Browse Topic: Drive cycles

Items (394)
Driving cycles are usually defined by vehicle speed as a function of time and they are typically used to estimate fuel consumption and pollutant emissions. Currently, certification driving cycles are mainly used for this purpose. Since they are artificially generated, the resulting estimates and analyzes can generally be biased. In order to address these shortcomings, recent research efforts have been directed towards development of statistically representative synthetic driving cycles derived from recorded real-world data. To this end, this paper focuses on synthesis of multidimensional driving cycles using the Markov chain-based method and particularly on their validation. The synthesis is based on Markov chain of fourth order, where the road slope is accounted, as well. The corresponding transition probability matrix is implemented in the form of a sparse matrix parameterized with a rich set of recorded city bus driving cycles. A wide collection of statistical features, including the frequency domain indicators, unique cross-correlation velocity-acceleration-slope indicators, and indicators related to bus stops at stations are considered for the purpose of driving cycle validation. To prove the synthesis method validity, a comparative statistical analysis of distributions of the nominated statistical features of synthetic and recorded driving cycles is carried out. Finally, a multi-criteria method of driving cycle validation based on lumped metrics is outlined and examined.
Topić, JakovŠkugor, BranimirDeur, Joško
With the development of cellular communication technology and for the sake of reducing drag resistance, the multi-lane platoon technology will be more prosperous in the future. In this article, the cooperative vehicle platoon method on the public road is represented. The method’s architecture is mainly composed of the following parts: decision-making, path planning and control command generation. The decision-making uses the finite state machine to make decision and judgment on the cooperative lane change of vehicles, and starts to execute the lane change step when the lane change requirements are met. In terms of path planning, with the goal of ensuring comfort, the continuity of the vehicle state and no collision between vehicles, a fifth-order polynomial is used to fit every vehicle trajectory. In terms of control command generation module, a model predictive control algorithm is used to solve the multi-vehicle centralized optimization control problem. We use the two DOF vehicle model to simulate vehicle dynamics. The front wheel angle and acceleration or braking commands of multiple vehicles are optimized to ensure that the vehicle can well follow the trajectory of the vehicle which is calculated by the control command generation module. At the same time, the energy consumed by performing steering, acceleration and deceleration is also minimized. Finally, in the simulation process, we simulate one direction two lanes scenario. The result shows that the proposed method can effectively handle multi-lane platoon re-configuration scenario.
Chen, GuoshengWu, JianLi, ShuaiZhang, JinghuaDu, ZhiqiangWang, GuojunChen, Zhicheng
ITIS Phrase Lists (International Traveler Information Systems)J2540/2_202012 (Current)12/6/2020
This standard provides a table of textual messages meeting the requirements for expressing International Traveler Information Systems (ITIS) phrases commonly used in the ITS industry. The tables provided herein follow the rules of SAE J2540 and therefore allow a local representation in various different languages, media expressions, etc., to allow true international use of these phrases. The phrases are predominantly intended for use in the description of traffic-related events of interest to travelers and other traffic practitioners. Other phrases exist for other specific specialty areas of ITS, and all such phrases follow a set of encoding and decoding rules outlined in SAE J2540 to ensure that the use of these phrases in messages remain interoperable between disparate types of user equipment. Implementers are cautioned to obtain the most recent set of tables by means of the ITS data registry, a process which involves SAE and other standards-setting organizations, and which is intended to maintain and enhance the level of harmonization among ITS standards set by each of the organizations. This standard defines the normative index values to be used to provide phrases needed by ITS practitioners. This standard provides non-normative textual phrases which MAY be used by implementers to ensure intelligible results. This standard follows the formats and rules established in SAE J2540 in the expressions, manipulations, and use of such tables. It should be pointed out that within the rules established by this standard, a variety of final tables are all considered “conformant” with the standard, and may vary as fits the needs of implementers.
V2X Core Technical Committee
This SAE Recommended Practice pertains to electrical systems of motorcycles both with and without batteries.
Motorcycle Technical Steering Committee
A Connected Controls and Optimization System for Vehicle Dynamics and Powertrain Operation on a Light-Duty Plug-In Multi-Mode Hybrid Electric Vehicle2020-01-05914/14/2020
This paper presents an overview of the connected controls and optimization system for vehicle dynamics and powertrain operation on a light-duty plug-in multi-mode hybrid electric vehicle developed as part of the DOE ARPA-E NEXTCAR program by Michigan Technological University in partnership with General Motors Co. The objective is to enable a 20% reduction in overall energy consumption and a 6% increase in electric vehicle range of a plug-in hybrid electric vehicle through the utilization of connected and automated vehicle technologies. Technologies developed to achieve this goal were developed in two categories, the vehicle control level and the powertrain control level. Tools at the vehicle control level include Eco Routing, Speed Harmonization, Eco Approach and Departure and in-situ vehicle parameter characterization. Tools at the powertrain level include PHEV mode blending, predictive drive-unit state control, and non-linear model predictive control powertrain power split management. These tools were developed with the capability of being implemented in a real-time vehicle control system. As a result, many of the developed technologies have been demonstrated in real-time using a fleet of four instrumented Chevrolet Volts which are equipped with on-board sensors, rapid prototyping embedded controllers, and V2X communication devices. This paper provides an overview of each tool developed, its implementation, energy reduction in isolation, and the net energy reduction of various tool combinations. A breakdown of the energy savings and range extension possible for the connected vehicle control and optimization tool set is provided which shows energy reduction benefits approaching 20% and range extension upwards of 8%, dependent on the driving and traffic scenarios and initial vehicle state of charge.
