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나재원(Jaewon Nah),김원균(Wongun Kim),이경수(Kyongsu Yi),이종석(Jongseok Lee) 한국자동차공학회 2009 한국자동차공학회 학술대회 및 전시회 Vol.2009 No.11
It is very important for autonomous vehicles to have an ability of detecting and tolerating a fault of each sensor or actuator by itself, because it drives not by a driver’s decision, but by its sensors and actuator. Thus in this paper, a fail-safe control algorithm that an autonomous vehicle can detect and treat with a fault is suggested. It consists of sensors fail-safe algorithm and actuators fail-safe algorithm, which is essential to autonomous driving. The essential sensors are a steering wheel angle sensor, a lateral acceleration sensor, a yaw-rate sensor, and wheel speed sensors. The essential actuators are a motor driven steering actuator, a throttle actuator, brake actuators and a gear-shift actuator. To detect a fault, yaw-rate redundant models, an open loop estimator, a disturbance observer and a longitudinal acceleration model are required. The strategy to tolerate a sensor fault is changing the sensor signal to an estimation and the strategy to tolerate an actuator fault is stopping the vehicle at once.
슬라이딩 모드 예견 제어 기법을 적용한 V2V 기반 능동 롤 제어
나재원(Jaewon Nah) 제어로봇시스템학회 2020 제어·로봇·시스템학회 논문지 Vol.26 No.2
Due to advances in the technology of mild hybrid and x-by-wire systems, the performance of active-roll control systems has recently improved. Also, the vehicle-to-vehicle (V2V) communication technology can be applied to chassis control systems. In this research, the active roll control algorithm was designed using the sliding mode preview control method based on V2V communication. The augmented state variable for the sliding surface contained future disturbances that are lateral acceleration signals given by the preceding vehicle via V2V communication. To compare this method with the proposed control algorithm, an LQ optimal preview control was designed. In addition, a sliding mode control algorithm without preview was designed for comparative verification. To assess the influence of the proposed controller, the Elk test driving simulation was performed. Based on the simulations, we demonstrated that the proposed control method is more effective for roll stability compared to the LQ optimal preview control. Otherwise, the sliding mode control without preview was similarly as effective as the proposed method because of its feed-forward control.
나재원(Jaewon Nah),김원균(Wongun Kim),이경수(Kyongsu Yi) 대한기계학회 2010 대한기계학회 춘추학술대회 Vol.2010 No.11
Actuators and sensors fault diagnosis is very important in autonomous vehicle system. In this research, fault diagnosis algorithm for yaw-rate sensor, lateral acceleration sensor, steering wheel angle sensor, steer-by-wire, throttle-by-wire, and brake-by-wire of an autonomous driving vehicle is designed. Vehicle sensors and steer system fault diagnosis algorithm consists of yaw-rate residuals which are differences between yaw-rate sensor signal and estimations. Thresholds of residuals are based on the actual vehicle actuator dynamics. Throttle system fault diagnosis algorithm and brake system fault diagnosis algorithm consist of longitudinal acceleration residual which is difference between longitudinal acceleration sensor and desired acceleration. Vehicle acceleration sensor and yaw-rate sensor signals are estimated by Kalman filter. Acceleration estimation of both throttle system fault diagnosis algorithm and brake system fault diagnosis algorithm consider the angle of inclination which can be estimated by difference between longitudinal acceleration and wheel acceleration. In order to verify this algorithm, Hardware-in-the-loop simulation is executed.
6륜 인휠 구동 차량의 야지 주행시 차량 속도 추정 알고리즘
나재원(Jaewon Nah),이경수(Kyongsu Yi),김원균(Wongun Kim) 한국자동차공학회 2012 한국자동차공학회 학술대회 및 전시회 Vol.2012 No.11
In-wheel driving vehicles have no speed sensor and speed of in-wheel driving vehicles is difficult to be estimated especially in off-road driving condition because of tire-slip. In this paper, vehicle speed estimation algorithm for off-road driving of six-wheeled in-wheel driving vehicles is described. From calculation of average wheel speed and acceleration of each wheel, the wheel speed value which is regarded as in severe slip circumstance is filtered and vehicle acceleration information is used for compensation. Speed estimation quality of the proposed vehicle speed estimation algorithm was investigated via computer simulation study with off-road profile given by TruckSim.
나재원(Jaewon Nah),이경수(Kyongsu Yi),이종석(Jongseok Lee),김종배(Jongbae Kim) 대한기계학회 2013 대한기계학회 춘추학술대회 Vol.2013 No.12
This paper describes development of fault tolerant driving control algorithm to deal with failures of the wheel components of skid-steered robot vehicles. The proposed fault tolerant driving control algorithm is based on control allocation method, which can decide torque command of each wheel satisfying desired net force and yaw moment. The strategy of the proposed fault tolerant driving control is to make the command to the faulty wheel zero, while those to the others are redistributed. The fault tolerant driving performance of a faulty skid-steered robot vehicle was investigated via computer simulations. Simulation studies show that the proposed fault tolerant driving control algorithm can significantly improve the vehicle maneuverability, as compared to the driving control without fault tolerant driving strategy
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.
F1 서킷 실차시험 데이터 기반 가진 재현 시험을 통한 감쇠력 특성 분석
김현일(Hyunil Kim),진병옥(Byungok Jin),김기환(Gihwan Kim),나재원(Jaewon Nah),이혜민(Hyemin Lee),이태희(Taehee Lee) 한국자동차공학회 2017 한국자동차공학회 부문종합 학술대회 Vol.2017 No.5
In this study, we developed a damper test method of damper test rig which can reproduce actual vehicle driving test based on vehicle driving data in Korea International Circuit(KIC). Damper displacement data of the test vehicle were measured by potentiometer. The damper test method was developed by adjusting the gain value of the damper test rig to coincide the actual measured damper displacement data of the vehicle with the damper displacement data in the damper test rig. Finally, we analyzed the results before and after the damper test developed in this study to compare damping characteristics.