• Wind and Structures
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• v.6 no.5
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• pp.325-346
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• 2003

High-sided road vehicles are susceptible to a sharp-edged crosswind gust, which may cause vehicle accidents such as overturning, excessive sideslip, or exaggerated rotation. This paper thus investigates the dynamic behaviour and possible accidents of high-sided road vehicles entering a sharp-edged crosswind gust with road surface roughness and vehicle suspension included. The high-sided road vehicle is modelled as a combination of several rigid bodies connected by a series of springs and dampers in both vertical and lateral directions. The random roughness of road surface is generated from power spectral density functions for various road conditions. The empirical formulae derived from wind tunnel test results are employed to determine aerodynamic forces and moments acting on the vehicle. After the governing equations of motion are established, an extensive computation work is performed to examine the effects of road surface roughness and vehicle suspension on the dynamic behaviour and vehicle accidents. It is demonstrated that for the high-sided road vehicle and wind forces specified in the computation, the accident vehicle speed of the road vehicle running on the road of average condition is relatively smaller than that running on the road of very good condition for a given crosswind gust. The vehicle suspension system should be taken into consideration, and the accident vehicle speed becomes smaller if the vehicle suspension system has softer springs and lighter dampers.

• Journal of Auto-vehicle Safety Association
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• v.10 no.1
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• pp.32-37
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• 2018

This paper proposes autonomous speed control strategy for an Electric Vehicle on urban road. SNU campus road is used to reperesent urban road situation. Motor efficiency of driving on campus circulation road can be improved by controlling velocity properly. Given information of campus road, especially slope of road, acceleration is selected from candidate, considering consumed power, human factor and driving time. To apply urban situation, preceding vehicle is also considered. With preceding vehicle, acceleration is defined according to clearance and relative velocity. Acceleration is bounded in normal range. Proposed acceleration control method is activated with proper velocity range for campus circulation road. With acceleration control, motor efficiency becomes better than driving with constant vehicle. To evaluate the performance of proposed acceleration controller, simulation study is conducted via MATLAB.

• Wind and Structures
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• v.20 no.2
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• pp.191-211
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• 2015

Several frameworks for the dynamic analysis of wind-vehicle-bridge systems were presented in the past decade to study the safety or ride comfort of road vehicles as they pass through bridges under crosswinds. The wind loads on the vehicles were generally formed based on the aerodynamic parameters of the stationary vehicles on the ground, and the wind loads for the pure bridge decks without the effects of road vehicles. And very few studies were carried out to explore the dynamic effects of the aerodynamic interference between road vehicles and bridge decks, particularly for the moving road vehicles. In this study, the aerodynamic parameters for both the moving road vehicle and the deck considering the mutually-affected aerodynamic effects are formulized firstly. And the corresponding wind loads on the road vehicle-bridge system are obtained. Then a refined analytical framework of the WVB system incorporating the resultant wind loads, a driver model, and the road roughness in plane to fully consider the lateral motion of the road vehicle under crosswinds is proposed. It is shown that obvious lateral and yaw motions of the road vehicle occur. For the selected single road vehicle passing a long span bridge, slight effects are caused by the aerodynamic interference between the moving vehicle and deck on the dynamic responses of the system.

• Journal of the Korean Society of Industry Convergence
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• v.22 no.5
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• pp.575-582
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• 2019

Advanced driving assist system can support safety of driver and passengers which may require vehicle dynamics states as well as road geometry. It is essential to have in real-time estimation of related variables and parameters. Among the road geometry parameters, road slope angle which can not be measured is essential parameter in pose estimation, adaptive cruise control and others on sag road. In this paper, Kalman filter based method for the estimation of the vehicle dynamics and road slope angle using a nonlinear vehicle model is proposed. It uses a combination of Kalman filter as Cascade Extended Kalman Filter. CEKF uses measured vehicle states such as yaw rate, longitudinal/lateral acceleration and velocity. Unknown vehicle parameters such as center of gravity and inertia are obtained by 2 D.O.F lateral model and experimentally. Simulation and Experimental tests conducted with commercialized vehicle dynamics model and real-car.

