• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.34 no.8
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• pp.63-70
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• 2006

Due to the small size and weight of micro aerial vehicle (MAV), only miniaturized MEMS type sensors are applicable for MAV autonomous flight system. In this paper, we propose a accelerometer and gyro mixing algorithm to improve an attitude performance of MEMS type sensors. The performance of the proposed mixing algorithm is compared with the performance of fuzzy-based mixing algorithm through simulation. The simulation results show that the attitude compensation method through the attitude compensation has better performance than the fuzzy-based mixing method for MAV attitude estimation.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.38 no.3
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• pp.294-299
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• 2010

ELT(Emergency Locator Transmitter) is used to send distress signal in the event of an aircraft crash. It is very useful but the ELT may transmit wrong signal caused by misjudging between crash and hard-landing. The reason of this problem is the low accuracy of the mechanical G-switch currently in use. To improve the ELT, we developed an ELT system using the MEMS(Micro Electro-Mechanical Sensor) accelerometer. The ELT system consists of acceleration data acquisition/analysis system, program of crash recognition, and GPS receiving system for the position information of an aircraft crash site. A free-drop table was developed for verification of the ELT system. The free-drop table was designed to replicate the acceleration and the pulse duration of the hard landing and the crash. By using the free-drop table, we showed that the ELT system performed well.

• Journal of the Semiconductor & Display Technology
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• v.9 no.2
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• pp.41-47
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• 2010

In this paper we suggest an improvement upon the previous method of estimating a body's attitude. This paper presents a method that overcomes the shortcomings of previous studies. Applying the method of separating the acceleration of gravity component from the accelerometer's output improves the performance of the attitude estimation and extends the scope. In order to apply the method of the attitude estimation in an actively moving body, a new acceleration value containing the acceleration of gravity is calculated. This paper also proposes the method which minimizes the estimation error in estimating the moving body's attitude which is changing rapidly. Finally, this paper suggests a method that detects the gyroscope's drift and compensates for this drift using accelerometer. Applying the method improves the performance of the attitude estimation.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.26 no.4
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• pp.271-274
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• 2013

Inclinometer sensors are widely applied in many fields. Especially in the field of construction of high-rise buildings also measure the horizontal and vertical help has been applied to monitor. Recent micro electro-mechanical system(MEMS) technology with the development of the many sensors have been developed. In this paper, a MEMS inclinometer is based on a MEMS accelerometer. The sensor can measure the angle of inclination using the relationship between static acceleration and gravity acceleration from an accelerometer. From this principle, inclinometer has been developed that has more accurate. The accuracy is proved by the experiment with laser displacement. Results in the experiment express high-accuracy, stability and economics of MEMS inclinometer. In conclusion, wireless MEMS inclinometer sensor is expected to be applicable in the areas of construction and many other industries with accurate and convenient monitoring system.

• Smart Structures and Systems
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• v.6 no.1
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• pp.1-16
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• 2010

This paper presents a novel smart MEMS accelerometer which employs a hybrid control algorithm and an estimator. This scheme is realized by adding a sliding-mode controller to a conventional PID closed loop system to achieve higher stability and higher dynamic range and to prevent pull-in phenomena by preventing finger displacement from passing a maximum preset value as well as adding an adaptive nonlinear observer to a conventional PID closed loop system. This estimator is used for online estimation of the parameter variations for MEMS accelerometers and gives the capability of self testing to the system. The analysis of convergence and resolution show that while the proposed control scheme satisfies these criteria it also keeps resolution performance better than what is normally obtained in conventional PID controllers. The performance of the proposed hybrid controller investigated here is validated by computer simulation.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2004.10a
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• pp.475-478
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• 2004

