Development of a model of the dual clutch transmission in autonomie and validation with dynamometer test data

Owing to ever more stringent regulations and customers’ expectations, auto manufacturers have been considering numerous technology options to improve vehicle fuel economy. One of these is transmission technology, which has been shown to be one of the most cost-effective technologies. Over the past few years, transmissions have significantly evolved and have impacted both performance and fuel efficiency. As one of the advanced tranmissions, the dual clutch transmission (DCT) is the first automatic transmission to provide better efficiency than manual transmissions. DCTs provide reduced shift shocks and better driver comfort in addition to higher top speeds and torques. In this paper, a model and shifting controller for the DCT are developed in the vehicle systems context using Autonomie, a model-based vehicle simulation tool. Finally, the Autonomie DCT model and control strategy are validated using vehicle test data from Argonne’s Advanced Powertrain Research Facility.     

On-road chasing measurement of exhaust particle emissions from diesel,CNG, LPG,and DME-fueled vehicles using a mobile emission laboratory

We designed and applied a mobile emission laboratory for on-road measurements of exhaust particles emitted from conventional diesel, compressed natural gas (CNG), liquefied petroleum gas (LPG), and dimethyl ether (DME)-fueled vehicles. Fuel type and vehicle driving conditions significantly affected the particle size distribution and the number concentrations of the nucleation mode. For all buses, the size distributions of particles in the exhaust under idling conditions had larger mode diameters than at constant speed conditions of 50 km/h or 80 km/h. The nucleation mode (< 50 nm) fraction of diesel, CNG, LPG, and DME at a constant speed of 50 km/h was 53%, 63%, 79%, and 99%, respectively, indicating that the DME-fueled bus emitted the most nanoparticles. As the vehicle speed increased from 50 km/h to 80 km/h, the nucleation mode fraction of diesel, CNG, LPG, and DME changed to 43%, 99%, 99%, and 99%, representing a significant increase in the number concentrations of nanoparticles in the CNG and LPG-fueled vehicles. The particle size distributions in the exhaust of diesel, CNG, LPG, and DME-fueled vehicles were not affected by increase in the chasing distance.     

Viable combined cycle design for automotive applications

A relatively new approach for improving fuel economy and automotive engine performance involves the use of automotive combined cycle generation technologies. The combined cycle generation, a process widely used in existing power plants, has become a viable option for automotive applications due to advances in materials science, nanotechnology, and MEMS (Mico-Electro Mechanical Systems) devices. The waste heat generated from automotive engine exhaust and coolant is a feasible heat source for a combined cycle generation system, which is basically a Rankine cycle in the context of this study. However, there are still numerous technical issues that need to be solved before the technology can be implemented in automobiles. A simulation was performed to examine the amount of waste energy that could be recovered through the use of a combined cycle system. A simulation model of the Rankine cycle was developed using Cycle-Tempo software. The simulation model was ultimately used to evaluate the rate of waste heat recovery and the consequential increase in the overall thermal efficiency of the engine with the combined cycle generation system under typical engine operating conditions. The most effective automotive combined cycle system recovered 68% of the waste heat from the exhaust and coolant, resulting in a 6% improvement in engine efficiency. The results are expected to be beneficial for evaluating the feasibility of combined cycle generation systems in automotive applications.     

Modeling and control of an anti-lock brake and steering system for cooperative control on split-mu surfaces

The brake and steering systems in vehicles are the most effective actuators that directly affect the vehicle dynamics. In general, the brake system affects the longitudinal dynamics and the steering system affects the lateral dynamics; however, their effects are coupled when the vehicle is braking on a non-homogenous surface, such as a split-mu road. The yaw moment compensation of the steering control on a split-mu road is one of the basic functions of integrated or coordinated chassis control systems and has been demonstrated by several chassis suppliers. However, the disturbance yaw moment is generally compensated for using the yaw rate feedback or using wheel brake pressure measurement. Access to the wheel brake pressure through physical sensors is not cost effective; therefore, we modeled the hydraulic brake system to avoid using physical sensors and to estimate the brake pressure. The steering angle controller was designed to mitigate the non-symmetric braking force effect and to stabilize the yaw rate dynamics of the vehicle. An H-infinity design synthesis was used to take the system model and the estimation errors into account, and the designed controller was evaluated using vehicle tests.     

