bluuebunny/crossref_metadata_2025 huggingface dataset:
Investigation Of Variable Displacement Oil Pump and Its Influence on Fuel Economy for a 1.5 L, 3 Cylinder Diesel Engine
Authors: Sithick basha Abubakker , vinaya murthy Vijayendra , Rengaraj Chandrasekaran , Dharan R Bharani , Kumar PS Adm Venkatesh
Published: April 2023

The Introduction of Corporate Average Fuel Economy (henceforth will be addressed as CAFE) regulations demand suitable technological upgrades to meet the significant increase in targets of vehicle fleet fuel economy. Engine Downsizing and Friction Reduction measures help in getting one step closer to the target. In a Conventional Oil Pump, the pump discharge flow and pressure are a direct function of operating speed. There is no control over lubricant flow which results in increased power and fuel consumption due to its unnecessary pumping characteristics irrespective of the actual engine demand. This paper discusses the introduction of a variable displacement oil pump (henceforth will be addressed as VDOP) that was adapted to a 1.5-liter 3 Cylinder Diesel Engine. This approach helps the system to reduce parasitic losses as the oil flow is regulated based on the mechanical needs of the engine. The flow is regulated with help of a solenoid valve which receives input from the ECU. The engine Oil Pump has a major role in enabling the transfer of lubricant to all moving engine components. The demand majorly depends on engine performance characteristics, bearing clearances, operating temperatures, and wear behavior of engine components. The paper explains the boundary conditions for VDOP design packaging, challenges in system adaptation, impact on engine lubrication circuit, performance, and friction reduction benefit.
Reducing Fuel Consumption on a Heavy-Duty Nonroad Vehicle: Conventional Powertrain Modifications
Authors: Goodenough Bryant , Czarnecki Alexander , Robinette Darrell , Worm Jeremy , Latendresse Phil , Westman John
Published: April 2023

This investigation focuses on conventional powertrain technologies that provide operational synergy based on customer utilization to reduce fuel consumption for a heavy-duty, nonroad (off-road) material handler. The vehicle of interest is a Pettibone Cary-Lift 204i, with a base weight of 50,000 lbs. and a lift capacity of 20,000 lbs. The conventional powertrain consists of a US Tier 4 Final diesel engine, a non-lockup torque converter, a four-speed powershift automatic transmission, and all-wheel drive. The paper will present a base vehicle energy/fuel consumption breakdown of propulsion, hydraulic and idle distribution based on a representative end-user drive cycle. The baseline vehicle test data was then used to develop a correlated lumped parameter model of the vehicle-powertrain-hydraulic system that can be used to explore technology integration that can reduce fuel consumption. Two conventional powertrain modifications are explored that provide potential pathways that significantly alter the base powertrain and include 1.) a torque converter disconnect clutch and 2.) a low voltage stop-start system that have the potential to reduce fuel consumption on the end user representative drive cycle by 10.3% and 9.8%, respectively. Details of how the powertrain modifications would be executed, physical hardware, and application to other heavy-duty nonroad vehicle applications are included in the discussion.
Development of New Powertrain System for the Global Deployment of Hybrid Vehicles
Authors: Akiyama Katsunori , Murakami Hiroyuki , INABA ICHIRO
Published: April 2023

A new hybrid system has been developed to increase the permissible system weight and raise dynamic performance/system efficiency for the global rollout of Honda's electric vehicles.

The powertrain consists of a 2.0L direct injection engine, a Front Drive Unit (FDU) with a built-in traction motor/generator and gear that directly transmit engine torque to the wheels (engine driving gear), a Power Control Unit (PCU) mounted on the FDU, and an Intelligent Power Unit (IPU) mounted under the cargo area.

The FDU has a higher RPM (+12%) and higher torque (+6%) traction motor for enhanced launch acceleration performance and maximum vehicle speed settings tailored to regional needs.

In addition, a new engine driving gear for low-speed driving has been added to heighten system efficiency by avoiding traction motor driving in low-speed, high-load areas where electrical losses are high, and instead using a driving mode with an engine driving gear (ENGINE MODE).

In uphill towing, where the conventional system used to use a motor, the ENGINE MODE can suppress the heat generated by the motor, enabling the same towing performance as the conventional system to be provided to heavier vehicle types.

By reducing the diameter of the generator and changing the structure of the traction motor/generator from a coaxial arrangement to a parallel axis arrangement, the system can be installed in the same engine compartment as before while accommodating the addition of engine driving gear.