In this paper, a magnet-type automatic pipe cutting machine that binds itself to the surface of the pipe using magnetic force and executes unmanned cutting process is proposed. During pipe cutting process when the machine moves around the pipe laid vertical to the gravitational field, the gravity acting on the pipe cutting machine widely varies as the position of the machine varies. That is, with same driving force from the driving motor the cutting machine moves faster when it climbs down the surface of the pipe and moves slower when it climbs up to the top of the pipe. To maintain a constant velocity of the pipe cutting machine and improve the cutting quality, the authors adopted a conventional PID controller with a feedforward effort designed based on the encoder measurement of the driving motor. It is, however, impossible for the encoder at the motor to measure the absolute position and consequently the absolute velocity of the cutting machine in the case where the slip between the surface of the pipe and wheel of the cutting machine is not negligible. As an attempt to obtain a better estimation of the absolution angular position/velocity of the machine the authors proposes the use of the MEMS-type accelerometer which can measure static acceleration as well as dynamic acceleration. The estimated angular velocity of the cutting machine using the MEMS-type accelerometer measurement is experimentally obtained and it indicates the significant slipping of the machine during the cutting process.

• Journal of IKEEE
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• v.18 no.1
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• pp.119-127
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• 2014

This paper presents a CMOS readout circuit for MEMS(Micro Electro Mechanical System) acceleration sensors. It consists of a MEMS accelerometer, a capacitance to voltage converter(CVC) and a second-order switched-capacitor ${\Sigma}{\Delta}$ modulator. Correlated-double-sampling(CDS) and chopper-stabilization(CHS) techniques are used in the CVC and ${\Sigma}{\Delta}$ modulator to reduce the low-frequency noise and DC offset. The sensitivity of the designed CVC is 150mV/g and its non-linearity is 0.15%. The duty cycle of the designed ${\Sigma}{\Delta}$ modulator output increases about 10% when the input voltage amplitude increases by 100mV, and the modulator's non-linearity is 0.45%. The total sensitivity is 150mV/g and the power consumption is 5.6mW. The proposed circuit is designed in a 0.35um CMOS process with a supply voltage of 3.3V and a operating frequency of 2MHz. The size of the designed chip including PADs is $0.96mm{\times}0.85mm$.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2018.11a
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• pp.328-330
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• 2018

A floating body with a device that converts solar energy into electrical energy is moved by waves. To evaluate the safety of a floating body, measurement and interpretation of the float motion is required, which is generally based on 6 degrees of freedom motion. The 6 degree of freedom motion can be measured using MEMS (Micro-Electro Mechanical System), which features low power, small size and low cost. The key issue is, meanwhile, the low precision of the MEMS. In this study, the safety evaluation technique by analyzing the behavior of floating body using MEMS was examined. As a result of the study, it was found that the marine floating body can be modeled through the inertial measurement platform using the 3-axis accelerometer and the 3-axis gyroscope, and the safety of the float can be evaluated through this model.

• Proceedings of the KIPE Conference
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• 2010.11a
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• pp.40-43
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• 2010

This paper deals with a new two dimensional clinometer based on dual axis micromachined accelerometers. The clinometer is a small and low-cost product, which is mainly developed to help golfers read easily the tilt of a putting green. First, this paper proposes the principle of two dimensional clinometer and also a calibration method with respect to the offset voltage and sensitivity of a accelerometer. Experimental results on the developed clinometer show that the proposed clinometer can provide useful information on the tilt angle and direction of an inclined plane.

• Journal of the Korea institute for structural maintenance and inspection
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• v.18 no.1
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• pp.160-165
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• 2014

In this study, an efficiency test was performed by fabricating MEMS (Micro Electro Mechanical Systems) based 3-axis acceleration sensor modules and an earthquake monitoring system was composed. Data acquisition device (NI-9239) with a 24bit ADC (Analog to Digital Converter) was used for improving the performance of 3-axis acceleration sensor modules and filtered data (100Hz Low Pass Filter) was used for reducing noises. Also this paper focused on detecting meaningful vibration in the building by developing the earthquake monitoring software. If vector sum of 3-axis acceleration is greater than the preset value, the value will be recorded and saved to the file.