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Journal Article

Fuzzy Control of Autonomous Intelligent Vehicles for Collision Avoidance Using Integrated Dynamics

2018-03-01
Abstract This study aims to take the first step in bridging the gap between vehicle dynamics systems and autonomous control strategies research. More specifically, a nested method is employed to evaluate the collision avoidance ability of autonomous vehicles in the primary design stage theoretically based on both dynamics and control parameters. An integrated model is derived from a half car mathematical model in the lateral direction, consisting of two degrees of freedom, lateral deviation and yaw angle, with a traction mathematical model in the longitudinal direction, consisting of two degrees of freedom, the longitudinal velocity and rolling velocity of the wheel. The integrated model uses a mathematical power train model to generate the torque on the wheel and connects the two systems via the magic formula tyre model to represent the tyre non-linearity during augmented longitudinal and lateral dynamic attitudes.
Journal Article

Computational-Based Aerodynamic Design for a Formula SAE Vehicle

2018-03-01
Abstract The computational analysis and design of an aerodynamics system for a Formula SAE vehicle is presented. The work utilizes a stochastic-approximation optimization (SAO) process coupled with a computational fluid dynamics (CFD) solver. The methodology is presented in a general manner, and is applicable to other complex parametrizable systems. A mix of discrete and continuous variables is established to define the airfoil profile, location, sizing and angle of all wing elements. Objectives are established to maximize downforce, minimize drag and maintain a target vehicle aerodynamic balance. A combination of successive 2D and 3D CFD evaluations have achieved vehicle aerodynamic performance targets at a minimal computational cost.
Journal Article

Experimental Investigation of the Near Wall Flow Downstream of a Passenger Car Wheel Arch

2018-03-01
Abstract The flow around and downstream of the front wheels of passenger cars is highly complex and characterized by flow structure interactions between the external flow, fluid exiting through the wheelhouse, flow from the engine bay and the underbody. In the present paper the near wall flow downstream of the front wheel house is analyzed, combining two traditional methods. A tuft visualization method is used to obtain the limiting streamline pattern and information about the near wall flow direction. Additionally, time resolved surface pressure measurements are used to study the pressure distribution and the standard deviation. The propagation of the occurring flow structures is investigated by cross correlations of the pressure signal and a spectral analysis provides the characteristic frequencies of the investigated flow.
Journal Article

Integrated Positioning Method for Intelligent Vehicle Based on GPS and UWB

2017-09-23
Abstract Knowledge of intelligent vehicle absolute position is a vital premise for the implementation of decision programming, kinematic and dynamics control. In order to achieve high accuracy positioning and reduce running cost as much as possible under all operating conditions, this paper proposed an integrated positioning method based on GPS and Ultra Wide Band(UWB) for intelligent vehicle’s navigation and position system. In this method, GPS and UWB are alternately active according to the confidence level of GPS signal. When the vehicle is traveling in a wide-open area and GPS signal is well received, the positioning results of Dead Reckoning system are corrected by the low frequency positioning output from GPS. During the correcting process, in order to realize the better fusion of measurement data, a simplified federal Kalman filter was designed by using indirect method.
Journal Article

Obstacle Avoidance for Self-Driving Vehicle with Reinforcement Learning

2017-09-23
Abstract Obstacle avoidance is an important function in self-driving vehicle control. When the vehicle move from any arbitrary start positions to any target positions in environment, a proper path must avoid both static obstacles and moving obstacles of arbitrary shape. There are many possible scenarios, manually tackling all possible cases will likely yield a too simplistic policy. In this paper reinforcement learning is applied to the problem to form effective strategies. There are two major challenges that make self-driving vehicle different from other robotic tasks. Firstly, in order to control the vehicle precisely, the action space must be continuous which can’t be dealt with by traditional Q-learning. Secondly, self-driving vehicle must satisfy various constraints including vehicle dynamics constraints and traffic rules constraints. Three contributions are made in this paper.
Journal Article

