• Smart Structures and Systems
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• v.1 no.1
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• pp.63-82
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• 2005

This paper introduces a technology for robust and low maintenance cost sensor network capable to detect accelerations below a micro-g in a wide frequency bandwidth (above 1,000 Hz). Sensor networks with such performance are critical for navigation, seismology, acoustic sensing, and for the health monitoring of civil structures. The approach is based on the fabrication of an array of high sensitivity accelerometers, each utilizing Fabry-Perot cavity with wavelength-dependent reflectivity to allow embedded optical detection and serialization. The unique feature of the approach is that no local power source is required for each individual sensor. Instead one global light source is used, providing an input optical signal which propagates through an optical fiber network from sensor-to-sensor. The information from each sensor is embedded onto the transmitted light as an intrinsic wavelength division multiplexed signal. This optical "rainbow" of data is then assessed providing real-time sensing information from each sensor node in the network. This paper introduces the Fabry-Perot based accelerometer and examines its critical features, including the effects of imperfections and resolution estimates. It then presents serialization techniques for the creation of systems of arrayed sensors and examines the effects of serialization on sensor response. Finally, a fabrication process is proposed to create test structures for the critical components of the device, which are dynamically characterized.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.39C no.1
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• pp.82-89
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• 2014

Recently, inertial sensors are popularly used for the location and position recognition of small devices for M2M/IoT. In this paper, we designed low power, low noise, small sized 6-axis inertial sensor IC for mobile applications, which uses a 3-axis piezo-electric gyroscope sensor and a 3-axis piezo-resistive accelerometer sensor. Proposed IC is composed of 3-axis gyroscope readout circuit, two gyroscope sensor driving circuits, 3-axis accelerometer readout circuit, 16bit sigma-delta ADC, digital filter and control circuit and memory. TSMC $0.18{\mu}m$ mixed signal CMOS process was used. Proposed IC reduces 27% of the current consumption of LSM330.

• Current Research on Agriculture and Life Sciences
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• v.32 no.2
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• pp.79-84
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• 2014

The precision aerial application of agricultural unmanned helicopters has become a new paradigm for small farms with orchards, paddy, and upland fields. The needs of agricultural applications require easy and affordable control systems. Recent developments of MEMS technology based on inertial sensors and high speed DSP have enabled the fabrication of low-cost attitude system. Therefore, this study evaluates inertial MEMS sensors for estimating the attitude of an agricultural unmanned helicopter. The accuracies and errors of gyro and acceleration sensors were verified using a pendulum system. The true motion values were calculated using a theoretical estimation and absolute encoder measurement of the pendulum, and then the sensor output was compared with reference values. When comparing the sensor measurements and true values, the errors were determined to be 4.32~5.72%, 3.53~6.74%, and 3.91~4.16% for the gyro rate and x-, z- accelerations, respectively. Thus, the measurement results confirmed that the inertial sensors are effective for establishing an attitude and heading reference system (AHRES). The sensors would be constructed in gimbals for the estimating and proving attitude measurements in the following paper.

• 전자공학회논문지 IE
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• v.49 no.1
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• pp.12-17
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• 2012

Fast development of ubiquitous technology prompted the broadening of the related application area. Application of ubiquitous techniques and system into the construction sites may give us many benefits. There are always a lot of hazard situations in construction sites, and the falling is known to have the high accident rate. To prevent the falling, there has been a lot of efforts including safety education and use of safety gears. In this study, we designed, fabricated and tested a system that can monitor the worker's safety and location informations in real time by using the wireless technology of TOA and RSSI. We used ATmegal28 that is popular in the industrial equipments as MCU and NanoPan 5357 module from Nanotron and CC2500 chipset from TI for radio circuits. We also used 3-axis accelerometer and pressure MEMS sensors to obtain the environmental information, and therefore to aquire the informations of the worker's movement and altitude. We used Labview software from National Instrument to monitor and control the system. We developed the system to send the warning alarms to the server operator and the workers when the workers in the danger zone did not wear the safety hook.

