• Transactions of the Korean Society of Mechanical Engineers A
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• v.38 no.5
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• pp.551-557
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• 2014

This paper presents a robust lateral controller for autonomous guidance of a farm tractor in field operations. Although mechanical steering actuators have recently been used for passenger vehicles, the steering actuator of the farm tractor is based on a hydraulic system, resulting in limited bandwidth and a larger time delay. Based on a kinematic tractor model with steering actuator dynamics, a nonlinear control technique called dynamic surface control is applied to design a robust lateral controller that compensates for uncertainty owing to steering actuator and road geometry. Finally, tracking performance and robustness of the proposed controller are validated via commercial tractor simulations, with respect to the time delay of the steering actuator and road geometry (e.g., up and down hills), on a given field with a constant friction coefficient.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.38 no.11
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• pp.1291-1297
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• 2014

This paper proposes integrated chassis control (ICC) with electronic stability control (ESC) and active rear steering (ARS). Direct yaw moment control is used to generate a control yaw moment. A weighted pseudo-inverse-based control allocation (WPCA) method is adopted to distribute the control yaw moment into tire forces, generated by ESC and ARS. Simulation-based tuning of variables weights in the WPCA is used to enhance the yaw moment distribution performance. Simulations using the vehicle simulation software $CarSim^{(R)}$ show that the proposed ICC is effective in improving maneuverability and lateral stability.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.38 no.2
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• pp.180-187
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• 2010

In this paper, a GNSS-based AGV system was designed, and steering tested on a golf cart using electric wires in order to confirm the control efficiency of the low speed vehicle which used only position information of GNSS. After analyzed the existing AGVs system, we developed controller and steering algorithm using GNSS based position information. To analyze the performance of the developed controller and steering algorithm, straight-type and circle-type trajectory test are executed. The results show that steering performance of GNSS-based AGV system is ${\pm}\;0.2m$ for a reference trajectory.

• 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.

• Journal of the KSME
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• v.32 no.10
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• pp.847-857
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• 1992

일반적으로 자동차의 샤시(chassis)라 하면 총체적인 개념에서 자동차로부터 차체(body)를 제외한 부분을 일컫는데, 구동 및 제동장치, 바퀴 현가장치, 조향장치, 타이어 및 휠 등이 이에 속한다. 1970년대 마이크로 컴퓨터의 응용기술이 도입되면서 엔진분야에서 시작한 자동차 전자화기술은 구동 및 제동분야에서의 전자제어식 제동잠김 및 구동 미끄럼방지 시스템(ABS/TCS)의 응용기 술을 거쳐 1980년 중반부터 차량의 현가 및 조향분야에서 능동형의 시스템이 개발되기 시작하 였다. 그 대표적인 예로서 자동차용 적응식 및 반 능동식 가변댐퍼(variable damper), 능동식 현가시스템(active suspension system) 그리고 4륜조향 시스템(four wheel steering system)을 들 수 있다. 1990년대에 들어서는 이러한 각종 능동형 시스템이 종합적으로 고려되어 설계되는 이 른바 자동차의 샤시 통합제어 시스템(chassis integrated control system)또는 능동형 샤시 시스템 (active chassis system)으로 발전되어 가고 있는 추세에 있다. 이 글에서는 최근에 가장 대표 적인 능동형 샤시시스템으로서 각종 능동식 현가시스템 및 4륜조향 시스템의 개발동향 및 기 술적, 경제적인 측면에서의 종합적인 검토를 하고자 한다.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.41 no.2
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• pp.41-51
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• 2004

In this paper, the beam steering dipole phased array antenna systems for IMT-2000 base station have been designed. The designed beam steering dipole phased array antenna systems are constituted by the antenna part and the beam steering control system part. The antenna part is designed by the proposed flat dipole for the broadband characteristics, and the 8${\times}$8 dipole array antenna is constructed by the proposed flat dipole for the directional radiation pattern. Besides the vertical power divider is designed for the vertical power distribution. The beam steering control system part is designed the horizontal power divider for the horizontal power distribution, the 4-bit phase shifters and the driving circuit of phase shifters for the horizontal beam tilting. In order to evaluate a performance of the designed antenna systems, they were fabricated and the radiation characteristics were measured. From the measured results, we found that the horizontal beams were tilted by the each control signals, and the measured radiation characteristics showed good agreement with the design goals.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.38 no.3
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• pp.315-321
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• 2014

This paper presents an integrated chassis control system with fail safety using optimum yaw moment distribution for a vehicle with steer-by-wire and brake-by-wire devices. The proposed system has two-level structure: upper- and lower-level controllers. In the upper-level controller, the control yaw moment is computed with sliding mode control theory. In the lower-level controller, the control yaw moment is distributed into the tire forces of active front steering(AFS) and electronic stability control(ESC) with the weighted pseudo-inverse based control allocation(WPCA) method. By setting the variable weights in WPCA, it is possible to take the sensor/actuator failure into account. In this framework, it is necessary to optimize the variables weights in order to enhance the yaw moment distribution. For this purpose, simulation-based tuning is proposed. To show the effectiveness of the proposed method, simulations are conducted on a vehicle simulation package, CarSim.

• Journal of the Korean Institute of Telematics and Electronics T
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• v.36T no.1
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• pp.58-63
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• 1999

In this paper, We present a direction indicator algorithm for a mobile robot which uses VFF and neural networks. The structure of this neural network navigation system is composed of sensor system, backpropagation learning controllers for adjusting weight and the motion control system for real-time execution. The experimental results show that the direction indicator system operates properlv and strongly at any circumstance

• Journal of the Korea Institute of Information and Communication Engineering
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• v.24 no.7
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• pp.834-841
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• 2020

Among the autonomous driving systems based on visual sensors, the control method using a vanishing point is the most general method for autonomous driving. However, if the lane is lost or does not exist, it is very difficult to detect this and estimate the vanishing point. In this paper, we predict the vanishing point of the road and the vanishing point lines on the left and right sides using CNN for the camera image and design the steering controller for autonomous driving from the predicted results. As a result of the simulation, it was confirmed that the proposed method well tracked the center of the road regardless of the presence or absence of a solid lane, and was superior to the control method using a general method using the vanishing point.

• Transactions of the Korean Society of Machine Tool Engineers
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• v.11 no.2
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• pp.50-58
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• 2002

The test method using simulator to objectively measure the steering feel from several drivers was proposed. It has also described the ideas to analyse the principal factors affecting the steering feel of the driver using the correlation analysis of the measured data and the questionnaire. Proportional Derivative(PD) controller has been used to measure the steering feel, and the control parameters have been selected to obtain the optimal steering feel. Membership frictions of Sugeno fuzzy model are constructed from the assist torque values calculated from PD controller at each steering state. Moreover to verify the performance, this fuzzy controller has been compared with the another fuzzy controller of which membership frictions are derived from the knowledge of drivers. As a result it can be concluded that the proposed fuzzy controller improves the steering feel at each steering state more than any other conventional methods.