Discussion on Charging Control Strategy for Power Battery at Low Temperatures

2017-10-08
Abstract In the case of electric vehicles, due to the charging current limitation of lithium battery at low temperatures (below -20°C), it has been proposed to heat the battery pack up to a suitable temperature range before charging through a liquid-heating plate with PTC. However, at a low state of charge (SOC), there is a question which one could take the place of battery pack to supply power for PTC when heating. So that off-board charger (OFC) has been considered to supply power for PTC in this paper. In order to control the current charging into the battery pack as less as possible at low temperatures, three control schemes of battery management system (BMS) are proposed and compared. Scheme 1: BMS controls the value of charging current request close to the working current of PTC. Scheme 2: BMS controls the value of charging voltage request to reach a state of relative balance. Scheme 3: BMS disconnects the pack from the charger and keeps the connection between PTC and charger.
Journal Article

Bench Testing Validation of Wireless Power Transfer up to 7.7kW Based on SAE J2954

2017-10-08
Abstract Wireless Power Transfer (WPT) is presently being applied to consumer electronics in the low-power range and is planned to be commercialized in the high-power range for plug-in and electric vehicles in 2018. There are, however, many technology challenges remaining before widespread implementation of high-power WPT will occur. The SAE Vehicle Wireless Power and Alignment Taskforce published the Technical Information Report J2954 in 2016 to help harmonize the first phase of high-power WPT technology development. SAE J2954 adopts a performance-based approach to standardizing WPT by specifying ground and assembly coils to be used in a test stand (per Z-class) to validate performance, interoperability and safety. The main goal of this SAE J2954 bench testing campaign was to prove interoperability between WPT systems utilizing different coil magnetic topologies for SAE TIR J2954.
Journal Article

Automated ASIL Allocation and Decomposition according to ISO 26262, Using the Example of Vehicle Electrical Systems for Automated Driving

2018-04-18
Abstract ISO 26262 needs to be considered when developing safety-relevant E/E systems within the automotive industry. One part of the development process according to ISO 26262 is the derivation of the safety requirements for component functions. Here, one attribute of the safety requirements is the Automotive Safety Integrity Level (ASIL). The ASIL at a component level can be determined using ASIL allocation and decomposition. Considering complex systems such as vehicle electrical systems, countless possibilities can be identified for how the ASILs at a component level can be assigned in line with safety goals. In terms of efficiency, manual assignment is not expedient. Therefore, an algorithm for automated assignment of the ASILs will be introduced which considers constraints based on a fault tree analysis. The function of the approach will be demonstrated using the example of a vehicle electrical system from an automated vehicle.
Journal Article

Design, Analysis, and Optimization of a Multi-Speed Powertrain for Class-7 Electric Trucks

2018-04-17
Abstract The development, analysis, and optimization of battery electric class-7 heavy-duty trucks equipped with multi-speed transmissions are discussed in this paper. The designs of five new traction motors-fractional-slot, concentrated winding machines-are proposed for use in heavy-duty electric trucks. The procedure for gear-ratio range selection is outlined and ranges of gear ratios for three-to six-speed transmission powertrains are calculated for each of the proposed electric traction motors. The simulation and gear-ratio optimization tasks for class-7 battery electric trucks are formulated. The energy consumption of the e-truck with the twenty possible powertrain combinations is minimized over the four driving cycles and the most efficient powertrain layouts that meet the performance criteria are recommended.
Journal Article

Real-Time Optimal Control of Power Management in a Fuel Cell Hybrid Electric Vehicle: A Comparative Analysis

2018-03-08
Abstract Power split in Fuel Cell Hybrid Electric Vehicles (FCHEVs) has been controlled using different strategies ranging from rule-based to optimal control. Dynamic Programming (DP) and Model Predictive Control (MPC) are two common optimal control strategies used in optimization of the power split in FCHEVs with a trade-off between global optimality of the solution and online implementation of the controller. This is due to the fact that DP that offers the global optimal solution requires the pre-known knowledge of the driving condition for the whole drive cycle, which makes the real-time implementation of the strategy more challenging. In this paper, both control strategies are developed and tested on a FC/battery vehicle model, and the results are compared in terms of total energy consumption. In addition, the effects of the MPC prediction horizon length on the controller performance are studied.
Journal Article

