• Journal of the Korean Society for Precision Engineering
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• v.32 no.4
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• pp.377-386
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• 2015

Joint force/torque estimation by inverse dynamics is a traditional tool in biomechanical studies. Conventionally for this, kinematic data of human body is obtained by motion capture cameras, of which the bulkiness and occlusion problem make it hard to capture a broad range of movement. As an alternative, inertial motion sensing using cheap and small inertial sensors has been studied recently. In this research, the performance of inertial motion sensing especially to calculate inverse dynamics is studied. Kinematic data from inertial motion sensors is used to calculate ground reaction force (GRF), which is compared to the force plate readings (ground truth) and additionally to the estimation result from optical method. The GRF estimation result showed high correlation and low normalized RMSE(R=0.93, normalized RMSE<0.02 of body weight), which performed even better than conventional optical method. This result guarantees enough accuracy of inertial motion sensing to be used in inverse dynamics analysis.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.31 no.7 s.262
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• pp.747-755
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• 2007

To improve the reality of motion simulator, the method of data-driven motion generation has been introduced to simply record and replay the motion of real vehicles. We can achieve high quality of reality from real samples, but it has no interactions between users and simulations. However, in character animation, user controllable motions are generated by the database made up of motion capture signals and appropriate control algorithms. In this study, as a tool for the interactive data-driven driving simulator, we proposed a new motion generation method. We sample the motion data from a real vehicle, transform the data into the appropriate data structure(motion block), and store a series of them into a database. While simulation, our system searches and synthesizes optimal motion blocks from database and generates motion stream reflecting current simulation conditions and parameterized user demands. We demonstrate the value of the proposed method through experiments with the integrated motion platform system.

• Journal of the Korea Computer Graphics Society
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• v.18 no.3
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• pp.9-16
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• 2012

In this paper, we present a new method for reconstructing detailed facial expression from roughly captured data with a small number of markers. Because of the difference in the required capture resolution between the full-body capture and the facial expression capture, they hardly have been performed simultaneously. However, for generating natural animation, a simultaneous capture for body and face is essential. For this purpose, we provide a method for capturing the detailed facial expression only with a small number of markers. Our basic idea is to build a database for the facial expressions and apply the principal component analysis for reducing the dimensionality. The dimensionality reduction enables us to estimate the full data from a part of the data. We justify our method by applying it to dynamic scenes to show the viability of the method.

• Journal of Digital Convergence
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• v.14 no.1
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• pp.189-194
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• 2016

Recently, there is increasing demand for image processing technology while activated the use of equipments such as camera, camcorder and CCTV. In particular, research and development related to 3D image technology using the depth camera such as Kinect sensor has been more activated. Kinect sensor is a high-performance camera that can acquire a 3D human skeleton structure via a RGB, skeleton and depth image in real-time frame-by-frame. In this paper, we develop a system. This system captures the motion of a 3D human skeleton structure using the Kinect sensor. And this system can be stored by selecting the motion file format as trc and bvh that is used for general purposes. The system also has a function that converts TRC motion captured format file into BVH format. Finally, this paper confirms visually through the motion capture data viewer that motion data captured using the Kinect sensor is captured correctly.

• Journal of KIISE:Computing Practices and Letters
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• v.15 no.10
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• pp.791-795
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• 2009

There is a need for a system independent human data format that doesn't depend on a specific graphics tool or program to use interoperable human data in a network environment. To achieve this, the Web3D Consortium and ISO/IEC JTC1 WG6 developed the international draft standard ISO/IEC 19774 Humanoid Animation(H-Anim). H-Anim defines the data structure for an articulated human figure, but it does not yet define the data for human motion generation. This paper discusses a method of obtaining compatibility and independence of motion data between application programs, and describes a method of simplifying motion retargetting necessary for motion definition of H-Anim characters. In addition, it describes a method of generating H-Anim character animation using arbitrary 3D character models and arbitrary motion capture data without any inter-relations, and its implementation results.