The development of this powertrain system has achieved a 10% increase in permissible system weight and a 12% increase in maximum vehicle speed.
Design of Drive Cycle for Electric Powertrain Testing
Authors: Borgia Fabio , Samuel Stephen
Published: April 2023

Drive cycles have been the official way to create standardized comparisons of fuel economy and emission levels between vehicles. Since the 1970s these have evolved to be more representative of real-world driving, with today’s standard being the World Harmonized Light Vehicle Testing Procedure. The performance of battery electric vehicles which consist of electric drives, battery, regenerative braking and their management systems may differ when compared to that of vehicles powered by conventional internal combustion engines. However, drive cycles used for evaluating the performance of vehicles, were originally developed for conventional powered vehicles. Moreover, the kinematic parameters that can distinguish the real-world performance of the differently powered vehicles are not fully known. This work aims to investigate the difference between vehicles powered by pure internal combustion engine, electric hybrid and pure electric drive. A route was selected to develop drive cycles with three representative vehicles one for each category and data was collected. Efforts were made for minimizing the effect of traffic flow between vehicles during the experiments. A numerical model of Nissan Leaf, was constructed in GT-Suite software and validated against current standard drive cycles data from the Argonne National Laboratory. Two drive cycles were developed using a micro-trip approach, for intermediate and harsh driving conditions. The results from the novel drive cycles show the inevitable distinctions between differently powered vehicles, giving an estimated range prediction that is very similar to the one from the World Harmonized Light Vehicle Testing Procedure.
Revision of Modeling Scenario for Hydrogen Fueling Protocol under MC-MM
Authors: Yamaguchi Shigehiro , Handa Kiyoshi
Published: April 2023

A new hydrogen fueling protocol called MC Multi Map (MC-MM) was developed to reduce hydrogen station operating costs. With the MC-MM, the number of fueling control maps has increased from before and precise switching among them according to circumstances has achieved relaxation of precooling temperatures. Fueling control maps for hydrogen stations are created in accordance with Society of Automotive Engineers (SAE) protocol, but with the MC-MM, greater accuracy of mapping is necessary, so steps were taken to revise the boundary conditions prescribed by the SAE. The creation of fueling control maps for a hydrogen fueling protocol used to require outsourcing of map analysis. However, the National Renewable Energy Laboratory research institute in the US has made a hydrogen fueling simulation called H2FillS publicly available on the Web so that analysis of fueling control maps can now be performed by anyone. Therefore, revision of the SAE boundary conditions was examined on the assumption that analysis would be performed using H2FillS. With regard to the fueling control maps newly added with the MC-MM, since the boundary conditions are not indicated by the SAE, those conditions were specified independently in this research. The fueling control maps created for use with the MC-MM were compared with the fueling control maps of existing protocols to confirm the influence from revising boundary conditions and switching to H2FillS as the analysis tool. Finally, the accuracy of the fueling control map created in this research was verified by conducting fueling tests in accordance with the MC-MM protocol using that fueling control map.
A New Safety-Oriented Multi-State Joint Estimation Framework for High-Power Electric Flying Car Batteries
Authors: Liu Wenxue , Khalatbarisoltani Arash , Hou Cong , Hu Xiaosong
Published: April 2023

Accurate and robust knowledge of battery internal states and parameters is a prerequisite for the safe, efficient, and reliable operation of electric flying cars. Battery states such as state of charge (SOC), state of temperature (SOT), and state of power (SOP) are of particular interest for urban air mobility (UAM) applications. This article proposes a new safety-oriented multi-state estimation framework for collaboratively updating the SOC, SOT, and SOP of lithium-ion batteries under typical UAM mission profiles that explicitly incorporates the underlying interplay among these three states. Specifically, the SOC estimation is performed by combining an adaptive extended Kalman filter with a timely calibrated battery electrical model, and the key temperature information, including the volume-averaged temperature, highest temperature, and maximum temperature difference, is estimated using an adaptive Kalman filter based on a simplified 2-D spatially-resolved thermal model. The SOC and SOT estimations interact with the temperature dependence of electrical parameters and the time-varying heat generation. Afterward, the dynamic power capability estimation is fulfilled considering multiple operational constraints such as current, voltage, SOC, and temperature. Both instantaneous and continuous peak power are covered for practical applications, and a novel temperature-constrained peak power estimation method is incorporated to enable more accurate and reliable SOP estimation. The proposed SOC-SOT-SOP joint estimation framework is validated thoroughly by computer simulation and the results demonstrate satisfactory accuracy and resilience.
Transient Electrochemical Modeling and Performance Investigation Under Different Driving Conditions for 144Ah Li-ion Cell with Two Jelly Rolls
Authors: Braga Raphael , Mevawalla Anosh , Gudiyella Soumya , Panchal Satyam , Giuliano Mattia , Nicol Giovanna , Zheng Yi
Published: April 2023

