• Journal of the Korean Institute of Intelligent Systems
• /
• v.15 no.1
• /
• pp.75-80
• /
• 2005

In this paper, a 3-dimensional analysis of magnetic road and a position sensing system for an autonomous vehicle system is described. Especially, a new position sensing system, end of the important component of an autonomous vehicle, is proposed. In a magnet based autonomous vehicle system, to sense the vehicle position, the sensor measures the field of magnetic road. The field depends on the sensor position of the vehicle on the magnetic road. As the rotation between the magnetic field and the sensor position is highly complex, it is difficult that the relation is stored in memory. Thus, a neural network is used to learn the mapping from th field to the position. The autonomous vehicle system with the proposed position sensing system is tested in experimental setup.

• Proceedings of the Korean Society of Precision Engineering Conference
• /
• 2009.06a
• /
• pp.477-478
• /
• 2009

• Proceedings of the Korean Society of Precision Engineering Conference
• /
• 2008.06a
• /
• pp.281-282
• /
• 2008

• Progress in Superconductivity and Cryogenics
• /
• v.22 no.4
• /
• pp.1-5
• /
• 2020

Heart consists of myocardium cells and the electrophysiological activity of the cells generate magnetic fields. By measuring this magnetic field, magnetocardiogram (MCG), functional diagnosis of the heart diseases is possible. Since the strength of the MCG signals is weak, typically in the range of 1-10 pT, we need sensitive magnetic sensors. Conventionally, superconducting quantum interference devices (SQUID)s were used for the detection of MCG signals due to its superior sensitivity to other magnetic sensors. However, drawback of the SQUID is the need for regular refill of a cryogenic liquid, typically liquid helium for cooling low-temperature SQUIDs. Efforts to eliminate the need for the refill in the SQUID system have been done by using cryocooler-based conduction cooling or use of non-cryogenic sensors, or room-temperature sensors. Each sensor has advantage and disadvantage, in terms of magnetic field sensitivity and complexity of the system, and we review the recent trend of MCG technology.

• Smart Structures and Systems
• /
• v.19 no.3
• /
• pp.299-307
• /
• 2017

The magneto-electro-elastic (MEE) material under thermal environment exhibits pyroelectric and pyromagnetic coefficients resulting in pyroelectric and pyromagnetic effects. The pyroelectric and pyromagnetic effects on the behavior of multiphase MEE sensors bonded on top surface of a mild steel beam under thermal environment is presented in this paper. The aim of the study is to find out how samples having different volume fractions of the multiphase MEE composite behave in sensor applications. This is studied at optimal location on the beam, where the maximum electric and magnetic potentials are induced due to pyroelectric and pyromagnetic effects under clamped-free and clamped-clamped boundary conditions. The sensor which is bonded on the top surface of the beam is modeled using 8-node brick element. The MEE sensor bonded on mild steel beam is subjected to uniform temperature rise of 50K. It is assumed that beam and sensor is perfectly bonded to each other. The maximum pyroelectric and pyromagnetic effects on electric and magnetic potentials are observed when volume fraction is ${\nu}_f=0.2$. The boundary conditions significantly influence the pyroelectric and pyromagnetic effects on electric and magnetic potentials.

• Journal of the Korean Magnetics Society
• /
• v.12 no.6
• /
• pp.206-211
• /
• 2002

We have constructed a new kind of magnetic motion capture sensor based on the pulse magnetic field method. 3-orthogonal magnetic pulse fields were generated in turns only one period of sinusoidal waveform using 3-orthogonal magnetic dipole coils, ring counter and analog multiplier. These pulse magnetic fields were measured with 3-orthogonal search coils, of which induced voltages by the x-, y-, and l-dipole sources using S/H amplifier at the time position of maximum induced voltage. Using the developed motion capture sensor, we can measure position of sensor with uncertainty of ${\pm}$0.5％ in the measuring range from ${\pm}$0.5 m to ${\pm}$1.5 m.

• Journal of Sensor Science and Technology
• /
• v.4 no.2
• /
• pp.14-21
• /
• 1995

This paper deals with the active magnetic field measuring system which can measure the time-varying magnetic fields generated by power installations and lightning discharges. The magnetic field measuring system consists of the loop-type magnetic field sensor and the active integrator operated by a differential amplifier. The theoretical principle and design rule of the time-varying magnetic field measuring device and the calibration apparatus are introduced. From the calibration experiments, the frequency bandwidth of the full measuring system ranges from 270 Hz to about 2.3 MHz and the response sensitivity for magentic field strength is 128 $mV/{\mu}T$, respectively, and the calculated B-field values in the center of the loop-type sensor versus the the applied current made with a region of ${\pm}3\;%$error. The actual survey experiments by using lightning impulse current and oscillating impulse current were performed, the results of comparision between the input current waveforms and the magnetic field waveforms are a good agreement with each others and their deviations are less than 0.5 %.

• Journal of Institute of Control, Robotics and Systems
• /
• v.9 no.2
• /
• pp.140-144
• /
• 2003

A navigation sensor system for outdoor AGV(Automatic Guided Vehicle) using AMR(Anisotropic Magnetoresitive) sensors is described. We derive a formula of the position of AMR sensor using the measured magnetic field intensity due to permanent magnet with constant distance. The system consists of sensor board. sensor control board and position processing board. The sensor board measures magnetic field intensity, the sensor control board controls the measurement of six sensors sequentially, and the position processing board computes the accurate position of the permanent magnet using Least Square Method. We arranged six sensors at intervals of 30cm and measured the position of the permanent magnet moving at intervals of 30cm. Experimental results showed that we can get standard deviation of 2mm and error of &\pm&4.5mm at a height of 20cm from the permanent magnet.

• Journal of Sensor Science and Technology
• /
• v.14 no.2
• /
• pp.85-90
• /
• 2005

In this study, we have fabricated a three branches vertical Hall sensor for detecting three phases rotation informations of miniaturized brushless motor. The sensor gives three position signals phase shifted by $120^{\circ}$, corresponding to the motor driving signals. The branch has one Hall output and one input each other. The central part acts as common driving input. Sensor has branch width of $150{\mu}m$ and distance from central electrode to Hall electrode of $100{\mu}m$. The sensitivity of sensor is 250 V/$A{\cdot}T$ at magnetic field of 0.1 T. It has also showed three sine waves of Hall voltages with $120^{\circ}$ phase over a $360^{\circ}$ rotation. A packaged sensing part are $2{\times}2mm^{2}$ and has been successfully tested on a motor rotation at a speed up to 60,000 rpm.

• Journal of IKEEE
• /
• v.23 no.1
• /
• pp.230-234
• /
• 2019

This paper shows the development of current sensor for the measurement of hundreds of nanoseconds large current in pulsed power and its characteristics evaluation. The developed current sensor was designed for measuring induced voltage from magnetic flux under the operation of pulsed power. Output characteristics of developed current sensor was good consistent with commercial one, and the realistic current of fast pulsed power was detected easily with the calibration curve using output voltage of developed sensor. Therefore, the developed current sensor is possible to apply the realistic system.