Oncken, JosephOrlando, JoshuaBhat, Pradeep K.Narodzonek, BrandonMorgan, ChristopherRobinette, DarrellChen, BoNaber, Jeffrey
Construction and Simulation Analysis of Driving Cycle of Urban Electric Logistic Vehicles2020-01-10424/14/2020
In order to reflect the actual power consumption of logistics electric vehicles in a city, sample real vehicle road data. After preprocessing, the short-stroke analysis method is used to divide it into working blocks of no less than 20 seconds. Based on principal component analysis, three of the 12 characteristic parameters were selected as the most expressive. K-means clustering algorithm is adopted to obtain the proportions of various short strokes, according to the proportion, select the short stroke with small deviation degree to combine, and construct the driving cycle, it has the characteristics of low average speed, high idle speed ratio and short driving distance. AVL-cruise software builds the vehicle model and runs the driving cycle of urban logistic EV. Compared with WLTC, the difference in power consumption is 34.3%, which is closer to the actual power consumption, the areas with the highest motor speed utilization are concentrated only in the idle area. Therefore, the driving cycle is consistent with the actual use conditions of low average speed and high idle speed of urban logistics vehicles, which can provide theoretical basis for power matching, economic analysis and control strategy optimization of urban logistic EV, so as to achieve the purpose of saving energy and enhancing endurance.
Qian, ChengWang, LiangmoZou, XiaojunYuan, Liu-kai
Development of Drive Cycle using Fleet Data for Two-Wheelers in Indian Market2019-32-05451/24/2020
Generally, to produce reliable two-wheelers, manufacturers resort to intense engineering efforts to make sure the two-wheeler can withstand the most harsh testing conditions and requirements. This sometimes leads to a higher cost in realizing such outlier requirements. Thus, a drive cycle matching the actual riding characteristics will enable better understanding of the requirements and an optimized engineering effort. There have been several attempts by governmental and non-governmental organizations to realize a real drive cycle for various cities and countries, trying to capture the typical riding style in those regions. But the drive patterns observed in most representative cycles do not match with the scenario in India with frequently dense traffic, constrained roads and slow driving speeds. To understand the driving pattern in India, a drive cycle generation algorithm is developed which uses real time on-road data captured from a fleet of vehicles in India and creating a database of micro-trips. These micro-trips are first categorized based on their average speeds. The algorithm concatenates these micro-trips to make a drive cycle, such that the average speed of the resulting drive cycle matches closely to the average speed of the captured on-road data. The algorithm then iterates different sequencing of these micro-trips in the drive cycle to minimize the error in various parameters like average acceleration, time percentage of acceleration, & deceleration, time percentage of idle, between the resulting drive cycle and the captured on-road data. Representative cycles of different cities and regions have been developed and described in this paper. This paper aims in explaining the approach of extracting a drive cycle from the data collected from a fleet of two-wheelers on-road in the Indian market and comparing the different riding patterns found in different regions. The algorithm developed can be extended to any level of data, ranging from a particular city to even combining different countries together.
Satish, ArvindSabu, AbhijithSaldanha, Johnson XavierA P, Nagesh
Real-time Long Horizon Model Predictive Control of a Plug-in Hybrid Vehicle Power-Split Utilizing Trip Preview2019-01-234112/19/2019
Given a forecast of speed and load demands during a trip, a hybrid powertrain power-split Trajectory Optimization Problem (TOP) can be solved to optimize fuel consumption. This can be done on desktop to set performance benchmarks; however, it has been believed that the TOP could not be solved in real-time and is not a realizable controller. As such, several approximations of the TOP have been made in the interest of obtaining a real-time near-optimal controller, for example, Equivalent Consumption Minimization Strategies (ECMS) and their adaptive counterparts. These strategies decide on the power-split by, at each sampled time instant, minimizing a Horizon-0 (without predicting forward in time) composite function of fuel consumption and equivalent battery energy. The fuel economy that results from these strategies is highly sensitive to the calibration of the associated equivalence factor, and furthermore, must be chosen differently for different drive cycles. This paper presents a strategy for solving the TOP in real-time, i.e., as an Economic Model Predictive Controller (MPC) with horizon length sufficiently long to cover the entire trip. Unlike ECMS, this MPC is arguably calibration-free. Simulation results demonstrate the performance and robustness of the MPC by comparing the fuel consumption improvements to a rule-based Charge Deplete Charge Sustain (CDCS) strategy under both a perfect forecast assumption and a simple forecasting scheme using driving patterns in the California Household Travel Survey.
Huang, MikeZhang, ShengqiShibaike, Yushi
Calculation of Drag Torque Losses by Component of a Transfer Case2019-01-260510/22/2019
In recent decades, fuel economy has become a key indicator of an automaker corporate social responsibility and a market differentiation factor, and ultimately it is regulated by government agencies such as EPA through CO2 emissions compliance tests. The light pick-up truck and SUV production share has been increasing in the last few years, being 4-wheel drive capability one of the main features that customers seek. Within the 4-Wheel Drive system, the transfer case has a significant impact to both torque transfer efficiency and parasitic losses. The scope of this paper is to better understand the parasitic losses of a transfer case by the quantification of its individual drag losses by component. At product development phases, one measurement of interest is the system level spin loss which has a target value defined by the automakers, and contribution by component is often neglected if the system has the expected performance. This study summarizes the tests performed on a 2-speed chain driven transfer case, where as a first step, a baseline spin loss measurement was taken, then the chain and sprockets, planetary carrier, and oil pump were removed at different points within the test to quantify their contribution by comparing the results to the initial baseline measurement. Lastly, the transfer case with all its components assembled was tested and spin loss was measured using different oil levels.
