Search Results

This paper employs the motion-mode energy method (MEM) to investigate the effects of a roll-plane hydraulically interconnected suspension (HIS) system on vehicle body-wheel motion-mode energy distribution. A roll-plane HIS system can directly provide stiffness and damping to vehicle roll motion-mode, in addition to spring and shock absorbers in each wheel station. A four degree-of-freedom (DOF) roll-plane half-car model is employed for this study, which contains four body-wheel motion-modes, including body bounce mode, body roll mode, wheel bounce mode and wheel roll mode. For a half-car model, its dynamic energy contained in the relative motions between its body and wheels is a sum of the energy of these four motion-modes. Numerical examples and full-car experiments are used to illustrate the concept of the effects of HIS on motion-mode energy distribution.

The public Hybrid III family finite element models have been used in simulation of automotive safety research widely. The validity of an ATD finite element model is largely dependent on the accuracy of model structure and accurate material property parameters especially for the soft material. For Hybrid III 50th percentile male dummy model, the femur load is a vital parameter for evaluating the injury risks of lower limbs, so the importance of accuracy of knee subcomponent model is obvious. The objective of this work was to evaluate the accuracy of knee subcomponent model and improve the validity of it. Comparisons between knee physical model and knee finite element model were conducted for both structure and property of material. The inaccuracy of structure and the material model of the published model were observed.

Effectively obtaining physical parameters for vehicle dynamic model is the key to successfully performing any computer-based dynamic analysis, control strategy development or optimization. For a spring and lump mass vehicle model, which is a type of vehicle model widely used, its physical parameters include sprung mass, unsprung mass, inertial properties of the sprung mass, stiffness and damping coefficient of suspension and tire, etc. To minimize error, the paper proposes a method to estimate these parameters from vehicle modal parameters which are in turn obtained through full-car dynamic testing. To verify its effectiveness, a visual vehicle with a set of given parameters, build in the Adams(Automatic Dynamic Analysis of Mechanical Systems)/Car environment, is used to perform the dynamic testing and provide the testing data for the parameter estimation.

With the development of advanced ABE fermentation technology, the volumetric percentage of acetone, butanol and ethanol in the bio-solvents can be precisely controlled. To seek for an optimized volumetric ratio for ABE-diesel blends, the previous work in our team has experimentally investigated and analyzed the combustion features of ABE-diesel blends with different volumetric ratio (A: B: E: 6:3:1; 3:6:1; 0:10:0, vol. %) in a constant volume chamber. It was found that an increased amount of acetone would lead to a significant advancement of combustion phasing whereas butanol would compensate the advancing effect. Both spray dynamic and chemistry reaction dynamic are of great importance in explaining the unique combustion characteristic of ABE-diesel blend. In this study, a semi-detailed chemical mechanism is constructed and used to model ABE-diesel spray combustion in a constant volume chamber.

The around view monitor (AVM) system for vehicles usually suffers from the distortion of surrounding objects caused by incomplete rectification and stitching, which seriously affects the driver's judgment of the surrounding environment during the reversing process. In response to solve this problem, an augmented around view monitor (AAVM) system fusing image and depth information is proposed, which highlights the point clouds of persons or vehicles at the rear of the vehicle. First, an around view image is generated from four fisheye cameras. Then, the calibration of multi TOF cameras is conducted to improve their accuracy of depth estimation and obtain extrinsic camera positions. Next, the 2D-driven object point cloud detection method is proposed to localize and segment object point clouds like vehicles or persons.

This paper intends to present a novel optimal trajectory planning method for obstacle avoidance on highways. Firstly, a mapping from the road Cartesian coordinate system to the road Frenet-based coordinate system is built, and the path lateral offset in the road Frenet-based coordinate system is represented by a function of quintic polynomial respecting the traveled distance along the road centerline. With different terminal conditions regarding its position, heading and curvature of the endpoint, and together with initial conditions of the starting point, the path planner generates a bunch of candidate paths via solving nonlinear equation sets numerically. A path selecting mechanism is further built which considers a normalized weighted sum of the path length, curvature, consistency with the previous path, as well as the road hazard risk.

The driver's face detection and tracking method important for Advanced Driver Assistance Systems (ADAS) and autonomous driving in various situations. The deep SORT algorithm has integrated appearance information, the motion model and the intersection-over-union (IOU) distance methods, and has been applied to face tracking, but it depends on detection information in every frame. Once the detection information lacks, the deep SORT algorithm will wait until the target detects bounding boxes appear again, even if the target didn’t disappear or shield. Hence, we propose to use a new tracker that not completely depend on the detection algorithm to cascade with the deep SORT algorithm to realize stable driver's face tracking. At first, the driver's face detection and tracking will be accomplished by the MTCNN-deep-SORT algorithm.

