International Journal of Automotive Technology最新文献

Automated Valet Parking Systems (AVPS) relieve the driver of the entire parking process. Many of the systems known today rely on a combination of automotive sensors with sensors of the infrastructure. For this purpose, parking facilities are equipped with comprehensive sensor technology to support the vehicles in environment sensing and route planning. This approach is comparatively expensive which is why many parking operators don’t provide that technology to their customers. This paper proposes a lean AVPS system architecture that requires minimal effort to adapt the infrastructure. At the same time, state-of-the-art vehicle technology is used to make AVPS more profitable overall. At the beginning, an overview will be given describing the state of the art of AVPS. Subsequently, requirements for the AVPS will be elaborated, whereby the system can be designed and implemented in the following. Finally, the presentation of simulation results shows that one doesn’t have to extend the infrastructure with sensors to develop a safe and reliable AVPS.

The steer-by-wire (SbW) system is a promising system in the realm of automotive engineering. It substitutes the mechanical connection between the steering wheel and the front road wheels with an electronic signal-based functional connection. The SbW system offers several advantages over conventional steering systems, including weight reduction, reduced vibration, and enhanced steering functionality configuration. However, the absence of a mechanical linkage in the SbW system gives rise to certain challenges. The SbW system requires endowing adequate steering feel such as damping and reaction force using feedback motor, and the road wheel needs robust control of pinion motor for normal load variation by passengers and self-aligning torque as external disturbance. The SbW system is composed of the steering feedback module (SFM) and the road wheel module (RWM). This paper proposes a control approach to generate steering feel for SFM, in which steering feel is generated using an admittance model based on velocity control. A disturbance observer is applied to ensure robustness of velocity control. The steering wheel torque versus steering wheel angle (T–A) curve is used to analyze steering feel characteristic and evaluate steering feel. The proposed steering system is validated through experiments that confirm its ability to provide satisfactory steering feel for vehicles. This work may offer a novel solution for the design of advanced steering systems in the field for the future mobility such as an autonomous driving.

Abstract

This study aims to investigate the relationship between the static characteristics of non-pneumatic tires (NPTs) and spoke design parameters using the finite element (FE) method. A three-dimensional FE model of the NPT was established. The influence of different ranges of stress and strain on the calculation accuracy of the Neo-Hookean and Yeoh constitutive models was analyzed. Subsequently, the main design parameters—spoke thickness, spoke number, and arc curvature—were selected according to the geometric characteristics of the spokes. The effects of these three parameters on the vertical stiffness, maximum spoke stress, overall maximum stress, and maximum and average contact pressures were examined using univariate and multivariate analysis methods. The range and variance analysis results indicated that the spoke thickness, spoke number, and arc curvature had a significant effect on the vertical stiffness. Finally, the relationship between the vertical stiffness and product of the spoke thickness and number was obtained using a nonlinear fitting method. When the arc curvature of the spoke was less than 5 m⁻¹, the errors between the calculated and simulated vertical stiffness did not exceed 5%. This observation can be used to facilitate the rapid design of spoke parameters under different load capacity requirements.

The advancement of transportation machinery has played a crucial role in driving global economic and societal growth. However, this progress has also given rise to challenges, such as the depletion of chemical resources and the escalating impact of climate change. As a result, automobile companies are now prioritizing energy efficiency and transitioning towards eco-friendly vehicles. In response to this demand, various efforts have been made to harvest energy and improve the efficiency of eco-friendly vehicles, with energy-harvesting dampers emerging as a promising solution. This study focuses on the optimization of the shape and design of a rotary power generation system integrated within an energy harvesting system. The primary objective of the rotary power generation system is to convert mechanical motion into electrical energy, thereby enhancing the overall efficiency and sustainability of eco-friendly vehicles. By considering the specific characteristics of SAE 30 W working oil within the damper, the optimal blade shape and generator can be determined to maximize the power generation capabilities of the system.

The paper presents a new internal model control (IMC) based control technique for lateral trajectory tracking of autonomous vehicles. The controller’s proposed structure employs a robust, fault-tolerant nonlinear internal servo control with optimal reference generation concerning vehicle yaw stability and physical limitations. The presented inscription of the reference generation creates a convex optimization task that can be used in real-time applications. Improvements in yaw-rate stability of vehicle motion control are first shown through simulation results performed in a Simulink environment. The controller structure was also implemented in a real-time model and was examined in a Mercedes C-Class vehicle. In this article, the simulation results and the real-time measurements are presented. The results show that the proposed controller has high efficiency in disturbance rejection and lower sensitivity towards parameter changes compared to a model predictive control (MPC) structure.

In this experiment, it was experimentally investigated the combustion and exhaust characteristics, as well as the thermal efficiency, of RCCI combustion using gasoline, ethanol, and propane as low-reactivity fuels under four operating conditions. For each operating condition, gISNO_x was limited to 0.15 g/kWh, and gISSmoke was limited to below 15 mg/kWh. The experiment was conducted by determining the operating conditions that satisfied these limitations and resulted in the highest city thermal efficiency. The low-reactivity fuels were supplied by port injection, while diesel was directly injected into the combustion chamber using a diesel injector. As a result, when gasoline is replaced with low-carbon fuels like ethanol and propane, the reduction in CO₂ emissions occurred. Under maximum power conditions, using ethanol allowed for a maximum reduction in CO₂ emissions of 6.81%. Depending on the driving conditions, ethanol showed a reduction ranging from 3.60 to 6.81%, while propane exhibited a reduction ranging from 3.10 to 5.64%. Additionally, by substituting with ethanol and propane, the GIE could be improved up to 44.73 and 43.56%, respectively.

