• Proceedings of the IEEK Conference
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• 2002.06b
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• pp.137-140
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• 2002

This paper is proposed a 8-bit anolog to digital converter for CMOS image sensor. A anolog to digital converter for CMOS image sensor is required function to control gain. Proposed anolog to digital converter is used frequency divider to control gain. At 3.3 Volt power supply, total static power dissipation is 8mW and programmable gain control range is 30dB. The gain control range can be easily increased with insertion of additional flip-flop at divided-by-N frequency divider circuit.

• Proceedings of the Korean Reliability Society Conference
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• 2000.04a
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• pp.231-238
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• 2000

The distributed digital control system has many shared common components, and a single fault in the system may have effects on not a single function. Not as in an analog system, the faults in a digital system usually make discrete and abrupt changes in its output, which are hard to be expected. To cope with these situations, the fault-tolerance is an inevitable property of a distributed control system. A distributed digital control system consists of many equipments, and each equipment can be implemented by many different technologies. The fault-tolerance has to be implemented depend-ing on the overall architecture and how each equipment is implemented. The paper analyzes and compares the strategies and tactics to add the fault-tolerances in a distributed digital control system, and studies how they can be combined appropriately.

• 제어로봇시스템학회:학술대회논문집
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• 2001.10a
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• pp.147.3-147
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• 2001

We have proposed a digital control method, where the controlled variable is a joint angular velocity, of space robot manipulators using the transpose of Generalized Jacobian Matrix. The explicit relationship between the control law and the sampling period, however, is unknown because the controller gains include the sampling period implicitly. This paper presents a novel digital control method which explicitly describes the relation between the sampling period and the controller gains. Computer simulation of a 3-DOF planar space robot manipulator is peformed. Simulation result demonstrates the effctiveness of the proposed method.

• Journal of the Korean Institute of Telematics and Electronics B
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• v.33B no.6
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• pp.128-135
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• 1996

In this paper, a digital signal processing method of AFC (automatic frequency control) is proposed for a home use VCR system. The proposed method has the ability of frequency tracking of a wide range. Implemented with digital circuits, the system is to be used in a digital video system and saves the cost of a hardware compared with a conventional analog automatic frequency control method using several PLL's in case of making home use VCR systems compatible with several TV systems.

• Journal of the Korean Society for Precision Engineering
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• v.10 no.4
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• pp.7-15
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• 1993

This paper introduces a new concept to analyze the digital control system where the continuous-time plant is stabilized by the digital controller with sampler and hodl. It gives some methods to handle the inter-sampling behavior which has not been considered in the digital controller design. Also, the new trend and future direction in digital control are introduced.

• Journal of the Korean Society for Precision Engineering
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• v.13 no.8
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• pp.112-119
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• 1996

Among the various type of accelerometer, the servo rebalancing type accelermoter can be suitable for Inertial Navigation System, because of its high sensitivity and good response in low frequency. In this paper, we proposed a new technology to control inductive tuype accelerometer utilizing digital PWM method. The new developed digital PWM control has special design scheme for transmitting measurement value to outer device in its servo ollp. So it has no quantized error of transforming outputs of sensors to digital domain. The quantized error may make serious problem in INS system, because outputs of sensor are integrated once or twice by digital computer and it happens every sensor reading times. Therefore, in order to get the accurate information such as displacement, it is necessary to measure accurately the input current. In addition, Digital Signal Processing needs digital data transmission, digital PWM method is adaptive for this purpose. We realized a practical circuit for digital PWM control, analyzed the stability of the circuit, and designed the controller etc. In this study, we solved many practical problem for this application, and got out good results.

• 제어로봇시스템학회:학술대회논문집
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• 2005.06a
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• pp.794-799
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• 2005

Robust DC-DC converter which can cover extensive load changes and also input voltage changes with one controller is needed. In this paper, we propose a method for determining the parameters of 2DOF digital controller which makes the control bandwidth wider, and at the same time makes a variation of the output voltage very small at sudden changes of resistive load and the input voltage. The 2DOF digital controller whose parameters are determined by the proposed method is actually implemented on a DSP and is connected to a DC-DC converter. Experimental studies demonstrate that this type of digital controller can satisfy given specifications.

• Journal of Institute of Control, Robotics and Systems
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• v.13 no.4
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• pp.385-391
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• 2007

A class D digital audio amplifier with small size, low cost, and high quality is positively necessary in the multimedia era. Since the digital audio amplifier is based on the PWM signal processing, it is improper to analyze the principle of signal generation using linear system theories. In this paper, a class D digital audio amplifier based ADSM (Advanced Delta-Sigma Modulation) is considered. We first model the digital audio amplifier and then explain the operation principle using variable structure control algorithm. Moreover, the ripple signal generated by the hysteresis in the comparator has a significant effect on the system performance. Thus, we present a method to find the magnitude and the frequency of the ripple signal using describing function. Finally, simulations and experiments are provided to show the validity of the proposed methods.

• Journal of Institute of Control, Robotics and Systems
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• v.13 no.12
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• pp.1160-1166
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• 2007

This paper presents the design and implementation of an embedded image stabilization control system for a mobile phone with a built-in camera. Image stabilization is a family of techniques for reducing image blur resulting from minute camera shake due to hand-held shooting, thereby allowing the use of shutter speeds slower than values normally required to obtain sharp images. A mechanical image stabilizer mechanism developed for a camera mobile phone is introduced and a digital control system as a part of the image stabilization system is designed and implemented on an 8-bit microcontroller with integer arithmetic in C. This paper focuses primarily on issues that need to be taken into consideration for fixed-point implementation of the digital controller. Several experimental results are presented to demonstrate the performance of the implemented image stabilization control system.

• The Transactions of the Korean Institute of Electrical Engineers B
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• v.53 no.2
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• pp.82-89
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• 2004

In this paper, an active magnetic bearing(AMB) system is designed and controlled using a digital Proportional-Integral-Derivative(PID) control concept. The plant dynamics consisting of actuator and rigid rotor dynamics are described. A digital PID controller with a global control and a local control concept is designed and implemented using digital signal processor. Some experiments are conducted with each global control and local control concept. These include start-up test, impulse test, whirl response, and generator load test. The experimental results and comparison between those of a global control and a local control indicate that the global control of concept has impressive static and dynamic control performance for the prototype considered. From the whirl test, the developed system set can be controlled within about $\pm10\mu\textrm{m}$ gap variation at the rotational speed of 6000rpm and generate the AC power of frequency of $60\textrm{Hz}$, voltage of 100V and current of 0.8$\textit{A}$.