A Bibliographical Review of Electrical Vehicles (xEVs) Standards

2018-04-18
Abstract This work puts presents an all-inclusive state of the art bibliographical review of all categories of electrified transportation (xEVs) standards, issued by the most important standardization organizations. Firstly, the current status for the standards by major organizations is presented followed by the graphical representation of the number of standards issued. The review then takes into consideration the interpretation of the xEVs standards developed by all the major standardization organizations across the globe. The standards are differentiated categorically to deliver a coherent view of the current status followed by the explanation of the core of these standards. The ISO, IEC, SAE, IEEE, UL, ESO, NTCAS, JARI, JIS and ARAI electrified transportation vehicles xEV Standards from USA, Europe, Japan, China and India were evaluated. A total approximated of 283 standards in the area have been issued.
Journal Article

Investigation of a Six-Phase Interior Permanent Magnet Synchronous Machine for Integrated Charging and Propulsion in EVs

2018-04-17
Abstract Merits such as reduced weight, overall and operational costs of the electric vehicle (EV) while providing level 3 charging capability, are propelling research on integrated charging (IC) technology for EVs. Since the same interior permanent magnet synchronous machine (IPMSM) is used during IC and traction conditions, it is important to understand the behavior of the machine during these conditions and optimally design the machine. Hence, firstly, this paper presents a case study on performance of a laboratory 3-phase IPMSM under IC and traction conditions. Thereafter, understanding the challenges such as low magnet operating point, losses and torque oscillation in 3-phase IPMSM during IC, a 6-phase IPMSM with an unconventional configuration is investigated to yield traction characteristics like that of the 3-phase IPMSM and mitigate challenges during IC. In the process, mathematical model of the 6-phase IPMSM is developed employing the dq-axis theory.
Journal Article

On WTW and TTW Specific Energy Consumption and CO2 Emissions of Conventional, Series Hybrid and Fully Electric Buses

2018-04-17
Abstract Making use of a specifically designed dynamical vehicle model, the authors here presented the results of an activity for the evaluation of energy consumption and CO2 emissions of buses for urban applications. Both conventional and innovative (series hybrid, and fully electric) vehicles were considered to obtain interesting comparative conclusions. The derived tool was used to simulate the dynamical behaviour of these vehicles on a number of kinematic profiles measured during real buses operation in different contexts, varying from really congested city centre routes to fast-lane operated services. It was so possible to evaluate the energetic performances of those buses on a Tank-to-Wheel (TTW) basis.
Journal Article

An Adaptive Neuro-Fuzzy Inference System (ANFIS) Based Model for the Temperature Prediction of Lithium-Ion Power Batteries

2018-08-14
Abstract Li-ion batteries have been widely applied in the areas of personal electronic devices, stationary energy storage system and electric vehicles due to their high energy/power density, low self-discharge rate and long cycle life etc. For the better designs of both the battery cells and their thermal management systems, various numerical approaches have been proposed to investigate the thermal performance of power batteries. Without the requirement of detailed physical and thermal parameters of batteries, this article proposed a data-driven model using the adaptive neuro-fuzzy inference system (ANFIS) to predict the battery temperature with the inputs of ambient temperature, current and state of charge. Thermal response of a Li-ion battery module was experimentally evaluated under various conditions (i.e. ambient temperature of 0, 5, 10, 15 and 20 °C, and current rate of C/2, 1C and 2C) to acquire the necessary data sets for model development and validation.
Journal Article

Modeling and Optimal Design of All-Wheel-Drive Hybrid Light Trucks

2019-06-06
Abstract Fuel economy and performance are both important in the design of hybrid pickup trucks. All-wheel drive is essential to ensure superior performance compared to two-wheel-drive designs. In this article, as a comprehensive extension work to the article published in ASME Dynamic Systems and Control Conference [1] on all-wheel-drive (AWD) hybrid truck, we investigate the modeling, design, and control problem of AWD hybrid vehicles and develop a methodology to identify optimal designs. This methodology 1) formulates an automated modeling process, 2) searches exhaustively through all possible AWD designs, and 3) employs a near-optimal energy management strategy, to obtain a family of designs with superior performance and fuel economy. A design case study for a hybrid Ford F-150 is conducted, to showcase this design process.
Journal Article

