• Title/Summary/Keyword: Arc of motion

Search Result 117, Processing Time 0.032 seconds

Extended impedance control of redundant manipulators

  • Oh, Yonghwan;Chung, Wankyun;Youm, Youngil
    • 제어로봇시스템학회:학술대회논문집
    • /
    • 1996.10a
    • /
    • pp.73-76
    • /
    • 1996
  • An impedance control approach based on an extended task space formulation is addressed to control the kinematically redundant manipulators. Defining a weighted inner product in joint space, a minimal parametrization of the null space can be achieved and we can visualize the null space motion explicitly. Based on this formulation, we propose a control method called inertially decoupled impedance controller to control the motion of the end-effector as well as the internal motion expanding the conventional impedance control. Some numerical simulations are given to demonstrate the performance of the proposed control method.

  • PDF

An intelligent master controller with mixed mode for teleoperation (혼합제어모드를 이용한 텔레오퍼레이션 작업용 지능형 매스터 컨트롤러)

  • 이영우;권동수
    • 제어로봇시스템학회:학술대회논문집
    • /
    • 1996.10b
    • /
    • pp.461-465
    • /
    • 1996
  • Position and rate control modes arc the two common modes for controlling remote manipulators with joysticks or hand controllers. Generally, position mode is easier for teleoperation than rate modes, when the manipulation work space is small or comparable to the human operator's control space. When the telemanipulator's work space is very large, human operator's control motion range must be large to allow telemanipulator's full range of motion resulting poor control resolution. One way to solve the poor resolution problem is to use indexing. However, rate mode can provide any higher degree of resolution without use of indexing. If two modes are mixed, master controller will be more convenient. The mixed mode algorithm, changes operating mode from position mode to rate mode or vise versa using fuzzy logic. The fuzzy logic algorithm, which has been designed to recognize the teleoperator's intended motion properly, provides an intelligence to a master controller.

  • PDF

Dosimetric Comparison of One Arc & Two Arc VMAT Plan for Prostate cancer patients (Prostate Cancer 환자에 대한 One Arc와 Two Arc VMAT Plan의 선량 측정 비교 분석)

  • Kim, Byoung Chan;Kim, Jong Deok;Kim, Hyo Jung;Park, Ho Chun;Baek, Jeong Ok
    • The Journal of Korean Society for Radiation Therapy
    • /
    • v.30 no.1_2
    • /
    • pp.107-116
    • /
    • 2018
  • Purpose : Intensity-modulated radiation therapy(IMRT) has been widely used for radiation therapy of Prostate Cancer because it can reduce radiation adverse effects on normal tissues and deliver more dose to the Prostate than 3D radiation therapy. Volumetric modulated arc therapy(VMAT) has been widely used due to recent advances in equipment and treatment techniques. VMAT can reduce treatment time by up to 55 % compared to IMRT, minimizing motion error during treatment. Materials and Methods : In this study, compared the MU and DVH values of 10 patients with prostate cancer by classifying them into 4 groups with 5 LN-Prostate groups and 5 Only-Prostate. And DQA measurements were performed using ArcCHECK and MapCHECK. Results : The results of Target and OAR dose distribution of Prostate patients are as follows. $D_{max}$ was in the range of 100~110 % in 4 groups, and more than 110 % of hot spot was not seen. Only-Prostate ($P_1$, $P_2$) without LN had a satisfactory dose distribution for the target dose, but slightly better for 2 arc plan($P_2$) than 1 arc plan($P_1$). The target dose $D_{98%}$ distribution in the LN-Prostate ($P_{L1}$, $P_{L2}$) group showed better 2 arc plan($P_{L2}$) than 1 arc plan($P_{L1}$), But in the case of 1 arc plan($P_{L1}$), the target dose $D_{98%}$ value was not enough. In OAR, the dose distribution of 1 Arc($P_1$) Plan and 2 Arc($P_2$) Plan in the Only-Prostate ($P_1$, $P_2$) Group satisfied the prescribed dose value. But, The dose distribution of 1 arc($P_1$) was slightly higher. In LN-Prostate OAR, 1 Arc($P_{L1}$) Plan showed higher dose than the prescribed dose. The Gamma evaluation pass rate of ArcCHECK and MapCHECK calculated from the DQA measurements was slightly higher than 99 % and the mean error range of the point dose measurements using the CC04 ion chamber was less than 1 %. Conclusion : In this study, Only-Prostate ($P_1$, $P_2$) group, the dose of 2 Arc plan was better. However, considering the treatment time and MU value, 1 Arc treatment method was more suitable. In the LN-Prostate ($P_{L1}$, $P_{L2}$) group, 2 Arc($P_{L2}$) treatment method showed better results and satisfied with Target $D_{98%}$ and OAR prescription dose.

