• Proceedings of the KSR Conference
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• 1999.11a
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• pp.107-114
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• 1999

Pantograph, which collects current from cartenary system, is one of important parts of high-speed train. Kinematic analysis is basic component of pantograph design. But kinematic analysis is very complex and time-consuming. Therefore numerical calculation of pantograph kinematics is necessary. In this study, pantograph kinematic analysis software was developed and relationship between kinematic parameters and pantograph performance was investigated. The software and relationship between kinematic parameters and pantograph performance are helpful to pantograph designers

• Journal of the Korean Society for Precision Engineering
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• v.16 no.4 s.97
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• pp.26-36
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• 1999

A general procedure for determining the optimum location of suspension hard points with respect to kinematic design parametes is presented. Suspensions are modeled as connection of rigid bodies by ideal kinematic joints. Constraint equations of the kinematic joints are expressed in terms of the generalized coordinates and hard points. By directly differentiating the constraint equations with respect to the hard points, kinematic sencitivity equations are obtained. In order to cope with algebraic complexity associated with the differentiation process, a symbolic computation technique is used. A performance index is defined in terms of static design parameters such as camber, caster, toe, ect.. Gradient of the performance index can be analytically computed from the kinematic sensitivity equations. Optimization results show the effectiveness and validity of the procedure, which is applicable to any type of suspension if its kinematic configurations are given.

• Journal of Positioning, Navigation, and Timing
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• v.9 no.1
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• pp.15-21
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• 2020

In October 2019, the European Galileo navigation system operates a total of 24 satellites, two of them are in the testing phase. There are enough satellites in operation to enable precise point positioning (PPP) using Galileo signals. The number of visible satellites for Galileo in South Korea is investigated. In addition, to assess the latest performance of the Galileo kinematic PPP, data received at DAEJ reference station from October 1 to October 7, 2019, are analyzed. Galileo kinematic PPP presents some results in two categories, single-frequency PPP (SPPP) and dual-frequency PPP (DPPP). The positioning accuracy for Galileo kinematic SPPP solutions is less than 1 m root mean square (RMS) in all direction components. The Galileo kinematic DPPP achieves the positioning accuracy with an RMS value of less than 7 cm in all direction components. The results show that the latest performance of Galileo kinematic PPP at DAEJ station in South Korea is still relatively poor compared to GPS kinematic PPP. However, the residuals of Galileo code measurements are smaller than those of GPS code measurements.

• Journal of Institute of Control, Robotics and Systems
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• v.3 no.5
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• pp.482-489
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• 1997

This paper presents the analysis of the kinematics and dynamics of redundant parallel manipulators, and provides design guides for advanced parallel mainpulators with high performance. Three types of redundancies are considered which include the redundancies in serial chain, joint actuation, and parallelism. First, the kinematic and dynamic models of a redundant parallel manipulator are obtained in both joint and Cartesian spaces, and the kinematic and dynamic manipulabilities are defined for the performance evaluation. The effects of the three types of redundancies on the kinematic and dynamic performance of a parallel manipulator are then analyzed and compared, providing a set of guides for the design of advanced parallel manipulators. Finally, the simulation results using planer parallel manipulators are given.

• 제어로봇시스템학회:학술대회논문집
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• 1996.10b
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• pp.730-733
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• 1996

This paper presents the kinematic and dynamic analysis of parallel manipulators with redundant limbs, obtained by putting additional limbs to an existing parallel manipulator. We develop the kinematic and dynamic models of a parallel, manipulator with redundant limbs. The redundancy in parallelism due to the increased number of limbs and the redundancy in actuation due to the increased number of active joints are considered in the modeling. Based on the derived models, we define the kinematic and dynamic manipulabilities of a parallel manipulator with redundant limbs. The effect of the redundant limbs on the performance of parallel manipulators is analyzed in terms of kinematic and dynamic manipulabilities.