Recently, the automotive industry has experienced rapid growth in powertrain electrification, with more and more battery electric vehicles (BEV) and hybrid electric vehicles being launched. Lithium-ion batteries play an important role due to their high energy capacity and power density, however they experience high heat generation in their operation, and if not properly cooled it can lead to serious safety issues as well as lower performance and durability. In that way, good prediction of a battery behavior is crucial for successful design and management. This paper presents a 1D electrochemical model development of a 144 Ah prismatic rolled cell using the GT-Autolion software with a pseudo 2D approach. The model correlation is done at cell level comparing model results and test data of cell open circuit voltage at different temperatures and voltage and temperature profile under different C-rates and ambient temperatures. After the cell level validation, a lumped battery pack model was submitted to different drive cycles: EPA, CLTC-P and WLTC having the battery current as input and comparing battery voltage and SOC. The cell level model presented good correlation with test data and the battery model proved capable of accurately make performance predictions. This model be used for further advanced investigations, such as cell degradation, thermal runaway and gas generation.
Synthetic Grid Storage Duty Cycles for Second-Life Lithium-Ion Battery Experiments
Authors: Moy Kevin , Onori Simona
Published: April 2023

Lithium-ion batteries (LIBs) repurposed from retired electric vehicles (EVs) for grid-scale energy storage systems (ESSs) have the potential to contribute to a sustainable, low-carbon-emissions energy future. The economic and technological value of these “second-life” LIB ESSs must be evaluated based on their operation on the electric grid, which determines their aging trajectories. The battery research community needs experimental data to understand the operation of these batteries using laboratory experiments, yet there is a lack of work on experimental evaluation of second-life batteries. Previous studies in the literature use overly-simplistic duty cycling in order to age second-life batteries, which may not produce aging trajectories that are representative of grid-scale ESS operation. This mismatch may lead to inaccurate valuation of retired EV LIBs as a grid resource. This paper presents an end-to-end methodology that uses real-world electric grid power system data to simulate the cost-optimal dispatch for grid-scale ESSs. The dispatch is then used as an input to an algorithm which produces laboratory-prone, power-based synthetic duty cycles for second-life LIB cell aging experiments.
Comparison of Representative Wet and Dry Fire Suppressants to Retard Fire Propagation in Lithium-Ion Modules Initiated by Overcharge Abuse
Authors: Surampudi Bapiraju , Jones Kevin , Banks Zachary
Published: April 2023

Overcharging lithium-ion batteries is a failure mode that is observed if the battery management system (BMS) or battery charger fails to stop the charging process as intended. Overcharging can easily lead to thermal runaway in a battery. In this paper, nickel manganese cobalt (NMC) battery modules from the Chevrolet Bolt, lithium manganese oxide (LMO) battery modules from the Chevrolet Volt, and lithium iron phosphate (LFP) battery modules from a hybrid transit bus were overcharged. The battery abuse and emissions tests were designed to intentionally drive the three different battery chemistries into thermal runaway while measuring battery temperatures, battery voltages, gaseous emissions, and feedback from volatile organic compound (VOC) sensors. Overcharging a battery can cause lithium plating and other exothermic reactions that will lead to thermal runaway. During the testing, VOC sensors were used to determine what, if any, amount of forewarning they may provide in the event the battery enters thermal runaway. Additionally, three different fire suppressant agents were also used to judge whether one is more effective than the other in extinguishing the battery fires. The fire suppressants were engaged sixty seconds after thermal runaway was detected, and their effectiveness was judged by visually evaluating whether the fire was extinguished and remained extinguished. Data is analyzed to extract comparisons in peak thermal runaway temperatures, the amount of forewarning the battery may provide preceding thermal runaway as measured by the pre-thermal runaway temperatures and VOC sensors, and other qualitative metrics observed during the testing. The emissions collected during the overcharge testing are summarized for all the three chemistries and various suppressants.
Development of Inverter Drive Unit for Battery Electric Vehicle
Authors: Yuichi Shimo , Kanzaki Takao , Yanagi Takashi , Goto Yukio , Kurihara Takashi , Kobayashi Masayoshi
Published: April 2023

Toyota Motor Corporation has developed a new battery electric vehicle (BEV) on the dedicated e-TNGA platform for BEVs, which was designed to lower the center of gravity of the vehicle and increase body stiffness. In addition to a full-time 4WD system, another feature of this new BEV is its pleasurable driving experience. A new inverter drive unit was developed for this system. Unlike the previous inverter, the advantage of the new inverter is that it is small enough to be mounted inside the transaxle housing, thereby contributing to the availability of interior and luggage space. The temperature rise of the power semiconductors in the inverter was reduced considerably by the development of a new power semiconductor for BEVs. This enables a parallel layout of two power semiconductors instead of three. The components of the inverter were also downsized. A coreless current sensor was adopted, and capacitors were developed with significantly lower capacitance. The rear inverter adopts silicon carbide (SiC) power semiconductors, which significantly reduce energy loss compared to Si power semiconductors. This paper describes the technology developed for this new inverter unit.
Development of Control System for Parallel Hybrid System with Turbo Engine
Authors: Takeichi Akira , Kosaka Koshiro , NOBE Daigo , Suzuki Toshiaki , Miyake Shota , Tsukamoto Norihiro
Published: April 2023

