• Transactions of the Korean Society of Mechanical Engineers A
• /
• 제20권11호
• /
• pp.3398-3407
• /
• 1996

In this paper, we derive an algorithm and develope a computer program which analyze rapidly and precisely the inverse kinematics of robotic mechanism with spatial complex chain structure based on the relative coordinates. We represent the inverse kinematic problem as an optimization problem with the kinematic constraint equations. The inverse kinematic analysis algorithm, therefore, consists of two algorithms, the main, an optimization algorithm finding the motion of independent joints from that of an end-effector and the sub, a forward kinematic analysis algorithm computing the motion of dependent joints. We accomplish simulations for the investigation upon the accuracy and efficiency of the algorithm.

• Korean Journal of Applied Biomechanics
• /
• 제30권3호
• /
• pp.225-234
• /
• 2020

Objective: The purpose of this study was to investigate the kinematic sequence patterns according to movement times during Karate choku-tsuki. Method: Ten Korea national Karate athletes participated in this study. Participants asked to perform jodan and chudan choku-tsuki. 30 infrared cameras were used to measure angular kinematic of elbow, shoulder, trunk, pelvis, hip, knee, ankle. Results: The two-way repeated measures ANOVA revealed significant effects for the joints (p<.05). But no significant effect for the movement time and interaction of joints x movement time existed for the kinematic sequence variables. Conclusion: For karate kumite players to reduce the movement time of punch, it is necessary to train kinematic sequences that allow each joint to rotate at a relatively similar timing.

• Journal of Institute of Control, Robotics and Systems
• /
• 제8권3호
• /
• pp.233-242
• /
• 2002

A kinematic modeling method is proposed which models the sliding and skidding at the wheels as pseudo joints and utilizes those pseudo joint variables as augmented variables. Kinematic models of various type of wheels are derived based on this modeling method. Then, the transfer method of augmented generalized coordinates is applied to obtain inverse and forward kinematic models of mobile robots. The kinematic models of five different types of planar mobile robots are derided to show the effectiveness of the proposed modeling method.

• Journal of Institute of Control, Robotics and Systems
• /
• 제3권4호
• /
• pp.422-434
• /
• 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.

• The Journal of Korean Physical Therapy
• /
• 제22권6호
• /
• pp.21-28
• /
• 2010

Purpose: The purpose of this study was to investigate the kinematic adaptation of head and trunk to ascend stairs and a ramp. Subjects were healthy young adults. Three-dimensional kinematic patterns of head and trunk movements were examined during stair climbing and steeper ramp climbing. Methods: Fourteen young subjects with no history of chronic or acute musculoskeletal, cardiovascular or respiratory disorders took part in this experiment. Kinematic data were collected using a 6 camera Vicon system (Oxford Metrix, Oxford, England). Repeated measures ANOVA analyses were used to investigate the effect of gait mode on kinematics of the head and trunk. Results: The angle of the trunk while ascending stairs or a ramp was modified in three human planes (p<0.05). The angle of head and neck during the ascending of stairs or a ramp was not changed in the sagittal plane but was changed in the frontal and transverse planes (p<0.05). Conclusion: This study describes and discusses some basic kinematic mechanisms underlying the pattern of head and trunk changes during stair and ramp climbing and showed that postural adaptation of the head and trunk is necessary to maintain balance.

• Tribology and Lubricants
• /
• 제18권2호
• /
• pp.143-146
• /
• 2002

The effects of contact configuration and kinematic motion on the wear of ultrahigh molecular weight polyethylene (UHMWPE) were investigated. Two different contact configurations were adopted for wear testing under the two different kinematic motions with un-irradiated UHMWPE specimens. Wear of UHMWPE pins against the linear reciprocating stainless steel disks was 8% higher than that against the uni-directional repeat pass rotating disks. Wear of UHMWPE disks moving in the linear reciprocating motion against stainless steel ball was 37% higher than that moving in the uni-directional repeat pass rotating motion. The results in this study show that the contact configuration and kinematic motion of sliding definitely affect the wear of UHMWPE through the differences in the contact stress states of UHMWPE.

• Transactions of the Korean Society of Automotive Engineers
• /
• 제14권1호
• /
• pp.25-30
• /
• 2006

This study is about an optimum design to improve the kinematic and compliance characteristics of a torsion-beam suspension system. The kinematic and compliance characteristics of an initial design of the suspension was obtained through a roll-mode analysis. The objective function was set to minimize within design constraints. The coordinates of the connecting point between the torsion-beam and the trailing arm were treated as design parameters. Since the torsion-beam suspension has large nonlinear effects due to kinematic and elastic motion, Genetic Algorithms were employed for the optimal design. The optimized results were verified through a double-lane change simulation using the full vehicle model.

• Transactions of the Korean Society of Automotive Engineers
• /
• 제5권1호
• /
• pp.38-48
• /
• 1997

A method for performing kinematic design sensitivity analysis of vehicle suspension systems is presented. For modeling of vehicle suspensions, the multibody dynamic formulation is adopted, where suspensions are assumed as combination of rigid bodies and ideal frictionless joints. In a relative joint coordinate setting, kinematic constraint equations are obtained by imposing cut-joints that transform closed-loop shape suspension systems into open-loop systems. By directly differentiating the constraint equations with respect to kinematic design variables, such as length of bodies, notion axis, etc., sensitivity equations are derived. By solving the sensitivity equations, sensitivity of static design factors that can be used for design improvement, can be obtained. The validity and usefulness of the method are demonstrated through an example where kinematic sensitivity analysis of a MacPherson strut suspension of performed.

• Journal of Institute of Control, Robotics and Systems
• /
• 제18권9호
• /
• pp.823-829
• /
• 2012

An excitation table is commonly used for vibration and ride tests for parts or assemblies of automobiles, aircrafts, or other heavy systems. The authors have analyzed several kinematic properties of an excitation table that is under development for heavy transport vehicles. It consists of one table and 7 linear hydraulic actuators. The authors have performed mobility analysis, inverse kinematics, forward kinematics, and singularity analysis. Especially, we have proposed a fast forward kinematic solution considering the limited motion of the excitation table. On the assumption that the motion variables such as rotation angles and displacements are small, the forward kinematic problem is converted to the observer problem of a linear system. This provides a fast solution. Also we have verified that there are no singularity points in the working range by numerical analysis.

• Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
• /
• 한국윤활학회 2001년도 제33회 춘계학술대회 개최
• /
• pp.100-104
• /
• 2001

The effects of contact configuration and kinematic motion on the wear of ultrahigh molecular weight polyethylene (UHMWPE) were investigated. Two different contact configurations were adopted for wear testing under the two different kinematic motions with un-irradiated UHMWPE specimens. Wear of UHMWPE pins against the linear reciprocating stainless steel disks was 8% higher than that against the uni-directional repeat pass rotating disks. Wear of UHMWPE disks moving in the linear reciprocating motion against stainless steel ball was 37% higher than that moving in the uni-directional repeat pass rotating motion. The results in this study show that the contact configuration and kinematic motion of sliding definitely affect the wear of UHMWPE through the differences in the contact stress states of UHMWPE.