• Journal of Advanced Navigation Technology
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• v.25 no.1
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• pp.68-77
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• 2021

In this paper, a GPS/MEMS IMU integrated navigation receiver module capable of operating in a high dynamic environment is designed and fabricated, and the results is confirmed. The designed module is composed of RF receiver unit, inertial measurement unit, signal processing unit, correlator, and navigation S/W. The RF receiver performs the functions of low noise amplification, frequency conversion, filtering, and automatic gain control. The inertial measurement unit collects measurement data from a MEMS class IMU applied with a 3-axis gyroscope, accelerometer, and geomagnetic sensor. In addition, it provides an interface to transmit to the navigation S/W. The signal processing unit and the correlator is implemented with FPGA logic to perform filtering and corrrelation value calculation. Navigation S/W is implemented using the internal CPU of the FPGA. The size of the manufactured module is 95.0×85.0×.12.5mm, the weight is 110g, and the navigation accuracy performance within the specification is confirmed in an environment of 1200m/s and acceleration of 10g.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2014.04a
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• pp.540-542
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• 2014

This paper introduces main activities of ISO/TC 108/SC 3 and published standards. Two working groups (WG 1 and WG 6) have been orgnized to review and revise ISO standards, specifically related to measurement and calibration subjects of vibration and shocks. A new joint working group (JWG1) with IEC/SC 47E (Semiconductor acceleration calibration) has started to deal with calibration methods for analog and digital output MEMS accelerometers. Finally, Published ISO standards, technically super-visored by ISO/TC 108/SC 3, are listed in this paper to help readers understand their main contents.

• 제어로봇시스템학회:학술대회논문집
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• 2002.10a
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• pp.98.1-98
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• 2002

In principle, a resonance type sensor generally has an oscillation characteristic. Thus, an analysis on transient oscillation response takes a great interest since it is related to the performance of resonant sensor. In particular, system bandwidth has tradeoff with oscillation accuracy, i.e. quality factor. For an efficient analysis of the oscillation characteristic, several analytic methods are introduced and summarized. The results are fundamentally based on the classical describing function method, but can explain the transient oscillation by introducing time varying concept about the predicted limit cycle. After introducing those methods, the application results to the specified system...

• Proceedings of the KSME Conference
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• 2003.11a
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• pp.1642-1647
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• 2003

The market of the horizontal axis washing machine (drum washing machine) has been growing drastically in Korea by about 80% annually since 2000. As market grows fast, the customerTs demands concerning quality becomes more strict and various. Imbalance sensing is a key technology to reduce the NVH problem in a washing machine, because the laundry is time-variant and uncontrollable source of imbalance, which can cause more than 200kgf exciting force. In this paper, imbalance-sensing methods are briefly reviewed, new acceleration sensing circuits are examined, and finally the control algorithm of spinning process is proposed and validated.

• Journal of Institute of Control, Robotics and Systems
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• v.12 no.10
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• pp.1029-1034
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• 2006

In this paper, the tracking control of an automatic pipe cutting robot, called APCROM, with a magnetic binder is studied. Using magnetic force APCROM, a wheeled robot, binds itself to the pipe and executes unmanned cutting process. The gravity effect on the movement of APCROM varies as it rotates around the pipe laid in the gravitational field. In addition to the varying gravity effect other types of nonlinear disturbances including backlash in the driving system and the slip between the wheels of APCROM and the pipe also cause degradation in the cutting process. To maintain a constant velocity and consistent cutting performance, the authors adopt a repetitive learning controller (MRLC), which learns the required effort to cancel the tracking errors. An angular-position estimation method based on the MEMS-type accelerometer is also used in conjunction with MRLC to compensate the tracking error caused by slip at the wheels. Experimental results verify the effectiveness of the proposed control scheme.

• Journal of the Korean Society for Precision Engineering
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• v.26 no.12
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• pp.146-153
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• 2009

One of the most important issues in the wearable healthcare sensors is to minimize the motion artifacts in the vital signals for continuous monitoring. This paper presents a reflected type photoplethysmograph (PPG) sensor for monitoring heart rates at the artery of the wrist. Active noise cancellation algorithm was applied to compensate the distorted signals by motions with Least Mean Square (LMS) adaptive filter algorithms, using acceleration signals from a MEMS accelerometer. Experiments with a watch type PPG sensor were performed to validate the proposed algorithm during typical daily motions such as walking and running. The developed sensor is suitable for ubiquitous healthcare system and monitoring vital arterial signals during surgery.