International Journal of Vehicle Performance (28 papers in press)
Review of Rapid Aging Testing Methods of Three-way Catalyst for Gasoline Engine
by Sheng Su, Yitu Lai, ChunXiao Hao, Pan Hou, Tao Lv, Yunshan Ge
Abstract: Recently, many advanced automotive companies around the world have developed rapid aging methods for their three-way catalyst converters (TWC). However, the systematic summary of related research progress is still lacking. Therefore, this work introduces TWC equivalent aging mechanism, classifieds and summarizes the current typical rapid aging technology for TWC. The primary aging of TWC on gasoline vehicle is thermal aging, and the equivalent aging theory is based on the Arrhenius equation. The current rapid aging technology for TWC, including vehicle aging, engine bench aging, and burner aging. There are three kinds of modes for engine bench aging, which are single mode, two-mode and multi-mode aging cycle. Introduces the common two-mode and multi-mode aging cycle in detail. Meanwhile, the paper compares the characteristics of different aging technologies. In general, engine bench aging methods and burner aging methods take less time, manpower and consumable cost than traditional vehicle aging, but there is a certain deviation from the actual vehicle aging effect.
Keywords: gasoline vehicle; three-way catalyst; Arrhenius; Rapid Aging; vehicle aging; engine bench aging; burner aging.
Lightweight Design of Drive Axle Housing Based on Reliability
by Yang Chen, Xiandong Liu, Yingchun Shan, Tian He
Abstract: By introducing the influence of uncertain factors on the mechanical properties of drive axle housing, this paper investigates the method improving the reliability of the optimization scheme of a drive axle housing of off-road vehicle. Firstly, the finite element model of the drive axle housing is established, and its simulation is carried out according to the bench test standard. Then the Monte Carlo method is applied to study the influence of uncertain factors on the reliability of the axle housing. And the lightweight design of the axle housing is performed based on the 6? theory. The result shows that the weight of the axle housing is reduced by 12.48% under the premise of every performance with high reliability.
Keywords: drive axle housing; finite element analysis; reliability; lightweight design.
Unmanned Autonomous Ground Hybrid Vehicle Thermal Management System - Design and Control
by Junkui Huang, Shervin Shoai Naini, Richard Miller, Denise Rizzo, Katie Sebeck, John Wagner
Abstract: Modern autonomous hybrid vehicles are required to have longer range, better fuel economy and operate in diverse climate conditions. These constraints present new design challenges such as a more robust system architecture, varying component operating temperatures and complex electronic control. This paper examines the introduction of a heat pipe based thermal management system for the vehicles electric motors and battery pack. Mathematical models were developed to numerically describe the components thermal behavior. Nonlinear controllers were designed to maintain the electric motor, battery pack, and the internal combustion engine temperatures about their reference values by regulating multiple actuators (e.g., pump, radiator fan, blower, compressor and smart valve) for minimized temperature fluctuations and energy consumption. Numerical results considered various road grades and ambient conditions to demonstrate the thermal management system robustness. The electric motors stator temperature was maintained at approximately 70
Keywords: Autonomous vehicles; hybrid electric powertrain; heat pipe; thermal management; nonlinear control.
Quantitative Assessment of Modeling and Simulation Tools for Autonomous Navigation of Military Vehicles over Off-Road Terrains
by Michael Cole, Cesar Lucas, Kumar Kulkarni, Daniel Carruth, Christopher Hudson, Paramsothy Jayakumar, David Gorsich
Abstract: Autonomous systems are the future of the Army and Ground Vehicle Systems Center has aligned itself accordingly to support unmanned ground vehicle (UGV) development. Physically testing autonomous algorithms and vehicle systems can be expensive and time consuming, a problem addressed by the use of modeling and simulation (M&S) tools. A multitude of both Government owned and Commercial Off-the-Shelf Tools (COTS) are widely available, all claim to virtually evaluate autonomous ground vehicles operating on various environments and scenarios. Most of the COTS tools primarily focus on the commercial automotive industry where vehicles are driven in a structured environment. In this paper two M&S tools, viz., Autonomous Navigation Virtual Environment Laboratory (ANVEL) and Rover Analysis Modeling and Simulation (ROAMS) are evaluated for military applications, where the demands for navigation include both on-road and off-road, as well as both structured and unstructured environments as a preliminary benchmark.
