Academic Journals

Investigation of objective parameters for acceptance evaluation of automatic lane change system

The Psychological Record - Thu, 02/01/2018 - 00:00
Abstract

Recently, with increased interest in high levels of automated driving systems such as automatic lane change system, the need for reliable assessment methods of driver acceptance has arisen. Because the acceptance depends on the individual, the assessment of the acceptance can only be based on an individual’s personal attitude, expectations, and experiences. Accordingly, subjective evaluation methods have mostly been utilized to assess the acceptance of newly developed advanced driver assistance systems. In this study, an investigation of the effects of vehicle dynamic behavior and the traffic environment on driver acceptance is conducted to provide an objective evaluation method of driver acceptance for an automatic lane change system. In order to conduct the investigation, a specific experimental program is designed and a massive database, including information on interaction behaviors between drivers, a vehicle and the traffic environment is constructed with a selected group of 19 drivers. Then, 21 parameters and their descriptive statistics for an objective evaluation index are presented to illustrate the analysis results. The results of this research can be important not only for an objective evaluation of the acceptance, but can also be expanded to suggest design criteria for control of advanced and automated driving assistance systems.

Categories: Academic Journals

Influence of temperature on the tyre rolling resistance

The Psychological Record - Thu, 02/01/2018 - 00:00
Abstract

Temperature is a very important factor controlling rolling resistance of road vehicle tyres. There are at least three different temperatures that may be considered as important factors controlling thermal conditions of the rolling tyre. The most common measure of the thermal conditions during tyre rolling is ambient air temperature. The other two are: pavement temperature and “tyre” temperature. Tyre temperature is the most difficult to establish, as temperatures of different parts of rolling tyres differ considerably, thus there is a problem to obtain representative values. In the authors’ opinion, air temperature is the most universal and reliable parameter to measure. The article presents results obtained in the Technical University of Gdańsk during laboratory and road measurements of different car tyres rolling on different pavements. The knowledge of rolling resistance characteristics is important for modelling car dynamics as well as fuel consumption. It is also necessary to establish proper test conditions in the future standardized on-road method of measuring rolling resistance. The results indicate that generally each tyre and pavement combination is influenced by the air temperature in a unique way, but at the same it is possible to propose some general influence factors that may be used to normalize measurements to the standard temperature of 25 °C.

Categories: Academic Journals

System power loss optimization of electric vehicle driven by front and rear induction motors

The Psychological Record - Thu, 02/01/2018 - 00:00
Abstract

Power loss optimization aiming at the high-efficiency drive of front-and-rear-induction-motor-drive electric vehicle (FRIMDEV) as an effective way to improve energy efficiency and extend driving range is of high importance. Different from the traditional look-up table method of motor efficiency, power loss optimization of the dual- motor system based on the loss mechanism of induction motor (IM) is proposed. First of all, based on the power loss characteristic of FRIMDEV from battery to wheels, the torque distribution optimization model aiming at the minimum system power loss is put forward. Secondly, referring to d-q axis equivalent model of IM, the power loss functions of the dual-IM system are modeled. Then, the optimal torque distribution coefficient (β o) between the two IMs is derived, and the theoretical switching condition (T sw) between the single- and dual-motor-drive mode (SMDM and DMDM) is confirmed. Finally, a dual-motor test platform is developed. The derived torque distribution strategy is verified. The influence of motor temperature on β o and T sw are tested, and the correction models based on temperature difference are proposed. Based on the system power loss analysis, it can be confirmed that, under low load conditions, the SMDM takes priority over the DMDM, and the controller of the idling motor should be shut down to avoid the additional excitation loss. While under middle to high load conditions, even torque distribution (β o = 0.5) is preferred if the temperature difference between the two IMs is small; otherwise, β o should be corrected based on dual-motor temperatures. The theoretical T sw derived without dealing with temperature difference is a function only of motor speed, while temperature difference correction of it should be conducted in actual operations based on motor resistance changing with temperature.

Categories: Academic Journals

Similarity of the measured NIC of a BioRID II dummy in car-to-car rear end impact and sled experiments

The Psychological Record - Thu, 02/01/2018 - 00:00
Abstract

The Japan New Car Assessment Program (J-NCAP) evaluates the performance of cars in terms of protection against whiplash injuries in rear-end collisions. In the test protocol, a simplified triangular acceleration is applied to the sled. This study clarifies whether biofidelic rear-impact dummy II (BioRID II) measurements obtained for simplified triangular acceleration reflect car-to-car rear-end impacts in real-world accidents in Japan. We conducted a car-to-car rear-end impact experiment and a simplified-triangular-acceleration sled test. Our results indicate that the time series of dummy responses were approximately consistent in the two test conditions. The neck injury criterion (NIC) and maximum acceleration of the head and T1 measured using the BioRID II dummy were similar in the car-to-car and sled experiments. This revealed that the J-NCAP test protocol using simplified triangular acceleration reflects the car-to-car rear-end impact experiment using Japanese cars, in terms of the NIC and maximum acceleration of the head and T1.