This paper describes a new control technology that coordinates the operation of multiple actuators in a new hybrid electric vehicle (HEV) system consisting of a turbocharged engine, front and rear electric motors, two clutches, and a 6-speed automatic transmission. The development concept for this control technology is to achieve the driver’s desired acceleration G with a natural feeling engine speed. First, to realize linear acceleration G even while the engine is starting from EV mode, clutch hydraulic pressure reduction control is implemented. Furthermore, the engine start timing is optimized to prevent delayed drive force response by predicting the required maximum power during cranking. Second, to realize linear acceleration, this control selects the proper gear position based on the available battery power, considering noise and vibration (NV) restrictions and turbocharging response delays. Finally, to precisely control engine speed when the clutch is not directly connected, feedforward (F/F) controller and feedback (F/B) controller are implemented. The F/B controller for the engine was specially designed for response and stability considering the dead-time of engine torque response and disturbances. When disturbances occur, this controller reduces both the overshoot and settling time to the target value as compared to using a simple PI controller. These control technologies achieve shorter engine start time by 20%, powerful acceleration at low engine speed, and precise engine speed control. These contribute to driving pleasure of the new parallel hybrid system.
Architecture & Design of Common Hybrid Torque Controls within a Powertrain Domain Controller
Authors: Patel Nadirsh , Sha Hangxing , Madireddy Krishna , Tuller Zachary
Published: April 2023

The proliferation and increased complexity of electrified powertrains presents a challenge to the associated controls development. This paper outlines the strategy of common supervisory and domain torque management for such powertrains. The strategy covers the multitude of powertrain architectures that exist in the market today while maintaining the fundamental pillars of physics-based torque controls, state-of-the-art optimization methodologies, and common-core hybrid system constraints.

The electrified powertrain torque controls that Stellantis LLC. uses include key constituents such as optimization of powertrain state that relate to optimum engine speed and transmission gear, optimization of engine and motor torques, engine start-stop management, and hybrid shift execution which manages powertrain state transitions by interacting with various external transmission systems. The common backbone of these constituents are the dynamic/kinematic equations of the powertrain. Centralizing these dynamic and kinematic equations within the control structure allows for the downstream control constituents mentioned above to remain common for all electrified powertrain architectures. An added benefit of this strategy is the streamlining of calibration methodology and effort.
Early Stage Vehicle Aerodynamics Development using a GPU based LBM CFD Solver
Authors: Mortazawy Mehdi , Rao Mukul , Jilesen Jonathan , Work Dalon , Shock Richard
Published: April 2023

Developing synergy between styling design and aerodynamic efficiency has been an ongoing challenge in the automotive industry for many years. Designers and aerodynamicists have to meet strict deadlines and have limited resources to iterate and evolve the design and performance of the vehicle exterior during early concept development. The number of possible styling variants and configurations can often reach into the hundreds. Physical wind tunnel measurements are simply not practical from a time or cost perspective to evaluate these designs. Therefore, increased performance and accuracy of Computational Fluid Dynamics (CFD) simulations have become the main objective of every vehicle OEMs. Today, the GPU hardware, particularly the memory and performance, has reached a point where there is an increased interest in their usage for aerodynamics simulations. GPUs offer potential simulation performance improvements due to lower power consumption and hardware costs. With this in mind, a GPU based version of the Lattice Boltzmann Method (LBM) fluid solver has been recently implemented. LBM is known to be well suited for GPU computation as the method is naturally vectorizable. Additionally, as a low dissipation, inherently transient approach, it is also well-suited for accurate evaluation of external automotive aerodynamics.

This study provides a comparison between the relative performances of GPU based LBM vs its CPU based equivalent using the publicly available DrivAer aerodynamic model. A comparison of turn-around time on NVIDIA V100 and A100 cards vs an Intel Skylake CPU cluster is demonstrated. The resulting flow structures and forces will then be compared to show that the results are numerically equivalent, with significant performance gains on the GPU. Different models with different balances between surface elements and fluid nodes will also be evaluated, allowing for the relative computational cost of these different simulation elements to be discussed.
Automatic Generation of Evaluation Courses for Car Navigation Systems Via Combinatorial Optimization
Authors: Tomita Kiyohisa , Kojima Kousuke , Saito Susumu , Iwami Takuya , Matsumoto Ryo , Haba Renichiro , Ohzeki Masayuki
Published: April 2023

To accelerate development and improve the quality of car navigation systems, we have built a system for automatic generation of evaluation courses. In general, the operation of car navigation systems is verified by driving tests using vehicles. The evaluation courses need to be designed so that inspection sites, such as underground parking lots, tunnels, etc., will be visited during the evaluation period. They should be circuits that include as many inspection sites as possible within a defined distance. However, as the number of the inspection sites increases, the number of courses that can be designed becomes enormous. This makes it difficult to create courses that meet all of the requirements. Hence engineers have spent a lot of time on evaluation course design. For this reason, automatic course generation has become essential for reducing man-hours. We believe that one of the effective approaches is to treat automatic evaluation course generation as a combinatorial optimization problem. In our formulation, inspection sites are grouped into clusters according to the required number of courses, and the shortest circuit is constructed in each cluster.

