• Proceedings of the Korean Society for Agricultural Machinery Conference
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• 2017.04a
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• pp.19-19
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• 2017

자율주행 트랙터를 위한 트랙터 조향제어는 일반적으로 전자모터를 이용한 EPS(Electric Power Steering) 시스템을 스티어링 휠에 연결하여 회전변위를 변경하고 그 결과 오비트롤(Orbitrol) 밸브의 토출유량을 바꾸고 호스로 연결된 조향실린더의 변위를 조절하여 최종적으로 전방 타이어의 방향각을 변경하면서 이루어진다. 이러한 조향방식은 시스템 구조상 조향실린더와 오비트롤 밸브가 상대적으로 멀리 떨어져 있으며, 밸브 특성상 약 ${\pm}5^{\circ}$의 오버랩이 포함되어 있다. 또한, EPS의 전자모터는 관성력, 마찰, 백래시 등의 영향을 가진다. 이와 같은 복합적인 영향은 조향 응답을 느리게 만들어 상대적으로 빠른 속도에서 주행에서 추종성능이 떨어지는 문제가 발생한다. 본 연구에서는 자율주행 트랙터의 조향성능 개선 연구의 일환으로 조향 HILS 시뮬레이터를 설계제작하여 조향 성능의 요인을 실험적으로 구명하고자 하였으며 이를 바탕으로 조향 시스템의 설계개선 방안을 수립하고자 하였다. 시뮬레이터는 동양물산 80 마력급 TX803 트랙터에 사용되는 오픈센터방식의 오비트롤 유압회로 시스템을 기어펌프가 장착된 AC모터로 구동되게 구성하였으며, 유량은 모터의 주파수를 조절 회전속도를 조절 변경하였다. 추가적으로 EPS와 오비트롤 조합의 조향성능을 비교 및 개선하기 위해 비례제어밸브(PVG 32, Danfoss)를 추가 장착하였다. 실제 트랙터 조향 시 나타나는 마찰저항을 모사하기 위해 부하 실린더를 구성하였으며, 조향 실린더의 부하의 크기는 부하 실린더를 폐회로를 구성하고 유량비례제어밸브를 이용한 유로의 개구량 조절을 통해 부하의 크기를 약 4000 N 까지 증가시킬 수 있도록 하였다. EPS와 비례제어밸브를 제어하기 위해 CANoe 8.0 소프트웨어를 이용하여 CAN통신 기반 가상 조향ECU를 구성하였으며 오비트롤의 기본 성능을 확인하기 위해 조향휠에 따른 실린더 동특성 및 계단 추종성능을 비례제어밸브와 비교하였다. 오비트롤 밸브는 약 ${\pm}5^{\circ}$이상 동작 시 실린더 압력이 상승하기 시작하였으며, 이후 약 ${\pm}10^{\circ}$이상 동작 시 조향실린더가 동작하기 시작하였다. 계단 추종성능실험에서는 비례제어밸브가 약 2배 이상의 응답개선을 나타냈다. 자율주행 경로추종 성능을 향상시키기 위해서는 순간적인 출력밀도가 높은 비례제어밸브를 통해 응답개선이 필요한 것으로 나타났다.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.20 no.6
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• pp.86-94
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• 2019

This paper describes the development of unmanned vehicle remote control system which is configured with steering and accelerating/braking hardware to improve the sense of reality and safety of control. Generally, in these case of the remote control system, a joystick-type device is used for steering and accelerating/braking control of unmanned vehicle in most cases. Other systems have been developing using simple steering wheel, but there is no function of that feedback the feeling of driving situation to users and it mostly doesn't include the accelerating/braking control hardware. The technology of feedback means that a reproducing the feeling of current driving situation through steering and accelerating/braking hardware when driving a vehicle in person. In addition to studying feedback technologies that reduce unfamiliarity in remote control of unmanned vehicles, it is necessary to develop the remote control system with hardware that can improve sense of reality. Therefore, in this study, the reliable remote control system is developed and required system specification is defined for applying force-feedback haptic control technology developed through previous research. The system consists of a steering-wheel module similar to a normal vehicle and an accelerating/braking pedal module with actuators to operate by feedback commands. In addition, the software environment configured by CAN communication to send feedback commands to each modules. To verify the reliability of the remote control system, the force-feedback haptic control algorithms developed through previous research were applied, to assess the behavior of the algorithms in each situation.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.41 no.5
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• pp.367-374
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• 2017

