Effect of regenerative braking energy on battery current balance in a parallel hybrid gasoline-electric vehicle under FTP-75 driving mode

In recent years, a hybrid electric vehicle (HEV) has been considered a successful technology. Especially, in case of a full HEV, the motor can drive the vehicle by itself at low velocity or assist the engine at high load. To improve the hybrid electric vehicle’s efficiency, a regenerative braking system is also applied to recover from kinetic energy. In this study, an experimental control apparatus was set up with a parallel hybrid electric vehicle mounted on a chassis dynamometer to measure ECU (engine control unit) and MCU (motor control unit) signals, including the current and state of charge in the battery. In order to analyze regenerative braking characteristics, user define braking driving cycle was introduced and carried out using different initial velocities and braking times. The FTP 75 driving cycle was then adapted under different initial SOC (state of charge) levels. The experiment data was analyzed in accordance with the vehicle velocity, battery current, instant SOC level, motor RPM, engine RPM, and then vehicle driving mode was decided. In case of braking driving cycle, it was observed that SOC were increased up to 1.5 % when the braking time and the velocidy were 6 second and 60 km/h, respectively. In addition, using the FTP 75 driving cycle, mode 1 was most frequently operated at SOC 65 conditions in phase 1. In phase 2, due to frequent stop-go hills, percentage of mode 1 was increase by 22 %. Eventually, despite of identity, it was shown that the characteristics of phase 3 differed from phase 1 due to the evanishment of the effects of initial SOCs.     

Bayesian game-theoretic approach based on 802.11p MAC protocol to alleviate beacon collision under urban VANETs

Vehicular Ad-hoc Networks (VANETs) facilitate the broadcasting of status information among vehicles. In the IEEE 802.11p/WAVE vehicle network environment, the strict periodic beacon broadcasting of safety messages requires status advertisement to assist drivers in maintaining safety. The beacon broadcasting is required for real-time communication, and for avoiding the degradation of communication channels in high vehicular density situations. However, a periodic safety beacon in the IEEE 802.11p/WAVE standard can only transmit packets on a single channel using the MAC protocol. In high vehicular density situations, the channel becomes overloaded, thereby increasing the probability of beacon collision, and hence reducing the influx of successfully received beacons, which increases the delay. Many studies have indicated that appropriate congestion control algorithms are essential to provide efficient operation of a network. In this paper, to avoid beacon congestion, we have considered game theoretic models of wireless medium access control (MAC) where each transmitter makes individual decisions regarding their power level or transmission probability. We have evaluated the equilibrium transmission strategies of both the selfish and the cooperative user. In such a game-theoretic study, the central question is whether Bayesian Nash equilibrium (BNE) exists, and if so, whether the network operates efficiently at the equilibrium point. We proved that there exists only one BNE point in our game and validated our result using simulation. The performance of the proposed scheme is illustrated with the help of simulation results.     

Design and simuation of a vehicle test bed based on intelligent transport systems

As growing demand of vehicle safety system, especially regarding intelligent transport systems (ITS), automotive manufacturers are focusing more on driving safety and efficient transportation for vehicle users. Many safety systems have been launched in the market recently so, it is important to evaluate the vehicle safety systems and ITS. The ITS based intelligent vehicle test bed was constructed to meet the growing demand of test and verification for such ADAS and ITS systems. First, this paper describes in detail concept of the test-bed. This test-bed is carefully designed to meet the requirements of ISO/TC204 standards. In order to verify the design of the test-bed, virtual test with driving siulator was processed on a virtual test tracks. This test-bed will be used to conduct testing on various ITS and ADAS technologies, such as adaptive cruise control (ACC), lane departure warning system (LDWS), cooperative intersection warning system as well as rollover stability control (RSC) and electronic stability control (ESC), etc.     

Shape design optimization of interior permanent magnet motor for vibration mitigation using level set method

This paper presents a new optimization method to obtain the structural design of permanent magnet motor which can reduce the mechanical vibration. The optimization problem is formulated to minimize a multi-objective function including the mean compliance of the whole stator for maximizing the stiffness under the magnetic force and the torque ripple by aligning torque profiles to a constant target value for maximizing the magnetic performance, with constraint for material usage. The level set function is introduced for representing the structural boundaries and calculating the material properties. A coupled magneto-mechanical analysis is performed to verify the vibration characteristic of the motor system and obtain the design sensitivities. To confirm the usefulness of the proposed design method and to obtain the optimum structural design for low vibration motor, a design example of 20 kW interior permanent magnet motor developed for the power train of a hybrid electric vehicle is provided.     

Development of route information based driving control algorithm for a range-extended electric vehicle

A route information based driving control algorithm was developed for an RE-EV which consists of two motorgenerators, MG1 and MG2. A threshold power which controls the engine on/off to charge the battery was obtained by an optimization process using route information, such as the vehicle velocity and altitude. The threshold power allows the vehicle to travel to the final destination while making the final battery SOC close to SOC _low. Using the threshold power, route based control (RBC) was proposed by considering the driver’s characteristics and traffic conditions using the driving data base. In addition, a relationship between the threshold power and various initial battery SOC was obtained by off-line optimization. The performance of the RBC was evaluated by simulation and human-in-the-loop simulation (HILS) for city driving. It was found from the simulation and HILS results that the RBC achieved approximately 4 % to 12 % reduction in fuel consumption compared to the existing charge depleting/charge sustaining (CD/CS) driving control.     

