Fault Diagnosis of Exhaust Gas Recirculation and Variable Geometry Turbocharger Systems in a Passenger Car Diesel Engine Based on a Sliding Mode Observer for Air System States Estimation

Author(s):  
Hyunjun Lee ◽  
Joonhee Lee ◽  
Myoungho Sunwoo

In this paper, we propose a sliding mode observer based fault diagnosis algorithm for diesel engines with exhaust gas recirculation (EGR) and variable geometry turbocharger (VGT) systems. The nonlinear sliding mode observer is proposed for precise states estimation of air system in diesel engines. Based on the estimation results of the observer and the limited sensor information in mass-produced engines, a residual generation model is derived. A modified cumulative summation algorithm is applied to the residual generation model for robust fault detection and isolation of the EGR and VGT systems. The proposed observer based fault diagnosis algorithm is implemented on a real-time embedded system, and the bypass function of an engine management system (EMS) is applied to generate multiple types of fault conditions in the systems. As a result of this study, estimation performance of the proposed observer is validated and successful fault diagnosis of the EGR and VGT systems is demonstrated through engine experiments.

1999 ◽  
Author(s):  
I. Kolmanovsky ◽  
M. van Nieuwstadt ◽  
P. Moraal

Abstract This paper presents results on the optimal transient control of diesel engines with exhaust gas recirculation (EGR) and a variable geometry turbocharger (VGT). The implications of these results for feedback controller design axe discussed.


Author(s):  
Hyunjun Lee ◽  
Manbae Han ◽  
Jeongwon Sohn ◽  
Myoungho Sunwoo

This paper presents a novel method to estimate an exhaust pressure at 357 different steady-state engine operating conditions using a diesel particulate filter (DPF) mass flow model to precisely control the air quantity for a light-duty diesel engine operated with dual-loop exhaust gas recirculation (EGR) and variable geometry turbocharger (VGT) systems. This model was implemented on a 32 bit real-time embedded system and evaluated through a processor-in-the-loop-simulation (PILS) at two transient engine operating conditions. And the proposed model was validated in a vehicle. By applying Darcy's law, the DPF mass flow model was developed and shows a root mean square error (RMSE) of 3.7 g/s in the wide range of the DPF mass flow and above 99% linear correlation with actual values. With such reasonable uncertainties of the DPF mass flow model, the exhaust pressure was estimated via the application of a nonlinear coordinate transformation to the VGT model. The DPF mass flow based exhaust pressure estimation exhibits below 6% error of the exhaust pressure under steady-state conditions. The method was also validated through the PILS and the vehicle test under transient conditions. The results show a reasonable accuracy within 10% error of the exhaust pressure.


Author(s):  
Yeongseop Park ◽  
Inseok Park ◽  
Joowon Lee ◽  
Kyunghan Min ◽  
Myoungho Sunwoo

This paper investigates the design of model-based feedforward compensators for exhaust gas recirculation (EGR) and variable geometry turbocharger (VGT) systems using air path models for a common-rail direct injection (CRDI) diesel engine to cope with the nonlinear control problem. The model-based feedforward compensators generate set-positions of the EGR valve and the VGT vane to track the desired mass air flow (MAF) and manifold absolute pressure (MAP) with consideration of the current engine operating conditions. In the best case, the rising time to reach 90% of the MAF set-point was reduced by 69.8% compared with the look-up table based feedforward compensators.


2018 ◽  
Vol 21 (8) ◽  
pp. 1298-1313 ◽  
Author(s):  
Li Cheng ◽  
Pavlos Dimitriou ◽  
William Wang ◽  
Jun Peng ◽  
Abdel Aitouche