This study proposes the slope of the engine speed trend line (Slope_ESTL) as a new misfire detection index for a four-cylinder engine, not limited to four-cylinder engines. Slope_ESTL is defined as angular acceleration between the first and the last teeth of each cylinder in the cycle. Slope_ESTL is flat and near 0 when the cylinder is normally combusted. A misfire leads to an abrupt decrease under the threshold. While it is affected by post oscillation just after misfires, there is enough margin between Slope_ESTL of the misfired cylinder and post-oscillated Slope_ESTL. The mean misfire detection and detection fault rates of the Slope_ESTL were over 97% and under 1% in this study, making it a good misfire detection index. However, most of the first misfired cylinder on dual cylinder misfire can seldom be detected as a misfire at the high engine speed over 5000 rpm in the single cylinder misfire pattern. This is caused by the inertia force of the crankshaft system and is a demerit for the misfire detection index. It is one of the two RPM slopes used to calculate the Gap and ΔGap slopes proposed by the author. Slope_ESTL can be used with Gap and ΔGap slopes, because they have their specific characteristics as misfire detection indices and their combination logic should be studied more. Furthermore, Slope_ESTL can be affected by the machining tolerance of the teeth in the sensor wheel, torsional vibration, and non-uniformity in the stroke operation of the piston. However, it uses the tooth time measured using the existing crankshaft position sensor; an additional sensor is not required, which makes it economical.

Abstract

To promote the efficient and clean application of low-carbon alcohol fuels in internal combustion engines, this article compares and studies the effects of three internal EGR strategies, including exhaust valve lift strategy (EVVL), exhaust timing advance strategy (EVT), and intake valve timing advance strategy (IVT), on the combustion, performance, and emissions of gasoline, methanol, and ethanol. Under the same internal EGR rate, the internal EGR temperature generated by the three valve strategies is, from highest to lowest, as follows: EVT, EVVL, and IVT. With an increase in internal EGR in the cylinder, the ignition delay and combustion duration under the EVVL and IVT strategies increase progressively, whereas the ignition delay under the EVT strategy tends to first shorten and then lengthen. Methanol has the shortest combustion duration. Furthermore, methanol and ethanol have lower heat transfer and exhaust losses than gasoline. The thermal efficiency of methanol, ethanol, and gasoline can be raised by 7.7%, 7.5%, and 7.2%, respectively, using the IVT strategy; 3.1%, 3.9%, and 4.6% using the EVVL strategy; and 6.82%, 6.85%, and 7% using the EVT strategy. The combination of methanol and ethanol with internal EGR technology greatly reduces NOx emissions, with an 84.5% reduction under the EVVL strategy.

Fuel Cell Electric Vehicle (FCEV) powertrain layouts and control strategies have historically overlooked the asymmetric energy storage effect, despite its significant impact on system efficiency. In this study, we propose a novel FCEV powertrain layout using dual fuel cells to uncover hidden fuel efficiency improvement factors in comparison with the conventional Single Fuel Cell System (SFS). To address the issues of low efficiency operation in SFS and the limitations of existing energy management strategies that hinder high output performance, we present a minimum efficiency-based power control strategy. Additionally, we implement a partial system operation strategy to optimize efficiency according to the state of the power sources. This combined approach results in substantial improvements in both hardware and software efficiency, a possibility that was not previously achievable. Through this research, we demonstrate the potential for enhancing the fuel efficiency of the multi-stack system, a concept that has not been implemented yet. Moreover, we propose a new direction for the architectural design of FCEVs that overcomes the limitations of the SFS, thereby addressing potential malfunctions.

In road transport, varying fuel flow rates make it hard to maintain a consistent water ratio in non-surfactant emulsion fuels using the Real-Time Non-Surfactant Emulsion Fuel Supply System (RTES). Thus, it becomes more reasonable to establish an appropriate range of water content tailored to a road condition. Therefore, this study aims to evaluate fuel consumption and exhaust emissions of non-surfactant emulsion fuel in light-duty trucks equipped with RTES, focusing specifically on urban conditions. On-road testing and 300-s idling tests were used as the urban conditions to compare diesel with non-surfactant Water-in-Diesel Emulsion (WiDE) fuel with water percentages from low to high concentrations of water, namely WiDE low%, WiDE med%, and WiDE high%. During idling tests, all emulsion variants reduce fuel consumption. WiDE high% exhibits the most substantial NOx reduction of 9.2%. On-road testing reveals comparable WiDE and diesel fuel consumption, despite the RTES increased electrical load. WiDE high% shows an increment for NOx and CO emissions by 11.71% and 202.19%. In conclusion, a 7.4% to 21.1% water content range was suggested for non-surfactant emulsion fuel in urban road conditions.