• Title/Summary/Keyword: zero point

Search Result 893, Processing Time 0.026 seconds

NEW ITERATIVE METHODS FOR FINDING A COMMON ZERO OF A FINITE FAMILY OF MONOTONE OPERATORS IN HILBERT SPACES

  • Kim, Jong Kyu;Tuyen, Truong Minh
    • Bulletin of the Korean Mathematical Society
    • /
    • v.54 no.4
    • /
    • pp.1347-1359
    • /
    • 2017
  • The purpose of this paper is to give some new iterative methods for finding a common zero of a finite family of monotone operators in Hilbert spaces. We also give the applications of the obtained result for the convex feasibility problem and constrained convex optimization problem in Hilbert spaces.

Real-Time CoM/ZMP Trajectory Transformation Method for Humanoid Robots Considering Structure Characteristics (구조 특성을 반영한 인간형 로봇을 위한 실시간 CoM/ZMP 궤적 변환 방법)

  • Hong, Seok-Min
    • Journal of Advanced Navigation Technology
    • /
    • v.21 no.1
    • /
    • pp.132-137
    • /
    • 2017
  • This paper proposes a transformation method of the zero moment point (ZMP) and the center of mass (CoM) from one walking pattern to other patterns by considering the structure of a robot or walking situations in real time. In general, a humanoid robot has own structure characteristics like height and mass. The structure characteristics make the given CoM/ZMP walking pattern of one human or one humanoid robot to be difficult to apply to other robot directly. For this purpose, we analyze the characteristics of walking patterns according to the step length, duration of walking support phase and the CoM height by using the cart-table model as the simple humanoid robot model. A transformation equation is derived from the analyzation and it is verified with simulation.

A Parameter Selection Method for Multi-Element Resonant Converters with a Resonant Zero Point

  • Wang, Yifeng;Yang, Liang;Li, Guodong;Tu, Shijie
    • Journal of Power Electronics
    • /
    • v.18 no.2
    • /
    • pp.332-342
    • /
    • 2018
  • This paper proposes a parameter design method for multi-element resonant converters (MERCs) with a unique resonant zero point (RZP). This method is mainly composed of four steps. These steps include program filtration, loss comparison, 3D figure fine-tuning and priority compromise. It features easy implementation, effectiveness and universal applicability for almost all of the existing RZP-MERCs. Meanwhile, other design methods are always exclusive for a specific topology. In addition, a novel dual-CTL converter is also proposed here. It belongs to the RZP-MERC family and is designed in detail to explain the process of parameter selection. The performance of the proposed method is verified experimentally on a 500W prototype. The obtained results indicate that with the selected parameters, an extensive dc voltage gain is obtained. It also possesses over-current protection and minimal switching loss. The designed converter achieves high efficiencies among wide load ranges, and the peak efficiency reaches 96.9%.

Determination of Electric Parameters of Cell Membranes Using Dielectrophoretic Levitation (Dielectrophoretic Levitation을 이용한 세포막의 전기적 특성 결정)

  • Kim, Yong-Wook;Lee, Sang-Wook;Lee, Sang-Hun;Kim, Yong-Kweon
    • Proceedings of the KIEE Conference
    • /
    • 1994.07a
    • /
    • pp.183-185
    • /
    • 1994
  • A new method for determination of electric parameter of cell membranes is proposed. Two circular electrodes is designed to have repulsive force. From the potential energy analysis, stable points where a cell is levitated between electrodes exist and move as frequency or voltage change. The levitated cell in the stable point fall freely when DEP force is zero. The DEP force is dependent on the frequency and the force is zero at the critical frequency. The critical frequency is determined by measuring the difference between the time taken at zero-applied voltage and the time taken at the frequency and the voltage. For example, the critical frequency and stable points of N.crassa slime cell is numerically evaluated. In the exeriment, polystyrene in water is levitated at the stable point. We show that the stable point move as the applied voltage is changed.

