Kwangjin Han

Collision detection system design using a multi-layer laser scanner for collision mitigation

Collision detection plays a key role in collision mitigation systems. The malfunction of a collision mitigation system can result in a dangerous or unexpected situation for the driver and passengers. In order to prevent this situation, reliable collision detection algorithms are essential in terms of the collision time, the overlap and the collision decision. This study focuses on the reliable determination of the time to collision and the frontal overlap between the ego vehicle and the objects. The path prediction method using information on the ego vehicle is proposed to improve the accuracies of the time to collision and the frontal overlap calculations. The proposed algorithm is developed on the basis of a multi-layer laser scanner. The procedure of collision detection includes three steps. The first step is to select a high-risk object among multiple objects, the second step is to judge the time to collision and the frontal overlap to the high-risk object and, finally, the third step is to decide whether a crash is imminent or not. The performance of the proposed detection algorithm is validated in simulations and experiments.

Modeling and control of an electronic wedge brake

The electronic wedge brake is one of the brake-by-wire systems with a self-energizing effect. It is attractive because it can produce enough braking torque with the 12-voltage system. However, the electronic wedge brake cannot be implemented unless the self-energizing effect is effectively controlled. In this study, the electronic wedge brake is modeled into dynamic equations, and a sliding mode controller is designed based on the model. The clamping force is estimated based on the simplified electronic wedge brake model and the contact point detection algorithm is also provided. The performance of the proposed controller is verified in simulations and experiments using a prototype electronic wedge brake.

Model-based sensor fault detection algorithm design for Electro-Mechanical Brake

EMB (Electro-Mechanical Brake) can be applied to the intelligent vehicles because brake-by-wire units are lighter in weights and have faster response compared to conventional hydraulic brake units. For the implementation of the EMB systems, reliable and robust fault detection and diagnosis methods become increasingly important. In this study, a sensor fault diagnosis method is proposed with parity space and observer approach to detect faults in motor current sensor, speed (or position) sensor and clamping force sensor. The proposed method is verified through the closed loop simulation using Matlab/Simulink and the simulation result is compared with HILS bench test results.

Development of a Frontal Collision Detection Algorithm Using Laser Scanners

Collision detection plays a key role in collision mitigation system. The malfunction of the collision mitigation system can result in another dangerous situation or unexpected feeling to driver and passenger. To prevent this situation, the collision time, offset, and collision decision should be determined from the appropriate collision detection algorithm. This study focuses on a method to determine the time to collision (TTC) and frontal offset (FO) between the ego vehicle and the target object. The path prediction method using the ego vehicle information is proposed to improve the accuracy of TTC and FO. The path prediction method utilizes the ego vehicle motion data for better prediction performance. The proposed algorithm is developed based on laser scanner. The performance of the proposed detection algorithm is validated in simulations and experiments.

Modeling and Controller Design of the Electronic Wedge Brake

The electronic wedge brake is one of the brake-by-wire systems with a self-energizing effect. The electronic wedge brake has faster response than the conventional hydraulic brake and requires only about one-tenth the power to operate. However, the electronic wedge brake cannot be implemented unless the self-energizing effect is reliably controlled. The self-energizing mechanisms may result in unintentional lock up and are very sensitive to environment and parametric variations of the friction coefficient. In this study, the electronic wedge brake is modeled into dynamic equations, and a sliding mode controller is designed based on the model. The performance of the proposed controller is verified in simulations.

Real-Time Vehicle Mass Estimator for Active Rollover Prevention Systems

최근 소형 트럭이나 SUV(Sport Utility Vehicle) 차 량이 증가함에 따라 전복으로 인한 차량 사고를 줄이기 위하여, 최근 ESC(Electronic Stability Control)와 같은 ARP(Active Rollover Prevention) 제 어기가 상용화되고 있다. 이러한 제어기의 제어 성능은 차량의 관성 파라미터, 특히 차량의 질량 과 무게 중심의 높이에 민감하다. 이러한 차량 의 관성 파라미터는 승객의 인원수나 탑재된 하중 의 무게나 위치에 따라 달라진다. 특히, SUV 차량 은 지붕에 자전거나 보트 등의 무거운 짐을 탑재 하는 경우가 많기 때문에 제어기를 설계할 때, 이 러한 각각의 상황에 따라 변화하는 제어기가 고려 되어야 한다. 그러나 OEM 에서 제어기를 최악의 상황에 맞추어 안전도를 고려한 내용으로 설계하 고 있으며, 이런 경우 운전자의 의지가 급격한 또 는 불안정한 운동을 야기하는 경우에 제어기 작동 시 안정성은 확보된다고 할 수 있다. 하지만 때로 는 차량이 안정함에도 불필요한 개입을 통해 핸들 링감을 저하하는 원인으로 볼 수 있으며 설계 기 법은 종종 ESC 제어기에서의 차량의 핸들링 성능 을 현저하게 떨어뜨리는 원인이 되고 있다. 이러 한 문제점을 개선하기 위한 하나의 대책은 ARP 제어기에서 차량의 관성 파라미터에 대한 정확한 정보를 이용하는 것이다.

Design of Hardware Architecture and Control Algorithm for the Electronic Wedge Brake

Brake-by-wire (BBW) systems can be used for enhanced safety braking of intelligent vehicles and also for environmentally friendly vehicles such as hybrid electric vehicles (HEVs) and electric vehicles (EVs). The electronic wedge brake (EWB) is one of the brake-by-wire systems with a self-energizing effect. The EWB is faster than the conventional hydraulic brake and requires only about one-tenth the power to operate. However, the EWB can be unstable unless controlled properly since the self-energizing effect can unintentionally lock up the vehicle’s wheels. In addition, the self-energizing effect is very sensitive to environment and parametric variances, e.g. friction, temperature, speed, load, etc. In this paper, two control algorithms for the EWB are introduced and compared each other in performance. The performance of the proposed control algorithms is verified in simulations.Copyright

Sensor Fault Diagnosis of Electro-Mechanical Brake System

The brake-by-wire units such as EMB (Electro-Mechanical Brake) will be applied to the intelligent vehicles because the brake-by-wire units are lighter in weights and have faster response compared to conventional hydraulic brake units. However, the brake-by-wire units such as EMB should be at least as reliable as the conventional hydraulic brake units. Because there are no mechanical links between the brake pedal and brake-by-wire actuators, FDI (Fault detection and isolation) is essential in implementing EMB units. In this study, a model-based fault diagnosis system is developed for monitoring the brake status utilizing the analytical redundancy method. The performance of the proposed model-based fault diagnosis system is verified in simulations in various faulty cases.Copyright