Keywords: autonomous mobility; autonomy; soft soil; simulation; navigation algorithm; path planner; ANVEL; ROAMS;.
Transverse dynamic analysis of Semi-active quarter car model controlled with an optimal conventional controller
by Gurubasavaraju Tharehallimata, Vijay Mokenapalli
Abstract: Magneto-rheological (MR) fluid damper owing to its variable damping characteristics helps in significant reduction of vibration and thus offers better ride quality and stability (Road Holding) on-road of a semi-active vehicle. For further improvement in ride quality, it is necessary to employ a controller that would minimize the error and provide suitable controlled input to the damping system. In the present work, a monotube magneto-rheological damper is fabricated and its dynamic characteristics are evaluated at different input currents. The force versus displacement characteristics of the system is evaluated through experimentation. The non-parametric approach is used to model the dynamic characteristic of the magneto-rheological damper using the experimental results. A quarter car semi-active vehicle is considered and the passive damper is replaced with a magneto-rheological damper (in terms of a non-parametric model). The ride quality is estimated under different random road input conditions. Controlling the system is achieved by adopting the PID controller. The parameters of the proportional integral derivative (PID) controller are identified by coupling the PID with an optimization algorithm by considering three optimal criteria. After obtaining the desirable optimal parameters of the proportional integral derivative controller, the dynamic response of the vehicle subjected to random road excitation is estimated and compared with the vehicle with passive damper. The dynamic character of magneto-rheological damper under different input currents showed significant improvement in the damper force in comparison with the off-state condition. The representative model of this damper implemented in reducing the effect of road disturbance to the vehicle is done by adopting optimal PID controller. The results show that there is a reduction in the acceleration and vertical displacement of sprung mass in all classes of the road under optimal parameters conditions and thus leads to improved performance. On the concluding note, the usage of optimization techniques to tune and identify the optimal parameters of the controller would yield better results.
Keywords: Semi-active Suspension; Random road Excitation; PID controller; MR damper.
Robust Controller Design for Trajectory Tracking of Autonomous Vehicle
by Xueyun LI
Abstract: In order to improve the stability and fault tolerance of the control system of the autonomous vehicle in the middle and low speed lane changing, a dual loop weighted trajectory tracking robust PID control system is designed. By modifying the compound lane changing model of constant velocity offset and sine function, the mathematical model of vehicle lane changing path planning is obtained. The lateral displacement transfer function and yaw angle transfer function are derived by combining the mathematical model of trajectory planning and the mathematical model of vehicle motion, and the PID control parameters are calculated by mathematical derivation and transfer function reduction. Finally, the influence of weighting coefficient on system stability and its determination method are studied by simulation. The results show that the dual-loop weighted control is provided with good controllability, good tracking effect, and small lateral displacement error and yaw angular velocity error for lane changing conditions with the medium and low speed. While one of the feedback or feedforward channel fails, the control system can still maintain a high control accuracy and can successfully complete the trajectory tracking, indicating the advantage in fault tolerance of designed control system. The relationship between the lateral displacement error, yaw rate error and k value at different vehicle speeds is obtained by fitting the simulation data, which provides a certain reference for the of trajectory tracking weighted control strategy and parameters selection of TITO system weighted control.
Keywords: autonomous vehicle; lane changing; trajectory tracking; robust controller.
A Double-Layer Internal Model Robust Control Strategy Design for a Steer-by-Wire Vehicle
by Huan Guo, Weishun Deng, Fan Yu
Abstract: In this paper, a double-layer Internal Model Robust Control (IMRC)rnstrategy based on the Steer-by-Wire (SBW) vehicle is proposed to improve thernaccuracy, response rate and stability of the target trajectory tracking. A Generalized Internal Model Robust Controller (GIMRC) based on the improved Yoularnparameterization is designed in upper layer to track the desired yaw rate of the vehicle and improve the robustness of the vehicle against parameters' uncertainties and external disturbances. An IMRC controller is employed in lower layer to track the desired front-wheel steering angle. Then co-simulation is carried out via MATLAB/Simulink and CarSim to verify the effectiveness and rationality of the proposed strategy with double lane change (DLC) condition. The results indicate that the SBW vehicle can not only obtain better performance on the target trajectory tracking, but also guarantee the vehicle stability combining the proposed strategy.
