Distributed Formation Control based on Orientation Alignment and Position Estimation

오광교,안효성 제어·로봇·시스템학회 2018 International Journal of Control, Automation, and Vol.16 No.3

Formation control is studied for single- and double-integrators on the plane based on orientation alignment and position estimation. It is assumed that agents measure the relative positions of their neighbors with respect to their own local body-fixed reference frames without any common sense of orientation. The proposed control strategy consists of an orientation alignment, a position estimation, and a position control law. It is shown that the proposed control strategy allows the agents to achieve the desired formation if the interaction graph is uniformly connected and the orientation angles belong to an interval with arc length less than π.

Developpe a la seconde 동작 시 골반과 하지의 지향각(Orientation angles)의 운동학적 분석

정철정,정혜진 한국운동역학회 2004 한국운동역학회지 Vol.14 No.3

C. J. JUNG, H. J. JEUNG. Kinmatics Analysis of pelvis and lower extremity using orientation angles during a developpe a la seconde. Korean Journal of Sport Biomechanics, Vol. 14, No. 3, pp. 259-270, 2004. The purpose of this study was to analysis of pelvis and lower extremity using orientation angles during a developpe a la seconde. Data were collected by Kwon3D program. Two females professional modern dancer were participated in this experiment. Subjects performed a developpe a la seconde in meddle heights(about 90 deg.) The results were as follows. The orientation angles of pelvis were, in most cases, caused by the movement of trunk and thigh. It was restricted the movement of pelvis within narrow limits because the movement of pelvis was very important to lower extremity alignment. The orientation angle of shank against thigh showed a change of angle about 3-60 in internal ·external rotation The orientation angle of foot against shank showed a change of angle about 6-7 in internal ? external rotation.

Orientation of a MgB2 Powder in a Magnetic Field

강기혁,B. J. Mean,김성훈,B. Ndiaye,조병기,J. Y. Kim,이무희 한국물리학회 2010 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.57 No.61

We have attempted magnetic orientation of MgB2 powder grains in an epoxy resin under a 7-T horizontal magnetic field. The horizontal field was crucial to get rid of gravitational sedimentation by rotating the mixture of MgB2 powder grains and the epoxy resin along the horizontal axis. Since we did not know the principal axes and the magnitude of the magnetic anisotropy tensor for MgB2, we devised different alignment schemes assuming two cases: case I for the easy axis along the c-axis and case II for the two easy axes perpendicular to the c-axis. For each case, we built different rotation devices: namely, for case I, the rotation axis was parallel to the magnetic field whereas, for case II, it was perpendicular to the magnetic field. For both cases, the powder grains should be aligned along the rotation axis. For assessment of the c-axis alignment, X-ray diffraction (XRD) and 11B nuclear magnetic resonance (NMR) measurements were utilized. However, the XRD and 11B NMR data for both cases were the same as those for the powder sample and showed no evidence of orientation. For possible scenarios, we suggest two possibilities: negligible anisotropy of the magnetic susceptibility tensor and the large size of the ground MgB2 powder particles still in multi-grains.

Consensus under biased alignment

Ahn, Hyo-Sung,Trinh, Minh Hoang Elsevier 2019 Automatica Vol.110 No.-

<P><B>Abstract</B></P> <P>This paper studies a consensus problem under the presence of biased alignments in two-dimensional space. The <I>biased alignment</I> studied in this paper may arise, for example, due to a mismatch between the control and sensing directions of the agents. After formulating the problem, we provide some sufficient conditions for consensus or for divergence depending on the biased alignments’ magnitude. Moreover, we conduct analyses on convergence characteristics in terms of locations of eigenvalues. Additionally, we study consensus conditions when the biased alignments are time-varying with errors in measured distances. Finally, several extensions of the problem on complete graphs, double-integrator dynamics, and three-dimensional space are also provided.</P>

편광 FTIR 이미징 시스템을 이용한 액정 배향 연구

정재현(Jae Hyun Jung),배진우(Jin Woo Bae),송기국(Kigook Song) 한국고분자학회 2016 폴리머 Vol.40 No.5

편광 적외선(infrared, IR)을 사용한 FTIR 이미징 실험으로 시료 전체의 평균 배향 상태가 아닌 각 위치에서 의 분자 배열 정도를 측정할 수 있었다. 시료 내에서 분자들의 배향 방향이 서로 다른 액정 셀(cell)에 대하여 러빙(rubbing) 강도와 온도에 따른 편광 FTIR 이미징 실험을 수행하였다. 5CB 액정들이 불규칙하게 배열된 영역과 한 방향으로 나란히 배열된 두 영역의 경계 부분 IR 이미지는 러빙 강도에 따라 변하였으며, 5CB가 온도에 따라 액정상에서 액체상으로 변화하는 IR 이미지로부터는 배열이 흐트러진 마이크로미터 크기의 영역들이 배향된 액정상 내에서 부분적으로 먼저 나타난 후 전체의 배열이 모두 변하였다. Molecular orientations at each domains of a sample, not an average of whole area, could be measured using the FTIR imaging experiment with polarized IR beam. Polarized FTIR imaging experiments according to the rubbing strength and sample temperature were carried out for 5CB liquid crystal (LC) cell containing different molecular orientations. At the boundary between areas with random molecular arrangement and perfect LC alignment, the IR image of the cell was changed with rubbing strength. When 5CB changed from LC phase to isotropic liquid phase, disordered areas with micrometer-size were first observed within the area of perfect LC alignment, then whole LC molecules changed to the disordered isotropic phase.

