• Transactions of the Korean Society of Machine Tool Engineers
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• v.15 no.2
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• pp.16-23
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• 2006

Recently the design of multi-stage gear drive is being highly concerned. Until now, since the researches of gear drive are focused on the design for satisfying safety factor, the reliability evaluation of multi-stage gear drive is not included. In this paper, the life and reliability models of multi-stage gear drive are proposed using methods of probability and statistics. The life and reliability of the multi-stage gear drive have been evaluated, which is based on the life and reliability of each stage gear drive. The pinion and gear lives of each stage are calculated using the Lundberg-Palmgren theory and the Weibull failure distribution. These lives are combined using methods of probability and statistics to produce a life and reliability model of multi-stage gear drive.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 1999.10a
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• pp.470-475
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• 1999

Recently as the application of gear drive increases in high-speed and high-loading, the concern of designing multi-stage gear drive is being risen. Until now however, the research of gear drive is focused on single-stage gear drive and the design depends on experiences and know-how of designer and is carried out by trial and error. This research automated the basic design and the configuration design for two and three-stage gear drives which consist of cylindrical gears. In basic design, design is executed with two design processes, which minimize the overall volume of gear, and whose results are compared each other. In configuration design, the positions of gears are determined to minimize the volume of gearbox using the result of basic design and simulated annealing algorithm.

• KIEE International Transaction on Electrical Machinery and Energy Conversion Systems
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• v.11B no.4
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• pp.193-199
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• 2001

This paper suggests a novel single-stage drive for a switched reluctance motor (SRM) to achieve sinusoidal, near unity power factor input currents. The proposed drive is very simple without additional active switch. As a single-stage approach, which combines a DC link capacitor used as dc source and a drive used for driving the motor into one power stage, a simple structure and low cost drive in implemented. A prototype drive for an 8/6 pole SRM equipping a suitable encoder is designed to evaluate the proposed topology. Also subscription control algorithm is presented. The characteristics and validity of the proposed circuit will be discussed in depth through the experimental results.

• Proceedings of the KIEE Conference
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• 2003.11c
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• pp.735-739
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• 2003

This paper presents a direct seek control algorithm for swing-arm type dual stage servo system that consists of a coarse actuator and a fine actuator. The proposed scheme is to design a control system that attenuates the effect of dynamic coupling between the two actuators so that the seek operation can be performed in a single-shot with stability. In an optical drive system with dual stage servo mechanism, the effect of dynamic coupling between the two actuators needs to be handled during the coarse seek operation due to its inherent structure. In an extreme case, the two actuators can collide each other, which leads to critical degradation of the seek performance. To handle this problem, our proposed control scheme is to generate the drive signals such that the two actuators behave as if they are a single fixed body. To this end, a feedforward controller and two feedback controllers are designed that enable the current drive system perform wide range of track seek. Simulation results are provided to show the validity and feasibility of our proposed algorithm.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 1999.10a
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• pp.464-469
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• 1999

Recently, the need for designing multi-stage gear drive has been increased as the hear drives are used more in the applications with high-speed and small volume. The design of multi-stage gear drives includes not only dimensional design but also configuration design of various machine elements. Until now, however, the researches on the design of gear drives are mainly focused on the single-stage gear drives and the design practices for multi-stage gear drives, especially in configuration design activity, mainly depend on the experiences and 'sense' of the designer by trial and error. We propose a design algorithm to automate the dimension design and the configuration design of multi-stage gear drives. The design process consists of four steps. The number of stage should be determined in the first step. In second step, the gear ratios of each reduction stage are determined using random search, and the ratios are basic input for the dimension design of gears, which is performed by the exhaustive search in third step. The designs of gears are guaranteed by the pitting resistance and bending strength rating practices by AGMA rating formulas. In configuration design, the positions of gears are determined to minimize the volume of gearbox using simulated annealing algorithm. The effectiveness of the algorithm is assured by the design example of a 4-stage gear drive.