Selection of Reference Flux Linkage for Direct Torque Control Based Induction Motor Drive in Electric Vehicle Applications

2019-04-08
Abstract The surge in economic activities, in the developing nations, has resulted in rapid expansion of urban centres. This expansion of cities has caused a rapid increase in vehicular traffic, which in turn has caused deterioration of air quality. To overcome the problem of unprecedented air pollution, the governments worldwide have framed policies for faster adoption of electric vehicles. One of the major challenges faced is the development of low- cost drive for these vehicles and keeping the imports to a minimum. As a result of this, the trend is to move away from the permanent magnet-based motor technology and to use induction motor-based drivetrain. For the induction motors to be successful in electric vehicle drivetrain application, it is important to have a robust speed control algorithm. This work aims at adapting a direct torque control technique for induction motor’s speed control.
Journal Article

Electric Vehicle with Multi-Speed Transmission: A Review on Performances and Complexities

2018-12-04
Abstract Electric vehicles (EVs) with multi-speed transmission offer improved performances compared to those with single speed transmission system in terms of top speed, fast acceleration, or gradeability along with driving range. In this study, relevant literature is extensively analyzed to explore the performances and associated complexities with multi-speed automatic manual/mechanical transmission (AMT) system in EVs. In EV powertrain, the only torque generator component is electric motor, which is not equally efficient throughout wider speed range. To the other end, vehicles need to run at different speeds in diverse driving conditions. The study shows that multi-speed transmission system enables efficient operation of electric motor by choosing an appropriate gear at different driving torque-speed demands and thus contributes to achieve desired vehicle performances at minimum energy consumption.
Journal Article

Combined Battery Design Optimization and Energy Management of a Series Hybrid Military Truck

2018-10-31
Abstract This article investigates the fuel savings potential of a series hybrid military truck using a simultaneous battery pack design and powertrain supervisory control optimization algorithm. The design optimization refers to the sizing of the lithium-ion battery pack in the hybrid configuration. The powertrain supervisory control optimization determines the most efficient way to split the power demand between the battery pack and the engine. Despite the available design and control optimization techniques, a generalized mathematical formulation and solution approach for combined design and control optimization is still missing in the literature. This article intends to fill that void by proposing a unified framework to simultaneously optimize both the battery pack size and power split control sequence. This is achieved through a combination of genetic algorithm (GA) and Pontryagin’s minimum principle (PMP) where the design parameters are integrated into the Hamiltonian function.
Journal Article

Development of a Catalytic Converter Cool-Down Model to Investigate Intermittent Engine Operation in HEVs

2018-10-29
Abstract Catalytic converters, a primary component in most automotive emissions control systems, do not function well until they are heated substantially above ambient temperature. As the primary energy for catalyst heating comes from engine exhaust gases, plug-in hybrid electric vehicles (PHEVs) that have the potential for short and infrequent use of their onboard engine may have limited energy available for catalytic converter heating. This article presents a comparison of multiple hybrid supervisory control strategies to determine the ability to avoid engine cold starts during a blended charge-depleting propulsion mode. Full vehicle and catalytic converter simulations are performed in parallel with engine dynamometer testing in order to examine catalyst temperature variations during the course of the US06 City drive cycle. Emissions and energy consumption (E&EC) calculations are also performed to determine the effective number of engine starts during the drive cycle.
Journal Article

Compression Ratio Control of Free Piston Linear Generator with In-Cylinder Pressure Feedforward

2018-06-28
Abstract The free piston linear generator (FPLG) is a novel machine that functions as an Auxiliary Power Unit (APU) for hybrid electric vehicles, which contains two opposed free piston engines and one linear generator between them. FPLG has attracted extensive interest for its potential advantages in terms of high power density and multi-fuel flexibility. The guarantee of FPLG generating electricity steadily and efficiently is the high controllability of compression ratio. In this article, a control-oriented discrete-time model was established based on Otto cycle. Since the fluctuation of in-cylinder pressure caused by instable fuel injection mass and combustion process is the main disturbance, a composite controller is designed to precisely control the compression ratio of FPLG. The composite controller is made up of a feedforward controller and a feedback tracking controller.
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