Browse Topic: Electronic braking systems

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Quantitative Analysis of a Hybrid Electric HMMWV for Fuel Economy Improvement2024-01-33564/23/2025
ABSTRACT This paper presents a quantitative analysis and comparison of fuel economy and performance of a series hybrid electric HMMWV (High Mobility Multi-purpose Wheeled Vehicle) military vehicle with a conventional HMMWV of equivalent size. Hybrid vehicle powertrains show improved fuel economy gains due to optimized engine operation and regenerative braking. In this paper, a methodology is presented by which the fuel economy gains due to optimized engine are isolated from the fuel economy gains due to regenerative braking. Validated vehicle models as well as data collected on test tracks are used in the quantitative analysis. The regenerative braking of the hybrid HMMWV is analyzed in terms of efficiency from the kinetic energy at the wheels to the portion of regenerative power which is retrievable by the battery. The engine operation of both the series hybrid and conventional HMMWV are analyzed using a 2-D bin analysis methodology. Finally, the vehicle model is used to make recommendations on improving the fuel economy of the series hybrid as well as the conventional HMMWV.
Nedungadi, Ashok, Masrur, Abul, Khalil, Gus
Recurrent Neural Network Model for On-Board Estimation of the Side-Slip Angle in a Four-Wheel Drive and Steering Vehicle15-17-01-00039/23/2023
Abstract A valuable quantity for analyzing the lateral dynamics of road vehicles is the side-slip angle, that is, the angle between the vehicle’s longitudinal axis and its speed direction. A reliable real-time side-slip angle value enables several features, such as stability controls, identification of understeer and oversteer conditions, estimation of lateral forces during cornering, or tire grip and wear estimation. Since the direct measurement of this variable can only be done with complex and expensive devices, it is worth trying to estimate it through virtual sensors based on mathematical models. This article illustrates a methodology for real-time on-board estimation of the side-slip angle through a machine learning model (SSE—side-slip estimator). It exploits a recurrent neural network trained and tested via on-road experimental data acquisition. In particular, the machine learning model only uses input signals from a standard road car sensor configuration. The model adaptability to different road conditions and tire wear levels has been verified through a sensitivity analysis and model testing on real-world data proves the robustness and accuracy of the proposed solution achieving a root mean square error (RMSE) of 0.18 deg and a maximum absolute error of 1.52 deg on the test dataset. The proposed model can be considered as a reliable and cheap potential solution for the real-time on-board side-slip angle estimation in serial cars.
Giuliacci, Tiziano Alberto, Ballesio, Stefano, Fainello, Marco, Mair, Ulrich, King, Julian
V4-002 FK testSAE-PP-009554/26/2022
Heavy vehicles are essential for the modern economy, delivering critical food, supplies, and freight throughout the world. Connected heavy vehicles are also driven by embedded computers that utilize internal communication using common standards. However, some implementations of the standards leave an opening for a malicious actor to abuse the system. One such abuse case is a cyber-attack known as the “Address Claim Attack.” Proposed in 2018, this attack uses a single network message to disable all communication to and from a target electronic control unit, which may have a detrimental effect on operating the vehicle. This article demonstrates the viability of the attack and then describes the implementation of a solution to prevent this attack in real time without requiring any intervention from the manufacturer of the target devices. The defense technique uses a bit-banged Controller Area Network (CAN) filter to detect the attack. Once an attack is discovered, the defender induces a CAN protocol error to remove the malicious message from the network. We discuss our results in terms of their applicability for Address Claim Attacks and possible implications for preventing a variety of network-based attacks in real time.
Mutagaana, Festo
SAE J1698-1A Pedestrian Protection EDR Output Data Definition, Appendix to SAE J1698-1 Event Data Recorder - Output Data DefinitionJ1698/1A_202104 (Current)4/30/2021
SAE J1698-1A creates an appendix to SAE J1698-1. The appendix contains EDR Record parameters and definitions related to light duty passenger vehicle pedestrian protection systems.
Event Data Recorder Committee
Accurate Pressure Control Based on Driver Braking Intention Identification for a Novel Integrated Braking System2021-01-01004/6/2021
With the development of intelligent and electric vehicles, higher requirements are put forward for the active braking and regenerative braking ability of the braking system. The traditional braking system equipped with vacuum booster has difficulty meeting the demand, therefore it has gradually been replaced by the integrated braking system. In this paper, a novel Integrated Braking System (IBS) is presented, which mainly contains a pedal feel simulator, a permanent magnet synchronous motor (PMSM), a series of transmission mechanisms, and the hydraulic control unit. As an integrative system of mechanics-electronics-hydraulics, the IBS has complex nonlinear characteristics, which challenge the accurate pressure control. Furthermore, it is a completely decoupled braking system, the pedal force doesn’t participate in pressure-building, so it is necessary to precisely identify driver’s braking intention. To improve the control accuracy of the system, this paper proposed a novel pressure control strategy based on driver braking intention identification. Firstly, the structure and working principle of the novel integrated braking system was introduced. Secondly, the driver's braking intention identification strategy was designed. Thirdly, Considering the nonlinear and dynamic characteristics of the system, a cascade closed-loop control strategy including a pressure loop by the feedforward-feedback method, a position loop by the sliding-mode control method, and current loop with friction compensation was proposed. Finally, based on dSPACE products, a hardware-in-the-loop (HiL) experimental bench was built for algorithm verification. The HiL experiment results show that the pressure control strategy has the advantages of accurate response, the braking system pressure follows the driver's expected pressure well.
