Seung-Han You

Vehicle lateral stability management using gain-scheduled robust control

This paper deals with the design of a yaw rate controller based on gain-scheduled H∞ optimal control, which is intended to maintain the lateral stability of a vehicle. Uncertain factors such as vehicle mass and cornering stiffness in the vehicle yaw rate dynamics naturally call for the robustness of the feedback controller and thus H∞, optimization technique is applied to synthesize a controller with guaranteed robust stability and performance against the model uncertainty. In the implementation stage, the feed-forward yaw moment by driver’s steer input is estimated by the disturbance observer in order to determine the accurate compensatory moment. Finally, HILS results indicate that the proposed yaw rate controller can satisfactorily improve the lateral stability of an automobile.

Fault diagnostics in the differential brake control system using the analytical redundancy technique

This paper presents a novel analytical redundancy technique for fault diagnostics of a differential brake control system. The proposed diagnostic algorithm builds upon open loop and closed loop state estimators to generate residuals and identify failures. By judiciously utilizing the residual information, it is possible to detect faults at the component level rather than at the system level. In addition, robust and adaptive estimators are shown to effectively combat with two perennial nuisances of fault diagnostic algorithms: sensitivity to disturbance and false alarms. Hardware-in-the-loop simulation studies show how reliably the proposed diagnostic algorithm detects faults in the differential brake control system that is expected to play a crucial role in active vehicle safety.

OPTIMAL INTEGRATION OF ACTIVE 4 WHEEL STEERING AND DIRECT YAW MOMENT CONTROL

Abstract We investigate an optimal integrated control of the vehicle equipped with active steering system and independent braking system. The proposed controller uses DYC(Direct Yaw moment Control) and active 4 wheel steering simultaneously to improve the handling and stability of vehicle. A model following robust controller that specifies the required yaw moment and total lateral force is designed through LMI(Linear Matrix Inequality) formulation. To generate the target steer angles and reference brake pressures in each 4 wheel, the control allocation method is synthesized via QP(Quadratic programming). Simulation results show that the proposed integrated controller enhances the stability and handling of vehicle effectively in several driving maneuvers.

Virtual Brake Pressure Sensor Using Vehicle Yaw Rate Feedback

최근 자동차 업계는 안전 기술 측면에서는 차량 사고 피해를 최소화 하고자 하는 수동적 안전 개념에서 벗어나, 사고 자체를 회피하고자 하는 능동적 안전 개념으로 진화하고 있으며, 동시에 최Key Words: Yaw Moment Control(요모멘트제어), Virtual Sensor(가상센서), Empirical Modeling(경험적모델링), Optimal Observer(최적관측기), Robust Observer(견실관측기), Adaptive Observer(적응관측기) 초록: 본 연구에서는 좌/우 편제동을 통해 차량의 요 모션을 제어하는 제동 기반 요모멘트 제어 시스템에서의 가상 제동 압력 센서를 개발하였다. 제동 압력을 추정하기 위해 유압시스템을 경험적 방법으로 모델링하였고 이를 기반으로 요레이트 피드백 제동 압력 관측기를 설계하였다. 차량 요레이트 동역학에 존재하는 외란의 영향을 최소화 하기 위해 외란 적응 기법, 외란 축소 기법 및 최적 이득 기법을 관측기 설계에 적용하였고 그 방법들 간의 성능 비교 및 검증을 HILS 를 통해 수행하였다. 그 결과 외란 축소 방식의 견실 관측기의 압력 추정 성능이 일반적인 Luenberger 관측기 대비 가장 우수하였으며 그 원인에 대해 분석하였다. Abstract: This paper presents observer-based virtual sensors for YMC(Yaw Moment Control) systems by differential braking. A high-fidelity empirical model of the hydraulic unit in YMC system was developed for a model-based observer design. Optimal, adaptive, and robust observers were then developed and their estimation accuracy and robustness against model uncertainty were investigated via HILS tests. The HILS results indicate that the proposed disturbance attenuation approach indeed exhibits more satisfactory pressure estimation performance than the other approach with admissible degradation against the predefined model disturbance.

A Fault Diagnostics Algorithm for Differential Brake Control System

Abstract This paper presents a novel analytical redundancy technique for fault diagnostics of a differential brake control system. The proposed diagnostic algorithm builds upon an adaptive observer to generate residuals and identify faults. By judiciously utilizing the residual information, it is possible to detect faults at the component level rather than the system level. In addition, the adaptive observer is shown to effectively combat with the perennial nuisances of fault diagnostic algorithms, sensitivity to disturbance and false alarms. Hardware-in-the-loop simulation results show how reliably the proposed diagnostic algorithm detects faults in the differential brake control system, which is expected to play a crucial role in active vehicle safety.