Keywords: Steer-by-Wire; Generalized Internal Model Robust Controll; Yoularnparameterization; desired front-wheel steering angle; model uncertainties; external disturbances; response rate; robustness; driving stability; co-simulation.
Design and analysis of novel bio inspired BELBIC and PSOBELBIC controlled semi active suspension
by Pankaj Sharma, Vinod Kumar
Abstract: Passenger comfort, quality of ride and handling brings a lot of attention and concern of the automotive design engineers. Researchers are working and introducing a number of new techniques or approaches to attain the same. Some approaches like Artificial Neural Network, Genetic Algorithm, Fuzzy and hybrid control techniques have been proposed, modeled, simulated and tested to check their impact on the above mentioned parameters. A new controller based on learning mode of human brain known as Brain Emotional Learning Based Intelligent Controller (BELBIC) and PSOBELBIC optimized by PSO is introduced here. A 6 degrees of freedom (DOF) mathematical model of quarter car along with passenger is modeled and simulated against two speed bump profile i.e. trapezoidal and circular as per IRC (Indian Road Congress) specification and random road profile of ISO Grade-C. The performance of proposed controller is also analysed for half car model to have even more in depth analysis of vehicles performance. The bump is taken as road disturbance to know their vibratory effect on passenger body parts and reduction in root mean square acceleration and sprung mass displacement of half car model. The results were compared for passive, PID, BELBIC and PSOBELBIC controlled configuration of suspension. The result shows that proposed BELBIC and PSOBELBIC controller has improved the ride quality of passenger by reducing the vibration effect on different body parts. The PSOBELBIC gives the best performance with overall improvement of about 26 % and 32.54 % for circular and trapezoidal bump respectively for quarter car model with passenger. The improvement against random road profile by PSOBELBIC comes out 52.79% and 34.58% respectively.
Keywords: Emotional learning; BELBIC; genetic algorithm; intelligent controller; pso; optimization; speed bump; PID; overshoot; fuzzy; semi active.
EEG-Based Assessment in Novice and Experienced Drivers' Braking Behavior during Simulated Driving
by Jie Zhang, Gang Guo, Yingzhang Wu, Qiuyang Tang, Changshao Liang
Abstract: The driver is an essential factor in the traffic system, and inexperienced drivers are special high-risk groups. We used electroencephalography (EEG) and reaction time to quantify the differences between experienced and novice drivers' risk perception and braking behavior in a driving simulator. Twenty-seven participants were asked to drive through a 12-kilometer dynamic scenario with EEG signals recorded simultaneously. There are mainly four frequency bands for human EEG activity: alpha, beta, theta, and delta. The power spectral density of beta activity was analyzed because it dominated when drivers braked in an emergency. The results indicate that the indicators of ? activity and reaction time discriminated between the novice and experienced drivers. The reaction time of drivers was related to the increment of the ? activity, indicating that the driver's risk perception stage will affect their risk reaction. The study provides us with the operating performance and internal physiological activities of drivers' in the braking process.
Keywords: traffic safety; driving experience; braking behavior; EEG activity; driving simulator.
INTEGRATION OF GEOMETRY AND ANALYSIS FOR THE STUDY OF CONTINUUM-BASED AIRLESS TIRES OF PLANETARY WHEELED ROBOTS
by Edoardo Samarini, Ahmed A. Shabana, Emanuele Grossi, Aurelio Soma
Abstract: Because of the scientific challenges of space explorations, several space agencies are involved in the design of autonomous planetary surface exploration devices. Examples are Mars rovers, designed with the goal of collecting terrain information, including dust, soil, rocks, and liquids. The design of such sophisticated rovers can be enhanced by less reliance on trial-and-error process, building expensive physical models, and time-consuming experimental testing. Physics-based virtual prototyping is necessary for an efficient and credible Mars rover designs. In this paper, a new flexible multibody system (MBS) rover model for planetary exploration is developed. Because the rover, a wheeled robot, must be designed to negotiate uneven terrains, the airless wheels must be able to adapt to different soil patterns and harsh operating and environmental conditions. In order to describe accurately the airless-wheel complex geometry and capture its large deformations and rotations, the absolute nodal coordinate formulation (ANCF) finite elements are used. A numerical study is performed to compare the ANCF kinematics and tractive force results with the results of the discrete brush tire model, widely used in the vehicle-dynamics literature. Several simulation scenarios are considered, including a drop test and acceleration along a straight line. The numerical results obtained are verified using data published in the literature and are used to evaluate the accuracy and computational efficiency of the ANCF airless-tire modeling approach.
