• 제어로봇시스템학회논문지
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• 제5권1호
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• pp.47-53
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• 1999

CD-ROM(Compact Disk-Read Only Memory) is very attractive storage media because it has much storage space but is small size and portable. Optical pickup, one of the most important parts for reading data on a CD-ROM, is not produced tuned up. For the use of goods, we must tune up the optical pickup by adjusting the screw for adjustment. First, we developed analog servo system for optical pickup tuners. For eliminating some problems in analog servo system, this paper designed the modeling of digital servo system for optical pickup tuner. Though the characteristics of optical pickup are changed, the digital servo system for optical pickup tuner can easily apply to all pickup, and can reduce the measurement error among the optical pickup tuners. For the purpose of confirming the designed digital servo system, we produced data that specify the disk vibration and the disk eccentricity, and simulated servo system with MATLAB.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 1990년도 한국자동제어학술회의논문집(국내학술편); KOEX, Seoul; 26-27 Oct. 1990
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• pp.322-326
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• 1990

The solution of problems in the automation of mold manufacturing process are high speed and resolution. To catch two problems at once, digital servo system will be essential replacing the analog servo system. In this paper, we tried some hardware/software approach including, designing basic structure, modeling of servo actuator, and designing & simulating of velocity & position controller. Finally, we constructed the hardware for 1 axis digital servo controller of NC system. As a result we obtained the design technics of digital servo systems for high speed NC system.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 1996년도 추계학술대회 논문집
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• pp.346-350
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• 1996

In optical disk drives, one of commonly used pickup actuator is a Sliding and rotary type of pickup actuator which is cheaper than other pickup actuators and has simple assembly. However, it reported that non-linearity due to friction between a shaft and a sleeve had to be considerably analyzed in design and servo system in employing this type of pickup actuator. In this paper, this friction is modeled as a Coulomb's friction and the effect of friction is examined in the simulation. A digital servo system is applied to pickup actuator with friction in order to have good focusing servo. To enhance focusing servo performance using digital servo merit, frist PD-controller is applied to have fast response performance, second lead-lag compensator is applied to have stable focusing performance.

• 대한전기학회논문지
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• 제43권7호
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• pp.1186-1192
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• 1994

This paper presents an algorithm to design a robust digital model following servo control system in which optimal linear quadratic regulator problem is used to design the control system that make the step/ramp response of the plant kept close to a specified ideal step/ramp response of the model. The quadratic criterion function for a continuous system is used to design the robust digital servo control system. The feasibility of the design technique is shown by the simulation and the proposed method is applied to the speed control of DC servo motor.

• 한국정밀공학회지
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• 제16권3호통권96호
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• pp.154-163
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• 1999

In this paper, an ultra precision positioning system has been developed using dual servo loop control. For positioning system having long distance with ultra precision , the combination of global stage and micro stage was required. A servo motor based ball screw is used as a global stage and the piezo actuator as a micro stage. For the improvement of positional precision, the digital Chebyshev filter is implemented in the developed to dual servo system. Therefore, the positional repeatability has been achieved within ${\pm}$ 10 mm, and this technique can be applied to develop precision semiconductor equipments such as lithography steppers and probers.

• 전자공학회논문지SC
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• 제38권2호
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• pp.31-37
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• 2001

광디스크 재생기에서 사용되는 디지털 서보는 주변 블록과의 집적화가 유리하고, 온도변화에 따른 열화가 적으며, 각종 픽업에 대한 유연한 대응이 가능한 장점 때문에 이용도가 점점 높아지고 있는 추세이다.[6] 그러나 디지털 시그널 프로세서를 내장한 디지털 서보는 전력 소비량이 매우 큰 단점을 가지고 있다. 본 논문에서는 광디스크 재생기의 특성 상 초기화 시간에 대부분의 기능이 몰려 있으므로 DSP의 사이클 수는 많이 차지 하나, 실제로 전력 소비에 주된 영향을 끼치는 시간은 초기화 시간이 아닌 재생 모드 시간 임에 착안하여 디지털 서보의 소비 전류를 획기적으로 줄일 수 있는 방안을 제시하였다. 재생 모드에서의 필터 처리 사이클 수를 최대한 줄일 수 있도록 아키텍쳐를 변환함과 동시에 디지털 서보의 재생 모드를 병렬 처리함으로써, 전체 시스템의 소비 전력을 크게 줄이는 효과를 얻을 수 있도록 하였다. 즉, 광디스크 재생기의 디지털 서보에 포함되는 DSP 코아의 리소스 공유를 통해DSP의 동작 속도와 부하를 크게 줄임으로써 소비 전류를 획기적으로 줄이는 효과를 얻어낸 것이다. 이러한 개념은 DSP-코아 뿐만 아니라, ROM, RAM에도 모두 적용되어 기존 아키텍쳐의 디지털 서보에 비해 소비 전류를 83% 가까이 줄일 수 있는 효과를 얻을 수 있었다.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2002년도 하계종합학술대회 논문집(5)
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• pp.95-98
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• 2002

