• Transactions of the Korean Society of Mechanical Engineers A
• /
• v.32 no.2
• /
• pp.162-169
• /
• 2008

Compliance effect consideration method for real-time multibody vehicle dynamics is proposed using quasi-static analysis. The multibody vehicle model without bush elements is used based on the subsystem synthesis method which provides real-time computation on the multibody vehicle model. Reaction forces are computed in the suspension subsystem. According to deformation from the quasi-static analysis using reaction forces and bush stiffness, suspension hardpoint locations and suspension linkage orientation are changed. To validate the proposed method, quarter car simulations of McPherson strut and multilink suspension subsystems are performed. Full car bump run simulations and fish hook handling test simulations are also carried out comparing with the ADAMS vehicle model with bush elements. CPU times are also measured to see the real-time capabilities of the proposed method.

• Transactions of the Korean Society of Automotive Engineers
• /
• v.16 no.3
• /
• pp.118-126
• /
• 2008

The levitation stability of a Maglev vehicle utilizing electromagnetic suspension is primarily influenced by the deformation, roughness, and vibration of the guideway. Optimum design for both the vehicle and the guideway is desirable in order to reduce guideway construction cost, while meeting requirements for stability and ride quality. This paper presents an analysis of the levitation stability of the UTM-01, an urban Maglev vehicle, using a numerical simulation. The ODYN/Maglev, a dynamics analysis program, is used to simulate dynamics to evaluate the stability. A running test of the UTM-01 is also carried out to verify the results of the simulation. Using the simulation results, the levitation stability of the UTM-01 can be numerically analyzed at a variety of vehicle speeds.

• Transactions of the Korean Society of Automotive Engineers
• /
• v.10 no.2
• /
• pp.123-131
• /
• 2002

Simulators have been used to evaluate drivers'reactions to various transportation products. Most researches, however, have been concentrated on their technical performance, thus this paper considers drivers'senses of moving on a vehicle simulator through the analysis of human sensibility ergonomics. A sensibility ergonomic method is proposed in order to improve the faithfulness of vehicle simulators. A simulator of passenger vehicle consists of such three modules as vehicle dynamics, virtual environment, and motion representation modules. To evaluate drivers'feedback, human feelings are categorized into a set verbal expressions collected and investigated to find the most appropriate ones for translational and angular accelerations of the simulator The cutoff frequency of the washout alter ill the representation module is selected as one sensibility factor Sensibility experiments were carried out to find correlation between the expressions and the cut-off frequency of the filter. This study suggests a methodology to obtain an ergonomic database which can be applied to the sensibility evaluation of dynamic simulators.

• Transactions of the Korean Society of Automotive Engineers
• /
• v.19 no.5
• /
• pp.22-28
• /
• 2011

This paper presents an active roll motion control of a passenger vehicle. The roll controller is designed in the framework of $H_{\infty}$ control scheme based on the 3 DOF vehicle model taking into consideration parameter variations, which affect the roll dynamics, and unmodeled high frequency dynamics for robustness and performance. In order to investigate the feasibility of the active roll control system in a car, its performance is evaluated by simulation in a full vehicle model with nonlinear tire characteristics under various operating conditions. Finally, in order to enhance the performance in a transient region taking into account the limited bandwidth of the actuating module, a hybrid control strategy is presented.

• Transactions of the Korean Society of Automotive Engineers
• /
• v.25 no.3
• /
• pp.374-379
• /
• 2017

In vehicle to pedestrian accidents, cracks occur in the vehicle laminated glass due to impact of a pedestrian's head. In this study, FMH(Free Motion Headform) was used to experiment on and analyze the crack patterns on a vehicle laminated glass that collides with an adult headform at speeds of 20 km/h, 30 km/h, and 40 km/h, respectively. Applying the acquired experimental data and material property of the vehicle laminated glass to the structural analysis program LS-Dyna, we could develop the FE model of vehicle laminated glass similar to real vehicle laminated glass. We could estimate the head impact velocity and pedestrian's vehicle impact velocity using the Madymo program.

• Wind and Structures
• /
• v.20 no.2
• /
• pp.169-189
• /
• 2015

To investigate the effects of "sudden change" of wind fluctuations on vehicle running performance, which is caused by the artificial discrete simulation of wind field, a three-dimensional vehicle model is set up with multi-body dynamics theory and the vehicle dynamic responses in crosswind conditions are obtained in time domain. Based on Hilbert Huang Transform, the effects of simulation separations on time-frequency characteristics of wind field are discussed. In addition, the probability density distribution of "sudden change" of wind fluctuations is displayed, addressing the effects of simulation separation, mean wind speed and vehicle speed on the "sudden change" of wind fluctuations. The "sudden change" of vehicle dynamic responses, which is due to the discontinuity of wind fluctuations on moving vehicle, is also analyzed. With Principal Component Analysis, the comprehensive evaluation of vehicle running performance in crosswind conditions at different simulation separations of wind field is investigated. The results demonstrate that the artificial discrete simulation of wind field often causes "sudden change" in the wind fluctuations and the corresponding vehicle dynamic responses are noticeably affected. It provides a theoretical foundation for the choice of a suitable simulation separation of wind field in engineering application.