Keywords: Mars rover; airless-tire geometry; virtual prototyping; wheeled robots; Absolute Nodal Coordinate Formulation; I-CAD-A.
Preliminary design of an alternative energy storage system for a city car based on flywheel
by Michele Vignati, Davide Tarsitano, Francesco Braghin, Federico Cheli
Abstract: Vehicle energy storage systems have a crucial impact on the spreading of hybrid and electric vehicles. Nowadays the most adopted solution is represented by batteries. This solution suffers of aging phenomenon that reduces the battery capacity; moreover, the battery recycling at the end of its life is still a challenge and generate pollution.
This paper presents a preliminary design of a kinetic energy storage system intended for city micro-car. The energy is stored by means of high rotating flywheel.
First, an energetic model of the car powertrain including flywheel and bearings is proposed and used to evaluate the car energy requirement to accomplish its typical journey. Then, material, geometry and motor have been selected to fit all the vehicle space requirements considering also that flywheels operate in vacuum environment.
The paper than presents an analysis on the gyroscopic effects induced by the flywheel when it is subjected to car chassis acceleration in typical urban driving scenario. Finally, preliminary considerations on bearing layout are drawn by comparing different bearings types. Bearing loads have been evaluated with a multibody model that is fed with measured car chassis acceleration data.
Keywords: flywheel; kinetic energy storage system; electric vehicles.
Special Issue on: Multibody System Algorithms in Vehicle Dynamics and Virtual Prototyping
Simulation and Experiments on Three-wheeled Vehicle on Different Tracks
by G.S.G. Ravikanth, Sujatha C
Abstract: Three - wheeled vehicles are used both for public and private transport in most of the Asian and African countries. Ride comfort is very important for these small-sized transport vehicles. A 6 degrees of freedom (DOF) mathematical model of a three wheeled vehicle is developed for predicting its ride behavior. Simulations are carried out on this model and responses of the sprung and unsprung masses are found on different tracks like (i) Half circular bump and (ii) trapezoidal. Sprung mass and unsprung mass accelerations are compared with experimental results and discrepancies between simulation and experiments are found. The discrepancy is mainly due to the difference between the analytical input given to the vehicle model (actual road profile) and the corresponding measured input. In order to bridge this gap, the paths traced by the tyre for the two different profiles are obtained as 2D layouts and differences between the analytical road input and the actual input traced by the tyre are found. The road input to the vehicle model is updated with the path traced by the tyre. The simulated responses of the 6 DOF model are validated on the two different tracks using the paths traced by the tyres as input and good correlation is found between experimental results and simulations.
Keywords: Three wheeler; Ride comfort; Terrain modeling; Tyre path; Mathematical modeling.
A dynamic model of a Cardan joint to evaluate the effect of elasticity and manufacturing errors
by Marco Cirelli, Valerio Rossi, Pier Paolo Valentini, Ettore Pennestrì
Abstract: Cardan joint is a key component in many mechanical applications. Due to the redundancy of kinematic constraints, the accurate determination of reaction forces and the assessment of dynamic effects caused by joint tolerances are very challenging tasks. This paper presents a computer-aided multibody modelling approach for the simulation of a Cardan joint with manufacturing errors. During the modeling phase, the elasticity of flexible bodies is lumpedrnand the joint compliance is taken into account using concentrated non-rnlinear spring elements. Numerical examples have been developed and discussed in order to test the feasibility of the proposed methodology.
Keywords: Cardan joint; universal joint; flexibility; tolerance; elasticity; elastic coupling.
Model-Based Simulation of Dynamic Behaviour of Electric Powertrains and Their Limitation Induced by Battery Current Saturation
by Dario Mangoni, Alessandro Soldati
Abstract: The wide-spread e-mobility revolution is asking for new software solutions capable of providing meaningful information not only for the mechanical part of the vehicle architecture, as in the past, but also for novel electric and hybrid driveline components. The complexity of the system is due to many factors, mainly but not only the different coexisting time scales on the basis of which the two different sub-parts, the mechanical and the electrical ones, operate.