This paper presents a study on DSP(TMS320F240) controller design for multi-axes transportation system using BLDC servo motor. This BLDC servo motor controller was realized with DSP(Digital Signal Processor) and IPM (Intelligent Power Module). The multi-axes transportation system needs torque, speed, position control of servo motor for variable action. This paper implements those servo control with vector control and space vector modulation technique. As CPU of controller DSP(TMS320F240) is adopted because, it has PWM(Pulse Width Modulation) waveform generator, A/D(Analog to Digital) converter, SPI(Serial Peripheral Interface) port and input/output port etc. The controller of multi-axes transportation system consists of 3-level hierarchy structure that main host PC manages three sub DSP system which transfer downword command and are monitoring the states of end servo controllers. Each sub DSP system operates eight BLDC servo controllers which control BLDC servo motor using DSP and IPM Between host system and middle digital signal processor communicate with RS-422, between main processor and controller communicate with SPI port.

• 제어로봇시스템학회논문지
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• 제10권12호
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• pp.1202-1209
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• 2004

This paper presents a design methodology of a Digital Servo Signal Processor for high speed CD-RW drive systems. The proposed Digital Servo Signal Processor enables us to develop CD-related systems for the very high speed applications and is one of the key components of the CD-RW systems. The proposed center compensation servo control is newly built for an actuator shaking due to the fast response of a step motor when it jumps to a long distance. A control method compensating for eccentricity of a disc is implemented for operating robustly at a higher rotational speed. This servo mechanism is more size efficient and less power consumed because it is implemented using a ARM7 embedded processor and hardware digital filters. Furthermore, it is convenient to upgrade firmware for the future required functions. From experimental results, we can see that the performance of the control system is improved greatly. The proposed servo algorithm shows a shorter setting time including a pull-in time and a faster access time. It can be applied easily to the DVD-ROM and the DVD-RAM which have the same optical structure.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2003년도 하계학술대회 논문집 D
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• pp.2438-2440
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• 2003

This thesis presents a design methodology of a Digital Servo Signal Processor for high speed CD-ROM drive systems. The proposed Digital Servo Signal Processor enables us to develop CD-related systems for the very high speed applications and is one of the key components of the CD-ROM systems. The proposed center compensation servo control is newly built for a actuator shaking due to the fast response of a step motor when it jumps to a long distance. From experimental results, we can see that the performance of the control system is improved greatly. The proposed servo algorithm shows a shorter setting time including a pull-in time and a faster access time.

• 소성∙가공
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• 제25권1호
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• pp.21-28
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• 2016

In the current study, reduction of springback is quantified and the reasons for the reduction are investigated. The testing involved a digital servo motion applied to a U-draw bending to produce a hat-type product from high strength steels such as DP780 and DP980. The change in springback is compared between the constant speed motion and three kinds of servocontrolled motions during forming experiments. In order to predict the springback for the servo-controlled tool motion, a finite element method was utilized for the springback analysis considering a kinematic hardening model for the steel. The comparison of springback between the analysis and the experiments shows that they have similar tendencies. Also, the analysis results indicate that the springback reduction is greatly influenced by a decrease in the friction coefficient, which originates from the contact and detach phenomena between the tooling and the blank during the up-and-down motion of the upper die following the servo-controlled motion.