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The driving risk field model offers a feasible approach for assessing driving risks and planning safe trajectory in complex traffic scenarios. However, the conventional risk field fails to account for the vehicle size and acceleration, results in the same trajectories are generated when facing different vehicle types and unable to make safe decisions in emergency situations. Therefore, this paper firstly introduces the acceleration and vehicle size of surrounding vehicles for improving the driving risk model. Then, an integrated decision-making and planning model is proposed based on the combination of the novelty risk field and model predictive control (MPC), in which driving risk and vehicle dynamics constraints are taken into consideration. Finally, the multiple driving scenarios are designed and analyzed for validate the proposed model.

Automated parking is an efficient way to solve parking difficulties and path planning is of great concern for parking maneuvers [1]. Meanwhile, the starting region of path planning greatly affects the parking process and efficiency. The present research of the starting region are mostly determined based on a single algorithm, which limits the flexibility and efficiency of planning feasible paths. This paper, taking parallel parking and vertical parking for example, proposes a method to calculate the starting region and select the most suitable path planning algorithm for parking, which can improve the parking efficiency and reduce the complexity. The collision situations of each path planning algorithm are analyzed under collision-free conditions based on parallel and vertical parking. The starting region for each algorithm can then be calculated under collision-free conditions.

This paper presents an optimal cooperative path planning method considering driver’s driving intention for shared control to address target path conflicts during the driver-automation interaction by using the convex optimization technique based on the natural cubic spline. The optimal path criteria (e.g. the optimal curvature, the optimal heading angle) are formulated as quadratic forms using the natural cubic spline, and the initial cooperative path profiles of the cooperative path in the Frenet-based coordinate system are induced by considering the driver’s lane-changing intention recognized by the Support Vector Machine (SVM) method. Then, the optimal cooperative path could be obtained by the convex optimization techniques. The noncooperative game theory is adopted to model the driver-automation interaction in this shared control framework, where the Nash equilibrium solution is derived by the model predictive control (MPC) approach.

The vibration and instability experienced in an ambulance can lead to secondary injury to a patient and discourage a paramedic from emergency care. This paper presents a hydraulically interconnected suspension (HIS) system which can achieve enhanced cooperative control of roll, pitch and bounce motion modes to improve the ambulance's ride comfort and handling performance. A lumped-mass model integrated with a mechanical and hydraulic coupled system is developed by using free-body diagram and transfer matrix methods. The mechanical-fluid boundary condition in the double-acting cylinders is modelled as an external force on the mechanical system and a moving boundary on the fluid system. A special modal analysis method is employed to reveal the vibration characteristics of the ambulance with the HIS.

In order to provide an improved countermeasure for occupant protection, a new type of active reversible preload seatbelt (ARPS) is presented in this paper. The ARPS is capable of protecting occupants by reducing injuries during frontal collisions. ARPS retracts seatbelt webbing by activating an electric motor attached to the seatbelt retractor. FCW (Forward Collision Warning) and LDW (Lane Departure Warning) provide signals as a trigger to activate the electric motor to retract the seatbelt webbing, thus making the occupant restraint system work more effectively in a crash. It also helps reduce occupant’s forward movement during impact process via braking. Four important factors such as preload force, preload velocity and the length and timing of webbing retraction play influential roles in performance of the ARPS. This paper focuses on studying preload performance of ARPS under various test conditions to investigate effects of the aforementioned factors.

A 3D grid model of engine brake is established for an automobile engine. The dynamic compression release braking process is simulated by using this model. In the process of engine braking, the movement of valve and piston causes changes of the internal flow field of the engine. In this paper, the movement of valve and piston were defined by using the dynamic grid technology, so that the numerical simulation is closer to the actual situation via the updating of grid. Based on the relevant parameters of compression release engine brake (including the opening of the exhaust valve, the engine speed and the exhaust back pressure), the pressure and power of the compression release braking system were simulated under the conditions of multiple operating conditions and experimental verification was carried out. The results showed that the braking works of the compression release engine brake are mainly from the compression stroke and the exhaust stroke.

