• Title, Summary, Keyword: 6DOF

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A multivariable controller design of 6 DOF motion simulator (6자유도 운동재현기의 다변수 제어기 설계)

  • 이호영;강지윤;이교일
    • Proceedings of the Korean Society of Precision Engineering Conference
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    • pp.449-454
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    • 1994
  • The Stewart Platform is one example of a motion simulator which generater 6DOF motion in space by six actuators in parallel. The presented control methrol of 6DOF motion simulator is generally classified into two types, one is SISO and the other is MIMO control type. The SISO control can't compensate for external load variation and different dynamic behavior of 6DOF motion, trerefore this type don's control motion precisely. On the other hand, the MIMO control compensates for a interference of 6DOF motion because MIMO controller is designed with 6DOF motion simulator synamics. But MIMO control of motion simulator has a complexity of 6DOF displacement feedback, because in oder to obtain feedback value we must solve the forward kinematics using measurement of cylinder length or design a state estimator, unless measurement of 6DOF displacement is possible. In this paper, a multivariable controller using H .inf. optimal control theory is designed to consider a interference of 6DOF motion and to obtain robust,precise control of system. Also in order to solve the mentioned problem of MIMO control, this paper presents a modified MIMO control model which control 6DOF motion by using feedback of measurement od cylinder length.

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Vision-based hybrid 6-DOF displacement estimation for precast concrete member assembly

  • Choi, Suyoung;Myeong, Wancheol;Jeong, Yonghun;Myung, Hyun
    • Smart Structures and Systems
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    • v.20 no.4
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    • pp.397-413
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    • 2017
  • Precast concrete (PC) members are currently being employed for general construction or partial replacement to reduce construction period. As assembly work in PC construction requires connecting PC members accurately, measuring the 6-DOF (degree of freedom) relative displacement is essential. Multiple planar markers and camera-based displacement measurement systems can monitor the 6-DOF relative displacement of PC members. Conventional methods, such as direct linear transformation (DLT) for homography estimation, which are applied to calculate the 6-DOF relative displacement between the camera and marker, have several major problems. One of the problems is that when the marker is partially hidden, the DLT method cannot be applied to calculate the 6-DOF relative displacement. In addition, when the images of markers are blurred, error increases with the DLT method which is employed for its estimation. To solve these problems, a hybrid method, which combines the advantages of the DLT and MCL (Monte Carlo localization) methods, is proposed. The method evaluates the 6-DOF relative displacement more accurately compared to when either the DLT or MCL is used alone. Each subsystem captures an image of a marker and extracts its subpixel coordinates, and then the data are transferred to a main system via a wireless communication network. In the main system, the data from each subsystem are used for 3D visualization. Thereafter, the real-time movements of the PC members are displayed on a tablet PC. To prove the feasibility, the hybrid method is compared with the DLT method and MCL in real experiments.

Design of 6 DOF Mechanism with Flexure Joints for telecommunication mirror and Experimental Stiffness Modeling (탄성힌지를 이용한 초정밀 통신용 미러 구동 6축 메커니즘 구현과 실험적 강성 모델링)

  • Kang, Byoung Hun
    • The Journal of The Institute of Internet, Broadcasting and Communication
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    • v.19 no.6
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    • pp.169-174
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    • 2019
  • Flexure joints are recently used in the ultra-precision mechanism for a telecommunication mirror stage. Flexure joints have several advantages coming from their monolithic characteristics. They can be used to reduce the size of manipulators or to increase the precision of motion. In our research, 6 dof(degree of freedom) mechanism is suggested for micrometer repeatability using a flexure mechanism. To design the 6-dof motion, the 2-dof planar mechanism are designed and assembled to make the 6-dof motion. To achieve a certain performance, it is necessary to define the performance of mechanism that quantifies the characteristics of flexure joints. This paper addresses the analysis and design of the 6-dof parallel manipulator with a flexure joint using a finite element analysis tool. To obtain experimental result, CCD laser displacement sensor is used for the total displacement and the stiffness for the 6-dof flexure mechanism.

Robust Nonlinear Control of a 6 DOF Parallel Manipulator : Task Space Approach

  • Kim, Hag-Seong;Youngbo Shim;Cho, Young-Man;Lee, Kyo-Il
    • Journal of Mechanical Science and Technology
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    • v.16 no.8
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    • pp.1053-1063
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    • 2002
  • This paper presents a robust nonlinear controller for a f degree of freedom (DOF) parallel manipulator in the task space coordinates. The proposed control strategy requires information on orientations and translations in the task space unlike the joint space or link space control scheme. Although a 6 DOF sensor may provide such information in a straightforward manner, its cost calls for a more economical alternative. A novel indirect method based on the readily available length information engages as a potential candidate to replace a 6 DOF sensor. The indirect approach generates the necessary information by solving the forward kinematics and subsequently applying alpha-beta-gamma tracker With the 6 DOF signals available, a robust nonlinear task space control (RNTC) scheme is proposed based on the Lyapunov redesign method, whose stability is rigorously proved. The performance of the proposed RNTC with the new estimation scheme is evaluated via experiments. First, the results of the estimator are compared with the rate-gyro signals, which indicates excellent agreement. Then, the RNTC with on-line estimated 6 DOF data is shown to achieve excellent control performance to sinusoidal inputs, which is superior to those of a commonly used proportional-plus-integral-plus-derivative controller with a feedforward friction compensation under joint space coordinates and the nonlinear controller under task space coordinates.

