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Optimization of control allocation with ESC, AFS, ARS and TVD in integrated chassis control
나재원,임성진 대한기계학회 2019 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.33 No.6
This paper presents an optimization of control allocation in integrated chassis control with active front steering, active rear steering, electronic stability control and torque-vectoring device under the saturation of lateral tire forces on front wheels. After a control yaw moment is calculated in the upper-level controller, a weighted pseudo-inverse based control allocation is used for yaw moment generation in the lower-level controller. Variable coefficients of the weighted pseudo-inverse based control allocation are used to represent various actuator combinations and are optimized for each actuator combination to enhance control performances using simulation on vehicle simulation package, CarSim. Due to severe cornering on low friction road, the front lateral tire forces can be easily saturated. Under the condition, the active front steering has little effect on control performance and, consequently, the desired control yaw moment cannot be generated. So, the lateral force generated by AFS should be restricted to its maximum, and a constrained weighted pseudoinverse based control allocation with electronic stability control, active rear steering and torque-vectoring device is applied to compensate the loss of the control yaw moment. Variable coefficients of the constrained weighted pseudo-inverse based control allocation with electronic stability control, active rear steering and torque-vectoring device are also optimized using simulated-based tuning. To validate the proposed method, simulation was done on CarSim. From simulation, it was verified which actuator combination is effective for integrated chassis control if the lateral forces on front wheels are saturated.
최소 자승 평균을 적용한 통합 섀시 제어 시스템의 적응형 고장 안전 요 모멘트 제어 전략
나재원,임성진 대한기계학회 2019 大韓機械學會論文集A Vol.43 No.6
This paper presents an adaptive fail-safe yaw moment control for an integrated chassis control with active front steering and electronic stability control functions, controlled by X-by-wire systems. Owing to the nature of motordriven devices, sensor faults are inherent in steer-by-wire (SBW) and brake-by-wire (BBW) systems and can cause critical damage to vehicles. A simple direct yaw moment control is adopted to design a fail-safe integrated chassis control. To cope with sensor failure in SBW systems, an adaptive algorithm, the least mean squares method, is adopted in the procedure for yaw moment distribution. Simulations on a vehicle simulation software, CarSim, show that the proposed method is effective in case of sensor failures in SBW systems. 본 논문은 X-by-wire 시스템이 적용된 차량에 대해 능동 전륜 조향(AFS)과 자세 제어 장치(ESC)의 기능을 가지는 통합 섀시 제어 시스템에서 Steer-by-Wire의 센서 고장 상황에 대한 적응 제어 방법에 관한 것이다. 모터 등의 구동기로 작동되는 X-by-wire시스템에서 Brake-by-Wire(BBW)와 Steer-by-Wire(SBW)는 기계적 연결이 없으므로 고장 상황 발생 시 치명적인 결과를 초래한다. SBW의 센서 고장에 대한 고장 안전 제어를 위하여 요 모멘트 분배 제어기를 설계하였으며, 적응형 알고리즘인 최소 자승 평균(LMS)을 적용하여 고장 상황에 대비하였다. 차량동역학 시뮬레이션 프로그램인 CarSimÒ을 활용한 시뮬레이션을 통하여 SBW의 센서 고장에 대해 본 논문에서 제안한 고장 안전 제어 알고리즘의 성능을 검증하였다.
차량 안정성 제어를 위한 H-infinity 게인 스케쥴링 방법
나재원 제어·로봇·시스템학회 2019 제어·로봇·시스템학회 논문지 Vol.25 No.8
This paper presents a gain scheduling method of H-infinity optimal control for vehicle stability using active front steering(AFS) and electronic stability control (ESC). Two factors in vehicle stability that trade off with each other are drivability and lateralstability. Hence, weighting factors for the LQ cost function should be decided with consideration of the driver’s purpose. In this paper,three gain scheduling methods are proposed: use of the sideslip angle (β ) only, use of the β −β phase plane, and use of a simplemap. To assess the effectiveness of the proposed gain scheduling methods, a simulation study using CarSim was implemented. Itshowed that using H-infinity gain can generate a trade-off relationship for both drivability and lateral stability in terms of yaw-rateerror and side slip angle, respectively. Using the proposed methods, the study shows that the sideslip angle can be maintained in astable region while the yaw-rate error does not increase.
능동 롤 제어를 위한 피드포워드 제어기 설계에 관한 연구
나재원,임성진 제어·로봇·시스템학회 2019 제어·로봇·시스템학회 논문지 Vol.25 No.6
This article describes a design procedure of feedforward controller for active roll stabilization (ARS). To design a controller, a linear 1-DOF roll model is adopted. With the linear model, feedback controllers, i.e., linear quadratic regulator and sliding mode controller, are designed. In order to use the lateral acceleration for control, a feedforward term is derived from the discrete-time state-space equation. The designed controllers use the roll angle, the roll rate and the lateral acceleration. To estimate the roll angle and the lateral acceleration, a discrete-time Kalman filter is used. For verification of the effectiveness of the proposed control method, simulation has been performed via the vehicle simulation tool package, CarSim. From simulation, it has been verified that the proposed method can enhance the performance of active roll stabilization.
전륜 횡력 포화 시 요모멘트 보상을 위한 통합 섀시 제어
나재원,임성진 제어·로봇·시스템학회 2019 제어·로봇·시스템학회 논문지 Vol.25 No.1
In this paper, we present the integrated chassis control strategy with electronic stability control (ESC), active rear steering (ARS) and torque vectoring device (TVD) under the saturation of the lateral tire force on front wheels, caused by the excessive application of active front steering (AFS). The control yaw moment was calculated using sliding mode control. Contrary to the previously proposed method that uses the optimization-based method, the simple distribution method was adopted under the assumption that a single actuator of the chassis control system was used for yaw moment distribution. The lateral tire forces of front wheels were easily saturated by the excessive sole application of AFS. To cope with the situation, the corrective steering angle of AFS has been limited, and it compensated the loss of the control yaw moment with ESC, ARS and TVD in this paper. For verification of the effectiveness of the proposed control method, simulation has been performed via the vehicle simulation tool package, CarSim. From simulation, it has been verified that the proposed method can enhance maneuver performance and lateral stability if the lateral forces on front wheels are saturated.
6WD/6WS 차량의 스티어-바이-와이어 고장 진단 및 고장 안전 주행 제어
나재원(Jaewon Nah),김원균(Wongun Kim),이경수(Kyongsu Yi),이종석(Jongseok Lee) 대한기계학회 2011 대한기계학회 춘추학술대회 Vol.2011 No.10
Fault detection and tolerant is one of the most important issues in x-by-wire vehicle systems. This paper describes a fault tolerant driving strategy for dealing with independent steer-by-wire system failures in a 6WD/6WS vehicle. When a serious failure is detected in a certain steer-by-wire component, the proposed fault tolerant controller gives a redistributed traction control command to the other components. The proposed fault tolerant controller gives torque command to the faulty wheel component differently, while the other components compensate desired longitudinal and lateral behavior. Fault tolerant performance of a faulty 6WD/6WS vehicle has been evaluated by computer simulations. In order to clarify the advantage of the proposed fault tolerant driving control algorithm, recovery rate of the fault tolerant controller has been defined and calculated.