Analysis of a large injection-molded body using knowledge-based flow process technology

A knowledge-based flow process is presented for large injection-molded body technology (LIMBT). Injection molding of a large body is a difficult technique because of the many factors and their interactions during the molding process. The proposed flow process can support LIMBT through integration of CAE(Computer-Aided Engineering), CAI (Computer-Aided Inspection), and monitoring systems. CAE and DOE (Design of Experiment) are used to construct an optimal mold design in terms of gates and runners and to identify working conditions for the molding process. CAI and monitoring systems with temperature sensors and pressure sensors can be used to inspect the physical molding process and the molded parts. The flow process of a large body is systematically planned and constructed using a knowledge-based flow process with DOE and computer-aided technologies. The proposed flow process is implemented for the molding process of an automobile front bumper fascia.     

Lateral controller design for an unmanned vehicle via Kalman filtering

This paper proposes a lateral control system for an unmanned vehicle that is designed to improve the responsiveness of the system with the use of a PD control. The vehicle heading error can be stabilized, and the transient response characteristics can be improved using the proposed controller. A mathematical model of the vehicle dynamics using two degrees of freedom was developed for the controller design. The waypoint tracking method for autonomous navigation was tested with incorporation of the Point-to-Point algorithm with position and heading measurements received from GPS receivers via Kalman filtering. The performance of the designed controller was verified through experiments with a real vehicle.     

Zonal centrality measures and the neighborhood effect

The goal of this study is to develop a robust methodology for computing zone centrality measures in an urban area. Centrality refers to the relative importance of a zone in terms of network efficiency and utility for both transportation and urban study. Centrality indices that were developed to describe human relationships in the field of structural sociology were adopted. It is important to accommodate the neighborhood effect in dealing with centrality. The neighborhood effect describes the phenomenon whereby the attractiveness of a specific zone is affected by its neighbor zones. Kernel functions were employed to accommodate the neighborhood effect. The optimal bandwidth parameters were derived indirectly within the framework of trip attraction estimation under the assumption that the trip attraction of a zone is influenced by the integrated centrality, which includes the neighborhood effect. The well-known estimation tool of maximum likelihood estimation (MLE) was adopted to find the optimal bandwidth. As a byproduct of accommodating the neighborhood effect in centralities, a considerable advantage of the present study is an enhancement of the performance of trip attraction model. Another meaningful contribution of this study is a solution to the question of an acceptable delineation of the two city centers in Seoul. The boundaries of the two city centers were derived based on both the kernel function and its bandwidth.     

Accumulated tolerance analysis of suspension by geometric tolerances based on multibody elasto-kinematic analysis

Tolerance design of vehicle suspension is an important factor that affects the ride and handling quality and cost of the vehicle. Also, applying geometric tolerance to an analysis model is found to be a difficult process. This paper presents a method for tolerance analysis of wheel alignment of vehicle suspension. Monte-Carlo simulation method is applied to multibody elasto-kinematic model to analyze the accumulated geometric tolerances. As an example, Macpherson Strut Type front half car model is used, and wheel alignment dispersion and contribution ratio to the dispersion by accumulated geometric tolerances is computed. This paper also presents an efficient modeling and analysis method for elasto-kinematic model of vehicle suspensions by computing the stiffness matrix analytically. The simulation results of a Macpherson Strut Type demonstrates the validity and accuracy of the proposed method.     

Stability Analysis of the Human Controlled Vehicle Moving Along a Curved Path

A method to study handling characteristics of a vehicle moving along a curved path is presented. A simple bicycle model and a feedback controller with proportional gain are used to simulate the vehicle and the driver. The lateral stability of the vehicle/driver system is analyzed by using the root locus method and numerical integration in the time domain. The effect of the curvature on the system stability is discussed in detail. A new suggestion is made for the look ahead distance to calculate the preview lateral error of the vehicle with respect to the center of the road. Interesting results are shown for some important parameters such as the gain factor, the vehicle speed and the curvature of the path. Possible extensions of the method to more general cases and other applications are discussed.     

Experimental investigation of wing-in-ground effect with a NACA6409 section

The aerodynamic characteristics of NACA6409 in the vicinity of the ground were experimentally studied in a wind tunnel. Lift and drag forces, the pitching moment, and the center of pressure were measured with respect to various major aerodynamic parameters, such as the ground clearance, the angle of attack, the aspect ratio (AR), and the endplate type, which resulted in a total number of 420 conditions. In addition, a smoke trace test was conducted to visualize the flow pattern around NACA6409 in the vicinity of the ground. As a result of the ground effect and the influence of the endplate, the lift-to-drag ratio increased at low ground clearance and the center of pressure moved forward to the leading edge; that is, the endplate and ground effects were equivalent to the aerodynamic advantage that results from increasing the AR of the wing. Extended experimental results are useful for understanding the aerodynamic characteristics influenced by each aerodynamic parameter during ground effect as well as for verifying numerical simulation.