• 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.

• Proceedings of the KSME Conference
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• 2003.11a
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• pp.1524-1529
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• 2003

In this paper deals with a unique method for measuring vehicle states such as body sideslip angle and tire sideslip angle using GPS velocity information in conjunction with other sensors. A method for integrating Inertial Navigation System (INS) sensors with GPS measurements to provide higher update rate estimates of the vehicle states is presented, and the method can be used to estimate the tire cornering stiffness. The experimental results for the GPS velocity-based sideslip angle measurement and cornering stiffness estimates are compared with the theoretical predictions. From the experimental results, it can be concluded that the proposed method has an advantage for future implementation in a vehicle safety system.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.18 no.4
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• pp.10-15
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• 2019

In this paper, we report a robust steering control using time delay control for the vehicle dynamics variation due to tire/road contact condition variation, the lateral disturbance force due to the side wind, and the yaw disturbance moment due to the difference between the left and right tires' pneumatic pressure. We controlled the side slip and yaw damping compensation for rapid steering at the high velocity of the vehicle. Based on the developed control, the driver can only consider the desired path without concerning on the vehicle dynamics variation, disturbances, and undesired side slip and yaw oscillations. Simulation results show that robustness from the vehicle dynamics variation and disturbances was achieved by using the developed time delay control. We evaluated the side slip and yaw damping compensation capability for the rapid steering at the high velocity of the vehicle in the cases of three control methods.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.42 no.12
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• pp.997-1003
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• 2014

This paper describes modeling process to obtain precise landing gear model which is necessary to design a control law for ground auto-taxi, auto take-off/landing of UAV. In this paper, landing gear side force modeling is studied to complete a landing gear model of UAV. Side force modeling is performed by calculating cornering angle including steering angle. And ground directional controller is designed by using nose wheel steering and rudder steering at the same time to control course angle error. Accuracy of landing gear side force modeling and ground directional controller is proved by comparing of auto-taxi test results with simulation results.

• Aerospace Engineering and Technology
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• v.6 no.1
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• pp.19-28
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• 2007

In this study, a nonlinear 2 degree of freedom mathematical model has been developed for impact analysis of the nose landing gear of a light aircraft which is composed of an wheel & tire, an Oleo-pneumatic shock strut and the castering wheel fork for the differential braking steering, and then the response of impact is computed using a numerical method. The mathematical model of a nose landing gear contains nonlinear characteristics which are an impact load - deflection property of a tire and internally frictional forces between an inner surface of an upper cylinder and a bearing of a lower rod due to side forces like the declined angle of strut, the moment due to an wheel fork, the side drag due to a steering and it is computed using the 4th-order Runge-Kutta method. The comparison process between analytical results and experimental results of the other proven nose landing gear is carried out to verify the mathematical model.

• 제어로봇시스템학회:학술대회논문집
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• 2003.10a
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• pp.1706-1709
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• 2003

This paper demonstrates a unique method for measuring vehicle states such as body sideslip angle and tire sideslip angle using Global Positioning System(GPS) velocity information in conjunction with other sensors. A method for integrating Inertial Navigation System (INS) sensors with GPS measurements to provide higher update rate estimates of the vehicle states is presented, and the method can be used to estimate the tire cornering stiffness. The experimental results for the GPS velocity-based sideslip angle measurement. From the experimental results, it can be concluded that the proposed method has an advantage for future implementation in a vehicle safety system.

• Proceedings of the IEEK Conference
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• 2001.06d
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• pp.93-96
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• 2001

In this paper, we present a vision algorithm and method for input image improvement and preprocessing of dented and raised characters on the sidewall of tires. we define optical condition between reflect coefficient and reflectance by the physical vector calculate. On the contrary this work will recognize the engraved characters using the computer vision technique. Tire input images have all most same grey levels between the characters and backgrounds. The reflectance is little from a tire surface. therefore, it's very difficult segment the characters from the background. Moreover, one side of the character string is raised and the other is dented. So, the captured images are varied with the angle of camera and illumination. For optimum input images, the angle between camera and illumination was found out to be with in 90。 .In addition, We used complex filtering with low-pass and high-pass band filters to improve input images, for clear input images. Finally we define equation reflect coefficient and reflectance. By doing this, we obtained good images of tires for pattern recognition.

• Transactions of the Korean Society of Automotive Engineers
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• v.19 no.3
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• pp.113-121
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• 2011

Rollover accident is one of the serious traffic accident and rollover accident takes high portion of all accident. The most common type of rollover is a tripped rollover which occupy 95% of all type of single-vehicle rollover. Tripped rollover occurs when a vehicle leaves normal road way and tripped by loose gravel, soil of fixed object such as guard rail, curbs and ditches. And the rest of the type of rollover is un-tripped rollover. An un-tripped rollovers that occurs during high-speed collision avoidance maneuvers. In this paper, presents the explanation of the un-tripped rollover test method and procedure, additionally this paper deals with various occurrence in the un-tripped test such as occurring excessive tire camber in the un-tripped test, tire side-wall contact with road surface and roll oscillation. And this paper analyzes the analysis of the roll rate amplitude in specific frequency through the FFT (Fast Fourier Transform) and the roll angle at the steering reverse timing which is the Fishhook test roll rate feedback time. Finally, this paper analyzes the relations between the estimated steady state roll gain and rollover stability.

• Journal of Institute of Control, Robotics and Systems
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• v.17 no.4
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• pp.313-320
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• 2011

Multi-axle driving vehicles that are used in special environments require high driving performance, steering performance, and stability. Among these vehicles, 6WS/6WD vehicles with middle wheels have structural safety by distributing the load and reducing the pitch angle during rapid acceleration and braking. 6WS/6WD vehicles are favored for military use in off road operations because of their high maneuverability and mobility on extreme terrains and obstacles. 6WD vehicles that using in-wheel motor can generate the independent wheel torque without other mechanical parts. Conventional vehicles, however, cannot generate an opposite driving force at each side wheel. Using an independent steering and driving system, six-wheel vehicles can show better performance than conventional vehicles. Using of independent steering and driving system, the 6 wheel vehicle can improve a performance better than conventional vehicle. This vehicle enhances the maneuverability under low speed and the stability at high speed. This paper describes an independent 6WS/6WD vehicle, consists of three parts; Vehicle Model, Control Algorithm for 6WS/6WD and Simulation. First, vehicle model is application of TruckSim software for 6WS and 6WD. Second, control algorithm describes the optimum tire force distribution method in view of energy saving. Last is simulation and verification.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.27 no.5
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• pp.666-672
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• 2003

This paper presents a design of the controller for vehicle lateral dynamics using active yaw moment. Vehicle lateral motion is incorporated with directional controllability and stability. These are conflicting each other from the view of vehicle handling performance. To compromise the trade-off between these two aspects, we suggest a new control algorithm based on the sliding mode with time-varying switching surface according to the body side slip angle. The controller can deal with the nonlinear region in vehicle driving condition and be robust to the parameter uncertainties in the plant model. Control performance is evaluated from the simulation for the vehicle of real parameters on the road with various tire-road frictions.