  • PDF

Energy-Efficient Reference Walking Trajectory Generation Using Allowable ZMP (Zero Moment Point) Region for Biped Robots (2족 보행 로봇을 위한 허용 ZMP (Zero Moment Point) 영역의 활용을 통한 에너지 효율적인 기준 보행 궤적 생성)

  • Shin, Hyeok-Ki;Kim, Byung-Kook
    • Journal of Institute of Control, Robotics and Systems
    • /
    • v.17 no.10
    • /
    • pp.1029-1036
    • /
    • 2011
  • An energy-efficient reference walking trajectory generation algorithm is suggested utilizing allowable ZMP (Zero-Moment-Point) region, which maxmizes the energy efficiency for cyclic gaits, based on three-dimensional LIPM (Linear Inverted Pendulum Model) for biped robots. As observed in natural human walking, variable ZMP manipulation is suggested, in which ZMP moves within the allowable region to reduce the joint stress (i.e., rapid acceleration and deceleration of body), and hence to reduce the consumed energy. In addition, opimization of footstep planning is conducted to decide the optimal step-length and body height for a given forward mean velocity to minimize a suitable energy performance - amount of energy required to carry a unit weight a unit distance. In this planning, in order to ensure physically realizable walking trajectory, we also considered geometrical constraints, ZMP stability condition, friction constraint, and yawing moment constraint. Simulations are performed with a 12-DOF 3D biped robot model to verify the effectiveness of the proposed method.

Surface Properties of the High Porous Carbon Aerogels (고다공성 카본 에어로젤(C-Aerogel) 표면 특성)

  • Kim, Ji-Hye;Lee, Chang-Rae;Jeong, Young-Soo;Kim, Yang-Do;Kim, In-Bae
    • Journal of Surface Science and Engineering
    • /
    • v.41 no.3
    • /
    • pp.114-120
    • /
    • 2008
  • The pyrolysized carbon xerogel and aerogels were prepared from the sol-gel polymerization of resorcinol-formaldehyde(RF) followed by the dry process under ambient pressure and supercritical carbon dioxide condition respectively. The thermal behaviour of RF polymer xerogel was investigated with TGA analyzer to correspond with the pyrolysis process. The surface properties such as particle size, morphology and the point of zero charge of the pyrolysized porous carbon aerogels were studied for the precious metal catalyst supported media. It was found that the volume of the polymer aerogel decreased because of the significant linear shrinkage and weight loss of polymer gel during the carbonization. The point of zero charge of the carbon aerogel pyrolysized at $1050^{\circ}C$ under inert gas flow was about 10.

Modeling and Application Research of Zero Crossing Detection Circuit (Zero Crossing Detection 회로 Modeling 및 응용연구)

  • Jeong, Sungin
    • The Journal of the Institute of Internet, Broadcasting and Communication
    • /
    • v.20 no.4
    • /
    • pp.143-148
    • /
    • 2020
  • In the case of a system that detects and controls the phase of an alternating voltage, the analog control method compensates the phase offset part by filtering for the detected phase and applies it to the control. However, in the digital control method, precise control cannot be achieved due to an error between the operating frequency of the microprocessor or the microcontroller and the input phase time when controlled using such phase detection. In general, when the method used is a certain time, the accumulated error is compensated and adjusted at random. To solve this problem, a method of detecting a zero point in real time and compensating for the operating frequency of the microprocessor is needed. Therefore, the research to be performed in this paper to reduce these errors and apply them to precise digital control is as follows. 1) Research on how to implement Zero Crossing Detection algorithm through simulation modeling to compensate the zero point to match the operating frequency through detection. 2) A study on the method of detecting zero points in real time through the Zero Crossing Detection design using a microcontroller and compensating for the operating frequency of the microprocessor. 3) A study on the estimation of the rotor position of BLDC motors using the Zero Crossing Detection circuit.

Ammonia-fueled Solid Oxide Fuel Cell Recirculation Systems for Power Generation (암모니아 활용 고체산화물 연료전지 재순환 발전 시스템)

  • JIN YOUNG PARK;THAI-QUYEN QUACH;JINSUN KIM;YONGGYUN BAE;DONGKEUN LEE;YOUNGSANG KIM;SUNYOUP LEE;YOUNG KIM
    • Journal of Hydrogen and New Energy
    • /
    • v.35 no.1
    • /
    • pp.40-47
    • /
    • 2024
  • Ammonia is drawing attention as carbon free fuel due to its ease of storage and transportation compared to hydrogen. This study suggests ammonia fueled solid oxide fuel cell (SOFC) system with electrochemical hydrogen compressor (EHC)-based recirculation. Performance of electrochemical hydrogen pump is based on the experimental data under varying hydrogen and nitrogen concentration. As a result, the suggested system shows 62.04% net electrical efficiency. The efficiency is 10.33% point higher compared to simple standalone SOFC system (51.71%), but 0.02% point lower compared to blower-based recirculation system (62.06%). Further improvement in the EHC-based SOFC recirculation system can be achieved with EHC performance improvement.