• Structural Engineering and Mechanics
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• v.51 no.2
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• pp.315-331
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• 2014

The present study investigated the effect of the correlation of the measured road roughness profiles corresponding to the left and right wheels of a vehicle on the vibration of a vehicle-bridge coupling system. Four sets of road roughness profiles were measured by a laser road-testing vehicle. A correlation analysis was carried out on the four roughness samples, and two samples with the strongest correlation and weakest correlation were selected for the power spectral density, autocorrelation and cross-correlation analyses. The scenario of a three-axle truck moving across a rigid-frame arch bridge was used as an example. The two selected road roughness profiles were used as inputs to the vehicle-bridge coupling system. Three different input modes were adopted in the numerical analysis: (1) using the measured road roughness profile of the left wheel for the input of both wheels in the numerical simulation; (2) using the measured road roughness profile of the right wheel for both wheels; and (3) using the measured road roughness profiles corresponding to left and right wheels for the input corresponding to the vehicle's left and right wheels, respectively. The influence of the three input modes on the vibration of the vehicle-bridge system was analyzed and compared in detail. The results show that the correlation of the road roughness profiles corresponding to left and right wheels and the selected roughness input mode both have a significant influence on the vibration of the vehicle-bridge coupling system.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2003.05a
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• pp.357-361
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• 2003

According to the remarkable reduction of the vehicle noise, the important of tire noise which is generated from the vehicle and the necessities of the researches for the noise reduction are emphasized. In this study, we have studied the road noise which is excited by the interaction between tire and road. In order to evaluate the road noise, we carry out the subjective test(feeling test). In order to consider the effect of the vehicle suspension for the tire/road noise, we are equipped with identical tires on the differential vehicle suspension and evaluate the road noise. In order to consider the effect of the tire structure for the tire/road noise, we evaluate the some tires with various structures. From the test results, we fine that the difference of road noise is generated by the variation of the vehicle suspension. Also, we can select the optimized tire structure which can be reduced the road noise.

• 제어로봇시스템학회:학술대회논문집
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• 1991.10a
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• pp.773-778
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• 1991

In this paper we describe a road following method for an autonomous vehicle. From a road image in gray level, a road boundary is detected using a gradient operator, and then the road boundary is converted to orthogonal view of the road showing the vehicle position and heading direction. In this research an efficient road boundary search technique is developed to support real time vehicle control. Also, an obstacle detection method, using images taken from two different positions, has been developed.

• Transactions of the Korean Society of Automotive Engineers
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• v.3 no.6
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• pp.154-161
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• 1995

There are several kinds of driving conditions according to the characteristic of each vehicle diver. Automaker produces vehicle strong enough to satisfy this several driving conditions at the point of vehicle durability. In order to develop the car in a short period, Automaker engineer tests vehicle at serveral accelerated durability test roads. Before testing the vehicle durability, test engineer must know how much this test road severe than general field road which is composed of high way, city road, paved road and unpaved road. This paper suggests two types of road severity test method that is using relative fatigue life prediction method and using absolute fatigue life prediction method, and also present the merits and demerits of two test methods.

• Journal of Auto-vehicle Safety Association
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• v.15 no.4
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• pp.6-15
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• 2023

This paper develops scenarios to evaluate the safety performance of Unmanned Ground Vehicle on military circumstances. The scenarios were created using Pegasus Project 6-layer format. These scenarios consist of straight road, curved road, merging road and crossroad. We adapt these scenarios to unpaved road. The characteristics of unpaved roads were divided into roughness, friction coefficient and road frequency. This adaption is validated via computer simulation. We observe the scan lines of vehicle become tangled of the straight road that make the cognitive abilities of the vehicle low and the lane-keeping is unable when vehicles entering curved off-roads over 40 km/h. The developed scenarios will contribute to enhancing stability from the perspective of introducing autonomous driving technology to Korean military.

• Journal of the Institute of Electronics and Information Engineers
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• v.51 no.9
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• pp.208-214
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• 2014

Vehicle dynamic states used in various advanced driving safety systems are influenced by road geometry. Among the road geometry information, the vehicle pitch angle influenced by road slope and acceleration-deceleration is essential parameter used in pose estimation including the navigation system, advanced adaptive cruise control and others on sag road. Although the road slope data is essential parameter, the method measuring the parameter is not commercialized. The digital map including the road geometry data and high-precision DGPS system such as DGPS(Differential Global Positioning System) based RTK(Real-Time Kinematics) are used unusually. In this paper, low-cost cascade extended Kalman filter(CEKF) based road slope estimation method is proposed. It use cascade two EKFs. The EKFs use several measured vehicle states such as yaw rate, longitudinal acceleration, lateral acceleration and wheel speed of the rear tires and 3 D.O.F(Degree Of Freedom) vehicle dynamics model. The performance of proposed estimation algorithm is evaluated by simulation based on Carsim dynamics tool and T-car based experiment.