• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.21 no.10
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• pp.897-904
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• 2011

When whole-body is exposed to vertical vibration, asymmetry shape of human body affects the response on the translational(fore-aft, lateral, vertical) and rotational(roll, pitch, yaw) motion. While the translational motion has been studied with various titles, it has been rare to study the rotational motion of human body exposed to vertical excitation because of lack of experimental equipment. This study was performed by using a 6-axis force plate installing strain gage type sensors for the rotational response. Sixteen male subjects were exposed to vertical vibration on rigid seat in order to investigate apparent mass of three translational motion and apparent eccentric mass of three rotational motion. Random signal was generated to make excitation vibration which was on an effective frequency range of 3~40 Hz, and magnitude of 0.224 m/$s^2$ r.m.s. The frequency range and magnitude used was selected for the vibration of passenger vehicle on idling condition. As the result, cross-axis apparent masses of fore-and-aft and lateral direction were not significant showing 20 % and 3 % of vertical apparent mass relatively. And apparent eccentric mass of pitch motion was dominant when compared to that of roll and yaw motion, which is reasoned by asymmetry direction of human body sitting on a seat.

• The Journal of the Acoustical Society of Korea
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• v.40 no.4
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• pp.382-390
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• 2021

Synthetic aperture sonars as well as side scan sonars or multibeam echo sounders have been commercialized and are widely used for seafloor imaging. In Korea related research such as the development of a towed synthetic aperture sonar system is underway. In order to obtain high-resolution synthetic aperture sonar images, it is necessary to accurately estimate the platform motion on which it is installed, and a precise underwater navigation system is required. In this paper we are going to provide reference data for determining the required navigation accuracy and precision of navigation sensors by quantitatively analyzing how much distortion of the sonar images occurs according to motion characteristics of the platform equipped with the synthetic aperture sonar. Five types of motions are considered and normalized root mean square error is defined for quantitative analysis. Simulation for error analysis with parameter variation of motion characteristics results in that yaw and sway motion causes the largest image distortion whereas the effect of pitch and heave motion is not significant.

• Journal of Navigation and Port Research
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• v.34 no.7
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• pp.525-532
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• 2010

Mobile Harbor (MH) is a new transportation platform that can load and unload containers onto and from very large container ships at sea. It could navigate near harbors where several vessels run, or it could navigate through very narrow channels. In the conceptual design phase when the candidate design changes frequently according to the various performance requirements, it is very expensive and time-consuming to carry out model tests using a large model in a large towing tank and a free-running model test in a large maneuvering basin. In this paper, a new Planar Motion Mechanism(PMM) test in a Circulating Water Channel (CWC) was conducted in order to determine the hydrodynamic coefficients of the MH. To do this, PMM devices including three-component load cells and inertia tare device were designed and manufactured, and various tests of the MH such as static drift test, pure sway test, pure yaw test, and drift-and-yaw combined test were carried out. Using those coefficients, course-keeping stability was analyzed. In addition, the PMM tests results carried out for the same KCS (KRISO container ship) were compared with our results in order to confirm the test validity.

• Transactions of the Korean Society of Automotive Engineers
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• v.4 no.6
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• pp.39-51
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• 1996

In the turning maneuver of the vehicle, its motion is mainly dependent on the genuine steering characteristics in view of the directional stability for stable turning ability. The under steer vehicle has an ability to maintain its own directonal performance for unknown external disturbances to some extent. From a few years ago, in order to acquire the more enhanced handling performance, some types of four wheel steering vehicle were considered and constructed. And, various rear wheel control logics for external disturbances has not been suggested. For this reason, in this posed rear wheel control logic is based on the yaw rate feed back type and is slightly modified by an yaw rate tuning factor for more stable turning performance. And an external disturbance is defined as a motivation of the additional yaw rate in the center of gravity by an uncertain input. In this study, an external disturbance is applied to the vehicle as a form of the additional yawing moment. Finally, the proposed rear wheel control logic is tested on the multi-body analysis software(ADAMS). J-turn and double lane change test are performed for the validation of the control logic.