측면진동보조전계 전기영동 전착방식을 적용한 YBCO 초전도 후막의 제작

소대화,전용우 한국전기전자재료학회 2003 전기전자재료학회논문지 Vol.16 No.11

In order to improve the surface uniformity and the conduction properties of the fabricated YBCO thick films, a system that applies alternating field vertically to the EPD field has been developed for the first time and applied to the electrophoretic deposition process. The applied alternating electric field, so called Shaky Alternating Assisted Field, caused a force to be exerted on each YBCO particle and resulted in a shaking of the particle in the direction of applied electric field, accomplishing a uniform particle orientation. The usual commercial electrical power was used for the vertically applied alternating voltage and the induced electric field was 25-120 V/cm at 60Hz. The thick film fabricated by the method developed in this paper showed better surface uniformity without crack and porosity and improved film characteristics such as critical temperature (Tc,zero = 90 K) and critical current density (2354 A/$\textrm{cm}^2$), Therefore, it is expected that the shaky-aligned electrophoretic deposition method can be used to fabricate superconductor films through a simpler process and at less expense.

좌표변환 기반의 두 자세 정렬 기법 비교

이정근 ( Jung-keun Lee ),정우창 ( Woo-chang Jung ) 한국센서학회 2019 센서학회지 Vol.28 No.1

Inertial measurement units (IMUs) are widely used for wearable motion-capturing systems in the fields of biomechanics and robotics. When the IMUs are combined with optical motion sensors (hereafter, OPTs) for their complementary capabilities, it is necessary to align the coordinate system orientations between the IMU and OPT. In this study, we compare the application of two coordinate transformation- based orientation alignment methods between two coordinate systems. The first method (M1) applies angular velocity coordinate transformation, while the other method (M2) applies gyroscopic angle coordinate transformation. In M1 and M2, the angular velocities and angles, respectively, are acquired during random movement for a least-square algorithm to determine the alignment matrix between the two coordinate systems. The performance of each method is evaluated under various conditions according to the type of motion during measurement, number of data points, amount of noise, and the alignment matrix. The results show that M1 is free from drift errors, while drift errors are present in most cases where M2 is applied. Thus, this study indicates that M1 has a far superior performance than M2 for the alignment of IMU and OPT coordinate systems for motion analysis.

운동역학 : Developpe derriere 수행시 골반과 하지 신체정렬에 관한 사례연구

이경화(LeeGyeongHwa),박기자(ParkGiJa),권문석(KwonMunSeog) 한국체육학회 2004 한국체육학회지 Vol.43 No.2

The purpose of this study was to present proper alignment of pelvis and lower extremity using orientation angles during a developpe derriere. Data were collected by Kwon3D program. Two females professional modern dancer were participated in this experiment. Subjects performed a developpe derriere in meddle heights(about 90°)The results were as follows:1. The orientation angle of pelvis against trunk was leaned on toward about 40°, and right and left in frontal aspect paralleled the trunk, forward and backward in rotation aspect showed forward rotation about 30°2. The orientation angle of thigh against pelvis showed a change of angle about 28° in axes of X and thigh was showing adduction about 15° and internal rotation about 25°. 3. The orientation angle of shank against thigh showed a change of angle about 11° in axes of X and shank was showing the range of the adduction about 5° and the range of the internal rotation from 5° to 6°.4. The orientation angle of foot against shank aligned about 11° in axes of X and foot was showing the range of the inversion, eversion from 3° to 5° and the range of the supination about 5°.

Effect of β-Chain Alignment Degree on the Performance of Piezoelectric Nanogenerator Based on Poly(Vinylidene Fluoride) Nanofiber

Khatatbeh Ibtehaj,Mohammad Hafizuddin Hj Jumali,Sameer Al-Bati,Poh Choon Ooi,Bandar Ali Al-Asbahi,Abdullah Ahmed Ali Ahmed 한국고분자학회 2022 Macromolecular Research Vol.30 No.3

This work demonstrated the effect of the β-chain alignment degree on piezoelectric nanogenerator (PNG) performance. A simple, safe and low-cost fastcentrifugal spinning technique was used to produce self-poled poly(vinylidene fluoride) (PVDF) nanofiber. PNG based on acetone-prepared PVDF fibers, with high β-chain alignment, generated output open-circuit voltage (VOC) and short-circuit current (ISC) five times higher than the film counterpart. In addition, the fibers showed a remarkable increase in β-chain alignment degree as the ratio of N,N-dimethylformamide (DMF) solvent increased. The optimum nanofiber with the highest β-chain alignment degree, β-fraction and piezoelectric charge coefficient of 0.93, 91.8% and -120 pC.N-1 was obtained, respectively. PNG based on the optimum fiber displayed the highest VOC, ISC and power density of 14 V, 1.4 μA and 6.7 μWcm-2, respectively. This performance is greater than any PNG made from electrospun PVDF fiber. The excellent performance of the fabricated PNGs was strongly related to the high alignment degree of β-chains parallel along the fiber axis. In addition, due to low Young’s modulus (1.63 MPa) of the optimum fibers, the related lead-free PNG is sensitive to small movements and can be used in wearable and implanted medical devices.

Formation Control of Rigid Bodies Based on Orientation Alignment and Position Estimation

Kwang-Kyo Oh,Hyo-Sung Ahn 제어로봇시스템학회 2014 제어로봇시스템학회 국제학술대회 논문집 Vol.2014 No.10

We study cooperative formation control based on orientation alignment and position estimation for kinematic rigid bodies moving in two- or three-dimensional space. We assume agents sense relative positions of their neighbors with respect to their own local reference coordinates, orientations of which are not aligned to each other initially. The proposed formation control strategy consists of orientation alignment, position estimation, and position control laws. If the interaction graph is strongly connected and orientations of the agents are initially close enough, the orientations of the agents are exponentially aligned and the estimated and actual positions asymptotically converge to actual and desired positions, respectively, up to translation in a common reference coordinate.