Aerodynamic noise generated in a miniature car had been evaluated using numerical simulation. Large Eddy Simulation (LES) was applied to analyze the transient flow field and the Ffowcs Williams-Hawkings (FW-H) acoustic analogy was employed to conduct acoustic analysis. The time accurate flow data was obtained using a finite volume flow solver on an unstructured grid. The flow field around the rear view mirror was obtained by numerical for two cases with different side view mirrors. Moreover, the distribution of acoustic source was predicted on side windows, and the aerodynamic noise was lowed through optimizing the shape of the rear view mirror and some experiments were done to validate the effect. Present study ascertained the feasibility and applicability of finite volume method (FVM) with SGS model towards prediction of aerodynamic noise generated in production vehicle.

Suspension system dynamics can be obtained by various methods and vehicle design has gained great advantages over the dynamics analysis. By employing the new Udwadia-Kalaba equation, we endeavor some attempts on its application to dynamic modeling of vehicle suspension systems. The modeling approach first segments the suspension system into several component subsystems with kinematic constraints at the segment points released. The equations of motion of the unconstrained subsystems are thus easily obtained. Then by applying the second order constraints, the suspension system dynamics is then obtained. The equations are of closed-form. Having the equations obtained, we then show its application on dynamical load analysis. The solutions for the dynamical loads at interested hard points are obtained. We use the double wishbone suspension to show the systematic approach is easy handling.

In vehicles equipped with conventional Electric Power Steering (EPS) systems, the steering effort felt by the driver can be unreasonably low when driving on slippery roads. This may lead inexperienced drivers to steer more than what is required in a turn and risk losing control of the vehicle. Thus, it is sensible for tire-road friction to be accounted for in the design of future EPS systems. This paper describes the design of an auxiliary EPS controller that manipulates torque delivery of current EPS systems by supplying its motor with a compensation current controlled by a fuzzy logic algorithm that considers tire-road friction among other factors. Moreover, a steering system model, a nonlinear vehicle dynamics model and a Dugoff tire model are developed in MATLAB/Simulink. Physical testing is conducted to validate the virtual model and confirm that steering torque decreases considerably on low friction roads.

Optimization design for vehicle front-end structures has proven rather essential and been extensively used to improve the vehicle performance. Nevertheless, the front-end structure needs to meet the requirement of both pedestrian safety and structural stiffness which are somewhat contradicting to each other. Furthermore, an optimal design could become less meaningful or even unacceptable when some uncertainties present. In the paper, a multi-objective discrete robust optimization (MODRO) algorithm is used to minimize the injury of head and maximize the structural stiffness involving uncertainties. MODRO algorithm is achieved by coupling grey relational analysis (GRA) and principal component analysis (PCA) with Taguchi method. The optimized result shows that the MODRO algorithm improved performance of pedestrian head injury and robustness of the vehicle front-end structure.

With the wider use of biofuels in the marketplace, a program was conducted to study the deposit forming tendencies and performance of E85 (85% denatured ethanol and 15% gasoline) in a modern Flexible Fuel Vehicle (FFV). The test vehicle for this program was a 2006 General Motors Chevrolet Impala FFV equipped with a 3.5 liter V-6 powertrain. A series of 5,000 mile Chassis Dynamometer (CD) Intake Valve Deposits (IVD) and performance tests were conducted while operating the FFV on conventional (E0) regular unleaded gasoline and E85 to determine the deposit forming tendencies of both fuels. E85 test fuels were found to generate significantly higher levels of IVD than would have been predicted from the base gasoline component alone. The effects on the weight and composition of IVD due to a corrosion inhibitor and sulfates that were indigenous to one of the ethanols were also studied.

Cold start vehicle driveability performance depends on many parameters, one of which is the distillation character of the fuel. In the late 90's, a gasoline driveability index (DI) was developed for spark ignited combustion vehicles by a consortium of automotive and petroleum industry scientists based on correlation studies between controlled fuel quality matrices and vehicle performance under specific ambient conditions. The DI equation uses a weighted sum of gasoline distillation temperatures at the 10, 50 and 90 percent evaporation volumes, commonly called T10, T50 and T90. These three distillation volatility points are specified by the ASTM International D 4814 fuel specification and are seasonally adjusted. This paper studies the cold start driveability performance of Federal EPA Bin 5 and Bin 8 vehicles with respect to fuel distillation characteristics at temperatures other than T10, T50 and T90.