• The Journal of the Korea Contents Association
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• v.6 no.9
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• pp.98-107
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• 2006

By improving performance of mobile machine(3D engine, 3D accelerator chip set, etc) and developing wireless network technology, a demand for actual contents of users is being increased rapidly. But, there are some difficulties yet for the speedy development of actual contents because of the limitation of development resources that is dependent on each mobile device's different performance. In general, much of the animated character-creation work for mobile environment is still done manually by experienced animator with the method of key frame processing. However, it needs a lot of time and more costs for creating motion. Additionally, it is possible to cause a distortion of motion. In this paper, I solved the difficulties by using a optical motion capture system, it was able to acquire accurate motion data more easily and quickly, and then it was possible to make 3D dance contents efficiently. Also, I showed techniques of key reduction and controlling frame number for using huge amounts of motion capture data in mobile environment which requires less resources. In making 3D dance contents, using an optical motion capture system was verified that it was more efficient to make and use actual-reality contents by creating actual character motion and by decreasing processing time than existing method.

• 제어로봇시스템학회:학술대회논문집
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• 2005.06a
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• pp.2126-2131
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• 2005

Interactions of a humanoid with a human are important, when the humanoid is requested to provide people with human-friendly services in unknown or uncertain environment. Such interactions may require more complicated and human-like behaviors from the humanoid. In this work the arm motions of a human are discussed as the early stage of human motion imitation by a humanoid. A motion capture system is used to obtain human-friendly arm motions as references. However the captured motions may not be applied directly to the humanoid, since the differences in geometric or dynamics aspects as length, mass, degrees of freedom, and kinematics and dynamics capabilities exist between the humanoid and the human. To overcome this difficulty a method to adapt captured motions to a humanoid is developed. The geometric difference in the arm length is resolved by scaling the arm length of the humanoid with a constant. Using the scaled geometry of the humanoid the imitation of actor's arm motions is achieved by solving an inverse kinematics problem formulated using optimization. The errors between the captured trajectories of actor arms and the approximated trajectories of humanoid arms are minimized. Such dynamics capabilities of the joint motors as limits of joint position, velocity and acceleration are also imposed on the optimization problem. Two motions of one hand waiving and performing a statement in sign language are imitated by a humanoid through dynamics simulation.

• Korean Journal of Applied Biomechanics
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• v.17 no.4
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• pp.37-44
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• 2007

This study compared the Character Studio of 3ds Max and OpenGL to find an adequate modeling method of character animation to be used in motion analysis in the area of motor mechanics. The subject was one male golfer. We obtained the positional coordinates of marks needed by photographing the subject's golf swing motions. Because the method based on the Character Studio used meticulously designed character meshes, it enabled high.level animation but it took a long time in applying physique and demanded the repeated adjustment of each motion data. With the method based on OpenGL, a character completed once could be usable to almost every testee and desired program control was available, but because each character had to be created by making a computer program, it was hard to make characters delicately. Because the method using the Character Studio is actively studied not only in motor mechanics but also in many research areas, it is expected to be more usable in the near future. On the contrary, the method based on OpenGL is easily applicable and allows the convenient use of other mechanical data.

• Proceedings of the KSME Conference
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• 2003.04a
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• pp.805-809
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• 2003

We developed a human-sized BWR(biped walking robot) named KUBIR1 driven by a new actuator based on the ball screw which has high strength and high gear ratio. KUBIR1 was developed to walk autonomously such that it is actuated by small torque motors and is boarded with DC battery and controllers. To utilize the information on the human walking motion and to analyze the walking mode of robot, a motion capture system was developed. The system is composed of the mechanical and electronic devices to obtain the joint angle data. By using the obtained data, a 3-D graphic interface was developed based on the OpenGL tool. Through the graphic interface, the control input of KUBIR1 is performed.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2002.10a
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• pp.507-510
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• 2002

We developed a human-sized BWR(biped walking robot) named KUBIRI driven by a new actuator based on the ball screw which has high strength and high gear ratio. KUBIRI was developed to walk autonomously such that it is actuated by small torque motors and is boarded with DC battery and controllers. To utilize informations on the human walking motion and to analyze the walking mode of robot, a motion capture system was developed. The system is composed of the mechanical and electronic devices to obtain the joint angle data. By using the obtained data, a 3-D graphic interfacer was developed based on the open inventor tool. Through the graphic interfacer, the control input of KUBIRI is performed.