Categories: Academic Journals

Adaptive feedforward control of a steer-by-wire system by online parameter estimator

The Psychological Record - Thu, 02/01/2018 - 00:00
Abstract

The tracking control of the steer-by-wire (SBW) system to achevie desired steering motion is the core issue for the design of algorithm. Most of model-based tracking control assumed the constant parameters without the consideration of dynamic characteristics. The external disturbances and model nonlinearities can bring uncertainties of the system parameters. To reduce the influence of parameter uncertainties, an online estimator by output error identification method is proposed to estimate the dynamic parameters of a SBW system. Meanwhile, the parameter gradient projection method is applied to eliminate the parameter drift, while a full order state observer is developed to weaken the effects of noise disturbance during the parameter identification. Since the sensitivity of parameter uncertainties for the feedforward control, the online estimator is incorporated into the control model and improve the controlled robustness. The proposed adaptive feedforward controller is conducted by the real-time experiments to show the tracking performance.

Categories: Academic Journals

Effect of operating parameters on diesel/propane dual fuel premixed compression ignition in a diesel engine

The Psychological Record - Thu, 02/01/2018 - 00:00
Abstract

In this research, the effects of three operating parameters (Diesel injection timing, propane ratio, and exhaust gas recirculation (EGR) rates) in a diesel-propane dual fuel combustion were investigated. The characteristics of dual-fuel combustion were analyzed by engine parameters, such as emission levels (Nitrogen oxides (NOx) and particulate matter (PM)), gross indicated thermal efficiency (GIE) and gross IMEP Coefficient of Variance (CoV). Based on the results, improving operating strategies of the four main operating points were conducted for dual-fuel PCCI combustion with restrictions on the emissions and the maximum pressure rise rate. The NOx emission was restricted to below 0.21 g/kWh in terms of the indicated specific NOx (ISNOx), PM was restricted to under 0.2 FSN, and the maximum pressure rise rate (MPRR) was restricted to 10 bar/deg. Dual-fuel PCI combustion can be available with low NOx, PM emission and the maximum pressure rise rate in relatively low load condition. However, exceeding of PM and MPRR regulation was occurred in high load condition, therefore, design of optimal piston shape for early diesel injection and modification of hardware optimizing for dual-fuel combustion should be taken into consideration.

Categories: Academic Journals

Gasket life criteria at low temperatures adopting proportional compensation for loss of flexibility and conformability

The Psychological Record - Thu, 02/01/2018 - 00:00
Abstract

In the automobile industry, the service life of gaskets is defined as the time until which a released gasket recovers 60 % of the original compression. It was observed that the recovery curves of gaskets were highly nonlinear at high temperatures, and relatively nonlinear at temperatures above the room temperature. However, it was also noted that the recovery curves of the gaskets at temperatures below room temperature exhibited linearity with respect to the ln(time). Automotive manufacturers demand gasket life criteria that exceed a specific time or the entire life of a car. In the case of gaskets used at lower temperatures, since materials encounter losses in its flexibility and conformability, the definition of service life specifying a 60 % recovery may not be sufficiently safe to eliminate possible leakages. In this study, new gasket life criteria that could be used at low temperatures were proposed. The new criteria were proposed based on the change in Young’s modulus of the gasket material in order to conserve the sealing capability.

Categories: Academic Journals

Allocation control algorithms design and comparison based on distributed drive electric vehicles

The Psychological Record - Thu, 02/01/2018 - 00:00
Abstract

For a distributed drive electric vehicle (DDEV) which is equipped with redundant actuators, allocation control is a key technique. Three different allocation control algorithms are designated with fixed efficiency matrix, dynamic efficiency matrix, and direct yaw moment distribution, respectively. All these algorithms are applied in a vehicle stability control system with hierarchical control structure and evaluated from three aspects, namely, control precision, real-time characteristics, and control energy. Comparison results demonstrate that the algorithm with dynamic efficiency matrix has the best comprehensive performance, which is also validated in field tests based on a DDEV equipped with four motors.