Hydraulic retarder, as an auxiliary braking device, is widely used in commercial vehicles. Nowadays, the hydraulic retarder’s internal oil is mainly cooled by the coolant circuit directly. It not only aggravates the load of engine cooling system, but also makes the abundant heat energy not be recycled properly. In this study, an independent energy supply device with organic Rankine cycles is applied to solve the problems above. In the structure of this energy supply device, the evaporator’s inlet and outlet is connected in parallel with the oil outlet and inlet of the retarder respectively. A part of oil enters the evaporator to transfer heat with the organic fluid, and the rest of oil enters the oil-water heat exchanger to be cooled by the coolant circuit. According to the different braking conditions of the retarder, the oil temperature in the inlet of the hydraulic retarder can be kept within the proper range through adjusting the oil flow rate into the evaporator properly.

This paper introduces a vehicle model in CarSim, and replaces a portion of its standard suspension system with an HIS model built in an external software to implement co-simulations. The maneuver we employ to characterize the HIS vehicle is a constant radius method, i.e. observing the vehicle’s steering wheel angle by fixing its cornering radius and gradually increasing its longitudinal speed. The principles of the influence of HIS systems on cornering mainly focus on two factors: lateral load transfer and roll steer effect. The concept of the front lateral load transfer occupancy ratio (FLTOR) is proposed to evaluate the proportions of lateral load transfer at front and rear axles. The relationship between toe and suspension compression is dismissed firstly to demonstrate the effects of lateral load transfer and then introduced to illustrate the effects of roll motion on cornering.

Natural gas is a promising alternative fuel for internal combustion engines due to its rich reserves and low price, as well as good physical and chemical properties. Its low carbon structure and high octane number are beneficial for CO2 reduction and knock mitigation, respectively. Diesel and natural gas dual fuel combustion is a viable pathway to utilize natural gas in diesel engines. To achieve high efficiency and low emission combustion in a practical diesel engine over a wide range of operating conditions, understanding the performance responses to engine system parameter variations is needed. The controllability of two combustion strategies, diesel pilot ignition (DPI) and single injection reactivity controlled compression ignition (RCCI), were evaluated using the multi-dimension CFD simulation in this paper.

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.

Hybrid electric vehicles (HEVs) are considered as the most commercial prospects new energy vehicles. Most HEVs have adopted Atkinson cycle engine as the main drive power. Atkinson cycle engine uses late intake valve closing (LIVC) to reduce pumping losses and compression work in part load operation. It can transform more heat energy to mechanical energy, improve engine thermal efficiency and decrease fuel consumption. In this paper, the investigations of Atkinson cycle converted from conventional Otto cycle gasoline engine have been carried out. First of all, high geometry compression ratio (CR) has been optimized through piston redesign from 10.5 to 13 in order to overcome the intrinsic drawback of Atkinson cycle in that combustion performance deteriorates due to the decline in the effective CR. Then, both intake and exhaust cam profile have been redesigned to meet the requirements of Atkinson cycle engine.

This work presents a comprehensive computational study of diesel - natural gas (NG) dual fuel engine. A complete computational model is developed for the operation of a diesel - NG dual fuel engine modified from an AVL 5402 single cylinder diesel test engine. The model is based on the KIVA-3V program and includes customized sub-models. The model is validated against test cell measurements of both pure diesel and dual fuel operation. The effects of NG on ignition and combustion in dual fuel operation are analyzed in detail. Zero-dimensional computations with a diesel surrogate reaction mechanism are conducted to discover the effects of NG on ignition and combustion and to reveal the fundamental chemical mechanisms behind such effects. Backed by the detailed theoretical analysis, the engine operation parameters are optimized with genetic algorithm (GA) for the dual fuel operation of the modified AVL 5402 test engine.

In the present study, we developed a reduced chemical reaction mechanism consisted of n-heptane and toluene as surrogate fuel species for diesel engine combustion simulation. The LLNL detailed chemical kinetic mechanism for n-heptane was chosen as the base mechanism. A multi-technique reduction methodology was applied, which included directed relation graph with error propagation and sensitivity analysis (DRGEPSA), non-essential reaction elimination, reaction pathway analysis, sensitivity analysis, and reaction rate adjustment. In a similar fashion, a reduced toluene mechanism was also developed. The reduced n-heptane and toluene mechanisms were then combined to form a diesel surrogate mechanism, which consisted of 158 species and 468 reactions. Extensive validations were conducted for the present mechanism with experimental ignition delay in shock tubes and laminar flame speeds under various pressures, temperatures and equivalence ratios related to engine conditions.