Study on the Pose Control of a 6 DOF Simulator with Pneumatic Cylinder Driving Apparatus (공기압실린더 구동장치를 이용한 6자유도 시뮬레이터의 자세제어에 관한 연구)

  • Jeong, J.H.;Ji, S.W.;Jang, J.S.
    • Journal of the Korea Society For Power System Engineering
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    • v.11 no.3
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    • pp.59-65
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    • 2007
  • In this study, 6-DOF simulator using pneumatic cylinder driving apparatus was manufactured because a pneumatic cylinder driving apparatus is superior to electric driving motor and hydraulic actuator, which used in traditional 6-DOF simulator, in competitive price and acceleration performance, and, 6-DOF motion can be realized at a low price in case that relatively low load is imposed on the simulator. The possible range of pose control of the simulator was investigated by inverse kinematics, and, it was controlled by a linear controller derived from linear model of the simulator. The Experimental results show that the simulator follows given coordinate well.

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Study on real time controller design of heavy load 6-DOF mition simulator (대부하 6자유도 운동 시뮬레이터의 실시간 제어기 설계에 관한 연구)

  • 김영대;강석종;이상범;박정호
    • 제어로봇시스템학회:학술대회논문집
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    • pp.13-16
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    • 1989
  • The paper, introduce the real time controller Design method of heavy load 6-DOF motion simulator. And also, introduce the Geometric design of 6-DOF Motion generation, real time control A algorithm and the configuration method of real time controller H/W and S/W.

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Real-time system control for the 6-DOF simulation (6-DOF 시뮬레이터의 real-time 시스템 제어에 관한 연구)

  • 김영대;김충영;백인철;민성기
    • 제어로봇시스템학회:학술대회논문집
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    • pp.17-21
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    • 1989
  • 6-DOE simulator system is designed to real-time processing for motion control, data acquisition, image generation and image processing etc.. In this paper, we introduce hardware and software design technologies for distributed processing, event-trapping, system monitoring and time scheduling procedure in 6-DOF simulator system design.

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Measurement of Fine 6-DOF Displacement using a 3-facet Mirror (삼면반사체를 이용한 6자유도 미소 변위 측정)

  • 박원식;조형석;변용규;박노열
    • 제어로봇시스템학회:학술대회논문집
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    • pp.50-50
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    • 2000
  • In this paper, a new measuring system is :proposed which can measure the fine 6-DOF displacement of rigid bodies. Its measurement principle is based on detection of laser beam reflected from a specially fabricated mirror that looks like a triangular pyramid having an equilateral cross-sectional shape. The mirror has three lateral reflective surfaces inclined 45$^{\circ}$ to its bottom surface. We call this mirror 3-facet mirror. The 3-facet mirror is mounted on the object whose 6-DOF displacement is to be measured. The measurement is operated by a laser-based optical system composed of a 3-facet mirror, a laser source, three position-sensitive detectors(PSD). In the sensor system, three PSDs are located at three corner points of a triangular formation, which is an equilateral triangular formation tying parallel to the reference plane. The sensitive areas of three PSDs are oriented toward the center point of the triangular formation. The object whose 6-DOF displacement is to be measured is situated at the center with the 3-facet mirror on its top surface. A laser beam is emitted from the laser source located at the upright position and vertically incident on the top of the 3-fatcet mirror. Since each reflective facet faces toward each PSD, the laser beam is reflected at the 3-facet mirror and splits into three sub-beams, each of which is reflected from the three facets and finally arrives at three PSDs, respectively. Since each PSD is a 2-dimensional sensor, we can acquire the information on the 6-DOF displacement of the 3-facet mirror. From this principle, we can get 6-DOF displacement of any object simply by mounting the 3-facet mirror on the object. In this paper, we model the relationship between the 6-DOF displacement of the object and the outputs of three PSDs. And, a series of simulations are performed to demonstrate the effectiveness of the proposed method. The simulation results show that the proposed sensing system can be an effective means of obtaining 3-dimensional position and orientation of arbitrary objects.

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Useful evaluation of 3D target location correction by using Xsight spine tracking system in CyberKnife (사이버나이프에서 Xsight spine tracking system을 이용한 3D 표적위치보정의 유용성 평가)

  • Jeong, Young-Joon;Kim, Sang-Hyun
    • Journal of Digital Convergence
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    • v.13 no.1
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    • pp.331-339
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    • 2015
  • The purpose of this study is to evaluate utility of rotating adjustment using Xsight spine tracking system in 3D DOF location adjusting method, to minimize error between 6D DOF and 3D DOF in fiducial tracking system. In this study, the result of 6D DOF target location error is $0.124{\pm}0.058mm$, using fiducial inside tumor 3D DOF $0.673{\pm}0.142mm$, outside tumor $1.126{\pm}0.253mm$, apply with Xsight spine tracking system 3D DOF $0.542{\pm}0.103mm$. As the experiment shows, it was demonstrated that rotating adjustment through Xsight spine tracking system is valuable in case of treatment in 3D DOF location error that makes increasing accuracy and dose distribution each approximately 48% and 3%. In accordance with result of this study is useful rotation.

Geometrical Design Theory of a 6 DOF Vibration Absorber (6자유도 진동 흡진기의 기하적 설계 이론)

  • Jang Seon Jun;Choi Yong Je
    • Journal of the Korean Society for Precision Engineering
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    • v.22 no.7
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    • pp.191-199
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    • 2005
  • Many researchers have been investigating the design of multi-mode absorption vibration absorber for multi degree-of-freedom (DOF) system. The approach taken to this problem has been to find the optimized constants of stiffness and damping for the given set of single-DOF absorbers or single multi-DOF absorber attached to a multi degree-of-freedom system. This paper presents a novel geometrical and direct design theory of a 6 DOF vibration absorber via screw theory. Theoretical development is demonstrated by a practical example in which the diagonal stiffness matrix is synthesized using rectangular configuration of springs. The performance of this absorber is simulated by modal analysis.