Zhu, Bing, Zhang, Yihan, Zhao, Jian, Chen, Zhicheng, Jin, Wanli
Applying Automotive EDR Data to Traffic Crash Reconstruction Virtual Pre-Conference CertificationC20168/7/2020
EDR\'s were first installed in 1994 and are now installed in 99% of new light vehicles sold in the US. In the US EDR’s are not required, but vehicles with EDR’s made after 9/1/2012 must meet minimum standardized content requirements of 49 CFR, Part 563 including speed, throttle, brake on/off and Delta V. Data must be retrievable with a publicly available tool. Only a few manufacturers install EDR’s worldwide currently, but the EU and China are adopting regulations to require them in the next few years. Some manufacturers provide stability control system data far beyond the US regulation that aid in understanding vehicle movement in the 5 seconds prior to the crash. This course will provide the participant with the skills necessary to analyze EDR data that has already been imaged, apply it to crash reconstruction, and reconcile it with calculations using other data sources. The course will enable the participant to analyze current and potential future EDR data set without regard to manufacturer. The class presents the generic analysis step by step, then groups EDRs into manufacturer-specific families and their data limitations, and works case studies that highlight targeted key learning objectives. The student will also learn key points to satisfy court Frye and Daubert requirements for EDR data to be admissible, and suggest methods to present EDR data that will communicate the data understandably to attorneys and lay juries. This course has been approved by the Accreditation Commission for Traffic Accident Reconstruction (ACTAR) for 20 Continuing Education Units (CEUs). Upon completion of this seminar, accredited reconstructionists should mail a copy of their course certificate and the $5 student CEU fee to ACTAR, PO Box 1493, North Platte, NE 69103. By attending this seminar, you will be able to: Describe EDR sensor operation, recording interval and duration, resolution, accuracy, and time latency and articulate the limitations of applying the data to crash analysis Calculate min and max speeds prior to loss of control or braking, and at impact based on the last accurate EDR pre-crash speed data point Evaluate EDR vs. actual ground speed for specific vehicle operational conditions and vehicle equipment modifications Calculate speed at impact and closing speeds by combining EDR Delta V data with normally collected scene and vehicle data such as post crash travel distance, departure angle, drag factor, and vehicle weights Apply data to inline rear end, head on, and angular collisions Reconcile EDR data with other physical evidence and combine to narrow speed ranges Use time-distance and overlay EDR data on scene maps/diagrams to show where critical driving inputs were made vs. inputs required to avoid collisions CEUs
Articulated Vehicle Lateral Stability Management via Active Rear-Wheel Steering of Tractor Using Fuzzy Logic and Model Predictive Control02-13-02-00087/1/2020
In-phase rear-wheel steering, where rear wheels are steered in the same direction of front wheels, has been widely investigated in the literature for vehicle stability improvements along with stability control systems. Much faster response can be achieved by steering the rear wheels automatically during an obstacle avoidance maneuver without applying the brakes where safe stopping distance is not available. Sudden lane change movements still remain challenging for heavy articulated vehicles, such as tractor and semitrailer combinations, particularly on roads with low coefficient of adhesion. Different lateral accelerations acting on tractor and semi-trailer may cause loss of stability resulting in jackknifing, trailer-swing, rollover, or slip-off. Several attempts have been made in the literature to use active steering of semi-trailer’s rear wheels to prevent jackknifing and rollover. However, loss of stability in an articulated vehicle is usually caused by an oversteered tractor, and the semitrailer’s rear wheels have little effect on the tractor’s directional control. In this study, viability of active rear-wheel steering of tractor to maintain the stability of an articulated vehicle during a high-speed obstacle avoidance maneuver is investigated. Two different controllers, fuzzy logic and linear model-based predictive controllers, are proposed to minimize the off-tracking behavior of an articulated vehicle. The controllers were tested in IPG/TruckMaker environment with MATLAB/Simulink interface on roads with various coefficient of adhesions, performing single lane change maneuvers. The simulated results showed that jackknifing occurring right after sudden lane changes can be successfully prevented using the tractor’s active rear-wheel steering based on model predictive control algorithm when the feedback gains are tuned correctly.
Sahin, Hasan, Akalin, Ozgen
Integrated Regenerative Braking System and Anti-Lock Braking System for Hybrid Electric Vehicles & Battery Electric Vehicles2020-01-08464/14/2020
This paper describes development of an integrated regenerative braking system and anti-lock brake system (ABS) control during an ABS event for hybrid and electric vehicles with drivelines containing a single electric motor connected to the axle shaft through an open differential. The control objectives are to recuperate the maximum amount of kinetic energy during an ABS event, and to provide no degraded anti-lock control behavior as seen in vehicles with regenerative braking disabled. The paper first presents a detailed control system analysis to reveal the inherent property of non-zero regenerative braking torque control during ABS event and explain the reason why regenerative braking torque can increase the wheel slip during ABS event with existing regenerative braking control strategies. Then, the regenerative brake control problem during ABS events is formulated with a unified control system architecture where the regenerative braking torque is coordinated with the friction braking torque of ABS system. An integrated closed loop based wheel slip control including both regenerative braking control loop and friction braking control loop during ABS event, referred to as RBS-ABS event control, is developed. The maximum regenerative braking is achieved and optimal vehicle braking performances and vehicle stability are maintained during ABS event. Finally, simulation tests are provided to illustrate RBS-ABS event control as an effective solution to satisfy desired wheel slip with the same level of stop distance in comparison with that of ABS control only while performing energy recuperation.
Yao, Yixin, Zhao, Yanan, Yamazaki, Mark
Modeling, Validation and Control Strategy Development of a Hybrid Super Sport Car Based on Lithium Ion Capacitors2020-01-04424/14/2020
Today, the contribution of the transportation sector on greenhouse gases is evident. The fast consumption of fossil fuels and its impact on the environment have given a strong impetus to the development of vehicles with better fuel economy. Hybrid electric vehicles fit into this context with different targets, starting from the reduction of emissions and fuel consumption, but also for performance and comfort enhancement. Lamborghini has recently invested in the development of a hybrid super sport car, due to performance and comfort reasons. Aventador series gearbox is an Independent Shift Rod gearbox with a single clutch and during gear shifts, as all the single clutch gearbox do, it generates a torque gap. To avoid the additional weight of a Dual Clutch Transmission, a 48V Electric Motor has been connected to the wheels, in a P3 configuration, to fill the torque gap, and to habilitate regenerative braking and electric boost functions. This paper discusses the usage of a control-oriented vehicle and powertrain model to analyze the performance of the first Lithium Ion Capacitor-based hybrid V12 by Automobili Lamborghini. The internal combustion engine, the gearbox, the LiC and the vehicle longitudinal dynamics models have been initially validated through the comparison with experimental data from chassis dynamometer testing, in addition to experimental results from specific components’ testing. As shown in the paper, the validated model has then been used to develop control strategies aimed at increasing comfort and performance, but also to expand the hybrid system capabilities by widening the LiC working range, and to study the possibility of implementing CO2 reduction-oriented control functions.