Rivera Rodriguez, RicardoMartinez, Carlos
Test Methodology to Quantify and Analyze Energy Consumption of Connected and Automated Vehicles2019-01-01164/2/2019
A new generation of vehicle dynamics and powertrain control technologies are being developed to leverage information streams enabled via vehicle-to-vehicle (V2V) and vehicle-to-infrastructure (V2I) connectivity [1, 2, 3, 4, 5]. While algorithms that use these connected information streams to enable improvements in energy efficiency are being studied in detail, methodologies to quantify and analyze these improvements on a vehicle have not yet been explored fully. A procedure to test and accurately measure energy-consumption benefits of a connected and automated vehicle (CAV) is presented. The first part of the test methodology enables testing in a controlled environment. A traffic simulator is built to model traffic flow in Fort Worth, Texas with sufficient accuracy. The benefits of a traffic simulator are two-fold: (1) generation of repeatable traffic scenarios and (2) evaluation of the robustness of control algorithms by introducing disturbances. The traffic simulator is interfaced with a chassis dynamometer on which the real vehicle will be tested. Algorithms leverage information from the traffic simulator to produce control policies that are optimal in energy consumption. The control policy results in a specific speed of the “ego” vehicle. This speed is relayed back to the traffic simulator, which coordinates movement of the vehicles surrounding the ego vehicle. The second part of the test methodology analyzes energy consumption improvements enabled via CAV technologies. It is expected that the energy consumption reduction realized on a vehicle will differ from simulation studies that rely on simplified models. An advanced instrumentation and measurement scheme enables in-situ efficiency calculations across the powertrain by analyzing energy flows during transient operation of the vehicle. Preliminary results from vehicle testing on a chassis dynamometer are presented.
Rengarajan, Sankar B.Hotz, ScottHirsch, CharlesLobato, PeterGross, MichaelSturgeon, PurserSarlashkar, Jayant
Pure Electric Vehicles Simulation Using Powertrain Energy Estimator Tool2019-01-03674/2/2019
This paper describes first, the use of Powertrain Energy Estimator (PEE) tool to simulate and analyze the performance of the Pure Electric Vehicles (PEV’s) with all the powertrain components. The PEE uses basic physics calculations and measured components performance with the available vehicle parameters to model and simulate any conceptual PEV. The tool calculates the predicted torques, speeds, voltages, efficiency and power passed from one component to another then saves all the simulation results in a database for further user’s analysis. Secondly, we present a methodology to estimate the maximum power capacity required for PEV driving electric machine (E-Motor). The estimation approach is based on creating a power map, which combines the contour lines for all power levels over vehicle speeds/road climbing grades required for the PEV powertrain driving component (E-Motor) to meet all the vehicle’s performance requirements. The evaluation of the power map uses the vehicle’s specifications and performance requirements. The performance requirements are mainly cover the maximum vehicle speed, acceleration time and road climbing grade. Two types of PEV platform applications are considered in this paper for simulation and analysis: A 10 meters Rear Wheel Drive (RWD) commercial PEV transit bus with two speeds transmission gearbox, the second application is a typical Front Wheel Drive (FWD) OEM PEV passenger car with a single speed transmission gearbox.
Al-Assadi, SalemMcConnell, Jason
A Generalized Component Efficiency and Input-Data Generation Model for Creating Fleet-Representative Vehicle Simulation Cases in VECTO2019-01-12804/2/2019
The Vehicle Energy Consumption calculation Tool (VECTO) is used for the official calculation and reporting of CO2 emissions of HDVs in Europe. It uses certified input data in the form of energy or torque loss maps of driveline components and engine fuel consumption maps. Such data are proprietary and are not disclosed. Any further analysis of the fleet performance and CO2 emissions evolution using VECTO would require generic inputs or reconstructing realistic component input data. The current study attempts to address this issue by developing a process that would create VECTO input files based as much as possible on publicly available data. The core of the process is a series of models that calculate the vehicle component efficiency maps and produce the necessary VECTO input data. The process was applied to generate vehicle input files for rigid trucks and tractor-trailers of HDV Classes 4, 5, 9 and 10. Subsequently, evaluating the accuracy of the process, the simulation results were compared with reference VECTO results supplied by various vehicle manufacturers. The results showed that the difference between simulated and reference CO2 emissions was on average -0.6% in the Long Haul cycle and 1% in the Regional Delivery. Such a process could be a powerful tool for calculating HDV CO2 emissions for development and analysis purposes, e.g. for new vehicle prototypes or multistage vehicles, and for creating VECTO equivalent models that can be used to assess alternative operating conditions and mission profiles of existing vehicle models. The methodology was applied for creating input of various components in the US tool for HDV certification, GEM, for generic sample-vehicle models available.
