• Transactions of the Korean Society of Automotive Engineers
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• v.25 no.2
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• pp.167-178
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• 2017

The steering wheel of a vehicle has a typical characteristic of automatically returning to its neutral state when the driver releases it. Steering returnability originated from the tire forces and kingpin moments. It is proportional to the reaction torque that is generated through the rack and column, which are dependent on suspension and steering geometry. It is also important to accurately predict and design it because steering returnability is related to steering performance. In this study, a detailed multibody dynamics model of a vehicle was designed by using ADAMS/Car and simulated for steering returnability. In addition, a tolerance analysis of the chassis system in terms of part dimension and properties has been performed in order to minimize the design parameters. The sensitivity of the selected design parameters was then analyzed via Design of Experiments(DOE). As a result, we were able to obtain the main parameters through a contribution analysis. It can be used to predict steering returnability and improve its performance, which is represented by the angle of restoration and laterality.

• International Journal of Automotive Technology
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• v.5 no.2
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• pp.69-76
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• 2004

This paper evaluates the effectiveness of four-wheel-steering system from the viewpoint of lane-keeping control theory. In this paper, the lane-keeping control system is designed on the basis of the four-wheel-steering automobiles whose desired steering response is realized with the application of model matching control. Two types of desired steering responses are presented in this paper. One is zero-sideslip response, the other one is steering response which realizes zero-phase-delay of lateral acceleration. Using simplified linear two degree-of-freedom bicycle model, simulation study and theoretical analysis are conducted to evaluate the lane-keeping control performance of active four-wheel-steering automobiles which have different desired steering responses. Finally, the evaluation is conducted on straight and curved roadway tracking maneuvers.

• Korean Journal of Computational Design and Engineering
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• v.19 no.4
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• pp.332-339
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• 2014

This paper presents on the development of wheel-terrain interaction device using low-priced sensors, which will be used to predict the drawbar pull and optimal slip of off-road vehicle in real time. The essential variables obtained in the device to predict the mobility of vehicles are determined based on semi-empirical model describing the wheel-terrain interaction. Using the developed device, the experiments about the wheel-terrain interaction were performed on the soil of the Jumunjin standard sand, which yielded dynamic weight, motor driving torque, drawbar pull, and sinkage with respect to wheel slip ratio. Finally, the repeatability of the measured data are verified through repeating the experiments three times on the same condition.

• International Journal of Automotive Technology
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• v.6 no.6
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• pp.599-604
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• 2005

A functional suspension model is proposed as a kinematic describing function of the suspension, that represents the relative wheel displacement in polynomial form in terms of the vertical displacement of the wheel center and steering rack displacement. The relative velocity and acceleration of the wheel is represented in terms of first and second derivatives of the kinematic describing function. The system equations of motion for the full vehicle dynamic model are systematically derived by using velocity transformation method of multi-body dynamics. The comparison of test and simulation results demonstrates the validity of the proposed functional suspension modeling method. The model is computationally very efficient to achieve real-time simulation on TMS 320C6711 150 MHz DSP board of HILS (hardware-in-the-loop simulation) system for ECU (electronic control unit) evaluation of semi-active suspension.

• Journal of the Korean Society for Precision Engineering
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• v.29 no.7
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• pp.745-752
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• 2012

The pivot steering of an individual wheel motor drive vehicle is an effective steering maneuver in the narrow road, but it has become a matter of concern that the torque input of each wheel is very difficult to determine. In this study, the independent yaw moment control was proposed for the smooth pivot steering control of an in-wheel drive vehicle. For this control method, the vertical forces of tires were estimated from the trailing arm dynamic model, and the yaw moments of individual wheels were calculated from the vehicle dynamic model. Dynamic simulation results showed that the independent yaw moment control was much more effective on the minimization of the instabilities of pivot steering in comparison with the conventional direct yaw moment control with yaw rate feedback.