Franceschi, Alessandro, Cavina, Nicolo, Parenti, Riccardo, Reggiani, Maurizio, Corti, Enrico
Research on Compensation Redundancy Control for Basic Force Boosting Failure of Electro-Booster Brake System2020-01-02164/14/2020
As a new brake-by-wire solution, the electro-booster (Ebooster) brake system can work with the electronic stability program (ESP) equipped in the real vehicle to realize various excellent functions such as basic force boosting (BFB), active braking and energy recovery, which is promoting the development of smart vehicles. Among them, the BFB is the function of Ebooster's servo force to assist the driver's brake pedal force establishing high-intensity braking pressure. After the BFB function failure of the Ebooster, it was not possible to provide sufficient brake pressure for the driver's normal braking, and eventually led to traffic accidents. In this paper, a compensation redundancy control strategy based on ESP is proposed for the BFB failure of the self-designed Ebooster. Firstly, introduced the working principle of Ebooster and ESP, and a suitable pressure-building circuit was selected for the dual brake actuator system; Secondly, after the BFB failure of Ebooster, the rule-based strategy of braking awareness recognition was designed. Thirdly, a layered closed-loop compensation control strategy is designed based on the ESP to restore the pressure building capacity of the hydraulic system. Finally, based on dSPACE products, a hardware-in-the-loop (HiL) experimental bench with dual brake actuators including ESP and Ebooster was built for algorithm verification. The HiL experiment results show that after the BFB failure of Ebooster, the designed compensation redundancy control algorithm can restore the Pressure-Volume (P-V) characteristics of the brake system just like Ebooster's conventional BFB mode, and improve vehicle driving safety.
Zhao, Jian, Chen, Zhicheng, Zhu, Bing, Wu, Jian
Series Fuzzy PID with Anti-windup Controller for Intelligent Vehicle2020-01-01134/14/2020
A series fuzzy PID controller with anti-windup scope (SFPCA) is proposed in this paper to address saturation nonlinear problem and control disturbance caused by uncertainty of actuator model. In order to achieve novel dynamic and steady-state performance, the fuzzy controller and PID controller are fused into series, which realizes excellent dynamic performance of fast response and low overshoot like pure fuzzy controller at the initial response stage, and the excellent steady-state performance of stable and no static difference like PID control at the later response stage. The Hurwitz low is employed to configure PID parameters and 49 rules are designed for fuzzy controller. Since the input of the actuator could not be infinite, the actuator being saturated for a long time could reduce the stability of system and, even lead to irreversible damage. Moreover, after exiting the saturation state, it is difficult to quickly recover to the fast and stable response state of the original system. Therefore, an anti-windup scope is meticulously developed to limit the system input to a reasonable range under the saturation state, and, in the unsaturated state, the original Fuzzy PID control is restored. In order to verify the performance of the algorithm, four comparison algorithms were adopted, including pure PD, pure PID, pure Fuzzy and series Fuzzy PID controller (SFPC), and two typical commands like step and sine are employed as desired signals. The experimental results show that the SFPCA has more excellent dynamic and steady performance than pure PD, pure PID, pure Fuzzy and series Fuzzy PID controller (SFPC).
Luo, Chao
Effect of Stator Surface Area on Braking Torque and Wall Heat Dissipation of Magnetorheological Fluid Retarder2020-01-09374/14/2020
Magnetorheological fluid (MRF) is used as the transmission medium of the hydraulic retarder. The rheological properties are regulated by changing the magnetic field to achieve accurate control of the retarder's braking torque. Under the action of the external magnetic field, the flow structure and performance of the MRF retarder will be changed in a short time. The apparent viscosity coefficient increases by several orders of magnitude, the fluidity deteriorates and the heat generated by the brake cannot be transferred through the liquid circulation, which will affect the braking torque of the retarder. Changing the surface area of the stator also has an influence on the braking torque of the retarder and the wall heat dissipation. In this study, the relationship between the braking torque of the MRF retarder and the stator surface area of the retarder was analyzed. In addition, phase change materials were used to directly dissipate heat on the retarder surface to improve the heat dissipation rate of retarder and improve the stability of the retarder's braking torque. In order to study the effect of stator radius on braking torque of MRF retarder under an external magnetic field, a braking torque model was established based on MRF with Bingham model properties, and a heat transfer model of wall phase change material was established to analyze the relationship between heat transfer and braking torque of MRF retarder. The results show that the braking torque of the MRF retarder increases rapidly with the increase of the radius outside the effective working area of MRF, which increases faster at high speed and increases the stator wall surface heat dissipation, but the rate of heat dissipation increases relatively slowly. The wall surface with a heat pipe can take away the heat generated by the retarder and cool the retarder. Under the appropriate stator surface conditions, phase change materials are used on the wall surface of the retarder to dissipate heat, which improves the stability of the braking torque of the retarder and promotes the development of MRF retarder to high power.
Liu, ZhiQiang, Tan, Gangfeng, Tian, Zhongpeng, Zhou, Mi, Agyeman, Philip, Frimpong, Justice
A Pre-Warning Method for Cornering Speed of Concrete Mixer Truck2020-01-10034/14/2020
The high gravity center of the concrete mixer truck reduces the truck’s stability while steering. The rolling stirring tank makes the stability even worse than the regular engineering vehicle due to the dynamic variation of the centroid position. Most of the researches on the rollover stability of concrete mixer trucks focus on the rollover model establishment and dynamic simulation module. The change of concrete centroid is ignored when the safety cornering speed is calculated. This paper proposes a pre-warning method for the cornering speed of concrete mixer trucks based on centroid dynamic simulation. In the method, the mixing tank stirring model and the vehicle driving dynamic model are established on the Fluent and TruckSim simulation platforms, respectively. The theoretical speed threshold obtained by simulation is used as the evaluation index of the warning speed in the curve. Firstly, the dynamic simulation of the stirring tank model is carried out by Fluent. According to Newton Leibniz numerical calculation method, Matlab is used to obtain the mathematical model of the centroid position and the main parameters of the stirring tank. Then the model is verified by the neural network algorithm. Finally, according to the dynamic position and lateral acceleration of the vehicle’s centroid, the dynamic simulation is carried out by TruckSim to obtain the theoretical speed threshold. The pre-warning system can warn the driver according to the comparison of real-time speed and calculated velocity threshold. In this paper, a 7.8 m3 concrete mixer truck is selected for simulation experiments. The results show that the lateral offset of the centroid is up to 206.4 mm and the maximum lateral force is 682N under normal working conditions, and the safe turning speed of the vehicle is reduced by at least 4.71% due to the centroid change. The pre-warning method proposed in this paper can improve the safety of cornering traffic effectively, and can be utilized in the further intelligent transportation system.