A multi-step acetone-butanol-ethanol (ABE) phenomenological soot model was proposed and implemented into KIVA-3V Release 2 code. Experiments were conducted in an optical constant volume combustion chamber to investigate the combustion and soot emission characteristics under the conditions of 1000 K initial temperature with various oxygen concentrations (21%, 16%, 11%). Multi-dimensional computational fluid dynamics (CFD) simulations were conducted in conjunction under the same operation conditions. The predicted soot mass traces showed good agreement with experimental data. As ambient oxygen decreased from 21% to 11%, ignition delay retarded and the distribution of temperature became more homogenous. Compared to 21% ambient oxygen, the peak value of total soot mass at 16% oxygen concentration was higher due to the suppressed soot oxidation mechanism.

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.

With its advantages on cost and performance, the integrated exhaust manifold (casting with the turbine) is being used on more vehicles by auto makers. Generally, when compared with the divided exhaust manifold, the integrated exhaust manifold stands for higher vibratory excitation from gas dynamics. In this paper, the gas dynamics excitation has been computed through the GD (gas dynamics) software GT-Power which calculates the exhaust pipe surface pressure, and CFD code Star-CCM+ which calculates the turbine blade force. And the response of manifold has been solved under this excitation. On the other hand, the mechanical excitation has been computed through the MBD (multi-body dynamics) platform AVL-Excite-PU, and the responses under the gas excitation plus the mechanical load have been studied in order to analyze the effects of the fluid excitation on an integrated manifold.

Due to its load control strategy via fresh charge quantity, pumping loss in a homogenous charge gasoline engine is a significant contributor to the high fuel consumption rate at light load. Exhaust gas recirculation (EGR) and lean burn technologies are the common means to reduce gasoline engine pumping loss for fuel economy improvement. Many previous publications compared the EGR and lean burn concepts. However, few of those were able to compare the EGR and lean burn concepts under the same in-cylinder dilution basis. Usually the un-swept in-cylinder residual gas fraction (RGF), which can be significant at very low loads, was ignored due to lack of appropriate method to determine it. Also the theoretical potential and practical limitations were rarely discussed. In this paper, a Naturally Aspirated (NA) gasoline engine was systematically tested for both the EGR and lean mixture concepts on an engine dyno. under the same speed and load conditions.

This paper presents the different influence factors to vehicle's path planning, including the guide-potential shape and its parameters, the guild-potential influence scale factor, the stiffness of the elastic bands and the speed of the host vehicle. The assessment of emergency path is based on the dynamic performance of the host vehicle, the lateral acceleration and yaw rate, and its mean-square values accesses the stability of the host vehicle when following the path. In order to take evasion maneuvers more steadily, a guide-potential affecting the moving vehicles behind the obstacle is built, which encourages the host vehicle to change lane appropriately. Three different shape guide-potential models, namely half-circle-like, half-ellipse-like and parabola-like, are proposed and compared in this paper. Meanwhile, hazard map of the road environment which includes the lanes, borders and obstacles is generated.

To meet more stringent emission regulations for diesel engines, diesel particulate filters (DPF) have been widely used for diesel engines. However, the DPF regeneration is a great challenge for fuel economy. In this paper, a mathematical model characterizing the microwave regeneration process of a wall-flow particulate filter is introduced to better understand the process. Based on this model, important parameters such as evolutions of the energy stream densities of microwaves, wall temperature, regeneration efficiency and the pressure drop in the filters, both cordierite and SiC, are investigated. These results can provide an important theoretical guide for optimizing and controlling the microwave regeneration process.

Realizable k-ε turbulence model has been used widely for engineering development. In this turbulence model, the default values of empirical coefficients such as C₂, σk and σε are obtained from some particular experiments. They are a good choice for most simulations-though may be not the best choice for simulating the aerodynamic characteristics of road vehicle. In order to improve the accuracy of simulation, a set of new empirical coefficients should be designed especially for simulating the aerodynamic characteristics of road vehicle. These empirical coefficients are found out by DoE (design of experiments) in this paper. Firstly the value range of empirical coefficients is decided by the laws that the aerodynamic force coefficients change with altering of empirical coefficients. Secondly 20 sets of empirical coefficients are obtained randomly by applying optimal Latin Hypercube method in Isight.