Realization of pmp-based control for hybrid electric vehicles in a backward-looking simulation

Optimal control is generally not possible without information about the future coming up, and it is not easy to obtain an optimal solution even though the information is given a priori. In this paper, a control concept based on Pontryagin’s Minimum Principle (PMP) is introduced as an efficient solution to generate an optimal control trajectory for Hybrid Electric Vehicles (HVEs) when the performance of the vehicles is evaluated on scheduled driving cycles at a simulation level. The main idea of the control concept is to minimize Hamiltonian, which is interpreted as equivalent fuel consumption, and the Hamiltonian is characterized by a co-state, which is interpreted as a weighting factor for the electrical usage. A key aspect of the control problem is that an appropriate initial condition of the co-state is required to satisfy the boundary condition of the problem. In this study, techniques to calculate the Hamiltonian in different hybrid configurations are introduced, and a methodology to look for the initial condition of the co-state is studied, so that the controller is able to realize a desired State Of Charge (SOC) trajectory. To address the issue, we utilize a shooting method with multiple initial conditions based on the concept of the Newton-Raphson method, and all these techniques are realized in a backward looking simulator. The simulation results show that the PMP-based control is a very efficient approach to produce the optimal control trajectory, and the performance is compared to the optimal solution solved by Dynamic Programming (DP).     

Durability prediction for automobile aluminum front subframe using nonlinear models in virtual test simulations

This research work presents fatigue life evaluation techniques for an automotive vehicle aluminum front subframe using virtual test simulation technology with nonlinear suspension components model. The technology was used for improving the accuracy of the polynomial model used in conventional analysis. The proposed nonlinear suspension components models were developed using direct approach. The effects of the nonlinear elements on the prediction of the fatigue life were also analyzed. Actual aluminum front subframe was tested using half-car road test simulator to verify the accuracy of the models. It was found that the proposed nonlinear models yield more accurate results than conventional polynomial models. The proposed virtual test simulation technology with nonlinear suspension components model can be used to predict fatigue life for vehicle chassis structures more accurately.     

Impacts of improvements in rural roads on household income through the enhancement of market accessibility in rural areas of Cambodia

Rural areas in low-income countries often face severe poverty typically caused by insufficient accessibility to basic facilities. Improvements in rural roads are expected to reduce poverty although the mechanism has not been investigated sufficiently. This study empirically analyzes the impacts of rural road improvements implemented from 2012 to 2014 in Cambodia, highlighting local residents’ accessibility to local markets. This study assumes two causal relationships: rural road improvements have upgraded the accessibility and travel frequency to local markets, and the upgraded accessibility and travel frequency to local markets have led to a growth in local residents’ income. The hypotheses are statistically tested with a dataset developed through a questionnaire survey conducted in three areas in 2016. The dataset contains responses from 400 local residents to questions concerning their social attributes, livelihoods, travel modes, travel frequency, and time/cost of travels to the basic facilities. The quasi-experimental design incorporating a difference-in-differences design and an inverse possibility of treatment weighting approach revealed that the improvements in rural roads did not affect travel time nor travel cost but significantly enhanced travel frequency to local markets, and that an increase in the travel frequency to local markets and travel time savings significantly contributed to the households’ income growth. The results suggest that the improvement of seasonal reliability in accessing local markets through an introduction of all-weather roads could be critical to enhance household income, particularly in areas where agriculture is a leading industry and weather conditions are unstable across seasons.

     

Design of emergency braking algorithm for pedestrian protection based on multi-sensor fusion

Globally, safety has become an increasingly important issue in the automotive industry. In an attempt to reduce traffic fatalities, UNECE launched a new EU Road Safety Program which aims to decrease the number of road deaths by half by 2020. AEB (Autonomous Emergency Braking) is a very effective active safety system intended to reduce fatalities. This study involves the design of a multi-sensor data fusion strategy and decision-making algorithm for AEB pedestrian. Possible collision avoidance scenarios according to the EuroNCAP protocol are analyzed and a robust pedestrian tracking strategy is proposed. The performance of the AEB system is enhanced by using a braking model to predict the collision avoidance time and by designing the system activation zone according to the relative speed and possible distance required to stop for pedestrians. The AEB activation threshold requires careful consideration. The test results confirm the advantages of the proposed algorithm, the performance of which is described in this paper.     

Development of algorithms for commercial vehicle mass and road grade estimation

Estimation algorithms for road slope angle and vehicle mass are presented for commercial vehicles. It is well known that vehicle weight and road grade significantly affect the longitudinal motion of a commercial vehicle. However, it is very difficult to measure the weight and road slope angle in real time because of lack of sensor technology. In addition, the total weight of a commercial vehicles varies depending on the freight. In this study, the road grade and vehicle mass estimation algorithms are proposed using the RLS (Recursive Least Square) method and only the in-vehicle sensors. The proposed algorithms are verified in experiments using a commercial vehicle under various conditions.     

