• 한국자동차공학회논문집
• /
• 제18권2호
• /
• pp.122-128
• /
• 2010

To meet the NOx limit without a penalty of fuel consumption, urea-SCR system is currently regarded as promising NOx reduction technology for diesel engines. SCR system has to achieve maximal NOx conversion in combination with minimal $NH_3$ slip. In this study, the performance characteristics of urea-SCR system with open loop control were assessed in the European Transient Cycle(ETC) for heavy duty diesel engine. The SCR inlet temperaure varied in the range of 200 to $340^{\circ}C$ in the ETC cycle. Open loop control calculated the urea flow rate based on the NOx and NSR map which gave for each combination of SCR inlet temperature and space velocity the normalized $NH_3$ to NOx stoichiometric ratio which resulted in a steady-state $NH_3$ slip of 20ppm. During the ETC cycle, the open loop control with the optimized NSR offset achieved NOx reduction of 80% while keeping the average $NH_3$ slip below 10ppm and maximum 20ppm. It was also found that NOx sensor was cross-sensitive to $NH_3$ and a control strategy for cross-sensitivity compensation was required in order to use a NOx sensor as feedback device.

• 한국산학기술학회논문지
• /
• 제7권6호
• /
• pp.1064-1071
• /
• 2006

본 논문에서는 최대 견인력 제어를 위해서 부하토크외란관측기와 속도센서리스 벡터제어를 이용하여 점착력 계수를 추정하고 추정한 점착력 계수의 미분치를 PI 토크 제어하는 Anti-slip제어를 제안한다. 점착력 계수를 추정하기 위해서는 전압, 전류값 뿐만 아니라 자속이나 속도정보가 필요하다. 따라서 전동기의 회전속도를 정확하게 검출할 수 있는 속도센서가 필요하게 된다. 그러나 속도검출을 위해 속도센서를 부착하는 것은 여러 가지 면에서 단점을 가지고 있다. 이러한 문제점을 해결하기 위하여 속도센서 없는 센서리스 구동방식에 의한 부하토크외란관측기를 설계하여, 점착력 계수를 추정한다. 이와 같은 제어 알고리즘을 구현하기 위하여 1C1M 철도모의장치를 이용하여 제안된 알고리즘을 실험을 통하여 확인하였다.

• 제어로봇시스템학회논문지
• /
• 제15권8호
• /
• pp.831-838
• /
• 2009

This paper proposes an IR (infrared) LED (Light Emitting Diode)-based tactile fingertip sensor that can independently measure the normal and tangential force between the hand and an object. The proposed IR LED-based tactile sensor has several advantages over other technologies, including a low price, small size, and good sensitivity. The design of the first prototype is described and some experiments are conducted to show output characteristics of the proposed sensor. Furthemore, the effectiveness of the proposed sensor is demonstrated through anti-slip control in a multifunction myoelectric hand, called the KNU Hand, which includes several novel mechanisms for improved grasping capabilities. The experimental results show that slippage was avoided by simple force control using feedback on the normal and tangential force from the proposed sensor. Thus, grasping force control was achieved without any slippage or damage to the object.

• Transactions on Electrical and Electronic Materials
• /
• 제11권3호
• /
• pp.130-133
• /
• 2010

A flexible three-axial tactile sensor was fabricated on Kapton polyimide film using polymer micromachining technology. Nichrome (Ni:Cr = 8:2) strain gauges were positioned on an etched membrane to detect normal and shear loads. The optimal positions of strain gauges were determined through strain distribution from finite element analysis. The sensor was evaluated by applying normal and shear loads from 0 N to 0.8 N using an evaluation system. Sensitivity of the tactile sensor to normal and shear loads was about 206.6 mV/N and 70.1 mV/N, respectively. The sensor showed good linearity, and its determination coefficient ($R^2$) was about 0.982. The developed sensor can be applied in a curved or compliant surface that requires slip detection and flexibility, such as a robotic fingertip.

• 한국항공운항학회지
• /
• 제23권1호
• /
• pp.62-66
• /
• 2015

In this paper, a fretting testing machine is developed using ball-on-flat test apparatus. Precise micro-slip motion is produced by a linear stage. A relative displacement between a ball and a flat specimen is measured with a laser displacement sensor. Dry friction tests are conducted with AISI 52100 steel balls and cold-rolled high strength steel plates at room temperature and ambient humidity. The evolution of the kinetic friction coefficient is determined. Comparison between measured friction coefficients and those found in the literature is then carried out. Fretting tests with an electro-deposited coating are employed at an amplitude of 0.05 mm. Slip regime is identified with slip ratio. It is demonstrated that a developed testing machine allows determining the friction coefficient under fretting condition.