• Korean Journal of Computational Design and Engineering
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• v.3 no.1
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• pp.40-47
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• 1998

Recently, the various driving simulator have been used widely to analyze the handling performance of vehicle and to verify the motion control algorithm of vehicle. In this study, a virtual driving simulator based on the 20-DOF vehicle model is realized to estimate the handling performance and stability of a 4WS (Four-wheel-steering) and/or 4n(Four-wheel-driving) vehicle. Especially the DC motor controlled 4WS actuator is modelled in order to reflect the effect of the responsiveness of actuator on the handling performance and stability. And the realized simulator can be applied to develope a real time simulation system for designing and testing the real vehicles.

• Journal of the Korean Society for Railway
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• v.6 no.4
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• pp.257-264
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• 2003

In electric motor coaches, the rolling stocks move by the adhesive effort between rail and driving wheel. Generally, the adhesive effort is defined by the function of both the weight of electric motor coach and the adhesive effort between rails and driving wheel. The characteristics of adhesive effort is strongly affected by the conditions between rails and driving wheel. When the adhesive effort decreases suddenly, the electric motor coach has slip phenomena. This paper proposes a re-adhesion control algorithm which uses the maximum adhesive effort by instantaneous estimation of adhesion force using load torque disturbance observer. Based on this estimated adhesive effort, the re-adhesion control is performed to obtain the maximum transfer of the tractive effort.

• Journal of Institute of Control, Robotics and Systems
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• v.16 no.4
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• pp.353-360
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• 2010

A skid-steering method which applied to the various mobile robot platforms currently shows its effectiveness in the specified field areas and purposes. This system contains however, several problems of its intrinsic properties such as slippages occurred by different moving direction between vehicle's driving and wheel's rotary and difficulties of driving performance control and so on. This paper deals with the suggestion of suitable control algorithm for 6WD/6WS skid steering wheeled vehicle and verified its feasibility by analyzing the behavior of 6WD/6WS skid-steered wheeled vehicle model and by applying the engineering analytical method to the considered mobile platform. The Performance of vehicle model is evaluated by using slip mode control to follow the steering input and, as a future work, this control algorithm could be applied to real 6WD/6WS in-wheel drive type vehicle finally.

• Transactions of The Korea Fluid Power Systems Society
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• v.5 no.4
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• pp.1-9
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• 2008

In this paper, an energy regeneration algorithm is proposed to make the maximum use of the regenerative braking energy for a parallel hybrid electric vehicle(HEV) equipped with a continuous variable transmission(CVT). The regenerative algorithm is developed by considering the battery state of charge(SOC), vehicle velocity and motor capacity. The hydraulic module consists of a reducing valve and a power unit to supply the front wheel brake pressure according to the control algorithm. In order to evaluate the performance of the regenerative braking algorithm and the hydraulic module, a hardware-in-the-loop simulation (HILS) is performed. In the HILS system, the brake system consists of four wheel brakes and the hydraulic module. Dynamic characteristics of the HEV are simulated using an HEV simulator. In the HEV simulator, each element of the HEV powertrain such as internal combustion engine, motor, battery and CVT is modelled using MATLAB/$Simulink^{(R)}$. In the HILS, a driver operates the brake pedal with his or her foot while the vehicle speed is displayed on the monitor in real time. It is found from the HILS that the regenerative braking algorithm and the hydraulic module suggested in this paper provide a satisfactory braking performance in tracking the driving schedule and maintaining the battery state of charge.

• Proceedings of the KIEE Conference
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• 1998.11b
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• pp.448-450
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• 1998

Global competition of automotive market and affordable prices of electronic components become the major reason that automotive industries rapidly employ a large number of electric and electronic systems to improve vehicle performance and to meet various regulations such as emission, fuel efficiency, and safety. Especially, the provision of a motor-driven steering column (MDSC) for luxury vehicle is getting popular for drivers' convenience. In this study, an MDSC is developed, which provides several intelligent features such as the manual operation for tilting and telescoping the steering wheel, and the save/recall operation for three different steering wheel positions. In addition, the fault detection algorithm is developed.