Zacharof, NikiforosTansini, AlessandroPrado Rujas, IkerGrigoratos, TheodorosFontaras, Georgios
Feasibility of Virtual Environments to Develop Future Driving Cycles2018-01-18169/10/2018
The current procedure for testing emissions from new vehicles, the World Harmonised Light Vehicle Test Procedure (WLTP), was introduced in September 2017. The WLTP was developed by collecting over 765,000 kilometres worth of data in order to isolate driver behaviour from other real world variables. However, this is a very time consuming and costly process. This paper discusses the suitability of a cheaper and more time efficient alternative. Driver behaviour has a significant impact on the emissions produced from the same vehicle. This study explores the feasibility of utilising virtual environments as an alternative to real world testing to isolate driver behaviour to develop future drive cycles. The use of virtual environments have some significant advantages over real world testing: they can be strictly controlled in terms of the weather, topography and vehicle characteristics, thereby aiding the isolation of driver behaviour from other variables. A driving simulator facility based at the University of West of England was used to assess the suitability of determining driver behaviour using a virtual environment. A track was created based on a local route in the virtual environment. The virtual route was driven by volunteers and their driving behaviours were identified. The same route in the real world was driven by the same volunteers. The driving behaviour of the volunteers from both the virtual environment and the real world are compared to assess the realism of the virtual driving experience in terms of driver behaviour. Finally the data from the virtual environment were analysed to determine if driver behaviour can be isolated, along with the impact on vehicle emissions, with a view to using virtual environments to develop future drive test cycles for emissions testing.
Kay, Peter
Modeling and Simulation for Hybrid Electric Vehicle with Parallel Hybrid Braking System for HEV2018-28-00977/9/2018
A model for Hybrid electric vehicle power train with parallel hybrid braking system has been constructed. The hybrid vehicle utilized is based on integrated motor assist power train developed by Honda co utilized in Honda Insight car. The model is implemented using empirical formulation and power control schemes. A power control strategy based on throttle position (% throttle) and brake pedal position (% braking) is used. It incorporates the parallel hybrid braking system for the hybrid electric vehicle. The model allows for real time evaluation of wide range of parameters in vehicle operation as HEV without parallel hybrid braking system (PHBS) and with PHBS. Due to regenerative braking the structure design and control of braking system for HEV is different from conventional vehicle. The PHBS is the good option to provide safety of the vehicle and simultaneously recover reasonable amount of braking energy. In this paper a model for HEV is developed and simulated to evaluate major performance parameters on three different approximate drive cycles (NYCC, HWFET and WVU5). The results provide that the PHBS regenerates more amount of energy during highway cycle then existing braking control strategy on the other hand on city cycle it recaptures less amount of energy then existing braking control strategy recaptures.
Ahmed, MazahirNaiju, C D
Robust Optimization for Real World CO 2 Reduction2018-37-00155/30/2018
Ground transportation industry contributes to about 14% of the global CO2 emissions. Therefore, any effort in reducing global CO2 needs to include the design of cleaner and more energy efficient vehicles. Their design needs to be optimized for the real-world conditions. Using wind tunnels that can only reproduce idealized conditions quite often does not translate into real-world on-road CO2 reduction and improved energy efficiency. Several recent studies found that very rarely can the real-world environment be represented by turbulence-free conditions simulated in wind tunnels. The real-world conditions consist of both transversal flow velocity component (causing an oncoming yaw flow) as well as large-scale turbulent fluctuations, with length scales of up to many times the size of a vehicle. The study presented in this paper shows how the realistic wind affects the aerodynamics of the vehicle. The real-world aerodynamic drag of the vehicle is used in a system model tool to predict the changes in energy consumption and CO2 emissions under various driving cycles. The goal is to compare the on-road fuel economy considering realistic wind, in contrast to the standard drive cycle obtained under ideal ambient conditions. Different wind characteristics or wind profiles, representing different geographies or typical route conditions, were tested to assess their effects on the drive cycle. The use of real-world aerodynamics to predict a more realistic load curve could also impact the tuning of the vehicle sub-systems, like the transmission mappings, cooling module design, cooling flow sizing, heat exchanger properties, active grille shutter control map, etc. All these are also important in the design of autonomous vehicles. This work describes new techniques to design the vehicle including real-world aerodynamics, cooling module and other systems, in-order to improve fuel economy for on-road driving.
Gargoloff, JoaquinDuncan, BradleyTate, EdwardAlajbegovic, AlesBelanger, AlainPaul, Barnali
Control Optimization of a Charge Sustaining Hybrid Powertrain for Motorsports2018-01-04164/3/2018
The automotive industry is aggressively pursuing fuel efficiency improvements through hybridization of production vehicles, and there are an increasing number of racing series adopting similar architectures to maintain relevance with current passenger car trends. Hybrid powertrains offer both performance and fuel economy benefits in a motorsport setting, but they greatly increase control complexity and add additional degrees of freedom to the design optimization process. The increased complexity creates opportunity for performance gains, but simulation based tools are necessary since hybrid powertrain design and control strategies are closely coupled and their optimal interactions are not straightforward to predict. One optimization-related advantage that motorsports applications have over production vehicles is that the power demand of circuit racing has strong repeatability due to the nature of the track and the professional skill-level of the driver. The repeatable behavior from lap to lap allows for the efficient utilization of dynamic programming (DP) techniques to optimize vehicle speed and power management for a given race track, which is the focus of this research. The DP strategy is derived and described in detail using a hybrid rallycross vehicle as an example. The DP strategy minimizes lap time while sustaining battery charge at the end of each lap. Constraints on engine torque, electric motor power, battery capacity and tire friction are incorporated into the proposed strategy. The DP also generates an execution map that can be used for real-time on-vehicle implementation. This map includes optimal vehicle speed and power management strategies for all possible situations that the vehicle can experience during the real racing event.
