Active coolant control strategies in automotive engines

The coolant flow rate in conventional cooling systems in automotive engines is subject to the mechanical water pump speed, and high efficiency in terms of fuel economy and exhaust emission is not possible given this limitation. A new technology must be developed for engine cooling systems. The electronic water pump is used as a substitute for the mechanical water pump in new engine cooling systems. The new cooling system provides more flexible control of the coolant flow rate and engine temperature, which previously relied strongly on engine driving conditions such as load and speed. In this study, the feasibility of two new cooling strategies was investigated using a simulation model that was validated with temperatures measured in a diesel engine. Results revealed that active coolant control using an electronic water pump and valves substantially contributed to a reduction of coolant warm-up time during cold engine starts. Harmful emissions and fuel consumption are expected to decrease as a result of a reduction in warm-up time.     

Effects of mixture stratification on HCCI combustion of DME in a rapid compression and expansion machine

Compression ignition of homogeneous charges in internal combustion (IC) engines is expected to offer high efficiency of DI diesel engines without high levels of NOx and particulate emissions. This study is intended to find ways of extending the rich limit of HCCI operation, one of the problems yet to be overcome. Exhaust emissions characteristics are also explored through analyses of the combustion products. DME fuel, either mixed with air before induction or directly injected into the combustion chamber of a rapid compression and expansion machine, is compressed to ignite under various conditions of compression ratio, equivalence ratio, and injection timing. The characteristics of the resulting combustion and exhaust emissions are discussed in terms of the rate of heat release computed from the measured pressure, and the concentrations of THC, CO, and NOx are measured by FT-IR and CLD. The experimental data to date show that operation without knock is possible with mixtures of higher equivalence ratio when DME is directly injected rather than when it is inducted in the form of a perfectly homogeneous fuel-air mixture. Although fuel injected early in the compression stroke promotes homogeneity of the DME-air mixture in the cylinder, it causes the mixture to ignite too early to secure good thermal efficiency and knock-free operation at high loads. Low temperature reactions occur at about 660K regardless of the fueling methods, fuel injection timing and equivalence ratio. The main components of hydrocarbon emissions turned out to be unburned fuel (DME), formaldehyde and methane.     

Effects of valve timing and intake flow motion control on combustion and time-resolved HC & NOx formation characteristics

In SI engines, valve events have a major influence on volumetric efficiency, fuel economy and exhaust emissions. Moreover, swirl and tumble motions in the intake charge also improve combustion speed and quality by stratifying the mixture as well as intensifying the mixing rate of air and fuel. This paper investigates the behaviors of an engine and the combustion phenomenon for various intake valve timings and intake charge motions using CVVT system and port masking schemes. Test condition includes a part load and a cold idle condition inclusive of a cold start of the engine. Time-resolved HC and NOx emissions were also measured at an exhaust port to examine their formation mechanisms and behaviors with fast response HC/NOx analyzers. In conclusion, the fast burning of fuel and improved combustion quality by enhanced charge motions reduced unburned HC emissions, and advancing the intake valve opening reduced HC as well as NOx. Furthermore, HCs during the cold transient phase and idle conditions decreased with recalibrated start parameters such as lean air-fuel ratio and spark retardation via the enhancement of intake charge motions.     

Power control strategy for preventing thermal failure of passively cooled automotive battery packs

Safety mechanism is required for an automotive battery pack to prevent thermal failure which could lead to catastrophic events. Passively cooled battery packs can prevent thermal failure by conducting adaptive control of battery power without any external cooling device. The key to this power control is how to secure battery safety while minimizing energy loss. This paper proposes a novel, adaptive power control strategy for automotive passive-cooling battery packs. Four different cases with electrochemical battery model are simulated and compared to each other according to a city driving profile. Driving simulation result confirmed that the present power control algorithm is an effective solution for preventing thermal failure along with improving energy efficiency of automotive battery packs.     