Variable geometry turbocharger and exhaust gas recirculation valves are widely installed on diesel engines to allow optimized control of intake air mass flow and exhaust gas recirculation ratio. The positions of variable geometry turbocharger vanes and exhaust gas recirculation valve are predominantly regulated by dual-loop proportional–integral–derivative controllers to achieve predefined set-points of intake air pressure and exhaust gas recirculation mass flow. The set-points are determined by extensive mapping of the intake air pressure and exhaust gas recirculation mass flow against various engine speeds and loads concerning engine performance and emissions. However, due to the inherent nonlinearities of diesel engines and the strong interferences between variable geometry turbocharger and exhaust gas recirculation, an extensive map of gains for the P, I, and D terms of the proportional–integral–derivative controllers is required to achieve desired control performance. The present simulation study proposes a novel fuzzy logic control scheme to determine appropriate positions of variable geometry turbocharger vanes and exhaust gas recirculation valve in real-time. Once determined, the actual positions of the vanes and valve are regulated by two local proportional–integral–derivative controllers. The fuzzy logic control rules are derived based on an understanding of the interactions among the variable geometry turbocharger, exhaust gas recirculation, and diesel engine. The results obtained from an experimentally validated one-dimensional transient diesel engine model showed that the proposed fuzzy logic control scheme is capable of efficiently optimizing variable geometry turbocharger and exhaust gas recirculation positions under transient engine operating conditions in real-time. Compared to the baseline proportional–integral–derivative controllers approach, both engine’s efficiency and total turbo efficiency have been improved by the proposed fuzzy logic control scheme while NOx and soot emissions have been significantly reduced by 34% and 82%, respectively.


Author(s):  
Seungwoo Hong ◽  
Inseok Park ◽  
Jaewook Shin ◽  
Myoungho Sunwoo

This paper presents a simplified decoupler-based multivariable controller with a gain scheduling strategy in order to deal with strong nonlinearities and cross-coupled characteristics for exhaust gas recirculation (EGR) and variable geometry turbocharger (VGT) systems in diesel engines. A feedback controller is designed with the gain scheduling strategy, which updates control gains according to engine operating conditions. The gain scheduling strategy is implemented by using a proposed scheduling variable derived from indirect measurements of the EGR mass flow, such as the pressure ratio of the intake, exhaust manifolds, and the exhaust air-to-fuel ratio. The scheduling variable is utilized to estimate static gains of the EGR and VGT systems; it has a large dispersion in various engine operating conditions. Based on the estimated static gains of the plant, the Skogestad internal model control (SIMC) method determines appropriate control gains. The dynamic decoupler is designed to deal with the cross-coupled effects of the EGR and VGT systems by applying a simplified decoupler design method. The simplified decoupler is beneficial for compensating for the dynamics difference between two control loops of the EGR and VGT systems, for example, slow VGT dynamics and fast EGR dynamics. The proposed control algorithm is evaluated through engine experiments. Step test results of set points reveal that root-mean-square (RMS) error of the gain-scheduled feedback controller is reduced by 47% as compared to those of the fixed gain controller. Furthermore, the designed simplified decoupler decreased the tracking error under transients by 14–66% in various engine operating conditions.


Author(s):  
Kwangseok Oh ◽  
Kyongsu Yi

This paper describes a longitudinal model based probabilistic fault diagnosis algorithm of autonomous vehicles using sliding mode observer. Autonomous vehicles use various sensors such as radar, lidar, and camera to obtain environment information. And internal sensors such as wheel speed, acceleration, and steering angle sensors have been used in vehicle to measure vehicle dynamic states. Based on the measured environment and vehicle states information, autonomous vehicle decides how to drive and control steering, throttle, and brake. Therefore, fault diagnosis of sensors used in autonomous vehicles is the most important for safe driving. In order to diagnosis longitudinal acceleration sensor fault of autonomous vehicle, longitudinal kinematic model has been used. The relative acceleration has been reconstructed using sliding mode observer based on environment information such as relative displacement and velocity between preceding vehicle and subject vehicle. The reconstructed relative acceleration has been used to compute longitudinal acceleration probabilistically based on analyzed longitudinal vehicle’s acceleration. The computed acceleration has been compared with measured acceleration for fault diagnosis of the acceleration sensor. The probabilistic fault diagnosis algorithm has been proposed and evaluated using actual data with arbitrary fault signal. The evaluation results of the proposed fault diagnosis algorithm show the reasonable fault diagnosis performance.


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