Improving multi-channel wave-based V2X communication to support advanced driver assistance system (ADAS)

The advent of vehicle-to-everything (V2X) communication has opened the opportunity to design advanced driver assistance systems (ADAS) that collect information from sensors in neighboring vehicles and roadside infrastructure. IEEE and ETSI have designed network protocol standards for V2X communications. Despite the differences between the vehicular wireless communication architecture defined by ETSI and the IEEE protocol stack, the two standards have multichannel operations as a main commonality, with some channels dedicated to safety-critical applications and others to nonsafety services. Some recent studies have demonstrated that these standards might not provide sufficient channel utilization for reliable exchange of information in mid- and heavily congested scenarios. In this paper, we propose and evaluate the performance of a driver-assistance system to reduce the connectivity gaps between vehicles and roadside units (RSUs). This cooperative system of multi-service channel allocation will improve radio channel utilization. We also show that the required latency for this inter-vehicle communication can be obtained using the IEEE-WAVE standards and dedicated short-range communication (DSRC) proposed for vehicular environments. Simulation results show that the proposed scheme can improve the average throughput by up to 15 % in various traffic density conditions compared with the dynamic channel allocation method.     

Lateral stability control of dynamic steering for dual motor drive high speed tracked vehicle

In this paper, the torque and power required by dual motors for electric tracked vehicle during dynamic steering maneuvers with different steering radiuses are analyzed. A steering coupling drive system composed of a new type of center steering motor, two Electromagnetic (EM) clutches, two planetary gear couplers, and two propulsion motors is proposed for the dual motors drive high speed electric tracked vehicle (2MHETV), which aims to improve its lateral stability. An average torque direct distribution control strategy based on steering coupling and an optimization-distribution-based close-loop control strategy are designed separately to control the driving torque or regenerative braking torque of two propulsion motors for vehicle stability enhancement. Then models of the 2MHETV and the proposed control strategy are established in Recudyn and Matlab/Simulink respectively to evaluate the lateral stability of dynamic steering for the 2MHETV with different steering radiuses on hard pavement.The simulation results show that the lateral stability of the 2MHETV can be significantly improved by the proposed optimization-distribution-based close-loop control strategy based on steering coupling system.     

Comparison of computational and analytical methods for evaluation of failure pressure of subsea pipelines containing internal and external corrosions

In the designing stage of subsea pipelines, the design parameters, such as pipe materials, thickness and diameters, are carefully determined to guarantee flow assurance and structural safety. However, once corrosion occurs in pipelines, the operating pressure should be decreased to prevent the failure of pipelines. Otherwise, an abrupt burst can occur in the corroded region of the pipeline, and it leads to serious disasters in the environment and financial loss. Accordingly, the relationship between the corrosion amount and failure pressure of the pipeline, i.e., the maximum operating pressure, should be investigated, and then, the assessment guideline considering the failure pressure should be identified. There are several explicit type codes that regulate the structural safety for corroded subsea pipelines, such as ASME B31G, DNV RF 101, ABS Building and Classing Subsea Pipeline Systems, and API 579. These rules are well defined; however, there are some limitations associated with describing precise failure pressure. Briefly, all of the existing rules cannot consider the material nonlinearity, such as elastoplasticity effect of the pipeline, as well as the actual three-dimensional corrosion shape. Therefore, the primary aim of this study is to suggest a modified formula parameter considering the above-mentioned pipeline and corrosion characteristics. As a result, the material nonlinearity as well as the corrosion configuration, i.e., axial/circumferential corrosion length, width and depth, is reflected in a set of finite element models and a series of finite element analysis considering the operation conditions are followed. Based on the comparative study between the simulation and analytical results, which can be obtained from the classification society rules, the modified formulae for failure pressure calculation are proposed.     

Modelling daily activity program generation considering within-day and day-to-day dynamics in activity-travel behaviour

This paper presents a comprehensive econometric modelling framework for daily activity program generation. It is for day-specific activity program generations of a week-long time span. Activity types considered are 15 generic categories of non-skeletal and flexible activities. Under the daily time budget and non-negativity of participation rate constraints, the models predict optimal sets of frequencies of the activities under consideration (given the average duration of each activity type). The daily time budget considers at-home basic needs and night sleep activities together as a composite activity. The concept of composite activity ensures the dynamics and continuity of time allocation and activity/travel behaviour by encapsulating altogether the activity types that are not of our direct interest in travel demand modelling. Workers’ total working hours (skeletal activity and not a part of the non-skeletal activity time budget) are considered as a variable in the models to accommodate the scheduling effects inside the generation model of non-skeletal activities. Incorporation of previous day’s total executed activities as variables introduces day-to-day dynamics into the activity program generation models. The possibility of zero frequency of any specific activity under consideration is ensured by the Kuhn-Tucker optimality conditions used for formulating the model structure. Models use the concept of random utility maximization approach to derive activity program set. Estimations of the empirical models are done using the 2002–2003 CHASE survey data set collected in Toronto.

水下航行器近海底铺缆运动仿真研究

使用水下航行器进行铺缆较水面船铺缆有众多优势。为了快速有效地完成铺缆任务,该文对水下航行器近海底铺缆运动进行了仿真研究,分析了放缆速度、相对海流速度和航行高度等参数对铺缆运动的影响。在此基础上,为一台载人潜水试验艇拟定了近海底铺缆试验方案,并成功完成了试验任务。