The objective of the paper is to provide a lightweight model for a fully electric vehicle powertrain, trying to assess the current constraints imposed by the battery to the whole driveline, and able to reflect this limitation throughout the transmission line, down to the electric motor and thus to the performance of the full vehicle. The model is suitable for real-time performances thanks to the effective computation of the powertrain via analytical solutions. Moreover, the whole system has been modelled following a Model-Based approach in Modelica language and is made part of the Altair Activate Car Real-Time library, in which both the electrical and mechanical parts integrate smoothly.
Keywords: battery; electric vehicle; model-based; Modelica.
Dynamic behaviour modelling of an Internal Combustion Engine Water Pump Transmission Belt Drive
by Gaetano Sequenzia, Michele Calabretta, Ignazio Assenza, Salvatore Massimo Oliveri
Abstract: Belt drives are commonly used in various types of transmissions to link two or more rotating shafts. In order to transmit the motion, an effective grip on the pulley has to be set by imposing a pre-load on the belt. Moreover, the dynamic of the system is strongly affected by the geometrical and inertial properties but also by the imposed belt tension force as a functional parameter affecting the vibration characteristics. In the present work it is presented an integrated methodology, experimental and numerical, to determine the dynamic behavior of a water pump drive in a high-performance internal combustion engine.
Keywords: Belt; Internal Combustion Engine; natural frequency; vibration modes.
Wheelrail wear simulation and rail cant optimisation based on railway vehicle dynamics
by Wei Li, Pu Wang, Shuguo Wang, Daolin Si
Abstract: A numerical prediction model for the wheelrail wear development on heavy-haul railway is established herein, and a corresponding programme is written using MATLAB. Using Archards material wear theory, wear distributions in the wheelrail contact patch and along the rail profile are evaluated via vehicletrack dynamics simulation and wheelrail rolling contact analysis. In the vehicle dynamics model, various structural components and complex nonlinear interactions between components are precisely simulated to guarantee consistency with reality. The established model is employed to study the influences of rail cant on the wheel-rail wear distribution and development. The following two main conclusions are drawn. On straight railway section, the wheelrail contact region and wear distribution become unreasonable when the rail cant exceeds 1/20. On curved section, the influences of rail cant on the wear of the inner and outer rails are different. The changes of rail cant also obviously impact the changing rules of wear with the vehicle speed. A rail cant of 1/30 is recommended for the curved section of heavy-haul railway.
Keywords: heavy haul railway; vehicle-track dynamics; wheel–rail contact; wear; numerical simulation; rail cant; optimisation.
Study the Dynamic behaviour of seven DOF of full car model with semi-active suspension system
by Hemanth Krishna, Shamanth Vasanth, Devaraj Sonnappa, Hemanta Kumar, Gangadharan KV
Abstract: This paper presents an investigation on the ride comfort and road-holding performance of a vehicle equipped with the semi-active suspension system. The full car semi-active suspension model with 7 degrees of Freedom (7 DOF) system is adopted for the study and a fuzzy-logic control strategy is considered for minimizing the effect of road disturbance on vehicle performance. The responses of a vehicle have been analyzed under the Indian average random road profile (ISO8608) against the conventional passive suspension system. The performance of the semi-active suspension system is evaluated by heave, roll and pitch acceleration of the vehicle body around its center of gravity. The performance of a vehicle with the semi-active suspension system has been compared with the response conventional passive suspension system. The result specifies that, the semi-active suspension system with a Fuzzy-logic controller reduces around 43 % of vibration amplitude at the resonance frequency of vehicle than the passive suspension system.
Keywords: Full car; MR damper; Modified Bouc-wen; NSGA-II; optimization; fuzzy logic and Indian average road.
Research on Hierarchical Control Strategy of Electromagnetic Active Mounting System
by Zheming Chen, Heng Wang, Chenguang Lai
Abstract: In order to improve the vibration isolation performance of the automotive powertrain mounting system, a hierarchical control strategy is proposed according to the structural characteristics of the electromagnetic active mounting system and the influence of the dynamic characteristics of the actuator on the system control accuracy. Based on the analysis of the active mounting system 3 degree-of-freedom (DOF) 1/4 vehicle, the mathematical model of the mounting system and the electromagnetic actuator control circuit is derived. Guided by hierarchical control strategy, upper and lower controllers are designed for mount part of the active mounting system and actuator circuit respectively. The upper mounting controller is under LQR control with strong adaptability, fine robustness and easy implementation, and the weight coefficient of its performance index is optimized by genetic algorithm. The lower part of the actuator circuit is under simple and practical PID control and its parameters are optimized through particle swarm optimization algorithm. To verify the effectiveness of the control strategy, two typical working conditions are set for simulation research with the system input of the joint excitation of the engine and pavement. The results show that compared with the active mounting system under conventional control, the system designed according to the hierarchical control strategy can control different working conditions of the vehicle more precisely, which not only improves the vibration isolation performance of the powertrain mounting system to a certain extent, but also renders a better robustness and force tracking property.