Zhu, QilunSong, ShixinTan, XiaopingSong, ChuanxuePrucka, Robert
A Methodology of Making a Real World Driving Pattern (Case Study on Major Indian Cities)2018-01-06394/3/2018
Automotive manufacturers are striving to improve the real-world driving experience for customers. To provide the better overall performance like fuel economy, we must have the real world driving behavior of our customers. The driving behavior of customers may change from city to city or region to region. Thus to make a real representative driving behavior of customer for each different region becomes tedious task. The present paper describes a detailed methodology to make a representative driving pattern quickly based on a Matlab script. The vehicles were driven in major Indian cities (Delhi, Mumbai, Nasik and Pune). The data was recorded with a frequency of 1 Hz. This data is segregated into different short trips. These short trips are grouped together based on maximum vehicle velocity in each short trip & velocity acceleration frequency distribution. Velocity acceleration frequency distribution of individual short trip is compared with each other quantitatively using Matlab script. The best short trip is selected from each group which best represents the group. The selected short trip is further modified based on trip time frequency analysis & reducing difference between velocity acceleration frequency distribution of whole group and selected trip. In the end all the modified trips are joined together along with idle time to make a complete driving pattern.
Singh, BhoopendraMehra, ParikshitDhiman, SheetalVashisth, AjayKhanna, Vikram
Enabling Prediction for Optimal Fuel Economy Vehicle Control2018-01-10154/3/2018
Vehicle control using prediction based optimal energy management has been demonstrated to achieve better fuel economy resulting in economic, environmental, and societal benefits. However, research focusing on prediction derivation for use in optimal energy management is limited despite the existence of hundreds of optimal energy management research papers published in the last decade. In this work, multiple data sources are used as inputs to derive a prediction for use in optimal energy management. Data sources include previous drive cycle information, current vehicle state, the global positioning system, travel time data, and an advanced driver assistance system (ADAS) that can identify vehicles, signs, and traffic lights. To derive the prediction, the data inputs are used in a nonlinear autoregressive artificial neural network with external inputs (NARX). Two real world drive cycles were developed for analysis in the Denver, Colorado region: a city-focused drive cycle that passes through downtown as well as a highway-focused drive cycle that transitions across multiple interstates. A validated model of a 2010 Toyota Prius in Autonomie is used to determine the vehicle control fuel economy improvements that are possible from the NARX prediction. The optimal energy management control strategy is determined using dynamic programming due to its ease of use and that the solution produced is the globally optimal solution. The control strategies compared include the existing 2010 Toyota Prius control strategy as a baseline, the neural network prediction optimal energy management control strategy, and a 100% accurate prediction optimal energy management control strategy. Results show that inclusion of various sensors and signals enables a significant amount of the fuel economy improvement with respect to 100% accurate prediction. The conclusion is that prediction based optimal energy management enabled fuel economy improvements can be realized with currently available sensors and signals.
Asher, Zachary D.Tunnell, Jordan A.Baker, David A.Fitzgerald, Robert J.Banaei-Kashani, FarnoushPasricha, SudeepBradley, Thomas H.
V2V Communication Based Real-World Velocity Predictions for Improved HEV Fuel Economy2018-01-10004/3/2018
Studies have shown that obtaining and utilizing information about the future state of vehicles can improve vehicle fuel economy (FE). However, there has been a lack of research into whether near-term technologies can be utilized to improve FE and the impact of real-world prediction error on potential FE improvements. In this study, a speed prediction method utilizing simulated vehicle-to-vehicle (V2V) communication with real-world driving data and a drive cycle database was developed to understand if incorporating near-term technologies could be utilized in a predictive energy management strategy to improve vehicle FE. This speed prediction method informs a predictive powertrain controller to determine the optimal engine operation for various prediction durations. The optimal engine operation is input into a validated high-fidelity fuel economy model of a Toyota Prius. A tradeoff analysis between prediction duration and prediction fidelity was completed to determine what duration of prediction resulted in the largest FE improvement. This study concludes that speed prediction and prediction-informed optimal vehicle energy management can produce FE improvements with real-world prediction error and drive cycle variability. This Optimal Energy Management Strategy (EMS) achieved up to a 6% FE improvement over the Baseline EMS and up to 85% of the FE benefit of perfect speed prediction. Additionally, the results from this prediction method are compared to the results of a previous study that incorporates only local vehicle information in speed predictions.
Baker, DavidAsher, Zachary D.Bradley, Thomas
Development of 80- and 100- Mile Work Day Cycles Representative of Commercial Pickup and Delivery Operation2018-01-11924/3/2018
When developing and designing new technology for integrated vehicle systems deployment, standard cycles have long existed for chassis dynamometer testing and tuning of the powertrain. However, to this day with recent developments and advancements in plug-in hybrid and battery electric vehicle technology, no true “work day” cycles exist with which to tune and measure energy storage control and thermal management systems. To address these issues and in support of development of a range-extended pickup and delivery Class 6 commercial vehicle, researchers at the National Renewable Energy Laboratory in collaboration with Cummins analyzed 78,000 days of operational data captured from more than 260 vehicles operating across the United States to characterize the typical daily performance requirements associated with Class 6 commercial pickup and delivery operation. In total, over 2.5 million miles of real-world vehicle operation were condensed into a pair of duty cycles, an 80-mile cycle and a 100-mile cycle representative of the daily operation of U.S. class 3-6 commercial pickup and delivery trucks. Using novel machine learning clustering methods combined with mileage-based weighting, these composite representative cycles correspond to 90th and 95th percentiles for daily vehicle miles traveled by the vehicles observed. In addition to including vehicle speed vs time drive cycles, in an effort to better represent the environmental factors encountered by pickup and delivery vehicles operating across the United States, a nationally representative grade profile and key status information were also appended to the speed vs. time profiles to produce a “work day” cycle that captures the effects of vehicle dynamics, geography, and driver behavior which can be used for future design, development, and validation of technology.
