multi-layer planar coils. In this way, it is possible to develop dedicated
applications in reduced time. The tool also allows to calculate the interference that a planar conductive
target, of arbitrary geometry, can have on the coil inductance. Thus, it is possible to obtain the response
of an inductive sensor based on eddy currents during its development phase.
This thesis, in addition to detailing the development of the aforementioned tool, also describes all the
validation processes implemented using FEM simulations and experimental tests. The proposed methodology
was successfully applied in the development of an automotive angular position sensor based on eddy
currents. It was possible to prove that the precision of the developed analytical tool is in concordance with
the methodologies usually used, with the advantage of being faster and open source.Fundação para a Ciência e a Tecnologia (FCT) - bolsa de doutoramento PD/BD/128142/201
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