• Journal of the Society of Naval Architects of Korea
• /
• v.52 no.3
• /
• pp.206-221
• /
• 2015

Supercavitation is a modern technique which can be used to surround an underwater vehicle with a bubble in order to reduce the resistance of the vehicle. When the vehicle is at low speed in the deep sea, the cavitation number is relatively big and it is difficult to generate a cavity large enough to envelope the vehicle. In this condition, the artificial cavity, called ventilated cavity, can be used to solve this problem by supplying gas into the cavity and can maintain supercavitating condition. In this paper, a relationship between the ventilation gas supply rate and the cavity shape is determined. Based on the relationship a ventilation rate control is developed to maintain the supercavitating state. The performance of the ventilation control is verified with a depth change control. In addition, dynamics modeling for the supercavitating vehicle is performed by defining forces and moments acting on the vehicle body in contact with water. Simulation results show that the ventilation control can maintain the supercavity of an underwater vehicle at low speed in the deep sea.

• Proceedings of the Korean Society of Propulsion Engineers Conference
• /
• 2008.03a
• /
• pp.690-699
• /
• 2008

In this paper a conventional approach for design and analysis of subsonic air vehicle is used. First of all subsonic aerodynamic coefficients are calculated using Computational Fluid Dynamics(CFD) tools and then wind-tunnel model was developed that integrates vehicle components including control surfaces and initial data is validated as well as refined to enhance aerodynamic efficiency of control surfaces. Experimental data and limited computational fluid dynamics solutions were obtained over a Mach number range of 0.5 to 0.8. The experimental data show the component build-up effects and the aerodynamic characteristics of the fully integrated configurations, including control surface effectiveness. The aerodynamic performance of the fully integrated configurations is comparable to previously tested subsonic vehicle models. Mathematical model of the dynamic equations in 6-Degree of Freedom(DOF) is then simulated using MATLAB/SIMULINK to simulate trajectory of vehicle. Effect of altitude on range, Mach no and stability is also shown. The approach presented here is suitable enough for preliminary conceptual design. The trajectory evaluation method devised accurately predicted the performance for the air vehicle studied. Formulas for the aerodynamic coefficients for this model are constructed to include the effects of several different aspects contributing to the aerodynamic performance of the vehicle. Characteristic parameter values of the model are compared with those found in a different set of similar air vehicle simulations. We execute a set of example problems which solve the dynamic equations to find the aircraft trajectory given specified control inputs.

• Journal of the Korean Society of Safety
• /
• v.14 no.4
• /
• pp.85-92
• /
• 1999

Vehicle rollover is an important issue for the traffic safety. Rollover can occur from the driver's action, the vehicle characteristics, or the road condition. This study is about the rollover propensity analysis of a jeep vehicle using the steering and braking maneuver, which is the combined result by the driver and the vehicle. Simple equations of roll motion is used to analyze the roll motion and a special purpose vehicle dynamics program is used to simulate the rollover of the jeep vehicle. From the simulation, an incipient rollover motion of the vehicle was found. However, the more complete rollover propensity analysis would require further investigation using roll dynamic sensitivity study.

• Journal of Mechanical Science and Technology
• /
• v.20 no.1
• /
• pp.29-41
• /
• 2006

Nowadays, with the advancement of computers, computer simulation linked with VR (Virtual Reality) technology has become a useful method for designing the automotive driving system. In this paper, the VR simulation system was developed to investigate the driving performances of the ASV (Advanced Safety Vehicle) equipped with an ACC (Adaptive Cruise Control) system. For this purpose, VR environment which generates visual and sound information of the vehicle, road, facilities, and terrain was organized for the realistic driving situation. Mathematical models of vehicle dynamic analysis, which includes the ACC algorithm, have been constructed for computer simulation. The ACC algorithm modulates the throttle and the brake functions of vehicles to regulate their speeds so that the vehicles can keep proper spacing. Also, the real-time simulation algorithm synchronizes vehicle dynamics simulation with VR rendering. With the developed VR simulation system, several scenarios are applied to evaluate the adaptive cruise controlled vehicle for various driving situations.