International Journal of Automotive Technology最新文献

A vehicle system motion decoupling control method was proposed to address challenges in controlling articulated heavy vehicles (AHVs). The method, based on differential geometry theory, focused on distributed electric drive AHVs. Its objective was to separate the highly nonlinear and strongly coupled dynamics system into two relatively independent subsystems: longitudinal and lateral motions. Additionally, a robust controller was designed to improve the vehicle’s resistance to external disturbances like side winds. Simulation tests using a TruckSim model of a distributed electric drive AHV show significant improvements compared to vehicles without decoupling control. The rearward amplification (RA) is reduced by 4.5%, the longitudinal velocity deviation by 67.5%, and the yaw rate deviation by 69.7%. The vehicle also demonstrates enhanced stability when subjected to strong breeze disturbances. To validate the control performance in real-time systems, the hardware-in-the-loop tests were conducted, which confirms the effectiveness of the proposed control approach in practical applications.

Abstract

One of the popular development trends in diesel engine piston assembly is higher reliability and life of components. These can be ensured by actual engine testing and comparing the appearance of piston assembly. However, testing multiple iterations involves significant cost and development which can be avoided by using software for piston-assembly performance parameters simulation. This paper contains a detailed study conducted using commercially available piston secondary dynamics simulation software and actual testing on a 4-cylinder diesel engine. In this study, the effect of piston profile and clearance on piston secondary dynamics parameters and piston-liner appearance are studied. In this study, three piston skirt profiles are designed by varying piston axial profile (barrel shape), radial profile (oval shape), and nominal clearances. The simulation results are studied in which piston profile 2 has shown minimum piston tilting, radial displacement, radial velocity, tilting velocity, radial acceleration, tilting acceleration, pressure, and force at TS and ATS. Testing and component merit rating for liner bores and piston skirts were also conducted in which piston profile 2 has shown significantly less liner bore polishing. A good correlation was observed between piston secondary motion parameters obtained from simulation and piston and liner bore observations after testing.

The purpose of this study is to extend the mileage by improving the efficiency of the electric vehicle (EV) driving and thermal management system (TMS). The powertrain system and the TMS must be considered simultaneously from the architecture stage as complementary systems to maintain the driving performance of the EV. This paper proposes an EV architectural design method and a multi-physical EV modeling technique. The main components of the EV are standardized differently from those of the internal combustion engine (ICE) vehicle, and the TMS is designed by thermal system configuration. Therefore, instead of the traditional continuous variable-based design methodology, optimal combination design based on the component database (DB) and the configuration plot presents the combinational design method. The performance of an EV varies depending on the performance of driving components and TMS, and weather. This paper presents a Modelica-based vehicle modeling technique to integrate multiple physical phenomena. Finally, we implemented an automated design using the optimal combination design method and the multi-physical integrated vehicle model design framework. The design of the C-segment EV was carried out to review the validity of the proposed method. 2880 laboratories were planned and designed using design variables with 10 levels of mixing. As a result of the design, we have confirmed that the mileage increases by 5% compared to the previous one in NEDC mode.

To improve the robustness and effectiveness for detecting free parking spaces, we propose a LiDAR-based parking sensing system, which contains multi-modules, i.e., perception, free space parking lots’ construction, parking space tracking and obstacle detection. Comprehensive experiments demonstrate that our LiDAR-based parking sensing system can not only predict free parking spaces at a long distance, but also can achieve superior performance in terms of recall rate and accuracy of detected parking spaces. Moreover, our proposed LiDAR-based parking sensing system can achieve a significant gain over the ultrasonic-based one. Therefore, our proposed system can act an effective solution for detecting free parking slots at a long distance in the field of autonomous driving.

Abstract

This paper presents a new method for the layered equivalent modeling of slot winding in the stator of a flat wire motor to accurately study the thermal performance under steady-state conditions. The conventional equivalent model for flat wire winding involves treating the slot winding as a single copper rod for temperature analysis. This method is not applicable to flat wire motors under high-power density operating conditions. As the power density of the motor increases, the flat wire winding is more affected by skin effect and proximity effect, resulting in a sharp increase in AC loss and uneven distribution of losses in the slot winding. The conductor losses are highest near the slot opening, a characteristic that conventional model is unable to reflect. The proposed layered modeling method fully takes into account the characteristics of flat wire winding. This method involves adding interlayer insulation to divide the overall modeled conductor into layers and fully considers the thermal parameters, heat transfer characteristics, and distribution of materials within the slot to establish a new equivalent model for flat wire winding. Finally, the comparison of the results with the actual model and experimental tests demonstrates that this method effectively improves the calculation accuracy by 2.2% of the flat wire winding equivalent model.

