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극한성능 향상을 위한 4WD, ESC, ECS 통합 샤시 제어
좌은혁(Eunhyek Joa),이경수(Kyongsu Yi),김길수(Kilsoo Kim) 대한기계학회 2015 대한기계학회 춘추학술대회 Vol.2015 No.11
This paper presents an integrated chassis control of 4WD(Four wheel drive), ESC(Electronic stability control), and ECS(Electronic controlled suspension) for limit handling. The proposed algorithm consists of three layers : 1) Supervisor, which determine target yaw rate and target velocity from steering wheel angle and acceleration pedal, respectively, 2) Upper level controller, which calculate generalized force to track target values in the manner of sliding mode control method, 3) Lower level controller, which optimally allocates generalized force to actuators. In this study, to achieve limit handling of vehicle, the novel cost function is proposed. The main concept of the cost function is kept the tire stable by monitoring tire saturation with slip information. The proposed algorithm is validated via Matlab/Carsim co-simulation. Compared to base and ESC/4WD module, the proposed algorithm shows stable performance at the limit. The results show that with ESC/4WD modules, the performance at the limit is enhanced, but the yaw rate is oscillated. ECS module can reduce yaw rate oscillation by allocating vertical force.
통합 샤시 제어를 위한 횡방향 안전성 판단 조건에 관한 연구
안국진,좌은혁,고영일,이경수,손기모,Ann, Kookjin,Joa, Eunhyek,Koh, Youngil,Yi, Kyongsu,Sohn, Kimo 한국자동차안전학회 2017 자동차안전학회지 Vol.9 No.2
This paper presents the lateral stability criteria for integrated chassis control. To determine the intervention timing of chassis control system, the lateral stability criteria is needed. The proposed lateral stability criteria is based on velocity-yawrate gain domain to determine whether vehicle is stable. If the yawrate gain violates the proposed criteria, the stability of the vehicle is considered as unstable. Characteristic velocity and critical velocity are employed to distinguish lateral stability criteria. The inside of the two boundaries is stable and the outside is unstable. If yawrate gain of vehicle violates the lateral stability criteria, the chassis control begin to intervene. To validate the lateral stability criteria, both computer simulations and vehicle test are conducted with respect to circular turn scenario. The proposed lateral stability criteria makes it possible to reduce intervention of chassis control system.
전륜 인휠모터 후륜구동 차량의 선회 특성 변형을 위한 요모멘트 제어
차현수,좌은혁,박관우,이경수,박재용 사단법인 한국자동차안전학회 2021 자동차안전학회지 Vol.13 No.1
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 cau se the chattering problem becau se 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.
횡풍하의 차량 외란 추정을 이용한 차선 유지 조향 보조 제어기 설계
임형호,좌은혁,이경수,Lim, Hyeongho,Joa, Eunhyek,Yi, Kyongsu 한국자동차안전학회 2020 자동차안전학회지 Vol.12 No.3
This paper presents steering controller for unintended lane departure avoidance under crosswind using vehicle lateral disturbance estimation. Vehicles exposed to crosswind are more likely to deviate from lane, which can lead to accidents. To prevent this, a lateral disturbance estimator and steering controller for compensating disturbance have been proposed. The disturbance affecting lateral motion of the vehicle is estimated using Kalman filter, which is on the basis of the 2-DOF bicycle model and Electric Power Steering (EPS) module. A sliding mode controller is designed to avoid unintended the lane departure using the estimated disturbance. The controller is based on the 2-DOF bicycle model and the vision-based error dynamic model. A torque controller is used to provide appropriate assist torque to driver. The performance of proposed estimator and controller is evaluated via computer simulation using Matlab/Simulink.
기동성을 위한 후륜 조향 차량의 최적 성능에 대한 연구
안국진,좌은혁,박관우,윤영식,이경수,Ann, Kookjin,Joa, Eunhyek,Park, Kwanwoo,Yoon, Youngsik,Yi, Kyongsu 한국자동차안전학회 2019 자동차안전학회지 Vol.11 No.2
This paper presents an optimal performance of rear wheel steering vehicle for maneuverability. The maneuverability of vehicle is evaluated in terms of yaw rate, body slip angle and driver input. The maneuverability of vehicle can be improved by rear wheel steering system. To obtain optimal performance of rear wheel steering vehicle, the optimal control history is designed. The high dimensional trajectory optimization problem is solved by formulating a quadratic program considering rear wheel steer input. To evaluate handling performance 7 degree-of-freedom vehicle model with actuation sub-models is designed. A step steer test is conducted to evaluate rear wheel steering vehicle. A response time, a TB factor, overshoot, and yaw rate gain are investigated through objective criteria, assessment webs. The handling performance of vehicle is evaluated via computer simulations. It has been shown from simulation studies that optimal controlled rear wheel steering vehicle provides improved performance compared to others.
위상 궤적을 이용한 정상상태 드리프트을 위한 제어기의 시각적 검증
차현수(Hyunsoo Cha),좌은혁(Eunhyek Joa),이경수(Kyongsu Yi) 대한기계학회 2018 대한기계학회 춘추학술대회 Vol.2018 No.12
This paper presents visual validation of drift controllers for steady-state cornering using phase portrait to show the stability of steady-state drifting of a rear wheel drive vehicle. Phase portraits are drawn to display the change in vehicle states based on the time derivative of states at each phase coordinate. Phase portraits of bicycle model without a controller show the existence and vehicle state of an unstable drift equilibrium point where the vehicle states are not sustained with the lapse of the time. With the activation of steering angle or front tire lateral force controller, phase portrait reveals the existence of a stable drift equilibrium point. Successful implementation of the controllers can be confirmed through the convergence of trajectories to the stable drift equilibria.