Keywords: Automotive engineering; powertrain; electromagnetic actuator; active mount; LQR control; genetic algorithm; PID control; particle swarm optimization; hierarchical control; simulation analysis.
Performance evaluation of different centrifugal pendulum morphologies through multibody dynamics simulation
by Marco Cirelli, Ettore Pennestrì, Pier Paolo Valentini, Romualdo Paga
Abstract: This paper aims to evaluate the effectiveness of the centrifugal pendulum applied to an internal combustion engine as a vibration damper. In particular, a specific design strategy, based on an energy equivalence, is analyzed using a series of multibody simulations. A simplified model is initially discussed and different solution morphologies simulated. The present solution is based on the roller-in-slot centrifugal pendulum, designed to have the same kinematic behavior of lumped mass models. The reasons why the centrifugal pendulum has had in recent years numerous applications are evidenced, together with a discussion of some design strategies. The main characteristics and requirements of this vibration damper are presented. Simulation strategy is subsequently showed, with a description of all bodies, forces, and parameters used in the different systems analyzed. To assess the effectiveness of the design strategy, a comparison among the simulation results of the different solutions is offered.
Keywords: Centrifugal Pendulum; Vibration Absorber; Multibody Dynamics; Trapezoidal pendulum; Contact simulation; Equivalent mechanism;.
Out-of-Plane Flexible Ring Tire Model Development and Validation
by Bin Li, Xiaobo Yang, James Yang
Abstract: In this paper, a novel out-of-plane flexible ring tire model is developed, which is an extension of our previously proposed in-plane flexible ring tire model. The tire model includes a rigid rim, certain number of discretized belt points, and numerous tread blocks attached between the belt and the ground. In this model, the tire is divided into several layers, with each layer similar as the in-plane tire model. The parameters in the out-of-plane tire model are divided into in-plane tire parameters and out-of-plane tire parameters. The values of the in-plane tire parameters are borrowed directly from the in-plane tire model, and the out-of-plane tire parameters are identified based on a certain out-of-plane cleat test. Once the parameters are determined, various ADAMS
Keywords: Out-of-plane flexible ring tire model; tire model parameterization; tire cleat tests; tire dynamics; and tire model validation.
Special Issue on: Recent Advances in Energy-efficient Research for Vehicle Performance Improvement
A new model predictive torque control strategy for Permanent Magnet Synchronous Hub Motor of EVs
by Long Chen, Hao Xu, Xiaodong Sun
Abstract: This paper presents an optimal control strategy for a permanent magnet synchronous hub motor (PMSHM) of EVs drive using three voltage vectors. First, in order to simultaneously control torque and flux excellently, three voltage vectors including two active vectors and one zero voltage vector are selected. Second, the duration of the three voltage vectors in one period is calculated by the principle of simultaneous deadbeat control of torque and flux. Moreover, the cost function which eliminates the weight coefficient is proposed to reduce the amount of calculation. Finally, the proposed method is compared with the one- and two-vector-based model predictive torque control (MPTC) methods both in simulation and experiment. It is found that the proposed three-vector-based MPTC can obtain better performance such as smaller torque ripple and current total harmonic distortion (THD) both in steady and dynamic state.
Keywords: Model predictive torque control (MPTC); permanent magnet synchronous hub motor (PMSHM); three voltage vectors.