Jiang, Yifeng, Tan, Gangfeng, Wang, Haoyu, Wang, Zelong, Wang, Zhenyu, Li, Ming
Pressure Tracking Control of Electro-Mechanical Brake Booster System2020-01-02114/14/2020
The Electro-Mechanical Brake Booster system (EMBB) is a kind of novel braking booster system, which integrates active braking, regenerative braking, and other functions. It usually composes of a servo motor and the transmission mechanism. EMBB can greatly meet the development needs of vehicle intelligentization and electrification. During active braking, EMBB is required to respond quickly to the braking request and track the target pressure accurately. However, due to the highly nonlinearity of the hydraulic system and EMBB, traditional control algorithms especially for PID algorithm do not work well for pressure control. And a large amount of calibration work is required when applying PID algorithms to pressure control in engineering. In this paper, a fuzzy adaptive PI pressure control algorithm based on feed-forward is proposed to a novel self-designed EMBB mechanism, which is utilized to overcome the nonlinear pressure control problem when EMBB is in active braking and improve the control effect of PID algorithm. First, the structure of the EMBB system used in the paper and its working principle is presented. Second, this paper designs a two-layer control algorithm to implement the pressure control of EMBB. The upper layer is a pressure control loop using fuzzy PI algorithm based on feedforward, and the lower layer is a motor control loop composed of position loop and current loop. Finally, to verify the proposed control algorithm, a series of pressure tracking tests were performed under multiple operating conditions based on a real vehicle platform equipped with EMBB. The experimental results show that the proposed control algorithm can effectively enhance the accuracy of EMBB pressure control and its response speed during active braking compared with PID algorithm. Therefore, the proposed algorithm can effectively improve the effect of EMBB pressure control.
Yang, Weihong, Wu, Jian, He, Rui, Zhu, Bing, Zhao, Jian, Chen, Zhicheng
Brake Power Availability Led Optimisation of P0 versus P2 48V Hybrid Powertrain Architectures2020-01-04394/14/2020
Through improving the 48V hybrid vehicle archetype, governmental emission targets could be more easily met without incurring the high costs associated with increasing levels of electrification. The braking energy recovery function of hybrid vehicles is recognised as an effective solution to reduce emissions and fuel consumption in the short to medium term. The aim of this study was to evaluate methods to maximise the braking energy recovery capability of the 48V hybrid electric vehicle over pre-selected drive cycles using appropriately sized electrified components. The strategy adopted was based upon optimising the battery chemistry type via specific power capability, so that overall brake power is equal to the maximum battery charging power in a typical medium-sized passenger car under typical driving. This will maximise the regenerative braking energy whilst providing a larger torque assistance for a lower battery capacity. Dynamic simulation models were developed using GT-DRIVE software, emulating a mid-sized car with a 48V battery, and different turbocharged gasoline engines with motor-generator unit positions along a drivetrain. The 1.3 kWh battery pack was developed using a 14 Ah Lithium Iron Phosphate cell arranged in a 14 series 2 parallel configuration. A fuel economy comparison was produced using the FTP, WLTP, and HEFET drive cycles. When the motor-generator unit was attached via a synchronous belt, a 10-17% fuel saving was achieved in the WLTP drive cycle. Comparatively, when placing the electric machine after the clutch in a “P2” position, a 17-21% fuel saving was attained. The energy loss analysis of both P2 and P0 configurations revealed up to 7% overall reduction in total energy losses for the P2 setup. This was despite an increase in the motor-generator unit and battery losses due to the extended use of both in the electric-only mode capability with the P2 layout.
Alnamasi, Khaled, Terry, Simon, La Rocca, Antonino, Cairns, Alasdair
Real-time and Accurate Estimation of Road Slope for Intelligent Speed Planning System of Commercial Vehicle2020-01-01154/14/2020
In the intelligent speed planning system, real-time estimation of road slope is the key to calculate slope resistance and realize the vehicles’ active safety control. However, if the road slope is measured by the sensor while the commercial vehicle is driving, the vibration of the vehicle body will affect its measurement accuracy. Therefore, the relevant algorithm is used to estimate the real-time slope of the road when the commercial vehicle is driving. At present, many domestic and foreign scholars have analyzed and tested the estimation of road slope by the least square method or Kalman filter algorithm. Although the two methods both can achieve the estimation, the real-time performance and accuracy still need to be improved. In this paper, for traditional fuel commercial vehicle, the Kalman filter algorithm based on the kinematics and the extended Kalman filter algorithm based on the longitudinal dynamics are respectively used to estimate the road slope. In the process of estimation based on kinematics, considering the influence of road slope rate to estimate, the recursive least squares method with forgetting factor is used to estimate the road slope rate.Finally, the estimation results obtained by kinematics and dynamics are combined. It is expected that the error based on the algorithm-estimated slope value and the true slope value will be within 6% after the commercial vehicle is driving. The proposed algorithm has high accuracy, good real-time performance and strong stability. Using the commercial vehicle as a motion node and estimating the slope of a certain road, the intelligent planning of other vehicles’ speed in that region can be realized through the cloud platform. Then the fuel economy of the commercial vehicle can be improved.
Zhou, Mi, Tan, Gangfeng, Sun, Meng, Tian, Zhongpeng, Zhou, Fangyu, Liu, ZhiQiang
Requirements for Road Weather ApplicationsJ2945/3_202003 (Historical)3/24/2020
Inclement weather can have a significant impact on surface transportation systems. It can result in hazardous conditions for travelers due to poor visibility, or wet or icy roadways. Weather applications have the potential to provide additional data to surface transportation infrastructure owners and operators, allowing them to better assess the impacts of the weather environment on or around the roadway and to better manage the surface transportation system. Such weather applications can: Collect road weather data from connected vehicles and mobile devices, increasing the number of data sources available. Provide road weather related traveler information to travelers via connected vehicles and devices, such as when and where a hazardous condition exists. Provide the ability to manage road weather response on specific roadways. This SAE Standard specifies interface requirements between vehicles and infrastructure for weather applications, including detailed systems engineering documentation (needs and requirements mapped to appropriate message exchanges). The purpose of this SAE Standard is to enable interoperability supporting these weather applications over a communications technology agnostic interface.