• International Journal of Aeronautical and Space Sciences
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• v.18 no.4
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• pp.688-696
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• 2017

This paper presents an integrated roll-pitch-yaw autopilot using an equivalent based sliding mode control for skid-to-turn nonlinear time-varying missile system with lumped disturbances in its six-equations of motion. The considered missile model are developed to integrate the model uncertainties, external disturbances, and parameters perturbation as lumped disturbances. Moreover, it considers the coupling effect between channels, the variation of missile velocity and parameters, and the aerodynamics nonlinearity. The presented approach is employed to achieve a good tracking performance with robustness in all missile channels simultaneously during the entire flight envelope without demand of accurate modeling or output derivative to avoid the noise existence in the real missile system. The proposed autopilot consisting of a two-loop structure, controls pitch and yaw accelerations, and stabilizes the roll angle simultaneously. The Closed loop stability is studied. Numerical simulation is provided to evaluate performance of the suggested autopilot and to compare it with an existing autopilot in the literature concerning the robustness against the lumped disturbances, and the aforesaid considerations. Finally, the proposed autopilot is integrated in a six degree of freedom flight simulation model to evaluate it with several target scenarios, and the results are shown.

• Transactions of the Korean Society of Automotive Engineers
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• v.5 no.3
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• pp.76-85
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• 1997

The understeer characteristics of four wheel steering system(4WS system) in a high speed region have a negative effect upon the yaw velocity, leading to a decrease in the handling ability of vehicle. As a result, even if the side slip angle of vehicle can be kept up a minimum, a driver must compensate a decrease in yaw velocity by increasing the steering wheel angle in order to track the desired vehicle path. In this study, to keep the side slip angle of vehicle at zero and achieve a suitable yaw velocity in vehicle motion, a full active 4WS system(FA 4WS system) with actively steerable front and rear wheels is presented based on a nonlinear vehicle model and a model following control of yaw velocity. And the analysis results show the fat that, besides the excellent stability of vehicle, the FA 4WS system is able to realize better handling performance of vehicle than the previous 4WS systems in the high speed region.

• Journal of Auto-vehicle Safety Association
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• v.5 no.1
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• pp.37-43
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• 2013

This paper describes an investigation into coordinated control of electronic stability control (ESC) and active roll control system (ARS). The coordinated control is suggested to improve the vehicle stability and agility features by yaw rate control. The proposed integrated chassis control algorithm consists of a supervisor, control algorithms, and a coordinator. The supervisor monitors the vehicle status and determines desired vehicle motions such as a desired yaw rate and desired roll motion based on control modes to improve vehicle stability. According to the corresponding the desired vehicle dynamics, the control algorithm calculated a desired yaw moment and desired roll moment, respectively. Based on the desired yaw moment and the desired roll moment, the coordinator determines the brake pressures and the ARC motor torques based on control strategies. Closed loop simulations with a driver-vehicle-controller system were conducted to investigate the performance of the proposed control strategy using CarSim vehicle dynamics software and the integrated controller coded using Matlab/Simulink.

• Journal of Institute of Control, Robotics and Systems
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• v.19 no.12
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• pp.1111-1118
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• 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.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2001.11a
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• pp.235-240
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• 2001

A four degrees of freedom (dof) motion platform for bicycle simulator is developed. The motion platform, capable of the vertical linear and three angular motions, is designed based on analysis of the typical motion characteristics revealed by the existing six dof bicycle simulator. The platform essentially consists of two parts： the three dof parallel manipulator, consisting of a moving platform, a fixed base and three actuators, and the turntable to generate the yaw motion. The nonlinear kinematics and dynamics of the three dof parallel manipulator with multiple closed loop chains are analyzed for tracking control of the motion platform. The tracking performances of the three control schemes are experimentally compared： the computed torque method (CTM), the sliding mode control (SMC) and the PD control. The CTM and SMC, incorporated with the system dynamics model, are found to be equally better in performance than the PD controller, irrespective of the presence of external disturbance.

• Journal of the Korean Institute of Intelligent Systems
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• v.25 no.2
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• pp.168-173
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• 2015

The flight control of aircraft, which has nonlinear time-varying dynamic characteristics depending on the various and unexpected external conditions, can be performed on two motions: longitudinal motion and lateral motion. In the longitudinal motion control of aircraft, pitch and trust are major control parameters and roll and yaw are control ones in the lateral motion control. Until now, a number of efficient and reliable control schemes that can guarantee the stability and maneuverability of the aircraft have been developed. Recently, the intelligent flight control scheme, which differs from the conventional control strategy requiring the various and complicate procedures such as the wind tunnel and environmental experiments, has attracted attention. In this paper, an intelligent longitudinal control scheme has been proposed utilizing Interval Type-2 fuzzy logic which can be recognized as a representative intelligent control methodology. The results will be verified through computer simulation with a F-4 jet fighter.