Study on Comprehensive Performance of Ni-MH Power Battery Used in HEV at Different Temperatures
by Xiang Chen
Abstract: The safety concern of the lithium-ion battery drives major motor company such as Toyota to consider the nickel-hydrogen (Ni-MH) battery in their HEV (e.g. Prius). However, current understanding of the cycling life and SOC (State of Charge) estimate of Ni-MH battery in the HEV is still limited due to its insignificant market share. Thus, this study carries a comprehensive investigation on the influences of the key environmental and operating parameters on SOC and cycling life of the Ni-MH battery. Notably, the Ni-MH cells were tested through loading the actual road spectrum with different temperatures (25/35/45?) being used to identify the impacts based on the actual work condition. Other factors including discharge current and depth of discharge are operated at 15.5A and 10% by average, respectively. In addition, to obtain the battery polarization characteristics under different temperatures and SOCs, multiple trials have been performed to obtain the OCV (open circuit voltage)~SOC curves at different temperatures under the 1-C rate of charging/discharging. The investigation results show that the battery degradation is accelerated at the upper-end level of the operating temperature range. The capacity decay compared to initial capacity is increased by a slight 2.46% at 45?, which demonstrates an excellent cycling performance of the Ni-MH battery. The battery polarization effect is found to be correlated to the charging and discharging processes. The lower the temperature is, the greater the polarization effect can be observed as a more salient OCV difference presents between charging and discharging. The polarization effect almost disappeared after 3 hours resting according to the results in this study. In summary, this study presents a comprehensive factor analysis needed to achieve a reliable SOC estimate for the Ni-MH based HEV.
Keywords: Ni-MH battery; hybrid electric vehicle; polarization effect; Cycling life; SOC estimate.
Research on Modeling and Simulation of single-mode power split hybrid system
by Aihua Chu, Xiang Chen, Yinnan Yuan, Tong Zhang, Huijun Cheng, Wenran Geng
Abstract: Aiming at an optimized single-mode compound power split hybrid system, the main operating mode of the hybrid system and the torque control strategy were developed in this paper. LMS/AMESim was used to establish the plant model of the vehicle as well as the key components of the hybrid system, while the vehicle control model was established in Matlab/Simulink. Both control model and plant model were integrated in the same environment through co-simulation technology. In addition, the fuel economy of a certain SUV under the NEDC road spectrum was simulated by the co-simulation model, and the simulation results were compared with the experimental results on the auto chassis dynamometer. The results have shown that in the HEV operation mode, the electric energy consumption of the battery in experiment was 0.6241kWh well agreed with the value of 0.6220kWh through simulation, achieving only 0.33% deviation. Moreover other two key indicators, the SOC change and regenerative braking energy recovery, were found to be -4.8% and 694.90kJ, respectively, in the simulation. These results are strikingly compatible to the experimental values as well. The deviations are 0.7% and 3.8% respectively. The results demonstrated that the established simulation model is an accurate reflection of the physical reality under different road spectrum conditions. Application of the model can greatly reduce the difficulty of control strategy design and improve the efficiency of vehicle development.
Keywords: hybrid electric vehicle; power-split system; CHS2800; co-simulation; vehicle controller model; AMESim; MATLAB/Simulink.
The effect of peppermint odor on fatigue and vigilance in conditional automated vehicle
by Qiuyang Tang, Gang GUO, Meng Jin Zeng
Abstract: Drivers in conditionally automated vehicles have been found to become fatigued easier than manual drivers, and the risk of accidents increased due to the decrease in vigilance. Olfactory stimulation is a promising method to counterbalance fatigue and increase vigilance. However, little is known about the effect of peppermint odor on relieving fatigue and increasing vigilance during automated driving. Therefore, to better understand the effect of peppermint odor stimulation during automated driving, a driving simulator study with 34 participants was conducted. Subjective and objective variables were compared between two conditions: with peppermint odor and placebo (air). The results of the study indicated that the fatigue levels of drivers decreased after the release of peppermint odor. The indicators of reaction time and ocular variables supported that the drivers` vigilance increased during the peppermint stimulation. In conclusion, peppermint odor has a positive effect on relieving fatigue and increasing vigilance.
Keywords: Fatigue countermeasures; Peppermint odor; Driver vigilance; Eye movement.
Energy Management Optimal Strategy of FCHEV Based on The Radau Pseudospectral Method
by Yanwei Liu, Yuzhong Chen, Zhenye Li, Kegang Zhao
Abstract: Energy management of the fuel cell hybrid electric vehicle (FCHEV) is a significant study area with respect to improving FCHEVs dynamic and efficiency performance and durability. Radau Pseudospectral Method (RPM)-based optimal control of energy management of FCHEV is introduced to optimize the fuel cells lifetime by means of reducing its performance degradation. To utilize the RPM, both state variable and control variable are approximated by the global interpolation polynomial, and then differential equation of state variable is approximated by the derivative of interpolation polynomial. Accordingly, the optimal control problem is transformed into nonlinear problem to be solved. The fuel cells performance degradation which refers to fuel cells voltage decline is selected as objective function. The results of optimal control in NEDC show that battery with larger capacity is more beneficial than smaller one for reducing the fuel cells performance degradation, with the total time of large load change of the fuel cell reducing. The RPM is an effective way to optimize not only the fuel cells lifetime but other objectives to energy management.