Noise radiated by engine front cover is estimated using statistical energy analysis approach. Correlations are made with the results obtained using FEM and BEM approaches. Parametric studies are also carried out to assess the regions of applicability of the SEA approach for this class of structures.

As the length of the frontal structure of the minibus can't be as long as cars, some new methods have to be developed to maximum the effect of the energy absorption. In this paper, a step-by-step energy absorption method which based on reverse design was proposed. Two plates with different size and different thickness which can take part in the energy absorption step by step were added in each of the rectangular longitudinal beams. Finite element models were developed both for rectangular beam and minibus. Multi-body model was also developed for the restraint system. The validation of the rectangular beam model was done by sled test, and the minibus model was done by minibus crash test. The computational results matched well with the test results. Then, orthogonal experimental method was used to find the most effective parameters for the energy absorption. These parameters were optimized in the simulation of minibus crash.

A multidimensional numerical simulation method was developed to analyze air/fuel premixing, stratified combustion and NOx emission formation in a gasoline direct injection (GDI) engine. Firstly, many submodels were integrated into one Computational Fluid Dynamics (CFD) code: ICFD-CN, such as Sarre nozzle flow, Kelvin-Helmholtz (KH) dynamic jet model, Taylor-Analogy Breakup (TAB) model, Rayleigh-Taylor (RT) droplet breakup model, Lefebvre fuel vaporization model, Liu droplet drag & distortion model, Gosman turbulence & droplet dispersion model, O'rourke wall film model, O'rourke and Bracco droplet impinging & coalescence model, Stanton spray/wall impinging model, the Discrete Particle Ignition Kernel(DPIK)ignition model, the single step combustion and the patulous Zeldovich model for NOx generation mechanism. The integrated CFD code was then calibrated against experimental data in a gasoline direct injection engine for several engine operating conditions.

This paper describes an improved mathematical model to study the emission conversion effectiveness of a three-way catalytic converter, which employed detailed chemical reaction mechanism. The model also accounts for adsorption/release of oxygen in the catalyst monolith under non-stoichiometric A/F conditions. A commercial CFD code FLUENT was utilized to solve the governing equations for flow and pressure drop and to simulate the transient process in a three-way catalytic converter in a multi-dimensional manner. A comparison between simulation results and experimental data for a three-way catalyst was conducted and a good agreement was observed. Based on the improved model, some geometric parameters were studied for an elliptic monolith catalyst, which are widely used in today's converter systems because of its advantages in packaging.

The General Motors Allison Two-Mode compound split parallel hybrid EP system for transit buses has been in production for over three years, accumulating over 20 million fleet miles. During this period of operation, extensive fuel economy analysis has been performed over multiple use cycles in multiple locations. This paper describes the in-use fuel economy results, as well as the hybrid system mode operations, the component utilization, and the controls improvements to maximize the hybrid fuel economy. Actual in-use data will be presented from individual vehicles, as well as the fleet averages encompassing a broad range of duty cycles. A chassis dynamometer testing results are discussed as an alternative evaluation method.

The objective of this paper is to propose a new model in the identification of a contributing factor to the generation of Radio Frequency Interference (RFI) due to the operation of a spark-ignited engine. This model incorporates parameters in the electrical operation of the ignition system components and their interaction with the engine mechanical structure, which is also used as a circuit component (the ignition system “ground”). T he model was developed as a result of analysis of numerous studies that have been conducted over the years in an attempt to identify why RFI characteristics can differ when using identical components on different engines, or locating the components in different locations on identical engines. This situation is a problem due to the resulting uncertainty with respect to the determination of what is the optimum vehicle ignition system configuration to meet all electrical and RFI or electromagnetic compatibility (EMC) requirements.

The Hydra-Matic 6T70 is General Motors first model of a new, two-variant front wheel drive (FWD) six speed automatic transmission family. The second variant is a higher capacity model, the 6T75. The transmission was co-developed with Ford Motor Company. The 6F50 is the Ford variant that aligns with the GM 6T70 transmission. Approximately eighty five percent of the hardware is shared or common between the GM and Ford transmission variants. Ford will also have a higher capacity variant the 6F55 to align with the GM 6T75. The first GM application is the Saturn Aura for the 2007 Model Year. The Ford Edge and Lincoln MKX in MY 2007 will be the first applications for the 6F50. While the Hydra-Matic and Ford FWD six-speed family was designed with two variants in mind, the designed in modularity requires only changes to the second and third axis and case housings depending on specific torque requirements. This modular design enables a tremendous amount of part sharing.