Infrastructure Applications Technical Committee
New Integrated Vehicle Dynamics Control System Based on the Coordination of AFS, DYC, and ED for Improvements in Vehicle Handling and Stability10-04-02-00091/27/2020
An integrated vehicle dynamics control system aiming to improve vehicle handling and stability by coordinating active front steering (AFS), direct yaw control (DYC), and electric differential system is developed in this article. First, an electric differential system for electric vehicle, composed of two sets of bi-PMS, in-wheel motors connected in parallel and supplied by a single five-leg inverter, one on the front axle and one on the rear axle, is designed. However, each set is controlled by a proposed sliding mode backstepping control, which has replaced the hysteresis controllers in the conventional direct torque control (DTC), can obviously reduce the torque ripple, and provide better speed tracking performance using sliding mode speed controllers. Second, an integrated control system which coordinates AFS and DYC braking system is designed by using a stability index, based on stability domain in the phase plane portrait, and a gain scheduling parameter to improve vehicle steerability and maintain vehicle stability during extreme driving situations. Simulation results confirm the effectiveness of the proposed integrated vehicle dynamics control system and the overall improvements in vehicle handling and stability.
Aouadj, Norediene, Hartani, Kada, Fatiha, Mekri
Commercial vehicle pedal feeling comfort ranges definition2019-36-00161/13/2020
The brake pedal is the brake system component that the driver fundamentally has contact and through its action wait the response of the whole system. Each OEM defines during vehicle conceptualization the behavior of brake pedal that characterizes the pedal feel that in general reflects not only the characteristic from that vehicle but also from the entire brand. Technically, the term known as Pedal Feel means the relation between the force applied on the pedal, the pedal travel and the deceleration achieved by the vehicle. Such relation curves are also analyzed in conjunction with objective analysis sheets where the vehicle brake behavior is analyzed in test track considering different deceleration conditions, force and pedal travel. On technical literature, it is possible to find some data and studies considering the hydraulic brakes behavior. However, for pneumatic brake systems, the pedal feel theoretical study is not usual, where is normally used for these developments, exclusively the subjective evaluation which become necessary to have more specialists to define the brake pedal behavior. Throughout this article will be revised the characteristics concepts of brake pedal and what impact in pedal feel in pneumatic brake systems. Vehicular measurements will be also presented which provided important information on comfort curve definition of commercial vehicles pedal feel, correlating these measurements with subjective analysis and also considering technologies like ABS and EBS. Such study creates a methodology with objective parameters for the future vehicles to be developed by the brand.
Bolognesi Prado, Wesley, Faria Iombriller, Silvia, Rodrigues da Silva, Marco André, Renato Oliveira, Lázaro
Brake System Thermal Performance for Brazil Market Battery Electric Vehicles2019-36-00191/13/2020
The discussion in the braking industry that has been ongoing for over a decade now on how to specify brake systems for regenerative-brake intensive vehicle applications has intensified considerably in the past few years as the automotive industry ponders a future where electric vehicles become predominant. Major automotive manufactures have announced plans to create dedicated electric-only vehicle architectures, from which to offer a full range of electric vehicle configurations. The time to really figure out the translation of Voice of the Electric Vehicle Customer to technical requirements and brake system content is approaching very rapidly. One of the major design decisions in the brake system is the sizing of foundation brake components for thermal performance. There is no question that regenerative brakes can significantly reduce the demand on the friction brakes in normal usage, sometimes by a full order of magnitude or more. Brakes no longer need to be sized for everyday use, rather, the sizing is driven by “limit cases” such as failure of the regen system, a full state of charge in the battery at high elevation, or conditions of “de-rating” of regenerative braking due to drive motor and/or battery operating conditions including temperature. The present work takes an in-depth look at real world vehicle operating conditions that can drive high thermal loads to the brakes and proposes requirements and methodology for relating this to brake hardware selection. The methodology is illustrated through case studies and analysis, showing how brake temperatures are affected by changing from an internal combustion to an electric drive, and further showing how factors such as initial battery state of charge can have a significant effect on the brake temperatures.
Antanaitis, David
More than a brake2019-36-00201/13/2020
The automotive world is battling every day to provide innovation and product development without compromising the environment. The electrification of the engines can be a factor that divides eras into the market. The conventional brake system links the act of apply the brake pedal with the stop or deceleration of the vehicle. This is now possible thanks to the long-term use of the vacuum generated by the combustion engine or by auxiliary equipment (vacuum pump). New brake system technologies provides, without a vacuum source, more efficient and safer braking than the current power brake system. Embedded in technological developments, these systems interacts with other vehicle components (cameras, radars, ABS, ESC) bringing the driver advanced safety conditions.
Batagini, Emerson
Autonomy's ‘Pirouetting’ Future20AVEP01_061/1/2020
Protean Electric's novel 360-degree steering and in-wheel drive systems add new potential for urban mobility. Designing and engineering a 360-degree steering capability for a production electric autonomous road vehicle's four wheels is no mean achievement. But Protean Electric also combines this pirouetting capability with an in-wheel electric motor, “innovative” suspension and pneumatic ride height control into an all-in-one package. Its adroit wheel-at-each-corner module, called Protean360+, is designed initially for next-generation urban mobility pods. But it could also be applied to a wide variety of other autonomous vehicles. Development of the 360-degree capability began in early 2018. It is the latest element to be added to the company's ProteanDrive in-wheel system, on which work started more than a 10 years ago to specifically meet emerging needs for radical new urban vehicle technology combined with autonomous transport visions. These include autonomous passenger cars, light-duty commercial vehicles and other future mobility solutions.
