• International Journal of Automotive Technology
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• v.8 no.5
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• pp.629-636
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• 2007

This paper describes the process of analyzing vehicle stiffness in terms of frequency band in order to improve vehicle handling. Vehicle handling and ride comfort are highly related to the systems such as suspension, seat, steering, and the car body design. In existing analytical processes, the resonance frequency of a car body is designed to be greater than 25 Hz in order to increase the stiffness of the body against idle vibration. This paper introduces a method for using a band with a frequency lower than 20 Hz to analyze how stiffness affects vehicle handling. Accordingly, static stiffness analysis of a 1g cornering force was conducted to minimize the deformation of vehicle components derived from a load on parts attached to the suspension. In addition, this technology is capable of achieving better performance than older technology. Analysis of how body attachment stiffness affects the dynamic stiffness of a bushing in the attachment parts of the suspension is expected to lead to improvements with respect to vehicle handling and road noise. The process of developing a car body with a high degree of stiffness, which was accomplished in the preliminary stage of this study, confirms the possibility of improving the stability performance and of designing a lightweight prototype car. These improvements can reduce the time needed to develop better vehicles.

• Journal of Auto-vehicle Safety Association
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• v.13 no.1
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• pp.6-13
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• 2021

This paper presents yaw moment control for modification of steering characteristic in rear-driven vehicle with front in-wheel motors (IWMs). The proposed control algorithm is designed to modify yaw rate response of the test vehicle. General approach for modification of steering characteristic is to define the desired yaw rate and track the yaw rate. This yaw rate tracking method can cause the chattering problem because of the IWM actuator response. Large overshoot and settling time in IWM torque response can amplify the oscillation in control input and yaw rate. To resolve these problems, open-loop IWM controller for cornering agility was designed to modify the understeer gradient of the vehicle. The proposed algorithm has been investigated via the computer simulations and the vehicle tests. The performance evaluation has been conducted on dry asphalt using E-segment test vehicle. The performance of the proposed algorithm has been compared to general yaw rate tracking algorithm in the vehicle tests. It has been shown that the proposed control law improved the cornering agility without chattering problem.

• Proceedings of the KSME Conference
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• 2003.11a
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• pp.1394-1400
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• 2003

Tire subjected to inflation pressure and the load of passenger car has a important roll to dynamic performance characteristics of radial tires such as cornering and braking. These performance characteristics are directly related to the belt cord durability of tires. In this paper, we analyze the mechanism of belt cord broken due to cord tension at braking theoretically.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.28 no.8 s.227
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• pp.1125-1134
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• 2004

This paper presents a mathematical model which is about the dynamics of not only a two wheel steering vehicle but a four wheel steering vehicle. A sliding mode ABS control strategy and PID rear wheel control logic are developed to improve the brake and cornering performances, and enhance the stability during emergency maneuvers. The performances of the controllers are evaluated under the various driving road conditions and driving situations. The numerical study shows that the proposed full car model is sufficient to accurately predict the vehicle response. The proposed ABS controller reduces the stopping distance and increases the vehicle stability. The results also prove that the ABS controller can be employed to a four wheel steering vehicle and improves its performance. The four wheel steering vehicle with PID rear wheel controller shows increase of stability when a vehicle speed is high and sharp cornering maneuver when a vehicle speed is low compared to that of a two wheel steer vehicle.

• Korean Journal of Applied Biomechanics
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• v.23 no.2
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• pp.109-116
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• 2013