Then, we treat the clustering and shortest circuit generation problems separately as a bi-level combinatorial optimization problem. In other words, the original problem is divided into smaller parts of the combinatorial optimization problems. We then propose a Markov chain Monte Carlo method for solving the bi-level optimization problem, and construct a system for automatic generation of evaluation courses. The proposed method significantly reduces course-design time compared to manual course construction.
Thermomechanical Fatigue Crack Growth Simulation in a Turbo-Housing Model Using Nonlinear Fracture Mechanics
Authors: Makke Ali Hassan , Kassir Abdallah , Boughanmi Heni , Seifert Thomas , Chang Cherng-Chi , Kallepalli Ravi
Published: April 2023

Turbocharger housings in internal combustion engines are subjected to severe mechanical and thermal cyclic loads throughout their life-time or during engine testing. The combination of thermal transients and mechanical load cycling results in a complex evolution of damage, leading to thermo-mechanical fatigue (TMF) of the material. For the computational TMF life assessment of high temperature components, the DTMF model can provide reliable TMF life predictions. The model is based on a short fatigue crack growth law and uses local finite-element (FE) results to predict the number of cycles to failure for a technical crack. In engine applications, it is nowadays often acceptable to have short cracks as long as they do not propagate and cause loss of function of the component. Thus, it is necessary to predict not only potential crack locations and the corresponding number of cycles for a technical crack, but also to determine subsequent crack growth or even a possible crack arrest. In this work, a method is proposed that allows the simulation of TMF crack growth in high temperature components using FE simulations and non-linear fracture mechanics (NLFM).

A NLFM based crack growth simulation method is described. This method starts with the FE analysis of a component. In this paper, the method is demonstrated for an automotive turbocharger housing subjected to TMF loading. A transient elastic-viscoplastic FE analysis is used to simulate four heating and cooling cycles of an engine test. The stresses, inelastic strains, and temperature histories from the FEA are then used to perform TMF life predictions using the standard DTMF model. The crack position and the crack plane of critical hotspots are then identified. Simulated cracks are inserted at the hotspots. For the model demonstrated, cracks were inserted at two hotspot locations. The ΔJ integral is computed as a fracture mechanics parameter at each point along the crack-front, and the crack extension of each point is then evaluated, allowing the crack to grow iteratively. The paper concludes with a comparison of the crack growth curves for both hotspots with experimental results.
Engine Idle Creep Testing and Modeling of Vehicles Equipped with CVT, DCT, and Conventional Automatic Transmissions
Authors: Timbario Thomas A. , Stoner Jacob , Sheldon II Stuart
Published: April 2023

Determining impact speeds is an important factor in any accident reconstruction. Event data recorders are now commonplace in on-road vehicles and provide an added tool for the accident reconstructionist. However, in low-speed collisions where impact severity is often important, event data recorders fail to record data as the minimum threshold for impact severity sometimes is not met. Alternatively, damage-based methods may be ineffective in quantifying the severity of the impact due to a lack of defined vehicle crush damage. These types of scenarios oftentimes present themselves as a bullet vehicle in the beginning processes of accelerating from a stop or when a stopped target vehicle is rear-ended from behind by the bullet vehicle. A specific subset of this scenario might entail the foot of the driver of the bullet vehicle coming off the brake pedal, allowing the bullet vehicle to “creep” forward at engine idle speeds and impacting the target vehicle resulting in no visible crush damage to either vehicle. Eighteen vehicles with conventional automatic transmissions were tested, which included sedans, sport utility vehicles (SUVs), pickup trucks, and vans. Two vehicles (one sedan, one wagon) equipped with dual-clutch transmissions (DCTs) and three vehicles (one sedan, one hatchback, and one wagon) equipped with continuously variable transmissions (CVTs) were also tested. These vehicles were allowed to accelerate at idle with the brake pedals released. Acceleration, speed, distance, and engine speed data were collected for multiple vehicles runs in both forward and reverse directions over level ground. The data resulting from this study were then compared/contrasted among the different drivetrains and also previously published literature to determine similarities and differences. Previous study data sets were also incorporated with the authors’ data to improve predicted vehicle speed.
Aggregation of Lumbar Loads in Rear Impact Crash Tests
Authors: Kashdan Aryeh , Umale Sagar , Kazmierczak Alex , Kasselik Joseph , Randles Bryan , Furbish Christopher , Welcher Judson
Published: April 2023