  • PDF

A new configuration in a prosthetic knee using of hybrid concept of an MR brake with a T-shaped drum incorporating an arc form surface

  • Sayyaadi, Hassan;Zareh, Seiyed Hamid
    • Smart Structures and Systems
    • /
    • v.17 no.2
    • /
    • pp.275-296
    • /
    • 2016
  • This paper focuses on developing a new configuration on magnetorheological (MR) brake damper as prosthetic knee. Prosthetic knee uses magnetic fields to vary the viscosity of the MR fluid, and thereby its flexion resistance. Exerted transmissibility torque of the knee greatly depends on the magnetic field intensity in the MR fluid. In this study a rotary damper using MR fluid is addressed in which a single rotary disc will act as a brake while MR fluid is activated by magnetic field in different walking gait. The main objective of this study is to investigate a prosthetic knee with one activating rotary disc to accomplish necessary braking torque in walking gait via T-shaped drum with arc surface boundary and implementing of Newton's equation of motion to derive generated torque at the inner surface of the rotary drum. For this purpose a novel configuration of a T-shaped drum based on the effects of a material deformation process is proposed. In this new design, the T-shaped disc will increase the effective areas of influences in between drum and MR fluid together and the arc wall crushes the particles chains (fibrils) of the MR fluid together instead of breaking them via strain in a conventional MR brake. To verify the proposed MR brake, results of the proposed and conventional MR brakes are compared together and demonstrated that the resisting torque of the proposed MR brake is almost two times greater than that of the conventional brake.

A Study on Development of Algorithm for Seam Tracking by Considering Weld Defects in Horizontal Fillet Welding (수평필릿용접에서 용접결함을 고려한 용접선 자동추적 알고리즘개발에 관한 연구)

  • 문형순;나석주
    • Proceedings of the KWS Conference
    • /
    • 1996.10a
    • /
    • pp.139-141
    • /
    • 1996
  • Among various welding parameters, the welding current which is inversely proportional to the tip-to-workpiece distance in GMAW is an essential parameter to monitor the GMAW process of horizontal fillet joints. For the case of weld defect such as overlap in horizontal fillet welding, therefore, the signal processing for process monitoring or automatic seam tracking should be modified by considering the weld pool surface geometry including the corresponding weld defect. In other words, the adequate signal processing algorithm is indispensible to improve the performance of the arc sensor. However, arc sensor algorithm already developed usually focus on weld seam tracing but do not considering the weld qualities. In this paper, various experiments were carried out to investigate the tendencies of the weld defects when weaving motion is added, and the experimental method based on 2$^n$ factorial design was proposed for deriving the mathematical model between the leg length and the various welding conditions. Moreover, a signal processing method based on the artificial neural network(Adaptive Resonance Theory) was proposed far discriminating the current signal of sound weld beads from that of weld beads with overlap. Finally, the algorithm for weld seam tracking combined with the mathematical modeling and the signal processing method was carried out to track the weld line in conjunction with the improvement of the weld qualities. The reliability of the proposed algorithms were evaluated through various experiments, which showed that the proposed algorithms could be effectively used for arc welding automation.

  • PDF

The 29 May 2004 Offshore Southeast Coast of Korea Earthquake Sequence: Shallow Earthquakes in the Ulleung Back-arc basin, East Sea (Sea of Japan)

  • Kim, Won-Young;Noh, Myung-Hyun;Choi, Ho-Sun
    • Journal of the Korean Geophysical Society
    • /
    • v.9 no.3
    • /
    • pp.249-262
    • /
    • 2006
  • The 29 May 2004 offshore Uljin, Korea earthquake was predominantly thrust-faulting at a depth of approximately 12 (±2) km. The mainshock attained the seismic moment of M0 =5.41 (±1.87)  1016 N m (Mw = 5.1). The focal mechanism indicates a subhorizontal P-axis trending 264° and plunging 2°. The orientation of P- and T-axis is consistent with the direction of absolute plate motion generally observed within the plates, hence the cause of the May 29 shock is the broad-scale stress pattern from the forces acting on the downgoing slab along the Japan trench and inhibiting forces balancing it. The 29 May 2004 earthquake occurred along a deep seated (~12 km), pre-existing feature that is expressed on the surface as the basement escarpment along the western and southern slopes of the Ulleung basin. The concentrated seismicity along this basement escarpment suggests that this feature may qualify as a seismic zone - the Ulleung basement escarpment seismic zone (UBESZ).

