• Title, Summary, Keyword: Pitch motion

Search Result 361, Processing Time 0.033 seconds

Chaos Control of the Pitch Motion of the Gravity-gradient Satellites in an Elliptical Orbit (타원궤도상의 중력구배 인공위성의 Pitch운동의 혼돈계 제어)

  • Lee, Mok-In
    • Journal of the Korean Society for Aeronautical & Space Sciences
    • /
    • v.39 no.2
    • /
    • pp.137-143
    • /
    • 2011
  • The pitch motion of a gravity-gradient satellite can be chaotic, depending on the ratio of mass moments of inertia and the eccentricity of the satellite orbit. For a precise prediction of motion, chaotic pitch motion has to be changed to non-chaotic motion. Feedback control can be used to obtain nonchaotic pitch motion. For chaos control and stabilization of the pitch motion of a gravity-gradient satellite, a feedback control system is designed, based on the linear nonautonomous system obtained by linearizing the nonlinear pitch motion. The control law obtained has two parameters and is applied to chaotic nonlinear pitch motion. The nonlinear control system satisfies the proposed control objectives in the range of the nonchaotic parameter space.

Pitch Directional Swimming Control of Multi-Legged Biomimetic Underwater Robot (CALEB10) (다족형 생체모방 수중 로봇(CALEB10)의 Pitch 유영 제어)

  • Lee, Hansol;Lee, Jihong
    • The Journal of Korea Robotics Society
    • /
    • v.12 no.2
    • /
    • pp.228-238
    • /
    • 2017
  • The CALEB10 is a multi-legged biomimetic underwater robot. In the last research, we developed a swimming pattern named ESPG (Extended Swimming Pattern Generator) by observing diving beetle's swimming actions and experimented with a positive buoyancy state in which CALEB10 floats on the water. In this paper, however, we have experimented with CALEB10 in a neutral buoyancy state where it is completely immersed in water for pitch motion control experiment. And we found that CALEB10 was unstably swimming in the pitch direction in the neutral buoyancy state and analyzed that the reason was due to the weight proportion of the legs. In this paper, we propose a pitch motion control method to mimic the pitch motion of diving beetles and to solve the problem of CALEB10 unstably swimming in the pitch direction. To control the pitch motion, we use the method of controlling additional joints while swimming with the ESPG. The method of obtaining propulsive force by the motion of the leg has a problem of giving propulsive force in the reverse direction when swimming in the surge direction, but this new control method has an advantage that a propulsive moment generated by a swimming action only on a target pitch value. To demonstrate validity this new control method, we designed a dynamics-based simulator environment. And the control performance to the target pitch value was verified through simulation and underwater experiments.

Implementation of 3D Motion Simulator with Two Degrees of Freedom (2자유도를 갖는 3차원 운동 시뮬레이터 연구)

  • Choi, Myoung-Hwan;Kim, Young-Jin
    • Journal of Industrial Technology
    • /
    • v.21 no.A
    • /
    • pp.81-88
    • /
    • 2001
  • In this work, we have developed a 2 degrees of freedom(DOF) motion simulator that can generate the sensation of motion in a 6 DOF space. The motion base has the DOF of roll and pitch, and the purpose of the motion base is to create the sensation of riding a vehicle in a 3D space by controlling the motion base. The dynamics of the mechanism was analysed and the optimal design of the motion base mechanism has been reached. The prototype motion base mechanism was developed and tested. The multi-axis motion controller(MMC) was used to control the two AC servo meters that drive the roll and pitch motion.

  • PDF

Passive Maglev Carrier Control with Consideration of Pitch Motion (피치 운동을 고려한 자기부상 수동형 이송자 제어)

  • Lee, Younghak;Kim, Chang-Hyun;Ha, Chang-Wan;Park, Doh-Young;Yang, Seok-Jo;Lim, Jaewon
    • Transactions of the Korean Society of Mechanical Engineers A
    • /
    • v.40 no.2
    • /
    • pp.213-220
    • /
    • 2016
  • This research aims to develop core technologies for passive carrier (no power in carrier itself) transfer system. The technologies are passive levitation, propulsion, and guidance, which can be great benefits for semiconductor and display manufacturing industries. Passive maglev carrier is necessary to precise position control for quiet and stable transfer operation. However, the structural characteristics of carrier and the installation errors of gap sensors cause the pitch motion. Hence, the controller design in consideration of pitch motion is required. This study deals with the reduction control of carrier pitch motion. PDA controller and PDA controller with pitch control are proposed to compare the pitch angle analysis. The pitch angle and the levitation precision are measured by experiment. Finally, the optimized design of pitch controller is presented and the effects are discussed.

The Research of 2 DOF 3D Motion Simulator (2 DOF 3D 운동 시뮬례이터 실험)

  • 김영진;최명환
    • 제어로봇시스템학회:학술대회논문집
    • /
    • /
    • pp.260-260
    • /
    • 2000
  • In this work, we have developed a 2 degree of freedom(DOF) motion simulator that can generate the sensation of motion in a 6 DOF space. The motion base has the DOF of roll and pitch, and the purpose of the motion base is to create the sensation of riding a vehicle in a 3D space by controlling the motion base. The dynamics of the mechanism was analysed and the optimal design of the motion base mechanism has been reached. The prototype motion base mechanism was developed and tested. The multi-axis motion controller(MMC) was used to control the two ac servo motors that drive the roll and pitch motion.