Birch, Stuart
An Efficient, High-Precision Vehicle Testing Procedure to Evaluate the Efficacy of Fuel-Borne Friction Modifier Additives2019-01-235312/19/2019
Improved fuel economy is increasingly a key measure of performance in the automotive industry driven by market demands and tighter emissions regulations. Within this environment, one way to improve fuel economy is via fuel additives that deliver friction- reducing components to the piston-cylinder wall interface. Whilst the use of friction modifiers (FMs) in fuel or lubricant additives to achieve fuel economy improvements is not new, demonstrating the efficacy of these FMs in vehicles is challenging and requires statistical design together with carefully controlled test conditions. This paper describes a bespoke, efficient, high-precision vehicle testing procedure designed to evaluate the fuel economy credentials of fuel-borne FMs. By their nature, FMs persist on engine surfaces and so their effects are not immediately reversible upon changing to a non FM-containing fuel (“carryover” effect), therefore requiring careful design of the test programme. The solution presented here comprises a one-day chassis dynamometer test, internally referencing the fuel economy of an FM- containing test fuel to an FM-free reference fuel. When incorporated into a statistically designed test programme, two or more fuels are compared using a chosen test cycle. Comprehensive instrumentation, control and monitoring, integrated vehicle conditioning stages and strict acceptance criteria are major factors in achieving the required precision. This test design is also specially tailored to eliminate the problem of FMs carry-over effects to subsequent tests. Three programmes based on this test procedure have measured statistically significant fuel economy differences between FM-containing fuels and FM-free fuels, thus demonstrating that the required precision has been achieved to evaluate the efficacy of fuel- borne FMs.
Yow, Shuhui, Ziman, Pauline, Smith, Sue J., Walter, Dr. Marc, Bacchi, Robert J.
Conceptualization and Modeling of a Flywheel-Based Regenerative Braking System for a Commercial Electric Bus02-12-04-001811/19/2019
The following article illustrates the detailed study of the development of a unique flywheel-based regenerative braking system (f-RBS) for achieving regenerative braking in a commercial electric bus. The f-RBS is designed for installation in the front wheels of the bus. The particular data values for modeling the bus are taken from multiple legitimate sources to illustrate the development strategy of the regenerative braking system. Mechanical components used in this system have either been carefully designed and analyzed for avoiding fatigue failure or their market selection strategies are are explained. The positioning of the entire system is decided using MSC Adams View®, hence determining a suitable component placement strategy such that the f-RBS components do not interfere with the bus components. The entire system is modeled on MATLAB Simulink® with sufficient accuracy to get various results that would infer the performance of the system as a whole. The overall efficiency of the developed system in terms of battery consumption is also computed in this study.
Mathur, Kunal, Choudhary, Lalit Kumar, Natu, Aditya Manoj, Srinivas, Krovvidi, Rastogi, Vikas
Regenerative Braking Cooperative Control of Hybrid Electric Vehicle Based on System Efficiency Optimization2019-01-508911/19/2019
In order to improve the performance of electro-hydraulic composite braking system of hybrid electric vehicle (HEV), a new type of plug-in HEV with dual motor was taken as the research object. The model of motor loss was built to achieve maximum motor efficiency, and the hydraulic braking system model, which can dynamically control pressure, was built. Based on the optimization of a motor’s continuously variable transmission (CVT) joint efficiency, the real-time optimal allocation strategy based on threshold method and cooperative control strategy of the electro-hydraulic composite braking system were brought out to recover most of the regenerative energy under the premise of ensuring safety. The model was built to verify the performance by AMESim-Simulink. The results show that the control strategy can take the advantages of dual-motor braking recovery system, increase braking energy recovery rate, effectively improve the braking safety and ride comfort of the vehicle, and reduce braking force fluctuation.
Yang, Yang, Chen, Jing, Luo, Chang, Tang, Qingsong
Braking Control Strategy Based on Electronically Controlled Braking System and Intelligent Network Technology2019-01-503811/4/2019
In order to solve the coupling problems between braking safety, economical efficiency of braking and the comfort of drivers, a braking control strategy based on Electronically Controlled Braking System (EBS) and intelligent network technology under non-emergency braking conditions is proposed. The controller utilizes the intelligent network technology’s characteristics of the workshop communication to obtain the driving environment information of the current vehicle firstly, and then calculate the optimal braking deceleration of the vehicle based on optimal control method. The strategy will distribute the braking force according to the ideal braking force distribution condition based on the EBS according to the braking deceleration; the braking force will be converted to braking pressure according to brake characteristics. Computer co-simulations of the proposed strategy are performed, the strategy is verified under different initial speeds. The results show that the strategy enables the vehicle to stop within a safe distance, keeps the brake deceleration as smooth as possible for better braking comfort while at the same time obtaining better braking economy by increasing braking efficiency under different initial speeds.
Zheng, Hongyu, Li, Rui
Analysis of Active Collision Avoidance Performance Based on Cooperative Regenerative Auxiliary Braking System2019-01-502711/4/2019
Active collision avoidance can assist drivers to avoid longitudinal collision through active brake. Regenerative braking can improve the driving range and braking response speed. At this stage, conventional hydraulic braking system limits the implements of above technologies because of its poor performance of response speed and coordinated control. While the brake-by-wire system is a better actuator that can fulfill requirements of automotive electric and intelligent development due to its rapid response and flexible adjustment. However, the system control algorithm becomes more complicated with introduction of regenerative braking and active collision avoidance function, which is also the main problem solved in this paper. First, a new type of cooperative regenerative auxiliary braking system (CRABS) of intelligent electric vehicles, which integrates the functions of brake-by-wire, regenerative braking and active collision avoidance, is proposed, for purpose of analyzing the improvement of active collision avoidance performance after the introduction of regenerative braking. The design of the system focuses on the Electro Hydraulic Brake (EHB) unit, control strategy of active collision avoidance and brake force distribution. Then, modeling and simulation are done to validate the feasibility of the proposed system scheme. Based on the Autonomous Emergency Braking (AEB) test procedures of European New Car Assessment Programme(Euro-NCAP), the simulation analysis scheme is made including simulation process, simulation test conditions and evaluation indicators. Finally, the hardware-in-loop (HIL) test bench based on the real motor system is set up to validate the conclusion drawn in the simulation analysis. The results show that compared with the conventional hydraulic braking system, CRABS system proposed in this paper conducts faster in braking response and closer to the ideal braking distance, and the performance of active collision avoidance is improved.