The application of ‘Target Cascading’ in the product development process is well known to be effective in various industry fields, and it is a methodology that is already actively applied in various forms in the field of vehicle Ride & Handling (R&H) performance development. This paper proposes a model-based vehicle performance benchmarking methodology and a technology for setting system characteristics to achieve handling performance objectives as a means of utilization for this. Rather than introducing already well-known target deployment techniques, a process is proposed for practical use in the vehicle development phase through the development of interfaces between low degrees of freedom vehicle model and optimization software. The methodology presented in this study is expected to be available in a timely manner as a practical vehicle performance development tool.

This paper compares various angle-tracking algorithms to balance the performance and noise for a steering-by-wire (SBW) system. Direct and quiet steering experiences can improve drivers’ acceptance of the SBW system. Linear quadratic regulator (LQR) control, robust control, and conventional cascade proportional–integral (PI) control have been developed and compared both theoretically and experimentally. To avoid the risky and time-consuming parameter-tuning process, a high-fidelity steering resistance model, which comprises a linear two-degree-of-freedom vehicle model and a dynamic LuGre friction model is established. Step and sine wave tests are simulated in a Matlab/Simulink environment to determine the reasonable parameter region for various methods. Then, the three types of algorithms are implemented on a prototype SBW vehicle and compared under the same scenarios. Finally, the simulated and experimental results are illustrated in detail. According to the indicators of control bandwidths, steady-state errors, cockpit sounds, and current waveforms, it is clear that LQR and robust control can achieve faster response and more acceptable noise, with uncertain and relatively larger tracking errors. Cascade PI control, in comparison, can realize smaller steady-state errors and gentler current waveforms, with slight noise and slower response.

In general, a leaner mixture condition improves combustion efficiency in compression ignition (CI) combustion using diesel. However, in the case of leaner air–fuel mixture conditions, it disturbs flame propagation in spark ignition combustion using gasoline, i.e., low reactivity fuel, causing a decrease in combustion efficiency. Since dual-fuel combustion in a CI engine typically involves the use of high- and low-reactivity fuels together, the differing reactivity conditions in the cylinder become as important as the local equivalence ratio in the cylinder. Thus, there is a need to verify the effect of a leaner mixture condition on combustion efficiency in dual-fuel CI combustion. For this reason, this study experimentally evaluates the effects of varying equivalence ratios on the combustion efficiency of gasoline/diesel dual-fueled CI combustion in a 0.4-L single-cylinder engine under low-speed (1500 rpm) and low-load (total LHV 570 J/str) conditions. To vary the equivalence ratios, intake pressures and exhaust gas recirculation (EGR) rates were, respectively, changed under the part-load condition. The results emphasize that as the equivalence ratio becomes leaner by increasing the intake pressure, combustion efficiency worsens due to the low reactivity properties and certain flame propagation modes of gasoline combustion. On the contrary, increasing the EGR rate did not significantly influence combustion efficiency, but it effectively helped reduce nitrogen oxide (NOx) emissions. Based on these results, it is concluded that optimizing dual-fuel CI combustion to suppress NOx emissions is better achieved using EGR, rather than creating a leaner mixture condition.

The purpose of this study is to simultaneously reduce NO_X and CO harmful gases according to the promoters and support types of the H₂-SCR. The 0.5Pt-2CeO₂-5Ru/TiO₂ catalyst loaded with 7 wt% Ru showed a lower NO_X conversion rate compared to than the 0.5Pt-2CeO₂/TiO₂ (STD), but the window shifted to the right, and it showed NO_X reduction performance of up to 30% at 175 °C. When Zr was loaded, de- NO_X performance was not improved at the temperature of 200 °C starting from a low catalyst temperature of 75 °C. With in the influence of the support types, the 0.5Pt-2CeO₂/TiO₂ H₂-SCR catalyst showed the highest NO_X conversion rate below 125 °C, and the low-temperature activity of NO_X was higher than that of the three zeolite-loaded H₂-SCR catalysts. Low temperature activity was improved because the TiO₂ has excellent reducing and oxidizing ability. Among the three zeolites, the CO reduction performance of the 0.5Pt-2CeO₂/Zeolite (1) catalyst with high Al content was the lowest.

In the longitudinal driving of a heterogeneous platoon, external disturbances of local vehicles can cause safety problems of the intended functionality. Therefore, a cooperative control method based on situation assessment is proposed. First, the minimum safe distance is determined according to the state of adjacent vehicles. A novel situation assessment model is established to characterize the stability of the platoon. Vehicle spacing, speed, and acceleration are selected as evaluation indicators. Then, an improved active disturbance rejection controller (IADRC) is designed to improve platoon stability through feedback compensation control. In addition, considering the unnecessary continuous involvement of the IADRC, its intervention time is determined by the situation assessment results. Finally, simulation and hardware-in-the-loop (HIL) experiments are carried out under two communication topologies. The results show that the proposed method can effectively improve the stability and safety of the platoon.