Duran, AdamLi, Kekresse, JohnKelly, Kenneth
Development, Performance Analysis and Optimization of Parallel Hydraulic Hybrid System for City Bus Application2018-01-04194/3/2018
One of the key requisites for a sustained mobility development is to have an efficient public transport system. Fuel efficiency and emission control are extremely important in this respect. By the very nature of city driving, it is obvious that city traffic results in frequent vehicle start and stops; which involves huge waste of vehicle kinetic energy. Every time vehicle moving from idle, needs a bigger input of power and every time the brakes are applied, all energy built up disappears again, wasted in the brake pads as heat. An effort has been taken to recuperate vehicle kinetic energy, hydraulically during braking events and utilize it to assist the vehicle during acceleration. Hydraulic based hybrid vehicle working on the principle of regenerative braking is one of the most fuel-efficient technologies for city application. Parallel hydraulic hybrid vehicle has been developed and optimized for fuel efficiency gain at vehicle level. Objective of this paper is to study behavior, performance and optimization of hydraulic hybrid vehicle in city application. This paper deals with evaluation of simulation, integration, calibration and performance tests carried out at real world usage conditions. As a final proof of concept and performance, the hydraulic hybrid bus was tested back to back with conventional city bus of same configuration and results were analyzed and compared. This paper also deals on the scope of engine downsizing and major challenges faced in developing hydraulic hybrid system for extremely hot weather conditions such as South Asian countries.
Yaser, K U Syed TajBakatwar, RupeshBhargava, AashishTiwari, Sanjay
A Methodology of Real-World Fuel Consumption Estimation: Part 1. Drive Cycles2018-01-06444/3/2018
To assess the fuel consumption of vehicles, three sets of input data are required; drive cycles, vehicle parameters, and environmental conditions. As the first part of a series of studies on real-world fuel consumption, this study focuses on the drive cycles. In principle, drive cycles should represent real-world usage. Some of them aim at a specific usage such as a city driving condition or an aggressive driving style. However, the definition of city or aggressive driving is very subjective and difficult to quantitatively correlate with the real-world usage. This study proposes a methodology to quantify the speed and dynamics of drive cycles, or vehicle speed traces in general, against the real-world usage. After reviewing parameter sets found in other studies, relative cubic speed (RCS) and positive kinetic energy (PKE) are selected to represent the speed and dynamics through energy flow balance at the wheels. The authors suggest a normalised 2-dimensional coordinate space representing speed and dynamics of the drive cycles by statistical analysis of the parameters. The suggested space can be used for quantitative mapping of homologation drive cycles onto the given real-world usage data and identify which group of customers the homologation drive cycles represent. Another potential application of the methodology is to compare the multiple coordinate spaces generated from different data sets such as different vehicle segments. To demonstrate the proposed methodology, the 2-dimensional space is generated from a collection of data logged from passenger cars. The parameters of the collection show lognormal - normal distribution and are correlated to each other. Some homologation drive cycles are mapped onto the space and are compared to the real-world data followed by a discussion of the metrics of individual drive cycles.
Cho, BaekhyunKees, DonatusShah, Niravd'Urbal, Victor
A Hybrid Thermal Bus for Ground Vehicles Featuring Parallel Heat Transfer Pathways2018-01-11114/3/2018
Improved propulsion system cooling remains an important challenge in the transportation industry as heat generating components, embedded in ground vehicles, trend toward higher heat fluxes and power requirements. The further minimization of the thermal management system power consumption necessitates the integration of parallel heat rejection strategies to maintain prescribed temperature limits. When properly designed, the cooling solution will offer lower noise, weight, and total volume while improving system durability, reliability, and power efficiency. This study investigates the integration of high thermal conductivity (HTC) materials, carbon fibers, and heat pipes with conventional liquid cooling to create a hybrid “thermal bus” to move the thermal energy from the heat source(s) to the ambient surroundings. The innovative design can transfer heat between the separated heat source(s) and heat sink(s) without sensitivity to gravity. A case study examines the thermal stability, heat dissipation capabilities, power requirements, and system weights for several driving cycles. Representative numerical results show that the HTC materials and carbon fibers offer moderate cooling while loop heat pipes provide significant improvements for passive cooling.
Rizzo, DeniseSebeck, KatherineShurin, ScottShoai Naini, ShervinHuang, Junkui (Allen)Miller, RichardWagner, John R.
