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박희람(Heeram Park),최세범(Seibum Choi),김주곤(Joogon Kim),김명준(Myoungjune Kim) 한국자동차공학회 2009 한국자동차공학회 학술대회 및 전시회 Vol.2009 No.11
Simens VDO, German electronic and mechatronic developer announced an innovative braking device called Electronic Wedge Brake (EWB). It uses self-energizing effect, so it is the most energy-effective braking device among Brakeby-Wire systems which is compatible with existing 12 Volts system. A new type of EWB which is called Electronic Noncircular Gear Brake was developed by S. Kim and S. Choi. This brake system has the possibility applying variable wedge angle to system by using noncircular gears. But, as the brake also uses self energizing effect, it is very sensitive to parametric variance. For this reason adaptive controller was developed by Y. Hwang and S. Kim. In this research, the performance of previous adaptive controller is discussed. Based on the previous work, a modified adaption algorithm is proposed and verified by numerical simulation.
Choi, Mooryong,Choi, Seibum B SAGE Publications 2016 Proceedings of the Institution of Mechanical Engin Vol.230 No.4
<P>This paper presents a control architecture that simultaneously utilizes active front steering (AFS) and differential braking for vehicle lateral stability while minimizing longitudinal perturbations. This control scheme is based on the model predictive control (MPC) using the extended bicycle model that captures the lagged characteristics of tire forces and actuators. The nonlinearities of tire force are also reflected on the extended bicycle model by linearizing the tire forces at the operating points. Instead of casting the MPC problem into a quadratic program with constraints that require numerical solvers, the proposed method is designed to follow the reference states with desired inputs since the solutions of MPC problems with affine models to track desired states can be easily obtained by matrix inversion. Simulation results, obtained by the vehicle dynamics software Carsim, demonstrate that the suggested method is able to control the vehicle to track the desired path while keeping the vehicle lateral stability on various road surfaces.</P>
Dynamic driveline torque estimation during whole gear shift for an automatic transmission
Choi, Hyunseok,Hwang, Jaewoong,Choi, Seibum Elsevier 2018 Mechanism and machine theory Vol.130 No.-
<P><B>Abstract</B></P> <P>This study proposes a novel method for estimation of driveline torque of wet type AT (Automatic transmission). The previous methods of torque estimation in the clutch-to-clutch shift mechanism is mainly applicable to the single gear shift. Thus, they require specific definitions of each gear shift and signal processing corresponding to the multi-gear shift. This study distinctly develops driveline torque estimator based on the whole transmission model, which is capable in applying on any conditional gear shift. This paper, also, incomparably investigates brake/clutch model including centrifugal force, describing physical behavior of real parts. In addition, the development of the method includes adaptive brake and clutch torque estimator in order to compensate variation factor during the shift. The estimation performance of the proposed estimator is evaluated both in simulations and experiments. The results demonstrate that the proposed methods can estimate the driveline torques effectively during the whole gear shift and well describes the typical clutch-to-clutch phenomena such as inter-locking.</P> <P><B>Highlights</B></P> <P> <UL> <LI> A whole gear shift model without signal processing for a vehicle with an AT is developed with practical aspects. </LI> <LI> Wet typed brake and clutch are modeled describing physical behavior of real parts. </LI> <LI> A torque estimator with adaptation is designed to estimate torque through both brakes or clutches and the output shaft in an AT. </LI> <LI> The effectiveness of the developed torque estimator is demonstrated by simulations and experiments. </LI> <LI> The proposed methods well describe the typical clutch-to-clutch phenomena such as inter-locking. </LI> </UL> </P>
Mooryong Choi,Oh, Jiwon J.,Choi, Seibum B. IEEE 2013 IEEE TRANSACTIONS ON VEHICULAR TECHNOLOGY Vol.62 No.7
<P>The tire-road friction coefficient is critical information for conventional vehicle safety control systems. Most previous studies on tire-road friction estimation have only considered either longitudinal or lateral vehicle dynamics, which tends to cause significant underestimation of the actual tire-road friction coefficient. In this paper, the parameters, including the tire-road friction coefficient, of the combined longitudinal and lateral brushed tire model are identified by linearized recursive least squares (LRLS) methods, which efficiently utilize measurements related to both vehicle lateral and longitudinal dynamics in real time. The simulation study indicates that by using the estimated vehicle states and the tire forces of the four wheels, the suggested algorithm not only quickly identifies the tire-road friction coefficient with great accuracy and robustness before tires reach their frictional limits but successfully estimates the two different tire-road friction coefficients of the two sides of a vehicle on a split- μ surface as well. The developed algorithm was verified through vehicle dynamics software Carsim and MATLAB/Simulink.</P>
Model Predictive Control for Vehicle Yaw Stability With Practical Concerns
Mooryong Choi,Choi, Seibum B. IEEE 2014 IEEE Transactions on Vehicular Technology VT Vol.63 No.8
<P>This paper presents a method for electronic stability control (ESC) based on model predictive control (MPC) using the bicycle model with lagged tire force to reflect the lagged characteristics of lateral tire forces on the prediction model of the MPC problem for better description of the vehicle behavior. To avoid the computational burden in finding the optimal solution of the MPC problem using the constrained optimal control theory, the desired states and inputs as references are generated since the solution of the MPC problem can be easily obtained in a closed form without using numeric solvers using these reference values. The suggested method controls the vehicle to follow the generated reference values to maintain the vehicle yaw stability while the vehicle turns as the driver intended. The superiority of the proposed method is verified through comparisons with an ESC method based on ordinary MPC in the simulation environments on both high- and low- μ surfaces using the vehicle dynamics software CarSim.</P>