MPC-BASED steering control for backward-driving vehicle using stereo vision

We propose a steering control algorithm for autonomous backward driving in a narrow corridor. Passable spaces are detected using a stereo camera, and the steering angle is controlled by a model predictive controller (MPC). For passable space detection, an UV-disparity map is calculated from the original disparity map. Information regarding passable spaces collected by the stereo camera is used in steering control. Backward driving requires the driver’s preemptive actions, which can be learned by experience because of the non-intuitive responses (the initial motion of the vehicle is opposite to the driver’s steering angle input). This occurs because a backward-driving vehicle is a non-minimum phase system. One of the most popular steering control algorithms is Stanley method, which is based on the feedback of lateral displacement error and heading angle error. The method is very intuitive and works well for forward driving, but it exhibits significant undershoot for backward driving cases. Furthermore, the method does not explicitly consider any constraints on control inputs and states. We designed a steering controller based on the MPC technique that requires future information but can handle constraints explicitly. Because we have near-future information from the stereo camera under limited passable spaces, MPC can be effectively implemented. We performed several simulations and experiments to show the performance and superiority of the suggested method over a simple feedback-based control algorithm.     

Analysis of vehicle fuel efficiency and survival patterns for the prediction of total energy consumption from ground transportation in Korea

In this study, correlation between vehicle fuel efficiency and total fuel energy consumption is analyzed to support the energy consumption and greenhouse gas (GHG) emissions reduction master plan in Korea. The background and highlights of recently amended fuel economy regulations and fuel efficiency labeling standards in Korea are also introduced. 18 representative vehicle groups, classified by class, type, size, and fuel, are selected by investigating vehicle distribution statistics based on market penetration and registration data sets in order to reflect and predict total fuel energy consumption in the overall ground transportation sector in Korea. Validity of the vehicle survival patterns modeled and vehicle classification rules are confirmed by comparing national fuel energy consumption statistics to the total amount of fuel consumed by each selected representative vehicle group. The latter figures are approximated from representative number of registrations, weighted average fuel economy, and average annual distance traveled.     

Characterization of driving patterns and development of a driving cycle in a military area

This study develops a gradient-sensitive driving cycle for vehicles in military areas with paved and unpaved roads over steep and undulating terrain. The methodology develops the driving cycle using micro-trips extracted from real-world data taking into account factors that affect fuel consumption. The accuracy of cycle depended on the root mean square error and information value.     

Dynamic sensor zeroing algorithm of 6D IMU mounted on ground vehicles

The main focus of this paper is to compensate the steady state offset error of the 6D IMU which provides the measurements that include the vehicle linear accelerations and angular rates of all three axes. Additionally, the sensor compensation algorithm exploits the wheel speed data and the steering angle information, since they are already available in most of the modern mass production vehicles. These inputs are combined with the inverse vehicle kinematics to estimate the steady state offset error of each sensor inputs as it is done in a disturbance observer, and the raw sensor measurements are compensated by the estimated offset errors. The stability of the error dynamics regarding the integrated signal processing system is verified, and finally, the performance of the system is tested via experiments based on a real production SUV.     

An ERP approach for container terminal operating systems

The major characteristics of ERP (Enterprise Resource Planning) are an enterprise-wide system that covers all the business functions and information resources, integrated database, built-in best industry practice, packaged software and open architecture. ERP enables reduction of system development time, flexibility, standardization of workflow and effective business planning capability. ERP is mainly for the manufacturing industry. However, the principles of ERP can also be applied to container terminal operating systems. This paper presents an ERP system approach for a container terminal. It has clustered the workflow of a container terminal and analysed the business process to generate the best workflows. The integrated database is designed to eliminate redundancy and keep integration. The core of ERP for container terminal is the planning facility such as berth planning and yard planning. The planning capability is very tightly coupled with data flow from client entities such as shipping companies. The ERP can handle the existing problems of container terminal operation that are mainly caused by lack of integration of a whole information resource in a container terminal, ad-hoc and poor planning capability, disconnected and incorrect data from client companies. The ERP approach can not only resolve the problems of container terminals but also promote adoption of information systems for container terminals in the world that have not yet implemented terminal operating systems.     

Development of pictograms for dynamic traffic control systems in South Korea

This study developed a set of pictograms for lane control systems, to provide additional information to drivers on weather and traffic incidents. The results suggest that in the design of traffic signs, it is important to consider local context and not simply adopt standards and practices that are developed elsewhere. The differences in the social and cultural environments may affect the ease of reading and comprehension by local drivers. However, the study also showed that not all locally developed signs were rated higher for their ease of reading than others… Since some design characteristics are more salient, whereas others tend to be more dependent on the local context, it is important to conduct simple experiments and exploratory research to find the optimal designs to be used.