• Journal of Institute of Control, Robotics and Systems
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• v.9 no.4
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• pp.277-283
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• 2003

Recently, near-field recording (NFR) disk drive schemes have been proposed with a view to increasing recording densities of hard disk drives. Compared with hard disk drives. NFR disk drives have narrower track pitches and are exposed to more severe periodic disturbances resulting from eccentric rotation of the disk. It is difficult to meet servo system design specifications for NFR disk drives with conventional VCM actuators in that the servo system for an NFR disk drive generally requires a feater gain and higher bandwidth. To tackle the problem various dual-stage actuator systems composed of a microactuator mounted on top of a conventional VCM actuator have been proposed. This article deals with the problem of designing a tracking servo system far an NFR disk drive adopting a dual-stage actuator. We summarize design constraints pertaining to the dual-stage servo system and present a new servo scheme using iterative teaming control. We design feedback compensators and an iterative teaming controller for a target plant and verify the validity of the proposed control scheme through a computer simulation.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.33 no.11
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• pp.1217-1224
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• 2009

This paper presents a finite element (FE) analysis of the torsional rigidity of a two-stage cycloid drive. The cycloid disk makes contact with a number of pin-rollers simultaneously and eccentric shafts transmit not only torque of the spur gear stage to the cycloid disk, but also that of the cycloid disk to the output disk. Contacts between the disk and pin-rollers are simplified as linear spring elements, and the bearing of eccentric shaft is modeled as a rigid ring that has frictional contact to the disk and an elastic support. FE analysis for an ideal solid cycloid drive was performed and verified by a theoretical calculation. Accurate contact forces were then estimated by iterating between FE analysis for contact forces and Hertz theory calculations for nonlinear contact stiffness. In addition, torsional rigidity of the cycloid drive is analyzed to show that the bearing and nonlinear Hertz contact theory should be considered in analysis and design of a cycloid drive, which was verified with experiments. Finally, the effects of contact stiffness, bearing stiffness and cycloid disk structural stiffness according to the cycloid disk rotation on the torsional rigidity were investigated.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.25 no.5
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• pp.7-14
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• 2011

Currently high power Light Emitting Diode (LED) is in the limelight due to its characteristics of long durability, low maintenance costs, and high efficiency. Furthermore, it does not emit pollutants or poisonous gases and is a light source not using mercury, so it holds a high status in eco-friendly terms as well. In this paper, we studied a two-stage LED power drive circuit that can compensate only voltage regulation through LED output current, in order to improve efficiency of LED drive with constant current control in accordance with changes in temperature. The proposed LED drive has an advantage of reducing LED drive's voltage losses by controlling only voltage change of input power, compared with an existing circuit which controls input voltage. The suggested non-insulation compensating circuit for voltage change was verified to have improved efficiency relative to a LED drive using existing DC/DC converter.

• Transactions of the Korean Society of Machine Tool Engineers
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• v.16 no.4
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• pp.36-44
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• 2007

This paper is focused on the optimum design for decreasing volume and increasing reliability of multi-stage gear drive. For the optimization on volume and reliability, multi-objective optimization is used. The genetic algorithm is introduced to multi-objective optimization method and it is used to develop the optimum design program using exterior penalty function method to solve the complicated subject conditions. A 5 staged gear drive(geared motor) is chosen to compare the result of developed optimum design method with the existing design. Each of the volume objective, reliability objective, and volume-reliability multi-objectives are performed and compared with existing design. As a result, optimum solutions are produced, which decrease volume and increase reliability. It is shown that the developed design method is good for multi-stage gear drive design.

• Journal of Power System Engineering
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• v.17 no.3
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• pp.82-88
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• 2013

For commercialized servo drives of the motion stage to include embedded controller, external terminal is provided for tracking command and encoder output, but internal terminal is not for control input. Thus, it is difficult to combine out signal of embedded controller with that of external compensator such as disturbance observer. In this study, for precise tracking control of motion stage without hardware change of the servo drive, tacking control system is composed of an inner loop of servo drive and an outer loop of disturbance observer. Then, the control system is designed so that the output response of actual plant corresponds with nominal model's in transient state as well as in steady state. Finally, the experiment results show that the designed control system is effective to reconcile actual plant behavior with nominal model under nonlinear friction and parameter perturbation.