Hou, Xiaohui, Zhang, Junzhi, Zhang, Zhongshi, He, Chengkun
Cooperative Distribution Strategy of Regenerative Braking and Pneumatic Braking of an Electric Commercial Vehicle2019-01-503911/4/2019
This paper mainly proposes one type control strategy of the regenerative braking system of an electric commercial vehicle under normal braking condition. With the main goal of recovering as much energy as possible, the braking force distribution strategy based on maximum regenerative braking optimization is studied under the restriction of ECE regulation and state of charge (SOC) of battery. Firstly, the related models of the regenerative braking system and the target vehicle are separately established in MATLAB/Simulink. Then, the distribution strategy of braking force is developed and optimized considering the influence of SOC and vehicle speed respectively. Finally, the braking effects of this control strategy in the typical deceleration process are numerical simulated and analyzed. Simulation results depict that this control strategy can recover more braking energy under the premise of ensuring braking safety and great braking performance compared with the common braking strategies with traditional strategy and without regenerative braking.
Cheng, Qing, Pi, Dawei, Xie, Boyuan, Wang, Hongliang, Wang, Xianhui
Axle Torque Distribution to Improve Vehicle Handling and Stability2019-01-503711/4/2019
The majority of the fully electric vehicles currently on the market have a basic drivetrain configuration, consisting of multiple electric motors, which promise considerable performance enhancements in terms of vehicle behavior and active safety. A significant advantage was achieving measurable benefits in terms of vehicle cornering response through controlling the individual drivetrains. This paper presents an axle torque distribution method to improve a 4WD vehicle steering performance. The method can automatically adjust the output drive torque of the front and rear motors of the vehicle to change the vehicle yaw rate before ESP intervention, and at the same time remain the driver torque demand unchanged. In this paper we present a feedback yaw rate controller. When the estimated yaw rate differs from the actual yaw rate with a pre-defined small threshold, a yaw rate control is active, the purpose of the controller is to reduce the vehicle understeer characteristic. The simulation and experimental test results shows that this proposed method can reduce the vehicle understeer characteristic and improve the vehicle handling and stability performance.
Wu, Aibin, Li, Chao, Zhao, Yongqiang, Cui, Jinlong
Information on Brake-By-Wire (BBW) Brake Control SystemsAIR5372A (Current)10/25/2019
This SAE Aerospace Information Report (AIR) describes the design approaches used for current applications of aircraft Brake-by-Wire (BBW) control systems. The document also discusses the experience gained during service, and covers system, ergonomic, hardware, and development aspects. The document includes the lessons that have been learned during application of the technology. Although there are a variety of approaches that have been used in the design of BBW systems, the main focus of this document is on the current state of the art systems.
A-5A Wheels, Brakes and Skid Controls Committee
A Heavy Tractor Semi-Trailer Stability Control Strategy Based on Electronic Pneumatic Braking System HIL Test10-03-03-001610/15/2019
Aiming to improve the handling performance of heavy tractor semi-trailer during turning or changing lanes at high speed, a hierarchical structure controller is proposed and a hardware-in-the-loop (HIL) test bench of the electronic pneumatic braking system is developed to validate the proposed controller. In the upper controller, a Kalman filter observer based on the heavy tractor semi-trailer dynamic model is used to estimate the yaw rates and sideslip angles of the tractor and trailer. Simultaneously, a sliding mode direct yaw moment controller is developed, which takes the estimated yaw rates and sideslip angles and the reference values calculated by the three-degrees-of-freedom dynamic model of the heavy tractor semi-trailer as the control inputs. In the lower controller, the additional yaw moments of tractor and trailer are transformed into corresponding wheel braking forces according to the current steering characteristics. The HIL test bench of the electronic pneumatic braking system is built to verify the effectiveness of the strategy. Double lane-change maneuver, sinusoidal maneuver, and J-turn maneuver are selected as handling and stability test conditions. The LabView real-time (RT) system combined with the TruckSim vehicle model and ControlDesk real-time interface (RTI) system are adopted in the HIL test. The results obtained from the HIL tests show that the control method can effectively improve the lateral and handling stability of the heavy tractor semi-trailer.
Zheng, Hongyu, Miao, Yangyang, Li, Bin
Comparative Analysis between American and European Requirements for Electronic Stability Control (ESC) Focusing on Commercial Vehicles2019-01-21419/15/2019
Analysis of road accidents has shown that an important portion of fatal crashes involving Commercial Vehicles are caused by rollovers. ESC systems in Commercial Vehicles can reduce rollovers, severe understeer or oversteer conditions and minimize occurrences of jackknifing events. Several studies have estimated that this positive effect of ESC on road safety is substantial. In Europe, Electronic Stability Control (ESC) is expected to prevent by far the most fatalities and injuries: about 3,000 fatalities (-14%), and about 50,000 injuries (-6%) per year. In Europe, Electronic Stability Control Systems is mandatory for all vehicles (since Nov. 1st, 2011 for new types of vehicle and Nov. 1st, 2014 for all new vehicles), including Commercial Vehicles, Buses, Trucks and Trailers. On 2015, NHTSA published Federal Motor Vehicle Safety Standard (FMVSS) No. 136, Electronic Stability Control systems for heavy vehicles, requiring Electronic Stability Control (ESC) systems on truck tractors and buses with a gross vehicle weight rating greater than 11,793 kilograms (26,000 pounds) for implementation in 2017. In South America, CONTRAN Resolution 641/2016 establishes mandatory installation of Electronic Stability and Rollover Control in Commercial Vehicles, including Trailers (Jan. 1st, 2022 for new types of vehicle and Jan. 1st, 2024 for all new vehicles). However there isn’t a Brazilian standard to validate the system and its performance shall comply with ECE R13 (Annex 21) or FMVSS 136, as applicable. This paper shows a technical review regarding ESC function, its impact on Commercial Vehicles and clarifies the different systems available for trucks and trailers, considering the differences between stability control systems - full stability and roll-only stability. In addition it will show a comparative analysis between American and European requirements and procedures to validate these vehicles safely.