A Drag Coefficient for Test Cycle Application2018-01-07424/3/2018
The drag coefficient at zero yaw angle is the single parameter usually used to define the aerodynamic drag characteristics of a passenger car. However, this is usually the minimum drag condition and will, for example, lead to an underestimate of the effect of aerodynamic drag on fuel consumption because the important influence of the natural wind has been excluded. An alternative measure of aerodynamic drag should take into account the effect of nonzero yaw angles and a variant of wind-averaged drag is suggested as the best option. A wind-averaged drag coefficient (CDW) is usually derived for a particular vehicle speed using a representative wind speed distribution. In the particular case where the road speed distribution is specified, as for a drive cycle to determine fuel economy, a relevant drag coefficient can be derived by using a weighted road speed. This approach has been used to determine an effective drag coefficient for a range of cars using the proposed test cycle for the Worldwide harmonized Light vehicle Test Procedure (WLTP). A terrain-related wind profile, to give different mean wind velocities acting on the car, was applied to the various phases of the drive cycle, and an overall drag coefficient was then derived from the work done over the full cycle. This method has been updated using more detailed drag data at small yaw angles and, in this article, is also applied to the Environmental Protection Agency (EPA) drive cycle. This cycle-averaged drag coefficient (CDWC) is shown to be very similar to that obtained with the test cycle for WLTP and, in both cases, is significantly higher than the nominal zero yaw drag coefficient. Vehicle shape factors and add-on components which influence the drag rise at yaw are considered.
Howell, JeffPassmore, MartinWindsor, Steve
Experimental Evaluation of Rotational Inertia and Tire Rolling Resistance for a Twin Roller Chassis Dynamometer2017-36-021211/7/2017
Chassis dynamometers are important equipment to perform vehicular experiments in the automotive industry. Usually, these equipments are used according to standard procedures for emissions, fuel consumption, and performance analyses. In this paper, an alternative procedure was developed to experimentally determine the dynamometer inertia and losses related to bearings and transmission systems. Furthermore, a study on the tires rolling resistance, considering a double tire-roller contact, was carried out. The experiments were performed in a 4x2 chassis dynamometer with four rollers, equipped with an eddy current brake (coupled to a transmission reducer of 2.5 instrumented with a 3000 Nm torque flange) and with a 30 CV AC electric motor (coupled to a planetary transmission with reduction of 4.43 and instrumented with a 500 Nm torque flange). The dynamometer was also instrumented with an encoder system for speed measurement. All data were acquired by NI/LabVIEW™ software and post-processed in Matlab™ and Excel™ interfaces. The initial experiments resulted in the overall dynamometer bench inertia and equivalent inertias of the braking and electric motorization systems. The secondary experiments provided equations to determine the losses of the braking and electrical motorization systems, the overall bench losses and the vehicle/bench total rolling resistance according to the vehicle speed. Finally, a simplified coast-down experiment was performed on the dynamometer, and the results were compared to a Matlab/Simulink™ model of a hypothetical vehicle with similar mass.
Eckert, Jony JavorskiBertoti, ElvisCosta, Eduardo dos SantosSanticiolli, Fabio MazzariolYamashita, Rodrigo Yassudade Alkmin e Silva, Ludmila CorrêaDedini, Franco Giuseppe
Impact of Low and High Congestion Traffic Patterns on a Mild-HEV Performance2017-01-245810/8/2017
Driven by stricter mandatory regulations on fuel economy improvement and emissions reduction, market penetration of electrified vehicles will increase in the next ten years. Within this growth, mild hybrid vehicles will become a leading sector. The high cost of hybrid electric vehicles (HEV) has somewhat limited their widespread adoption, especially in developing countries. Conversely, it is these countries that would benefit most from the environmental benefits of HEV technology. Compared to a full hybrid, plug-in hybrid, or electric vehicle, a mild hybrid system stands out due to its maximum benefit/cost ratio. As part of our ongoing project to develop a mild hybrid system for developing markets, we have previously investigated improvements in drive performance and efficiency using optimal gearshift strategies, as well as the incorporation of high power density supercapacitors. In this paper, the fuel and emissions of a baseline conventional vehicle and mild hybrid electric vehicle (MHEV) are compared. The objective of this analysis is to compare the fuel economy and Greenhouse Gas (GHG) emissions of the baseline and MHEV models, using low and high-density traffic patterns chosen for their similarity to traffic density profiles of our target markets. Results demonstrate the benefits of a lower ongoing cost for the HEV architecture. These advantages include torque-hole filling between gear changes, increased fuel efficiency and performance.
Awadallah, MohamedTawadros, PeterWalker, PaulZhang, Nong
Driving Force Coordinated Control of Separated Axle Hybrid Electric Dump Truck2017-01-246210/8/2017
Due to the increase of mining production and rising labor costs, manufacturers of construction and mining equipment are engaged in developing large tonnage mining truck with good dynamic performance and high transport efficiency. This paper focuses on the improvement of the dynamic performance of a 52t off-highway dump truck. According to the characteristics of its operating cycle, electric auxiliary drive system is installed in the front axle aiming at improving the utilization rate of ground adhesion. The new all-wheel drive hybrid electric system makes it possible for dump truck transports at a higher velocity. Both the conventional dump truck model and the new all-wheel drive hybrid truck model are built based on the AVL-Cruise platform. Meanwhile, under the premise of enough dynamic performance, fuel consumption can be minimized by collaborative optimization in Isight. Multi-island genetic algorithm is adopted to get proper powertrain parameters for its wide use in finding a global optimal solution. The collaborative optimization results show that the new hybrid dump truck obtains high dynamic performance without sacrificing the fuel economy. By comparing the simulation results we find that the maximum velocity of full load all-wheel drive hybrid electric dump truck increases by 19% at 8% slope, by 21.4% at 12% slope. All these improvements are of great significance to the transport efficiency and fuel economy of the dump truck.