The goal of this study was to develop control algorithms to improve the steering performance of a 120-ton all-terrain crane. To accomplish this, a hydraulic steering system for the crane was modeled using AMESim software, and a PID steering control algorithm was designed in the MATLAB/Simulink environment. The performance of the designed controller was verified through multiphysics co-simulations based on a real-time simulator.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.14 no.2
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• pp.111-118
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• 2003

Notch Antenna is a travelling wave type antenna and can provide multioctave operation in phased arrays that scan over wide angle. In this paper, we designed a wideband E-plane phased array antenna using E-plane waveguide simulator which has a bandwidth of 3 : 1 and a scan volume of $\pm$45$^{\circ}$ in E-plane. We compared impedance of single antenna and infinite array antenna using equivalent circuit modeling. We analyzed full structure of 1$\times$9 phased array antenna and we evaluated active reflection coefficient with variation of beam scan angle through mutual coupling coefficient acquired from simulation and investigated the variation of antenna gain with variation of active element pattern as beam scan angle is varied.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.25 no.6
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• pp.923-929
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• 2001

Steering system is most important for vehicle in safety and driving feel. However, testing using real car to improve steering feel is often difficult in aspect to repeatability, safety and money. Repeatability in testing steering system is very important because steering feel for driver is variable according to the environment condition. And steering testing of vehicle is so dangerous that driver may not concentrate in testing. In this paper, the steering system simulator using front part of steering and suspension system was developed. We can test the electric power steering system for the light weight vehicle using this simulator cheap, safely and repeatably.

• 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.

• Proceedings of the Korean Society for Agricultural Machinery Conference
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• v.10 no.2
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• pp.64-67
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• 2005

• The Journal of the Korea institute of electronic communication sciences
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• v.15 no.3
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• pp.533-542
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• 2020

In this study, we developed a PC - based motorcycle simulator based on the development technology of the virtual patrol motorcycle training system. In order to get the impression that the motorcycle simulator is operating in a realistic way, it is important to have a reliable signal transmission and operation feeling between the driver and the simulator. In order to achieve this, we developed a system that can apply the sub-systems of the actual vehicle to the motorcycle simulator in order to generate the same operation feeling as the actual vehicle. Based on these results, We have developed a method for generating a feedback queue. Vehicle dynamics simulates real-time vehicle motion by receiving input from a steering wheel, accelerating / decelerating pedal, etc. operated by a driver on a vehicle simulator and transmitting the result to a visual and acoustic system, It is the central element of the simulator to generate. I want to summarize the main requirements of simulation dynamics.

• 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.24 no.9 s.180
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• pp.2228-2234
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• 2000

Steering of the vehicles on a slippery highway is a difficult task for most passenger car drivers. The steering vehicles on slippery roads tend to slide outward with less lateral forces than on nor mal roads. When the drivers notice that their vehicles on a slippery highway start to depart from the cornering lane, most of them make a sudden steering and/or braking, which in turn may induce spin-out and instability on their vehicles. In this paper, an active steering control method is proposed such that the vehicles in slippery roads are steered as if they are driven on the normal roads. In the proposed method, the estimated lateral forces acting on the steering tires are compared with the reference values and the difference is compensated by the active steering method. A fuzzy logic controller is designed for this purpose and evaluated on a steering Hardware-In-the-Loop Simulation (HILS) system. Steering performance results on the slippery curved and sinus roads demonstrate the effectiveness of the proposed controller. This method can be realized with the steer-by-wire concept and is promising as an active safety technology.