  • PDF

Longitudinal motion characteristics of a ship according to the location (선내 위치에 따른 선박의 종운동 특성)

  • Kang, Il-Kwon;Kim, Min-Seok;Park, Byung-Soo;Hong, Jin-Keun;Jeong, Seong-Jae;Ham, Sang-Jun
    • Journal of the Korean Society of Fisheries and Ocean Technology
    • /
    • v.48 no.2
    • /
    • pp.147-154
    • /
    • 2012
  • In head sea, a ship has mainly the longitudinal motion such as vertical acceleration and pitch. In that case, the motion characteristics of a ship will have changed as the location different from each of place vertically and horizontally on board. The author carried out an experiment about the ship's vertical acceleration and pitch according to the location for the head sea, and analyzed the data with the aid of the statistical and spectral analyzing method to get the motion characteristics of the vessels. The response of vertical acceleration and pitch not deeply depend on the decks vertically, but displayed the relative big different value horizontally even if same deck. The biggest response of vertical acceleration and pitch among the accommodations was shown at scientist room, but the value of it not reached to the minimum requirement of ISO 2631-1 for working on board.

Study on the Disturbance Applied to Launcher Hatch by Ship Motions (함정운동에 의해 발사대 해치에 작용하는 외란에 관한 연구)

  • Byun, Young-Chul;Kang, E-Sok
    • Journal of Institute of Control, Robotics and Systems
    • /
    • v.19 no.12
    • /
    • pp.1111-1118
    • /
    • 2013
  • In this paper, the disturbance applied to launcher hatch by ship motions is introduced to identify the vertical ship motion disturbance. Basically, ship motions are comprised of 6 degrees of freedom: roll, pitch, yaw, heave, surge and sway. In the case of the shipboard launcher hatch the coupled pitch, heave and roll are significant motions to be transformed to a vertical direction motion. The maximum acceleration values are obtained from the vertical motion model and the ship motion data in accordance with ship type and hatch location on the ship. We verify that the maximum pitch motion mainly influences the launcher hatch and also present the quantity of the maximum load disturbance by the ship's motion acceleration.

Reduced Frequency Effects on the Near-Wake of an Oscillating Elliptic Airfoil

  • Chang, Jo-Won;Eun, Hee-Bong
    • Journal of Mechanical Science and Technology
    • /
    • v.17 no.8
    • /
    • pp.1234-1245
    • /
    • 2003
  • An experimental study was carried out to investigate the reduced frequency effect on the near-wake of an elliptic airfoil oscillating in pitch. The airfoil was sinusoidally pitched around the center of the chord between -5$^{\circ}$and +25$^{\circ}$angles of attack at an airspeed of 3.4 m/s. The chord Reynolds number and reduced frequencies were 3.3 ${\times}$10$^4$, and 0.1, 0.7, respectively Phase-averaged axial velocity and turbulent intensity profiles are presented to show the reduced frequency effects on the near-wake behind the airfoil oscillating In pitch. Axial velocity defects in the near-wake region have a tendency to increase in response to a reduced frequency during pitch up motion, whereas it tends to decrease during pitch down motion at a positive angle of attack. Turbulent intensity at positive angles of attack during the pitch up motion decreased in response to a reduced frequency, whereas turbulent intensity during the pitch down motion varies considerably with downstream stations. Although the true instantaneous angle of attack compensated for a phase-lag is large, the wake thickness of an oscillating airfoil is not always large because of laminar or turbulent separation.

The Melnikov Analysis of the Pitch Dynamics of a Gravity Gradient Satellite (중력구배 인공위성의 Pitch운동의 Melnikov해석)

  • Lee, Mok-In
    • Transactions of the Korean Society of Mechanical Engineers A
    • /
    • v.33 no.12
    • /
    • pp.1427-1432
    • /
    • 2009
  • The pitch motion of a generic gravity gradient satellite is investigated in terms of chaos. The Melnikov method is used for detecting the onset of chaotic behavior of the pitch motion of a gravity gradient satellite. The Melnikov method determines the distance between stable and unstable manifolds of a perturbed system. When stable and unstable manifolds transverse on the Poincare section, the resulting motion can be chaotic. The Melnikov analysis indicates that the pitch dynamics of a generic gravity gradient satellite can be chaotic when the orbit eccentricity is small.

The Effect of Damping Plate on Mathieu-type Instability of Spar Platform (스파 플랫폼의 Mathieu형 불안정성에 미치는 감쇠판의 영향)

  • Rho, Jun-Bumn;Choi, Hang-Soon
    • Journal of the Society of Naval Architects of Korea
    • /
    • v.42 no.2
    • /
    • pp.124-128
    • /
    • 2005
  • This paper describes motion stability of a spar platform with and without a damping plate in regular waves. The heave and pitch motion equation is derived in terms of Mathieu equation and the stability diagram is obtained. It is shown that the spar platform with damping plate has smaller unstable region than that without damping plate in the stability diagram. Model tests are carried out to verify the mathematical analysis. Under the condition that the pitch natural period is approximately double the heave natural period and the heave motion is amplified at heave resonance, unstable pitch motions are evoked. However the unstable motion is stabilized in cases of spar platform with damping plate. Therefore the damping plate is an effective device to stabilize the motion of spar platform.