An analysis of peak lumbar load data collected from the existing peer-reviewed literature on rear impact crash tests was performed. Values for peak lumbar tension/compression, peak lumbar sagittal forces, and peak lumbar flexion/extension moments were aggregated from each study. The trends in the accumulated data were analyzed as functions of the changes in velocity (delta-Vs) measured during the crash tests. The data were further analyzed to identify differences in trends found across variations in the testing conditions used across studies. These testing conditions included type of anthropometric test device (ATD) used, type of ATD pelvis used, ATD seating position, production year of seat used, type of seat used, and type of seat restraint used. Data were also aggregated from peer-reviewed research quantifying peak lumbar compression in human subjects performing various tasks, including activities of daily living (ADLs), tasks related to sports and exercise, and industrial tasks typical of manual labor. The peak lumbar compression data from rear impact tests with ATDs was compared with the corresponding peak load data from the studies with human subjects. Linear regressions of the aggregated data from rear impact crash tests with impact severities between 5-45 km/h indicated some relationships between peak lumbar loads and delta-V. However, the relatively low R2 values observed from these regressions suggest that other variables may contribute to the variance in peak lumbar loading with respect to delta-V. It appears that individuals performing ADLs may experience peak lumbar compression similar to the compression measured in ATDs in rear impact crash tests with impact severities between 5-45 km/h. Aggregated peak lumbar compressive loading values in tasks related to sports, exercise, and industry were largely greater than the aggregated peak loads from crash testing.
Development of an Electronic Stability Control Algorithm for All-Terrain Vehicles
Authors: Zagorski Scott , Heydinger Gary
Published: April 2023

An Electronic Stability Control algorithm has been developed for All-Terrain Vehicles. The algorithm is implemented on SEA’s Robotic Test Driver which has been customized to drive ATVs unmanned. The ESC algorithm is incorporated in the real-time controller. When activated, ESC monitors vehicle states and when they exceed pre-determined thresholds, ESC intervenes by dropping throttle and applying the vehicle’s brakes. The intention of this algorithm is to prevent yaw instability and ultimately limit the vehicle’s roll angle. ESC is implemented on two vehicles, which exhibit varying degrees of understeer. Test data is provided to illustrate the determination in setting threshold limits. The efficacy of the ESC is demonstrated by showing the system being enabled and disabled.
Driveline Control Influence when ABS Active
Authors: Xing Xing , Clark Mark , Morris Robert
Published: April 2023

The interaction between driveline control and anti-lock braking system (ABS) control in electric vehicles (EV) was investigated based on multi-body dynamics (MBD) model and control model co-simulation. Two primary driveline control algorithms, active damping control and wheel flare control, were integrated with ABS control in Simulink model and the influence on ABS control was studied. The event for high mu to low mu transition was simulated. When ABS control is active on low mu surface, the vehicle shows large wheel slip and long duration time before wheel speed returns to stable control. This performance could be improved with activating driveline control. Deceleration uniformity metric shows that active damping control has very small effect when ABS control becomes stable after passing through the high mu to low mu transition period. Driveline damping control can help to reduce vibration, but it is difficult to find satisfied tuning for wheel speed performance. Wheel flare control can help to reduce the large wheel slip more effectively than ABS control. With proper tuning in ABS control, it can achieve smooth transition between wheel flare control and ABS control. Variation study on different brake torque level and different mu surface shows the performance is robust.
Methodologic Assessment of Brake-by-Wire System Modelling with Regard to Accuracy, Model Complexity and Optimization Efforts
Authors: Heydrich Marius , Kellner Björn , Ivanov Valentin
Published: April 2023

Brake-by-wire systems are an innovative and important component of modern high-performance and also electrified vehicles. Due to their decoupled architecture, they enable driver-independent vehicle dynamics control (e.g., brake torque blending) and easy integration of assistance functionalities (e.g. Emergency Brake Assist (EBA)). On the other hand, the development of these functions can cause high costs and development effort, and testing can be critical in case of improper gain tuning. Therefore, already in the concept phase, a large part of the testing is shifted to virtual environments and simulations that allow safe and reproducible experiments without damage. Therefore, suitable and reliable models are needed to represent reality as accurately as possible.

