• 한국군사과학기술학회지
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• 제10권3호
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• pp.161-172
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• 2007

This article suggests an inverse kinematics analysis of a two degree of freedom spatial parallel motion simulator and design methodology of the robust PID controller. The parallel motion simulator consists of a fixed base and a moving frame connected by two serial chains, with each serial chain containing one revolute joint and two passive spherical joint. First, an inverse kinematics problems are solved in order to find the joint variable necessary to bring the end effector to track the desired trajectory. Second, an inverse optimal PID controller is proposed to track trajectories in the face of uncertainty. And the $H_{\infty}$ optimality and robust stability of the closed-loop system is acquired through the PID controller. Finally numerical results show the effectiveness of the PID controller that is designed by square/linear tuning laws.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2013년도 춘계학술대회 논문집
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• pp.1413-1414
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• 2013

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2011년도 춘계학술대회 논문집
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• pp.801-802
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• 2011

• 한국임상수의학회지
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• 제34권5호
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• pp.318-324
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• 2017

The objective of this study was to establish kinematic reference ranges for the femorotibial (FT) joint and the patellofemoral (PF) joint in healthy small-breed dogs by measuring 3D kinematics at the walk. Single-plane fluoroscopy was used to image the stifle joints of five healthy beagle dogs while the dogs were walking. 3D bone models of the femur, patella, and tibia were reconstructed by computed tomography scanning of the beagle dogs' hind limbs. The shape-matching technique was used to measure kinematic data from the fluoroscopic images and the 3D bone models. The cranial translation of the tibia during walking was inversely proportional to the FT joint flexion. There were significant correlations between the patellar motion and the tibial motion. The FT joint flexion had a strong correlation with the patellar proximodistal translation and flexion. Additionally, the tibial mediolateral translation had a strong correlation with the patellar shift and tilt. In this study, normal in vivo 3D FT joint and PF joint kinematics were demonstrated, and the average kinematic parameters were determined in walking beagle dogs.

• 대한기계학회논문집
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• 제18권6호
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• pp.1421-1429
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• 1994

An algorithm is developed for solving the inverse kinematic problem of a 6-degree-of-freedom robot with a wrist offset for which the closed form inverse solutions are not obtainable, but knowledge of one joint variable allows closed form solutions of the remaining joint variables. The algorithm does not require Forward Kinematics nor Jacobian but uses the implicit kinematic relationships between joint variables and the given hand position. An iterative back substitution method is used to solve the inversion and the optimal conditions of the convergence are incoporated. An example is given to illustrate the concepts, the solution procedure and its convergency.

• 한국시뮬레이션학회:학술대회논문집
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• 한국시뮬레이션학회 1998년도 추계학술대회 및 정기총회
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• pp.120-123
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• 1998

In animating an articulated entity with motion capture data, especially when the reconstruction is based on forward kinematics, there could be large discrepancies at the end effector. The small errors in joint angles tend to be amplified as the forward kinematics positioning progresses toward the end effector. In this paper, we present an algorithm that enhances the motion capture data to reduce positional errors at the end effector. The process is optimized so that the characteristics of the original joint angle data is preserved in the resulting motion. The frames at which the end-effector position needs to be accurate are designated as“keyframes”(e.g. starting and ending frames). In the algorithm, corrections by inverse kinematics are performed at sparse keyframes and they are interpolated with a cubic spline which produces a curve best approximating the measured joint angles. The experiment proves that our algorithm is a valuable tool to improve measured motion especially when end-effector trajectory contains a special goal.

• 대한족부족관절학회지
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• 제27권1호
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• pp.17-23
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• 2023

