• 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.

• Journal of the Korean Society for Precision Engineering
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• v.22 no.2
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• pp.172-179
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• 2005

A high-precision centerless grinding machine has been recognized as a core equipment performing the finish outer-diameter grinding process of ferrules which are widely used as fiber optic connectors. In this study, in order to realize the high-precision centerless grinding machine, the structural characteristic analysis and evaluation are carried out on the virtual prototype consisted of the steel bed, hydrostatic GW and RW spindle systems, hydrostatic RW feed mechanism, RW swivel mechanism, and on-machine GW and RW dressers. The loop stiffnesses of centerless grinding machine are estimated based on the relative deformations between GW and RW caused by the grinding forces. And the simulated results illustrate that the concrete-filled bed has the considerable effect on the improvement of the structural stiffness of centerless grinding machine.

• Journal of the Korea Institute of Military Science and Technology
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• v.11 no.4
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• pp.141-148
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• 2008

In this paper, we develop a detailed full dynamic model which includes various rough terrains for 6-wheel skid-steering mobile robot based on the real experimental autonomous vehicle called Dog-Horse Robot. We also design a co-simulation for performance comparison of path tracking algorithms. The control architecture in the co-simulation can be divided into two levels. The high level control is the closed-loop control of path tracking to follow a given path, and the low level is concerned about torque control of wheel motion. The simulation using the mechanical data of the Dog-Horse Robot is performed under the Matlab/Simulink environment. We also simulate and evaluate the performance of the model based adaptive controller.

• Journal of Magnetics
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• v.15 no.3
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• pp.128-131
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• 2010

In this paper, we propose a new design of the permanent magnet reluctance wheel which will make it possible to attach the robot to a vertical plane and move it. In the newly suggested design, a permanent magnet is utilized to enhance the adhesive force during attachment, and an electromagnet is produced to weaken the magnetic field of the permanent magnet and reduce the adhesive force for easier detachment of wheels from steel plates. To characterize the performance of this new wheel design, a 3-D finite element analysis is executed using a commercial FE program. The results show that the adhesive force is reduced effectively by the electromagnet which flows in the reverse direction of the magnetic loop of the permanent magnet when the current is supplied to the coil.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.24 no.12
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• pp.2883-2890
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• 2000

In this study, a Hardware-In-The-Loop-Simulation(HILS) system for developing a Electric-Power-Steering(EPS) system is designed. To test a EPS by HILS system, a mathematical vehicle model with a steering system model has been constructed. This mathematical model has been constructed. This mathematical model has been downloaded to the Digital-Signal-Processor(DSP) board. To realize the lateral force acting on the front wheel in a real car. the steering wheel angle sensor and vehicle velocity have been used for input signal. The force sensor has been used for a feedback signal. The full vehicle states could by simulated by the HILS system. Consequently, the HILS system could by used to analyze control-parameters of a EPS that contributes to the maneuverability and stability of a vehicle. At the same time, the HILS system can evaluate the whole performance of the vehicle-steering system. Also the HILS system could do test could not be executed in real vehicle. The HILs system will useful for developing the control logic for the EPS system.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.26 no.3D
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• pp.461-467
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• 2006

To detect individual vehicular speed, double loop detection technique has been widely used. This paper investigates four methodologies to measure individual speed using only a single loop sensor in a traveling lane. Two methods developed earlier include estimating the speed by means of (Case 1) the slop of inductance wave form generated by the sensor and (Case 2) the average vehicle lengths. Two other methods are newly developed through this study, which are estimations by measuring (Case 3) the mean of wheelbases using the sensor installed traversal to the traveling lane and (Case 4) the mean of wheel tracks by the sensor installed diagonally to the traveling lane. These four methodologies were field-tested and their accuracy of speed output was compared statistically. This study used Equality Coefficient and Mean Absolute Percentage Error for the assessment. It was found that the method (Case 1) was best accurate, followed by method (Case 4), (Case 2), and (Case 3).

• Transactions of the Korean Society of Automotive Engineers
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• v.4 no.4
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• pp.87-96
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• 1996

The proportional pressure control valve(PCV) is an essential component in the open loop controlled rear wheel steering gear of the four wheel steering(4WS) system on the passenger car. The valve should have versatile functions and higher performance. But, it is hard to find the proportional pressure control valve suitable for the 4WS system. In this paper, the determination of the valve parameters was studied by the stability discrimination and the characteristic analysis for the purpose of the development of a new PCV for the 4WS. The mathematical model of the valve was derived from the valve-cylinder system and the programme for numerical computation was developed. The transfer function of the system was obtained from the mathematical model. The characteristics of the valve were inspected through the experiment and compared to those obtained by numerical method. And then the stability discrimination of the system was done by root locus and the analysis of characteristics was done by the developed programme. From the experiment and the analysis of characteristics was done by the developed programme. From the experiment and the inspection, the appropriation of mathematical model and the usefulness of the programme were confirmed. And the parameters which might affect the performance of the valve can be determined by considering the stability discrimination, the characteristics analysis and required functions.

• Journal of Astronomy and Space Sciences
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• v.25 no.4
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• pp.347-360
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• 2008

In this paper, a Hardware-In-the-Loop simulator to simulate attitude control of space craft using momentum wheels is developed. The simulator consists of a spherical air bearing system allowing rotation and tilt in all three axes, three momentum wheels for actuation, and an AHRS (Attitude Heading Reference System). The simulator processes various types of data in PC104 and wirelessly communicates with a host PC using TCP/IP protocol. A simple low-cost momentum wheel assembly set and its drive electronics are also developed. Several experiments are performed to test the performance of the momentum wheels. For the control performance test of the simulator, a PID controller is implemented. The results of experimental demonstrations confirm the feasibility and validity of the Hardware-In-the-Loop simulator developed in the current study.

• International Journal of Automotive Technology
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• v.6 no.1
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• pp.37-44
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• 2005

The creation of automotive systems of active safety with intelligent functions needs the use of new control principles for the wheel and automobile. One of such directions is the pre-extreme control strategy. Its aim is the ensuring of wheel's work in pre-extreme, stable area of tire grip wheel slip dependence. The simplest realization of pre-extreme control in automotive anti-lock brake systems consists in the threshold and gradient algorithms. A comparative analysis of these algorithms, which has been made on 'hardware in-the-loop' simulation results of the braking for bus with various anti-lock brake systems (ABS), indicated their high efficiency.

• 제어로봇시스템학회:학술대회논문집
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• 2003.10a
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• pp.548-552
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• 2003

In the braking system, the friction force is the most important factor of the design. For long time, many researchers have been strived for getting the exact friction coefficients. But the friction coefficients are affected by the road condition and changed by lots of parameters, such as normal force and characteristics between two contacted materials, temperature, etc. For the development of ABS of the aircraft, HILS(Hardware-In-the-Loop-Simulation) test and dynamometer test was carried out. For the calculation of the friction coefficients, the wheel moments were measured using the load cell mounted on the housing of the wheel. The test conditions were dry and greasy, as the 0.7 and 0.4 in friction coefficient, respectively. In this paper, the test results of the friction coefficients were represented and the improvement method was suggested.