Keywords: energy management; fuel cell vehicle; electric vehicle; Radau Pseudospectral Method; optimal strategy.
Control Strategy of Genetic algorithm for a Hybrid Electric Container Loader
by Jian Li, Hong Shu, Zhien Xu, Weizhou Huang
Abstract: Hybrid electric container loaders are used for cargo transportation in aviation airports, which have characteristics of relatively complicated operating conditions and large load changes. How to ensure that under various loads, battery state of charges (SOCs) and temperatures the loader runs in the high efficient zone, the SOC and temperature of battery are maintained within a reasonable range is an important issue that the control strategy needs to solve. A genetic algorithm is applied to optimize the control parameters of the hybrid loader. The optimal control parameters are the charging torque limit, the discharging torque limit, the generator charging torque, the motor discharging torque, the engine speed at high and low load, and the battery high SOC threshold. The optimization target is to take the minimum equivalent fuel consumption under loader cycle conditions, and maintain the battery SOC sustain or reach the optimal range. The optimal control parameters of the loader under multiple loads, battery temperatures and initial SOCs were optimized offline by using genetic algorithms. Finally, a multidimensional response surface model for control parameters was established by a response surface method. The simulation shows that under various loads, battery temperatures and initial SOCs, the fuel saving of the hybrid loader is significant, the battery maintains the charge sustain or reaches within the optimal range, the battery temperature rising is kept within a reasonable range, and the battery charge and discharge rate is controlled within 1C.The fuel consumption of the hybrid electric loader is reduced by more than 20% compared with the traditional loader under the full load conditions and the initial SOC in the range of 0.6-0.8.Compared with the original calculation model optimized by genetic algorithms and the dynamic programming control strategy, it was verified that the calculation accuracy and fuel saving significance of the response surface model for control parameters.
Keywords: Hybrid Electric Vehicles; Control Strategy; Genetic Algorithm; Response Surface.
Research on regenerative braking strategies for hybrid electric vehicle by co-simulation model
by Han Guo, Jianwu Zhang, Wenran Geng, Huijun Cheng, Haisheng Yu
Abstract: Regenerative braking is an important factor in improving hybrid electric vehicle fuel economy. This paper presents the simulation modelling of a power-split hybrid electric vehicle with different regenerative braking strategies. A co-simulation model is used to enhance the simulation capability for the hybrid vehicle performance and development of control strategy. AMESim is used to model the complex physical components including engine, transmission, motors, battery and hybrid vehicle, and the physical model is integrated with control model established by MATLAB/Simulink, which is required to operate the vehicle and the regenerative braking system through standard drive cycles. Simulation results show that a regenerative braking control strategy can recuperate significant amounts of energy. Vehicle fuel economy in EV and HEV modes is improved significantly by coupling the proposed regenerative braking strategy.
Keywords: hybrid electric vehicle; regenerative braking; energy management; AMESim; MATLAB/Simulink.
Potential and Challenges to improve vehicle energy efficiency via V2X: Literature Review
by Kai Yang, Yanjun Huang, Yechen Qin, Chuan Hu, Xiaolin Tang
Abstract: With the development of intelligent transportation system, V2X information offers great opportunities to promote the energy efficiency of vehicles. This paper systematically elaborates the state of art which focuses on improving the energy efficiency using the V2V (vehicle to vehicle), V2I (vehicle to infrastructure), V2N (vehicle to network) and V2G (vehicle to grid) technology. Firstly, V2V technology applied in energy management of single and vehicular platoon is investigated. Secondly, eco-driving for connected vehicles using V2I information is studied. Thirdly, the potential of enhancing the energy efficiency by the V2N communication between vehicles and network is analyzed as well. Fourthly, the utilization of V2G technology to increase the energy efficiency of smart grid is presented. Finally, the challenges are suggested to facilitate the application of V2X technology to the enhancement of energy efficiency.
Keywords: vehicle energy efficiency; V2X; V2V; V2I; V2N; V2G.