• 대한전기학회:학술대회논문집
• /
• 대한전기학회 2003년도 춘계학술대회 논문집 전기기기 및 에너지변환시스템부문
• /
• pp.388-390
• /
• 2003

Recent trend of sensor-less control of induction motor applied for commuter trains in Japan is introduced. Although many inverter-fed Induction motor driven trains have been produced so far, most of them were slip frequency based conventional V/f control system using shaft encoder. There arises a new trend to apply speed sensor-less vector control., for this inverter-fed induction motor drive system. The purpose of sensor-less control is to save, cost and improve system reliability. Several sensor-less systems now under testing on the actual railway company. This paper describes the survey of the fundamental structure and feature of representative sensor-less systems mentioned above.

• 전력전자학회:학술대회논문집
• /
• 전력전자학회 2003년도 춘계전력전자학술대회 논문집(2)
• /
• pp.998-1001
• /
• 2003

Recent trend of sensor-less control of induction motor applied for commuter trains in Japan is introduced. Although many inverter-fed induction motor driven trains have been produced so far, most of them were slip frequency based conventional V/f control system using shaft encoder. There arises a new trend to apply speed sensor-less vector control., for this inverter-fed induction motor drive system. The purpose of sensor-less control is to save, cost and improve system reliability. Several sensor-less systems now under testing on the actual railway company. This paper describes the survey of the fundamental structure and feature of representative sensor-less systems mentioned above.

• Journal of Power Electronics
• /
• 제8권3호
• /
• pp.228-238
• /
• 2008

Many induction motor broken bar diagnosis methods are based on evaluating special components in machine signals spectrums. Current, power, flux, etc are among these signals. Frequencies related to a broken rotor fault are slip dependent, therefore, correct diagnosis of fault - especially when obtrusive frequency components are present - depends on accurate determination of motor velocity and slip. The traditional methods typically require several sensors that should be pre-installed in some cases. This paper presents a diagnosis method based on only a vibration sensor. Motor velocity oscillation due to a broken rotor causes frequency components at twice slip frequency difference around speed frequency in vibration spectrum. Speed frequency and its harmonics as well as twice supply frequency, can easily and accurately be found in a vibration spectrum, therefore th motor slip can be computed. Now components related to rotor fault can be found. It is shown that a trained neural network - as a substitute for an expert person - can easily categorize the existence and the severity of a fault according to the features extracted from the presented method. This method requires no information about th motor internal and has been able to diagnose correctly in all the laboratory tests.

• 한국지반공학회:학술대회논문집
• /
• 한국지반공학회 2009년도 세계 도시지반공학 심포지엄
• /
• pp.700-709
• /
• 2009

FBG sensor system is applied to the concrete lining structure in Taegu subway. Near the structure, the power cable tunnel construction started. We wanted to measure the deformation of the structure due to the construction by the FBG sensor. The applied sensor has the gauge length of 1 meter to overcome the inhomogeneity of the concrete material with enough length. In order to fix tightly to the structure, the partially stripped parts of the sensor glued to the package and slip phenomenon between fiber and acrylate jacket was prevented. Prestrain of the sensor was imposed by controlling the two fixed points with bolts and nuts in order to measure compressive strain as well as tensile strain. The behavior of subway lining structure could be monitored very well.

• 제어로봇시스템학회:학술대회논문집
• /
• 제어로봇시스템학회 2005년도 ICCAS
• /
• pp.1802-1807
• /
• 2005

Tangible interface can be understood as a newly defined concept, which can provide an effective and seamless interaction between the human as a subjective existence and the cyberspace as an objective existence. Tactile sensation is essential for many exploration and manipulation tasks in the tangible space. In this paper, we suggest the design of an integrated tactile sensor-display system that provides both of sensing and feedback with kinesthetic force, pressure distribution, vibration and slip/stretch. A new tactile sensor with PDVF strips and display system with bimorph actuators has been developed and integrated by developed signal processing algorithm. In the scenario of haptic navigation in the tangible space, tactile feedback system is successfully experimented.