A suggestion of gap flow control devices for the suppression of rudder cavitation

This paper presents the numerical analysis of rudder cavitation in propeller slipstream and the development of a new rudder system aimed for lift augmentation and cavitation suppression. The new rudder system is equipped with cam devices which effectively close the gap between the horn/pintle and movable wing parts. A computational fluid dynamics code that solves the Reynolds-averaged Navier–Stokes equations is used to analyze the flow field of various rudder systems in propeller slipstream. The body force momentum source terms that mimic flow field behind a rotating propeller are added in the momentum equations to represent the influence of the propeller and its slipstream. For detailed explication of the new rudder system’s lift augmentation and cavitation suppression mechanism, three-dimensional flow analysis is carried out. Simulations clearly display the mechanism of the lift augmentation and cavitation suppression. The computational results suggest that the Reynolds-averaged Navier–Stokes-based computational fluid dynamics reproduces the flow field around a rudder in propeller slipstream and that the present concept for a cavitation suppressing rudder system is highly feasible and warrant further study for inclusion of the interaction with hull and mechanical design for manufacturing and operations.     

Autonomous Emergency Braking Considering Road Slope and Friction Coefficient

The Autonomous Emergency Braking (AEB) systems have been actively studied for the safety enhancement and commercialized for the past few years. Because the driver tends to overly rely upon active safety systems, AEB needs to be designed to reflect the real road situations such as various road slope and friction coefficient. In this study, an AEB control algorithm is proposed to compensate for the effects of the slope and the friction of road. Based on the maximum possible deceleration for the real road conditions, the minimum braking distance is described with margin parameters for AEB activation control. The deceleration controller with a feedforward term is designed to avoid the collision during AEB operation on real road conditions. The proposed algorithm is validated in simulations first and the experimental verification is performed in the various slope conditions.     

英国与荷兰非机动化交通模式比较研究

非机动化交通模式以其低能耗、健康、低消费、缓解交通拥堵等优势被认为是生态化且可持续化的绿色交通发展模式。近些年来,英国政府与荷兰政府提出了一系列的政策措施,加强了对交通安全的教育,用于降低机动化交通速度,促进非机动化交通模式的发展。通过对比发现非机动化交通配套设施在英国的发展远不及荷兰完善,且荷兰的非机动化交通与其他模...     

Analyzing the time frame for the transition from leisure-cyclist to commuter-cyclist

A recent survey reported that many commuter-cyclists had enjoyed leisure bicycling on a regular basis prior to becoming a commuter-cyclist. While bicycling for leisure, it is assumed that they considered various factors that led them to consider becoming commuter-cyclists. This study began with the question of how long it would take for a leisure-cyclist to become a commuter-cyclist, and it focused on the time that elapsed between leisure-cyclists transitioning to commuter-cycling. In order to analyze the time frame, it was hypothesized that the probability that a leisure-cyclist would become a commuter-cyclist at a certain time would be conditional on the duration that elapsed from the onset of leisure cycling till that time, which represents the “snowballing” or “inertial” dynamics of duration. A robust methodology, which is known as the “hazard model,” was adopted to accommodate such characteristics of a time period. In addition, various external covariates such as individual-specific characteristics, variables associated with the current or previous commuting mode, supply variables regarding bicycle facilities, and individual latent propensities were adopted to account for the duration of changes that would be generally applicable. As a result, many useful results were derived that could be used in fomenting policies to promote cycling to work. It was found that government should invest in establishing segregated lanes for leisure- and commuter-cyclists. It also turned out that a long distance to work hinders a leisure-cyclist from progressing to commuter-cycling. According to the results, young white-collar workers who live in high-rise apartments and enjoy intensive leisure-cycling in groups, are a good target toward whom promotions for commuter-cycling should be focused. However, an unfortunate development was that, when compared with car-commuters, it was found that transit-commuters are more likely to become commuter-cyclists.     

Research trends and agenda on the Belt and Road (B&R) initiative with a focus on maritime transport

The ‘Silk Road Economic Belt and the 21st-Century Maritime Silk Road’ (collectively known as Belt and Road, B&R) has been initiated by the Chinese government in 2013. The B&R is increasingly becoming a focal point for socio-economic–political interests because of its likely impact on land and sea transport and maritime logistics. The aims of this study were threefold: first, to provide an overview on the B&R, focusing on its key structural elements, such as transport corridors, city clusters, dry ports, infrastructure, zoning, and area development; second, to identify the expected impacts of the B&R on trade and implications on structural changes in transportation systems, port networks, and international logistics. Finally, to discuss major research trends and setting up of research agenda which will contribute to enriching the existing literature and shaping the global trade operations and drive economic growth in the context of the B&R.