This paper deals with the modelling of a purely electrohydraulic brake-by-wire system and a hybrid system with electrohydraulic brakes on the front axle and electromechanical brakes on the rear axle. For comparison, both an experimental approach based on a second-order transfer function and an analytical model are used. These approaches are then evaluated in terms of their accuracy and reliability using real measurements in different dynamic test setups. Finally, it is shown how accurate the approaches are and what advantages can be achieved by using the different methods for system modelling.
A Spline-Based Analytical Model for the Design of an Automotive Anti-Roll Bar
Authors: Chiari Alessandro , Mantovani Sara , Skrickij Viktor , Boulay Emilie
Published: April 2023

The new corner-based architecture of electrified road vehicles requires a redesign of vehicle suspension components. The design protocol must satisfy the target parameters derived from dynamics requirements. The roll stiffness of the anti-roll bar is a crucial parameter for the handling performance of a vehicle. During the development of a new suspension, the design of the anti-roll bar needs to be modified. To this aim, two-dimensional beam theory models can quickly provide a preliminary design of this component. However, the simplified models might be inaccurate due to the three-dimensional and complex shapes of the bars. The present study aims to overcome this limitation. An analytical beam model based on the spline description of the bar has been developed, which is accurate even for complex geometries of the bars. Assuming a hollow and closed circular cross-section, the model returns the average diameter and the radial thickness needed to achieve the stiffness performance. Three different approaches for the thickness have been analyzed by assuming: (I) a prescribed thickness, (II) a prescribed global mass, and (III) a prescribed maximum value of stress. The first two methods present a uniform thickness along the bar, whereas, in the third one, the thickness varies to obtain the lightest solution. This latter method can be modified to ensure a feasible minimum thickness. Finally, a full-factorial design of the experiments algorithm has been developed to reduce the stress by varying the position of the spline control points. The proposed methods can provide a good preliminary design of the bar and can drive a material replacement process from a lightweight viewpoint.
What Makes Passengers Uncomfortable In Vehicles Today? An Exploratory Study of Current Factors that May Influence Acceptance of Future Autonomous Vehicles
Authors: Mims Lauren K. , Gangadharaiah Rakesh , Brooks Johnell , Su Haotian , Jia Yunyi , Jacobs Julie , Mensch Sterling
Published: April 2023

Autonomous vehicles have the potential to transform lives by providing transportation to a wider range of users. However, with this new method of transportation, user acceptance and comfort are critical for widespread adoption. This exploratory study aims to investigate what makes passengers uncomfortable in existing vehicles to inform the design of future autonomous vehicles. In order to predict what may impact user acceptance for a diverse rider population for future autonomous vehicles, it is important to understand what makes a broad range of passengers uncomfortable today. In this study, interviews were conducted for a total of 75 participants from three diverse groups, including 20 automotive engineering graduate students who are building an autonomous concept vehicle, 21 non-technical adults, and 34 senior citizens. The results revealed both topics which made different groups of passengers uncomfortable as well as how these varied between the groups. The leading contributors to the highest discomfort for all groups were being a passenger in situations with a distracted driver, being in a vehicle that is following too closely, being near a vehicle that is following too closely, and being in foggy conditions. In addition, the results showed that passenger discomfort can be attributed to a broad range of factors ranging from behaviors of the driver/vehicle that one is traveling with/in, the behaviors of other surrounding vehicles, the environmental conditions and the vehicle’s interior, all of which may differ between different groups of passengers. This research provides important findings and insights into factors that may influence users’ acceptance and use of future autonomous vehicles.
Model-Based Coordinated Steering and Braking Control for a Collision Avoidance Driver Assist Function
Authors: Li Yiquan , Petrovich Simon , Nybacka Mikael
Published: April 2023

ADAS (Advanced Driver Assistance System) functions can help the driver avoid accidents or mitigate their effect when they occur, and are pre-cursors to full autonomous driving (SAE defined as Level 4+). The main goal of this work is to develop a Model-Based system to actuate the Evasive Maneuver Assist (EMA) function.

A typical scenario is the situation in which longitudinal Autonomous Emergency Braking (AEB) is too late and the driver has to adopt an evasive maneuver to avoid an object suddenly appearing on the road ahead. At this time, EMA can help improve the driver’s steering and braking operation in a coordinated way. The vehicle maneuverability and response performance will be enhanced when the driver is facing the collision. The function will additionally let the vehicle steer in a predetermined optimized trajectory based on a yaw rate set point and stabilize the vehicle.

The EMA function is introduced with some analysis of benchmarking data. Benchmarking has shown different strategies from several OEMs (Original Equipment Manufacturers) and suppliers, in which the discipline of how they want the vehicle performance to behave and where improvements could be found.

Functional requirement and performance metrics of EMA function are created. The performance metrics are based on objective and subjective evaluation.

Frequency analysis is used to develop transfer functions to understand actuator effects, and Model-Based Design (MBD) is employed to subsequently develop the controller function using co-simulation between Matlab/Simulink and VI-CarRealtime. Results and analysis are presented at key vehicle speeds where intervention could be necessary.