  • PDF

Exact solutions of variable-arc-length elasticas under moment gradient

  • Chucheepsakul, Somchai;Thepphitak, Geeraphong;Wang, Chien Ming
    • Structural Engineering and Mechanics
    • /
    • v.5 no.5
    • /
    • pp.529-539
    • /
    • 1997
  • This paper deals with the bending problem of a variable-are-length elastica under moment gradient. The variable are-length arises from the fact that one end of the elastica is hinged while the other end portion is allowed to slide on a frictionless support that is fixed at a given horizontal distance from the hinged end. Based on the elastica theory, exact closed-form solution in the form of elliptic integrals are derived. The bending results show that there exists a maximum or a critical moment for given moment gradient parameters; whereby if the applied moment is less than this critical value, two equilibrium configurations are possible. One of them is stable while the other is unstable because a small disturbance will lead to beam motion.

3-D vision sensor system for arc welding robot with coordinated motion by transputer system

  • Ishida, Hirofumi;Kasagami, Fumio;Ishimatsu, Takakazu
    • 제어로봇시스템학회:학술대회논문집
    • /
    • 1993.10b
    • /
    • pp.446-450
    • /
    • 1993
  • In this paper we propose an arc welding robot system, where two robots works coordinately and employ the vision sensor. In this system one robot arm holds a welding target as a positioning device, and the other robot moves the welding torch. The vision sensor consists of two laser slit-ray projectors and one CCD TV camera, and is mounted on the top of one robot. The vision sensor detects the 3-dimensional shape of the groove on the target work which needs to be weld. And two robots are moved coordinately to trace the grooves with accuracy. In order to realize fast image processing, totally five sets of high-speed parallel processing units (Transputer) are employed. The teaching tasks of the coordinated motions are simplified considerably due to this vision sensor. Experimental results reveal the applicability of our system.

  • PDF

Power & Industrial System R&D Center, Hyosung Corporation (부하 상태에 따른 선형 BLDC 전동기의 동특성 해석 및 실험적 고찰)

  • Jo, Won-Young;Kim, Byong-Kuk;Kim, Tae-Hyun;Hwang, Dong-Won;Jung, Kun-Seok;Cho, Yun-Hyun;Lee, Kwon-Soon
    • Proceedings of the KIEE Conference
    • /
    • 2005.10c
    • /
    • pp.80-82
    • /
    • 2005
  • This paper presents the dynamic characteristics of a linear brushless DC(BLDC) motor with permanent magnet excitation for the precision conveyor according to the load condition. In order to investigate the accurate dynamic performance of tile linear BLDC motor driving with 6 step inverter- fed, finite element techniques coupling with external circuit models, together with the simultaneous simulation of motion of the mover system, arc proposed. The results of finite element analysis arc compared to the experimental ones.

  • PDF

Study of variables influencing on the metal transfer in GMAW (GMAW의 금속이행에 영향을 주는 변수연구를 위한 계측 시스템과 조건해석)

  • 이세헌
    • Journal of Welding and Joining
    • /
    • v.11 no.1
    • /
    • pp.73-79
    • /
    • 1993
  • The phenomenon of metal transfer has been investigated for different transfer modes using a digital high speed motion analyzer and an arc shadow-graphing system based on a laser source and related optical system. It was observed that the pinch instability phenomenon did not occur for the globular transfer mode, since the liquid globule was then spherical rateher than a cylindrical liquid bar. On increasing the ratio of carbon dioxide to argon, the transition current from globular to spray transfer generally increased, but it is interesting that the transition was observed to occur at the lowest current in a 5% CO$_{2}$-95% argon gas mixture. For pure carbon dioxide and helium shielding gases, the drop frequency increased slowly with increasing current. At high currents or an argon based shielding gas, the length of liquid bar decreased as the carbon dioxide content increased. The acceleration of a droplet within the arc was determined using the gas drag force theory and was found to be greater than the experimental results.

  • PDF