Categories: Academic Journals

Dynamics characteristics analysis and control of FWID EV

The Behavior Analyst - Thu, 02/01/2018 - 00:00
Abstract

Compared with internal combustion engine (ICE) vehicles, four-wheel-independently-drive electric vehicles (FWID EV) have significant advantages, such as more controlled degree of freedom (DOF), higher energy efficiency and faster torque response of an electric motor. The influence of these advantages and other characteristics on vehicle dynamics control need to be evaluated in detail. This paper firstly analyzed the dynamics characteristics of FWID EV, including the feasible region of vehicle global force, the improvement of powertrain energy efficiency and the time-delays of electric motor torque in the direct yaw moment feedback control system. In this way, the influence of electric motor output power limit, road friction coefficient and the wheel torque response on the stability control, as well as the impact of motor idle loss on the torque distribution method were illustrated clearly. Then a vehicle dynamics control method based on the vehicle stability state was proposed. In normal driving condition, the powertrain energy efficiency can be improved by torque distribution between front and rear wheels. In extreme driving condition, the electric motors combined with the electro-hydraulic braking system were employed as actuators for direct yaw moment control. Simulation results show that dynamics control which take full advantages of the more controlled freedom and the motor torque response characteristics improve the vehicle stability better than the control based on the hydraulic braking system of conventional vehicle. Furthermore, some road tests in a real vehicle were conducted to evaluate the performance of proposed control method.

Categories: Academic Journals

Development of a self-driving car that can handle the adverse weather

The Behavior Analyst - Thu, 02/01/2018 - 00:00
Abstract

Lane and road recognition are essential for self-driving where GPS solution is inaccurate due to the signal block or multipath in an urban environment. Vision based lane or road recognition algorithms have been studied extensively, but they are not robust to changes in weather or illumination due to the characteristic of the sensor. Lidar is a sensor for measuring distance, but it also contains intensity information. The road mark on the road is made to look good with headlight at night by using a special paint with good reflection on the light. With this feature, road marking can be detected with lidar even in the case of changes in illumination due to the rain or shadow. In this paper, we propose equipping autonomous cars with sensor fusion algorithms intended to operate in a different weather conditions. The proposed algorithm was applied to the self-driving car EureCar (KAIST) in order to test its feasibility for real-time use.

Categories: Academic Journals

Schlieren, Shadowgraph, Mie-scattering visualization of diesel and gasoline sprays in high pressure/high temperature chamber under GDCI engine low load condition

The Behavior Analyst - Thu, 02/01/2018 - 00:00
Abstract

Three visualization methods, Schlieren, Shadowgraph, and Mie-scattering, were applied to compare diesel and gasoline spray structures in a constant volume chamber. Fuels were injected into a high pressure/high temperature chamber under the same in-cylinder pressure and temperature conditions of low load in a GDCI (gasoline direct injection compression ignition) engine. Two injection pressures (40 MPa and 80 MPa), two ambient pressures (4.2 MPa and 1.7 MPa), and two ambient temperatures (908 K and 677 K) were use. The images from the different methods were overlapped to show liquid and vapor phases more clearly. Vapor developments of the two fuels were similar; however, different liquid developments were seen. At the same injection pressure and ambient temperature, gasoline liquid propagated more quickly and disappeared more rapidly than diesel liquid phase. At the low ambient temperature and pressure condition, gasoline and diesel sprays with higher injection pressures showed longer liquid lengths due to higher spray momentum. At the higher ambient temperature condition, the gasoline liquid length was shorter for the higher injection pressure. Higher volatility of gasoline is the main reason for this shorter liquid length under higher injection pressure and higher ambient temperature conditions. For a design of GDCI engine, it is necessary to understand the higher volatility of gasoline.

Categories: Academic Journals

Influence of the geometric parameters of the vehicle frontal profile on the pedestrian’s head accelerations in case of accidents

The Behavior Analyst - Thu, 02/01/2018 - 00:00
Abstract

The goal of this paper is to determine how the geometry of the vehicle’s frontal profile is influencing the pedestrian’s head accelerations (linear and angular) in car-to-pedestrian accidents. In order to achieve this goal, a virtual multibody dummy of the pedestrian was developed and multiple simulations of accidents were performed using vehicles with different frontal profile geometry, from different classes. The type of accidents considered is characteristic for urban areas and occur at relatively low speed (around 30 km/h) when an adult pedestrian is struck from the rear and the head acceleration variation are the measurement of the accident severity. In the accident simulation 3D meshes were applied on the geometry of the vehicles, in order to define the contact surface with the virtual dummy, similar with real vehicles. The validation of the virtual pedestrian dummy was made by performing two crash-tests with a real dummy, using the same conditions as in the simulations. The measured accelerations in the tests were the linear and angular accelerations of the head during the impact, and these were compared with the ones from the simulations. After validating the virtual model of the car-to-pedestrian accident, we were able to perform multiple simulations with different vehicle shapes. These simulations are revealing how the geometric parameters of the vehicle’s frontal profile are influencing the head acceleration. This paper highlights the main geometric parameters of the frontal profile design that influence the head injury severity and the way that the vehicles can be improved by modifying these parameters. The paper presents an approach to determine the “friendliness” of the vehicle’s frontal profile in the car-to-pedestrian collision.

