• 대한기계학회논문집A
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• 제32권10호
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• pp.823-830
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• 2008

We present a high-accuracy digital-to-analog (DA) actuator using a load spring, specially designed to compensate the output displacement errors caused by fabrication errors. The compensated linear DA actuator is capable to change the slope of input-output modulation line in order to compensate fabrication errors. We design, fabricate, and characterize three different prototypes: one uncompensated design and two compensated designs respectively for a specific value and for a given range of fabrication error. The compensated linear DA actuators show the output displacement errors of $-0.20{\pm}0.23{\mu}m\;and\;-0.13{\pm}0.18{\mu}m$, respectively, reduced by 64.3% and 76.8% of the output displacement error, $0.56{\pm}0.20{\mu}m$, produced by the conventional uncompensated linear DA actuator. We experimentally verify the fabrication error compensation capability of the present compensated linear DA actuators, thus demonstrating high-accuracy actuation performance immune to fabrication errors.

• 전기학회논문지
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• 제58권1호
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• pp.137-146
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• 2009

We present a micromechanical digital-to-analog (DA) variable capacitor using a parallel digital actuator array, capable of accomplishing high-Q tuning. The present DA variable capacitor uses a parallel interconnection of digital actuators, thus achieving a low resistive structure. Based on the criteria for capacitance range ($0.348{\sim}1.932$ pF) and the actuation voltage (25 V), the present parallel DA variable capacitor is estimated to have a quality factor 2.0 times higher than the previous serial-parallel DA variable capacitor. In the experimental study, the parallel DA variable capacitor changes the total capacitance from 2.268 to 3.973 pF (0.5 GHz), 2.384 to 4.197 pF (1.0 GHz), and 2.773 to 4.826 pF (2.5 GHz), thus achieving tuning ratios of 75.2%, 76.1%, and 74.0%, respectively. The capacitance precisions are measured to be $6.16{\pm}4.24$ fF (0.5 GHz), $7.42{\pm}5.48$ fF (1.0 GHz), and $9.56{\pm}5.63$ fF (2.5 GHz). The parallel DA variable capacitor shows the total resistance of $2.97{\pm}0.29\;{\Omega}$ (0.5 GHz), $3.01{\pm}0.42\;{\Omega}$ (1.0 GHz), and $4.32{\pm}0.66\;{\Omega}$ (2.5 GHz), resulting in high quality factors which are measured to be $33.7{\pm}7.8$ (0.5 GHz), $18.5{\pm}4.9$ (1.0 GHz), and $4.3{\pm}1.4$ (2.5 GHz) for large capacitance values ($2.268{\sim}4.826$ pF). We experimentally verify the high-Q tuning capability of the present parallel DA variable capacitor, while achieving high-precision capacitance adjustments.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 1998년도 춘계학술대회논문집; 용평리조트 타워콘도, 21-22 May 1998
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• pp.664-669
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• 1998

This research is concerned with the active vibration controller design for smart structures by a modified LQG controller. The smart structure is defined as the structure equipped with smart actuators and sensors. Various analog and digital control, techniques aimed for the piezoceramic sensors and actuators have been proposed for the active vibration control of smart structures. In this paper, the modified LQG controller is developed for the active vibration suppression of smart structures to implement the predefined decay rate on modal displacements. The proposed modified LQG controller proved its effectiveness by experiments.

• 제어로봇시스템학회논문지
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• 제22권7호
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• pp.513-518
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• 2016

The piezoelectric actuating device is known for its large power density and simple structure. It can generate a larger force than a conventional actuator and has also wide bandwidth with fast response in a compact size. To control the piezoelectric actuator, we need an analog signal conditioning circuit as well as digital microcontrollers. Conventional microcontrollers are not equipped with an analog part and need digital-to-analog converters, which makes the system bulky compared with the small size of piezoelectric devices. To overcome these weaknesses, we are developing a single-chip controller that can handle analog and digital signals simultaneously using mixed-signal FPGA technology. This gives more flexibility than traditional fixed-function microcontrollers, and the control speed can be increased greatly due to the parallel processing characteristics of the FPGA. In this paper, we developed a floating-point multiplier, PWM generator, 80-kHz power control loop, and 1-kHz position feedback control loop using a single mixed-signal FPGA. It takes only 50 ns for single floating-point multiplication. The PWM generator gives two outputs to control the charging and discharging of the high-voltage output capacitor. Through experimentation and simulation, it is demonstrated that the designed control loops work properly in a real environment.

• 대한기계학회논문집A
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• 제34권5호
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• pp.557-560
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• 2010

본 논문에서는 4 비트 디지털구동기를 가변초점 유체렌즈에 적용하였다. 4 비트 디지털구동기는 총 16 단계로 렌즈곡면을 조절하여 렌즈의 초점을 변화시킨다. 본 가변초점 유체렌즈는 별도의 정밀 압력 및 유체량 제어기 없이 디지털구동기의 On/Off 제어만으로 렌즈곡면을 ${\pm}200nm$ 의 정밀도로 제어하여 초점거리를 3.63mm에서 38.6mm 까지 조절할 수 있다.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 1990년도 한국자동제어학술회의논문집(국제학술편); KOEX, Seoul; 26-27 Oct. 1990
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• pp.913-916
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• 1990

In this paper, attempts have been made to control AC synchronous servo motor used as actuators of joints of the FARA robot with high dynamic performance and precise positioning. The AC synchronous servo motors used in FARA robots have resolves as position sensors. Resolver to digital converters are used in order to obtain the information of rotor speed and position from resolver outputs. The proposed joint position control system consists of four speed controller and one position controller. Analog methods are used in the position controller, while digital methods are used in the position controller. For precise position control, PID control algorithm and interpolation functions are executed in two 16 bit microprocessors with sampling rate 2ms. Experimental results show that the proposed joint position control system can be effectively applied to industrial robots in order to obtain high dynamic performance and precise positioning. The proposed joint position control system is being used in the control of FARA robots of Samsung Electronics.

• Journal of Biosystems Engineering
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• 제20권3호
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• pp.226-235
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• 1995

과수원 방제 작업 시 인체에 해로운 농약으로부터 운전자를 보호하고 노동력 및 농약의 절감, 환경오염의 방지 등의 효과를 꾀하기 위하여 무선 전파 리모콘을 이용한 무인 스피드 스프레이어의 원격제어 시스템을 개발함과 동시에 유도케이블식 주행유도 장치에 의한 자율주행 무인스피드 스프레이어를 개발하였다. 무인 스피드 스프레이어는 원격조종 시스템, 유도케이블 시스템, 장해물 검출장치, 제어 액튜에이터 등으로 구성되어 있고 원격조종 및 자율주행이 가능한 시스템이다. 무인화 한 스피드 스프레이어의 특징은 다음과 같다. 1) 무선 전파 리모콘과 유도 케이블에 의한 주행 유도장치를 개발하여 스피드 스프레이어에 장착한 결과 리모콘 조작방식과 주행 유도방식 모두 가능하였다. 2) 원격 조종은 주행 (전진, 후진), 조향, 3방향의 노즐 및 팬, 분무기, 주행정지 등 16종류의 조작이 가능하다. 3) 농업용 리모콘으로는 FSK방식보다 전송에러가 적은 DTMF방식이 우수하였으며, 농업용 특정 소전력 무선국이 필요하다고 생각된다. 4) 5개의 저임피던스 검출코일과 윈도우 컴퍼레이터 회로로 구성된 디지털식 케이블 유도 시스템은 2개의 검출코일에 유기 된 상대적 전압치로서 궤도를 수정하는 아날로그 검출방식보다 주행 성능이 우수하였다.