The purpose of this study was to provide fundamental information for the enhancement of performance through kinematic analysis of cornering according to the radius of curve course in short track speed skating. To perform this study, six skaters: three narrow radius players(N, body mass: $56.0{\pm}7.2$ kg, height: $163.7{\pm}5.1$ cm, age: $21.3{\pm}1.5$ yrs) and three wide radius players(W, body mass: $61.0{\pm}9.5$ kg, height: $169.0{\pm}4.4$ cm, age: $20.0{\pm}1.7$ yrs). Three-dimensional motion analysis was performed on the section from the forth block starting to show the change of radius to the sixth block using eight infrared cameras(sampling frequency of 100 Hz for N and W players). The time of push-off was greater for N than for W(p<.05) while the radius of center of mass was greater for W than for N(p<.05). The flexion and extension of knee and hip joint were greater for N than for W(p<.05). The external rotation of left knee joint was greater for N than for W(p<.05). Based on the findings, a small radius by increasing the range of the flexion and extension of knee and hip joint with greater external rotation of left knee joint would be related to more efficient run at curve. It is expected that these results will be useful in developing a training program for enhancing performance of short track speed skating athletes.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1996.11a
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• pp.277-282
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• 1996

An asymmetrical cross-coupled compensator to improve the contouring performance is proposed. This is a refinement of the structure suggested by Koren. The position loop is closed with a proportional controller as in the uncoupled system. An additional input term proportional to the component of the contour error along the corresponding axis Is included. The controller gains are chosen to give an appropriate frequency response and an optimum range for the damping ratio. The effectiveness of the proposed controller is studied by means of digital simulations of the dynamics of the drives and the controller for 3 types of command trajectories; straight line contour, cornering contour, circular contour. Substantial improvement in contouring performance is obtained for a range of contouring conditions.

• Journal of the Korean Society for Precision Engineering
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• v.14 no.8
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• pp.65-72
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• 1997

An asymmetrical cross-coupled compensator to improve the contouring performance is proposed. This is a refinement of the structure suggested by Koren. The position loop is closed with a proportional controller as in the uncoupled system. An additional input term proportional to the component of the contour error along the corresponding axis is included. The controller gains are chosen to give an appropriate frequency response and an optimum range for the damping ratio. The effectiveness of the proposed controller is studied by means of digital simulations of the dynamics of the drives and the controller for 4 types of command trajectories: straight line contour, cornering contour, circular contour, elliptic contour. Substantial improvement in contouring performance is obtained for a range of contouring conditions.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2022.06a
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• pp.31-32
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• 2022

In Early vessels did not provide an exact equation for preventig the capsizing vessels. On land, many vehicle rollover prevention technologies using the steady-state Conrning Equations were developed, which showed better performance than the exiting method at sea. For better performance, It is proposed to improve safety mangement when turning vessel using the Ackerman geometic model-based Cornering Equations in this paper.

• Journal of Mechanical Science and Technology
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• v.14 no.8
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• pp.807-815
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• 2000

In this paper, modified discrete time preview control algorithms for active and semi-active suspension systems are derived based on a simple mathematical 4 DOF half-car model. The discrete time preview control laws for ride comfort are employed in the simulation. The algorithms for MIMO system contain control strategies reacting against body forces that occur at cornering, accelerating, braking, or under payload, in addition to road disturbances. Matlab simulation results for the discrete time case are compared with those for the continuous time case and the appropriateness of the discrete time algorithms are verified by the of simulation results. Passive, active, and semi-active system responses to a sinusoidal input and an asphalt road input are analysed and evaluated. The simulation results show the extent of performance degradation due to numerical errors related to the length of the sampling time and time delay.

• International Journal of Automotive Technology
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• v.7 no.5
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• pp.547-554
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• 2006

This paper is concerned with an optimal control suspension system using the preview information of road input based on a quarter car model. The main purpose of the control is to combine good vibration isolation characteristics with improved attitude control. The optimal control law is derived with the use of calculus of variation, consisting of three parts. The first part is a full state feedback term that includes integral control acting on the suspension deflection to ensure zero steady-state deflection in response to static body forces and ramp road inputs. The second part is a feed-forward term which compensates for the body forces when they can be detected, and the third part depends on previewed road input. The performance of the suspension is evaluated in terms of frequency domain characteristics and time responses to ramp road input and cornering forces. The effects of each part of the suspension controller on the system behavior are examined.