Categories: Academic Journals

Belief and fuzzy theories for driving behavior assessment in case of accident scenarios

The Behavior Analyst - Thu, 02/01/2018 - 00:00
Abstract

The estimation of the overspeed risk before the accident is among the main goals of this paper. The proposed method uses the Energy Equivalent Speed (EES) to assess the severity of an eventual accident. However, the driver behavior evaluation should take into account the parameters related to the Driver, the Vehicle and the Environment (DVE) system. For this purpose, this paper considers a two-level strategy to predict the global risk of an event using the Dempster-Shafer Theory (DST) and the Fuzzy Theory (FT). This paper presents two methods to develop the Expert Model-based Basic Probability Assignment (EM based BPA), which is the most important task in the DST. The first one is based on the accident statistics and the second method deals with the relationship between the Fuzzy and Belief measurements. The experimental data is collected by one driver using our test vehicle and a Micro-intelligent Black Box (Micro-iBB) to collect the driving data. The sensitivity of the developed models is analysed. Our main evaluation concerns the Usage Based Insurance (UBI) applications based on the driving behavior. So, the obtained masses over the defined referential subsets in the DST are used as a score to compute the driver’s insurance premium.

Categories: Academic Journals

Development of twin-chamber on-wheel resonator for tire cavity noise

The Behavior Analyst - Thu, 02/01/2018 - 00:00
Abstract

Tire cavity noise is a noise which produces reverberations. Given the ringing in the ears that it causes vehicle occupants, it has long been one of the main road noise issues. For the countermeasure against tire cavity noise, since drastic solution is still more difficult for the downstream measure against a body system with the increase of big weight, its device in the tire cavity of the countermeasure against the origin is the most effective for a light weight and drastic solution. Some reduction devices of tire cavity noise have come to be commercialized in recent years. As a commercialization example, what equipped the tire inside surface with the noise absorbing material, and the thing which equipped roadwheel with the resonator are developed. However, application of these devices is limited to some of tires and high-class vehicle types from cost restrictions, and at present, it does not result in technical generalization and has not diffused through it so much. Since the new structure which reduces weight and cost by 50 % or more was suggested towards generalization of the Helmholtz resonator technology which is a flexible device which can equip roadwheel and does not limit a tire brand and commercial production was realized, this paper introduces that theoretical background and realization structure. And this device has been successfully applied to mass-production models on the market.

Categories: Academic Journals

Model-based automatic test case generation for automotive embedded software testing

The Behavior Analyst - Thu, 02/01/2018 - 00:00
Abstract

We propose a method to automatically generate software and hardware test cases from a UML model developed through a model-based development process. Where languages such as source-code languages are used within the model, input and expected values for each test case are generated using a custom parser. As a next step, unit test cases are combined to generate integration test cases using a bottom-up approach. Then these cases are converted into hardware test cases for approval testing of embedded systems, using XQuery and hardware mapping tables. We demonstrate this process by applying it to the power window switch module of a Hyundai Santa Fe vehicle. Our approach provides an automatic testing procedure for embedded systems developed by model-based methods, and generates test cases efficiently using a recombination of signals. In conclusion, our proposed method could help reduce the resources needed for test case generation from software to hardware.

Categories: Academic Journals

Tire wear estimation based on nonlinear lateral dynamic of multi-axle steering vehicle

The Behavior Analyst - Thu, 02/01/2018 - 00:00
Abstract

This paper presents a novel nonlinear dynamic model of a multi-axle steering vehicle to estimate the lateral wear amount of tires. Firstly, a 3DOF nonlinear vehicle dynamic model is developed, including dynamic models of the hydropneumatic suspension, tire, steering system and toe angle. The tire lateral wear model is then built and integrated into the developed vehicle model. Based on the comparison of experimental and simulation results, the nonlinear model is proved to be better than a linear model for the tire wear calculation. In addition, the effects of different initial toe angles on tire wear are analyzed. As simulation results shown, the impact of the dynamic toe angle on the tire wear is significant. The tire wear amount will be much larger than that caused by normal wear if the initial toe angle increases to 1° - 1.5°. The results also suggest that the proposed nonlinear model is of great importance in the design and optimazation of vehicle parameters in order to reduce the tire wear.