• 제어로봇시스템학회:학술대회논문집
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• 1996.10b
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• pp.371-374
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• 1996

This paper presents the kinematic and dynamic analysis of parallel manipulators with redundant joints, obtained by putting additional active joints to an existing parallel manipulator. We develop the kinematic and dynamic models of a parallel manipulator with redundant joints. The redundancy in serial chain, due to the increased number of joints per limb, is considered in the modeling. Based oh the derived models, we define the kinematic and dynamic manipulabilities of a parallel manipulator with redundant joints. The effect of the redundant joints on the performance of parallel manipulators is analyzed in terms of kinematic and dynamic manipulabilities.

• 제어로봇시스템학회:학술대회논문집
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• 1996.10b
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• pp.535-538
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• 1996

This paper presents the kinematic and dynamic analysis of parallel manipulators with actuation redundancy, obtained by replacing the passive joints of an existing parallel manipulator with the active ones. We develop the kinematic and dynamic models of a parallel manipulator with actuation redundancy. The multiplicity in selecting the controllable active joints among the increased number of active joints is considered in the modeling. Based on the derived models, we define the kinematic and dynamic manipulabilities of a parallel manipulator with actuation redundancy. The effect of the actuation, redundancy on the performance of parallel manipulators is analyzed in terms of kinematic and dynamic manipulabilities.

• Transactions of the Korean Society of Automotive Engineers
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• v.8 no.5
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• pp.138-147
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• 2000

Vehicle suspension systems are parts which effect performances of a vehicle such as ride quality, handing characteristics, straight performance and steering effort etc. Kinematic design is a decision of joints` position for straight performance and steering effort. But, when vehicle is rebounding and bumping, chang of joints` displacement is nonlinear and a surmise of straight performance and steering effort at that joints` position is difficult. So design of suspension systems is done through a inefficient method of tried-and-error depending on designer`s experience. In this paper, kinematic design of suspension systems was done through the optimal design using a genetic algorithm. For this optimal design, the function for quantification of straight performance and steering effort was made, and the kinematic design method of suspension systems having this function as the objective function was suggested.

• Journal of Astronomy and Space Sciences
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• v.37 no.3
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• pp.199-208
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• 2020

This paper presents a kinematic ephemeris generator for Korea Pathfinder Lunar Orbiter (KPLO) and its performance test results. The kinematic ephemeris generator consists of a ground ephemeris compressor and an onboard ephemeris calculator. The ground ephemeris compressor has to compress desired orbit propagation data by using an interpolation method in a ground system. The onboard ephemeris calculator can generate spacecraft ephemeris and the Sun/Moon ephemeris in onboard computer of the KPLO. Among many interpolation methods, polynomial interpolation with uniform node, Chebyshev interpolation, Hermite interpolation are tested for their performances. As a result of the test, it is shown that all the methods have some cases that meet requirements but there are some performance differences. It is also confirmed that, the Chebyshev interpolation shows better performance than other methods for spacecraft ephemeris generation, and the polynomial interpolation with uniform nodes yields good performance for the Sun/Moon ephemeris generation. Based on these results, a Kinematic ephemeris generator is developed for the KPLO mission. Then, the developed ephemeris generator can find an approximating function using interpolation method considering the size and accuracy of the data to be transmitted.

• Journal of Institute of Control, Robotics and Systems
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• v.3 no.4
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• pp.422-434
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• 1997

In this paper, a two-stage kinematic optimal design for a 3 degree of-freedom (DOF) excavator subsystem, which consists of boom, arm and bucket, is performed. The objective of the first stage is to find the optimal parameters of the joint-actuating mechanisms which maximize the force-torque transmission ratio between the hydraulic actuator and the rotating joint. The objective of the second stage is to find the optimal link parameters which maximize the isotropic characteristic of the excavator subsystem throughout the workspace. It is illustrated that kinematic/dynamic performances of the kinematically optimized excavator subsystem have improved compared to those of original HE280 excavator, with respect to three performance indices such as maximum load handling capacity, maximum velocity capability, and acceleration capability.