The final part introduces driving simulator tests after the development of the function. The measured signal results could be compared with simulation results and driver’s performance without EMA. Eventually, a questionnaire survey was made to define a direction for further improvement. Additional ideas are presented for more advanced work.
Study on a Vehicle-Type-Based Car-Following Model using the Long Short-Term Memory Method
Authors: Yamazaki Tasuku , Oikawa Shoko , Hirose Toshiya
Published: April 2023

For car-following models, the car-following characteristics differ depending on the vehicle type, such as passenger cars, motorcycles, and trucks. Therefore, constructing a model for each category is essential. To that end, various modeling methods have been proposed; however, herein, we particularly focused on the long short-term memory (LSTM), which is the best method for forecasting long-term time-series data.[1, 2] The objective of this study was to construct a car-following model for each vehicle category using the LSTM and to evaluate the model accuracy for each vehicle category. In this study, US-101 and I-80 data provided by the next-generation simulation (NGSIM), which is based on natural traffic flow data, were used. In the NGSIM, only car-following situations were selected as car-following data, and these were classified into the vehicle type: motorcycles, passenger cars, and trucks. The classified data were then used to construct LSTM-based car-following models for each category. As the evaluation of this model was dependent on the amount of data, the model was built according to the amount of data for motorbikes, which was the lowest. A merged integrated model was also constructed by mixing the data obtained from all vehicle type, and the accuracy of the model was compared with that of the model for each vehicle category. Thus, this study investigated the impact of car-following models constructed for each vehicle category on the model accuracy using the LSTM. The results showed that for passenger cars and motorcycles, the RMSE values of the vehicle-specific models were smaller than those of the integrated model and the accuracy of the models was better than that of the integrated model. In future, we intend to construct car-following models for each vehicle characteristic.
MPC Based Car-Following Control for Electric Vehicles Considering Comfort
Authors: Tu Qingquan , Tan Gangfeng
Published: April 2023

This paper proposed a model predictive control(MPC) based car-following control strategy for electric vehicles considering comfort, in order to improve the comfort of the car-following control system of electric vehicles. The MPC algorithm is improved in the following three aspects to improve the comfort: Firstly, a five-state longitudinal car-following model is adopted, so that the MPC algorithm can optimize the acceleration and acceleration change rate of the ego vehicle. Secondly, for the weight coefficients of the output vector and the input vector of the objective function, the fixed weight coefficients are changed into variable weight coefficients by the way of Nash equilibrium game, so that the control system can improve the weight of the parameters used to control the comfort under suitable driving conditions. Finally, The NGSIM natural driving data set is used to change the fixed constraint on acceleration into the variable constraint that follows the velocity change, so as to avoid the impact of emergency acceleration and deceleration on comfort. The improved MPC algorithm continuously calculates the desired acceleration of the ego vehicle at the current moment through online rolling optimization, than transmits it to the lower-level controller. Due to the type of controlled vehicle is changed from fuel vehicle to electric vehicle, the motor model is used in the lower-level controller to replace the engine model. The control signal of the upper-level controller is converted into the desired motor torque or the desired braking pressure in the lower-level controller. The simulation results show that, on the basis of ensuring the safety and tracking capability, the fluctuation range of acceleration is reduced by 24.4% and the standard deviation of acceleration is reduced by 12.5% compared with the basic MPC algorithm. At the same time, the sudden change of acceleration is eliminated. Thus the comfort of the car-following process is significantly improved.
Operational Design Domain Feature Optimization Route Planning Tool for Automated Vehicle Open Road Testing
Authors: Rodriguez Zarazua Pedro , Alrousan Qusay , Alzu'bi Hamzeh , Tasky Tom
Published: April 2023

Autonomous vehicles must be able to function safely in complex contexts, involving unpredictable situations and interactions. To ensure this, the system must be tested at various stages as described by the V-model. This process iteratively tests and validates distinct parts of the system, starting with small components to system level assessment. However, this framework presents challenges when adapted to deal with testing problems that face autonomous vehicles. Open road testing is an effective way to expose the system to real world scenarios in combination with specific driving situations described by the Operational Design Domain (ODD). The task of finding a path between two points that maximizes the ODD exposure is not a trivial task, without mentioning that in most cases, the developers must design routes in unfamiliar regions. This represents a significant effort and resources consumption, which makes it important to optimize this task. This paper approaches this problem by proposing a tool for automation support to routes design by using a dataset of road attributes in addition with a search algorithm which considers the roadway attributes required by the ODD to find a set of optimal routes. The purpose of the tool is to reduce route planning times, optimize driving milage and facilitate further analysis. To show if the tool represents an improvement, we design a set of routes defining start and end points locations in 5 different cities of the US selecting from a list of available road attributes one route attribute at a time for optimization and contrasting the tool proposed routes against references routes that only optimizes driving distance or driving time. The results of this comparison were satisfactory in the sense that in every case the tool proposed routes that improved the selected attribute exposure.