Categories: Academic Journals

Hydraulic control system design for a PHEV considering motor thermal management

The Behavior Analyst - Thu, 02/01/2018 - 00:00
Abstract

In this paper, a design method for a PHEV hydraulic control system was proposed considering motor thermal management. Dynamic models of the target PHEV were developed including the hydraulic system, which consists of one mechanical and one electric oil pump. The required motor cooling flow was designed based on the motor temperature, which was obtained from a one-dimensional thermal equivalent circuit model including the heat source and oil spray cooling. Combining the PHEV powertrain model, hydraulic control system model, and the motor thermal model including the cooling system, an integrated simulator was developed for the target PHEV. Using the integrated simulator, the temperatures of MG1 and MG2 were investigated for various motor cooling flow rates when the PHEV underwent a highway driving cycle. The energy consumption of the hydraulic control system was also evaluated. It was found from the simulation results that a hydraulic control system of the target PHEV could be designed that satisfied the required flow for the motor cooling, lubrication and brake control using the design procedure proposed in this study.

Categories: Academic Journals

Flame propagation model for a rotary Atkinson cycle SI engine

The Behavior Analyst - Thu, 02/01/2018 - 00:00
Abstract

The rotary Atkinson cycle engine includes two modes of combustion: combustion initiation and propagation in ignition chamber and then flame jet entrainment and propagation in expansion chamber. The turbulent flame propagation model is a predictive model for SI engines which could be developed for this type of combustion for the rotary Atkinson engine similar to the congenital engine with pre-chamber; in split combustion chamber SI engines, small amount of fuel is burned in pre-chamber while the fuel burned in ignition chamber of rotary Atkinson cycle is considerable. In this study a mathematical modeling of spherical flame propagation inside ignition chamber and new combined conical flame and spherical flame propagation model of a new two-stroke Atkinson cycle SI engine will be presented. The mathematical modeling is carried out using two-zone combustion analysis and the model also is validated against experimental tests and compared with previous study using non-predictive Weibe function model.

Categories: Academic Journals

Investigation of objective parameters for acceptance evaluation of automatic lane change system

The Behavior Analyst - Thu, 02/01/2018 - 00:00
Abstract

Recently, with increased interest in high levels of automated driving systems such as automatic lane change system, the need for reliable assessment methods of driver acceptance has arisen. Because the acceptance depends on the individual, the assessment of the acceptance can only be based on an individual’s personal attitude, expectations, and experiences. Accordingly, subjective evaluation methods have mostly been utilized to assess the acceptance of newly developed advanced driver assistance systems. In this study, an investigation of the effects of vehicle dynamic behavior and the traffic environment on driver acceptance is conducted to provide an objective evaluation method of driver acceptance for an automatic lane change system. In order to conduct the investigation, a specific experimental program is designed and a massive database, including information on interaction behaviors between drivers, a vehicle and the traffic environment is constructed with a selected group of 19 drivers. Then, 21 parameters and their descriptive statistics for an objective evaluation index are presented to illustrate the analysis results. The results of this research can be important not only for an objective evaluation of the acceptance, but can also be expanded to suggest design criteria for control of advanced and automated driving assistance systems.

Categories: Academic Journals

Influence of temperature on the tyre rolling resistance

The Behavior Analyst - Thu, 02/01/2018 - 00:00
Abstract

Temperature is a very important factor controlling rolling resistance of road vehicle tyres. There are at least three different temperatures that may be considered as important factors controlling thermal conditions of the rolling tyre. The most common measure of the thermal conditions during tyre rolling is ambient air temperature. The other two are: pavement temperature and “tyre” temperature. Tyre temperature is the most difficult to establish, as temperatures of different parts of rolling tyres differ considerably, thus there is a problem to obtain representative values. In the authors’ opinion, air temperature is the most universal and reliable parameter to measure. The article presents results obtained in the Technical University of Gdańsk during laboratory and road measurements of different car tyres rolling on different pavements. The knowledge of rolling resistance characteristics is important for modelling car dynamics as well as fuel consumption. It is also necessary to establish proper test conditions in the future standardized on-road method of measuring rolling resistance. The results indicate that generally each tyre and pavement combination is influenced by the air temperature in a unique way, but at the same it is possible to propose some general influence factors that may be used to normalize measurements to the standard temperature of 25 °C.

Categories: Academic Journals

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