Purpose: Toe-in gait is defined as a style of walking in which the foot turns inward. It may be caused by an increase in femoral bone anteversion, tibia torsion, and metatarsus adductus. There are some conservative treatment approaches used to correct this condition. This review aimed to determine the effects of the toe-in gait on joint loading, kinematics, and kinetic parameters while walking. Moreover, it sought to determine the efficiency of various conservative treatments used to correct the condition. Materials and Methods: A literature search was conducted in the following databases: PubMed, Institute for Scientific Information (ISI), Web of Science database, EBSCO, and Embase, using the following keywords in toe, toe-in, toeing, in-toe, pigeon toe, and conservative treatment published between 1950 and 2021. The quality of the studies was evaluated using the Down and Black tool. Results: A total of 13 papers on the impact of toe-in gait on joint contact force, kinematics, kinetic parameters, and conservative approaches to management were found. The quality of the studies varied between a score of 11 and 22. The toe-in gait influences the joint contact forces and kinematics of the joints, especially the hip and pelvis. The effects of conservative treatment on the toe-in gait appear to be controversial. Conclusion: As the toe-in gait influences the joint contact force, it may increase the incidence of degenerative joint diseases. Therefore, treatment is recommended. However, there is no strong evidence on the efficacy of conservative treatments, and there are no recommendations for the use of these treatments in subjects with toe-in gait.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2004년도 ICEIC The International Conference on Electronics Informations and Communications
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• pp.263-268
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• 2004

The inverse kinematics problem is to find a set of joint variable values that will place the end effector of a robot manipulator into a given pose. Pieper has shown that a sufficient condition for a manipulator to have a closed form solution is that three adjacent joint axes intersects, hence the six axes robot with spherical wrist allows closed form solution. But many industrial robots have a non-spherical wrist to provide a stronger wrist configuration so that they can handle heavy payloads. Also, the use of a non-spherical wrist can result in a cheap and simple wrist arrangement than when all three axes intersect at a common point. In these cases, closed form solutions cannot be found. Therefore numerical technique must be used to solve the inverse kinematics equations. This paper proposes a new algorithm that can be used for finding inverse kinematics solution of the six axes robot with non-spherical wrist. Computer simulations are provided to prove the usefulness of our method.

• 한국정밀공학회지
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• 제25권11호
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• pp.107-118
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• 2008

In this study, lower extremity joint kinematics and kinetics and lumbar lordosis were investigated for two different symmetrical lifting techniques(squat and stoop) using the three-dimensional motion analysis. Twenty-six male volunteers lifted boxes weighing 5, 10 and 15kg by both squat and stoop lifting techniques. There were not significant differences in maximum lumbar joint moments between the two techniques. The hip and ankle contributed the most part of the support moments during squat lifting, and the knee flexion moment played an important role in stoop lifting. The hip, ankle and lumbar joints generated power and only the khee joint absorbed power in the squat lifting. The knee and ankle joints absorbed power, the hip and lumbar joints generated power in the stoop lifting. The bi-articular antagonist muscles' co-contraction around the knee joint during the squat lifting and the eccentric co-contraction of the gastrocnemius and semitendinosus were found to be important for straightening up during the stoop lifting. At the time of lordotic curvature appearance in the squat lifting, there were significant correlations in all three lower extremity joint moments with the lumbar joint. Differently, only the hip moment had significant correlation with the lumbar joint in the stoop lifting. In conclusion, the knee extension which is prominent kinematics during the squat tilling was produced by the contributions of the kinetic factors from the hip and ankle joints(extensor moment and power generation) and the lumbar extension which is prominent kinematics during the stoop lifting could be produced by the contributions of the knee joint kinetic factors(flexor moment, power absorption, bi-articular muscle function).

• 한국CDE학회논문집
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• 제19권4호
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• pp.356-367
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• 2014

A robotic sapatial augmented reality (RSAR) system, which combines robotic components with projector-based AR technique, is unique in its ability to expand the user interaction area by dynamically changing the position and orientation of a projector-camera unit (PCU). For a moving PCU mounted on a conventional robotic device, we can compute its extrinsic parameters using a robot kinematics method assuming a link and joint geometry is available. In a RSAR system based on user-created robot (UCR), however, it is difficult to calibrate or measure the geometric configuration, which limits to apply a conventional kinematics method. In this paper, we propose a data-driven kinematics control method for a UCR-based RSAR system. The proposed method utilized a pre-sampled data set of camera calibration acquired at sufficient instances of kinematics configurations in fixed joint domains. Then, the sampled set is compactly represented as a set of B-spline surfaces. The proposed method have merits in two folds. First, it does not require any kinematics model such as a link length or joint orientation. Secondly, the computation is simple since it just evaluates a several polynomials rather than relying on Jacobian computation. We describe the proposed method and demonstrates the results for an experimental RSAR system with a PCU on a simple pan-tilt arm.