Zhang, RuipengMeng, Kaichuang
Evaluation of Exhaust Heat Recovery System Effectiveness in Engine Friction Reduction and Fuel Economy Improvement for Indian Hatchback2017-01-01543/28/2017
With the upcoming regulations for fuel economy and emissions, there is a significant interest among vehicle OEMs and fleet managers in developing computational methodologies to help understand the influence and interactions of various key parameters on Fuel Economy and carbon dioxide emissions. The analysis of the vehicle as a complete system enables designers to understand the local and global effects of various technologies that can be employed for fuel economy and emission improvement. In addition, there is a particular interest in not only quantifying the benefit over standard duty-cycles but also for real world driving conditions. The present study investigates impact of exhaust heat recovery system (EHRS) on a typical 1.2L naturally aspirated gasoline engine passenger car representative of the India market. Computational Sciences Experts Group (CSEG) has developed a forward calculating Simulink model of the passenger car in order to calculate the engine loading, engine heat rejection and the exhaust energy generated during a drive cycle. The calibrated model was then used to simulate a Modified Indian Drive Cycle (MIDC), and closely integrated with a transient underhood thermal model to evaluate the warm-up impact and the engine friction reduction attributed to the addition of the EHRS system. This approach can assist in the selection of the appropriate powertrain to optimize fuel economy. Further, the tool and the methodology quantify benefits in real world driving conditions and can help designers make educated investment decisions a cost/benefit and emission impact of the technologies.
Uppuluri, SudhiR Khalane, HemantNaiknaware, Ajay
Drive Cycle Development for Electrical Three Wheelers2017-01-15933/28/2017
A drive cycle is a time series of vehicle speed pattern developed to simulate real world driving conditions. These driving cycles are used for estimating vehicle on-road energy consumption, vehicle emissions, and traffic impact. Vehicle operating on fossil fuels are a significant source of air pollution, and these are being replaced by a small electrical vehicle in congested road traffic conditions, such as densely populated residential areas, near hospitals and market places, etc. The electrical vehicle run quieter and does not produce emissions like combustion engines. So far, there is no existing drive cycle officially developed for electric three wheelers which can represent real world driving pattern in India. In this study, 15 electrical auto rickshaws were driven by different drivers in various routes of a Tier II city of India and vehicle speed and time pattern were recorded using onboard Global Positioning System (GPS). Trip data was analyzed and logically compressed to develop a driving cycle for electrical three wheelers. The critical driving parameters such as relative position acceleration, average speed, and positive kinetic energy were computed and compared with standard regulatory cycles used for motorcycles. This newly developed driving cycle is useful for the development of new drive train and efficient batteries and their evaluation.
Pathak, Sunil kumarSingh, YograjSood, VineetChanniwala, Salim Abbasbhai
A Multi-mode Control Strategy for EV Based on Typical Situation2017-01-04383/28/2017
A multitude of recent studies are suggestive of the EV as a paramount representative of the NEV, its development direction is transformed from “individuals adapt to vehicles” to “vehicles serve for occupants”. The multi-mode drive control technology is relatively mature in traditional auto control sphere, however, a host of EV continues to use a single control strategy, which lacks of flexibility and diversity, little if nothing interprets the vehicle performances. Furthermore, due to the complex road environment and peculiarity of vehicle occupants that different requirement has been made for vehicle performance. To solve above problems, this paper uses the key technology of mathematical statistics process in MATLAB, such as the mean, linear fitting and discrete algorithms to clean up, screening and classification the original data in general rules, and based on short trips in the segments of kinematics analysis method to establish a representative of quintessential driving cycle. Therefore, it can provide us a way of extracting characteristic data in original rules. What we further do is fuzzy reasoning and intention recognition for controlling action of driver; we divided different classifications into two types: SPORT model and ECONOMIC model in order to improve the performance of vehicle and its accessories. At last, taking a simulation experiment for EV’s velocity, motor efficiency and battery SOC by DSPACE, which depends on the different opening degree of accelerator pedal, and we can summarize the difference between two strategies under typical situation. In addition, by optimizing control strategy we can make a single vehicle achieve multi-mode drive control, which improves the occupants’ sensation and receptiveness, also leads to the EV matching an optimum control of multi-mode based on typical situation.
Gao, ZhenhaiSun, TianjunHe, Lei
Estimation of the Effects of Auxiliary Electrical Loads on Hybrid Electric Vehicle Fuel Economy2017-01-11553/28/2017
In recent years the fuel efficiency of modern hybrid electric vehicle (HEV) powertrains has progressed to a point where low voltage auxiliary electrical system loads have a pronounced impact on fuel economy (FE). While improving the energy consumption of an individual component may result in minor improvements, the collective optimization of such loads across a complete vehicle system can result in meaningful FE gains. Traditional methods using chassis dynamometer testing alone to quantify the impact of a specific auxiliary load can lead to issues where signal state changes are too small for accurate detection. This presents difficulties in accurately predicting the influence of such loads on FE of next-generation electrified vehicles under development. This paper describes a newly developed method where dynamometer test results are combined with computer simulation analyses to create a practical technique for assessing the impact of small changes in auxiliary load energy consumption. The process combines the best features of empirical testing with model-based system engineering and accurately estimates the effect of small changes in total average oncycle auxiliary load power. This approach supports timely and resource-efficient estimates of the FE impact of auxiliary load components and control strategies. An overview of the effects of auxiliary load power on the FE of a modern HEV is presented for different drive cycles and the estimation process is presented.
Rhodes, KevinKok, DanielSohoni, PallavPerry, EvanKraska, MarvinWallace, Michael
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