Iombriller, Silvia Faria, Bolognesi Prado, Wesley, Silva, Marco Andre
Brake Pedal Feeling Comfort Analysis for Trucks with Pneumatic Brake System2019-01-21409/15/2019
The brake pedal is the brake system component that the driver fundamentally has contact and through its action wait the response of the whole system. Each OEM defines during vehicle conceptualization the behavior of brake pedal that characterizes the pedal feel that in general reflects not only the characteristic from that vehicle but also from the entire brand. Technically, the term known as Pedal Feel means the relation between the force applied on the pedal, the pedal travel and the deceleration achieved by the vehicle. Such relation curves are also analyzed in conjunction with objective analysis sheets where the vehicle brake behavior is analyzed in test track considering different deceleration conditions, force and pedal travel. On technical literature, it is possible to find some data and studies considering the hydraulic brakes behavior. However, for pneumatic brake systems, the pedal feel theoretical study is not usual, where is normally used for these developments, exclusively the subjective evaluation which become necessary to have more specialists to define the brake pedal behavior. Throughout this article will be revised the characteristics concepts of brake pedal and what impact in pedal feel in pneumatic brake systems. Vehicular measurements will be also presented which provided important information on comfort curve definition of commercial vehicles pedal feel, correlating these measurements with subjective analysis and also considering technologies like ABS and EBS. Such study creates a methodology with objective parameters for the future vehicles to be developed by the brand.
Bolognesi Prado, Wesley, Iombriller, Silvia Faria, Silva, Marco Andre, Oliveira, Lázaro Renato
Downhill Safety Assistant Driving System for Battery Electric Vehicles on Mountain Roads2019-01-21299/15/2019
When driving in mountainous areas, vehicles often encounter downhill conditions. To ensure safe driving, it is necessary to control the speed of vehicles. For internal combustion engine vehicles, auxiliary brake such as engine brake can be used to alleviate the thermal load caused by the continuous braking of the friction brake. For battery electric vehicles (BEVs), regenerative braking can be used as auxiliary braking to improve brake safety. And through regenerative braking, energy can be partly converted into electrical energy and stored in accumulators (such as power batteries and supercapacitors), thus extending the mileage. However, the driver's line of sight in the mountains is limited, resulting in a certain degree of blindness in driving, so it is impossible to fully guarantee the safety and energy saving of downhill driving. Therefore, taking a pure electric light truck as an example, the system proposed in this paper first analyzes the driver's driving intention, proposes the system startup and exit strategy, and then combines the geographic information system (GIS) mountain road information, downslope speed limit and vehicle parameters, considering the motor and battery characteristics, establishes mathematical models such as the regenerative braking model and the brake temperature rise model based on vehicle dynamics and the conservation of energy, determines the appropriate braking mode(There are two braking modes)and the slope top safe speed by calculation, and reminds the driver when going uphill and downhill. The main goal is to use more regenerative braking, reduce the use or duration of the main brake, avoid overheating the main brake, improve the safety during continuous braking, and achieve smarter energy management. Finally, simulations are carried out under different conditions of vehicle speed, slope length, slope gradient and battery SOC. The results show that the system has a good energy-saving effect and can significantly improve the safety of BEVs running downhill.
Feng, Jia'ao, Tian, Zhongpeng, Cui, Jian, Zhou, Fangyu, Tan, Gangfeng
Development of Regenerative Brake Control Strategy to Remove Brake Rust2019-01-21259/15/2019
This study is the development concept of regenerative braking cooperative control to reduce creep groan noise considering fuel efficiency. Creep groan noise is a traditional brake system noise that has been improved with advances in technology such as brake materials, surface treatment and transfer path. However, recently creep groan noise is again an issue in electronic vehicle which applied a drive motor. Generally, creep groan noise frequently occurs when rust occurs on the friction surface of the brake disc and the brake pad is humidified, but it is easily removed by friction braking several times. However, in the case of electric vehicles which applied regenerative braking system, it is hard to remove. In case of electric vehicle, instead of friction braking, most of brake toques are made by motor regenerative braking. Therefore, even if the same conventional brake system and chassis system are applied, the noise level of the electric vehicle is higher than gasoline or diesel vehicle, and the field claim is also higher. To improve the noise, regenerative braking cooperative control logic was developed that detects long-term vehicle parking condition and control the regenerative brake ratio of total driver demand brake toque considering fuel efficiency. Also several tests are proceeded to review the effect of creep groan noise and fuel efficiency.
Jang, Sora, Kim, Gwichul
Braking Requirements for Optimizing Autonomous Emergency Braking Performance2019-01-21279/15/2019
Vehicle technology new developments have contributed to improve vehicle structural performance and therefore passive protection, but also the inclusion of electronic control units has provided new opportunities to expand active safety systems. This is the case for systems like anti-lock braking systems (ABS), electronic stability control (ESC) and brake assist (BA) among others. A more advanced generation of active systems includes sensorial units that monitor vehicle’s surrounding and detect potential hazards, such as an imminent collision, and performs an automatically and commanded emergency braking to lessen or mitigate the consequences of the impending accident. For this latest system, the so-called autonomous emergency braking (AEB), various consumer testing protocols, such as Euro NCAP protocols [1], propose and periodically update test catalogues in order to evaluate the performance of such systems and later to inform potential consumers. The aim of this study is to investigate the means of improving AEB performance in terms of efficiency and driver acceptance. For this, performance of current AEB system will be studied and compared with the limits of vehicle’s braking capabilities.
Esquer Molina, Álvaro, Bargallo, Jordi
SUPPLIER EYE19AUTP09_079/1/2019
The value - and risks - of Technology Testbeds The world has been awaiting the arrival of the latest generation Chevrolet Corvette for some time. This past July, among much fanfare the mid-engined C8 (8th generation of this iconic nameplate) Stingray was revealed to the world. As an early owner of the C7, I know my car will be the last front-engined Corvette. And while some fellow enthusiasts are defiantly asserting that “real” Corvettes have their engines ahead of the driver, there is no looking back. Nostalgia aside, this industry is always in need of ‘technology testbeds’, a role that Corvette has played since the C1 debuted in 1953. Such production vehicles stretch the limit in terms of performance, design, efficiency, or all of the above. During the past decade, General Motors has introduced other products which the organization, suppliers and dealers have been using as incubators for related technologies, business processes, and new sourcing models.
Holistic hydraulic designs add more sensors, controls19TOFHP08_078/1/2019
Hydraulic system developers are moving on many different fronts as they strive to improve performance and efficiency. A full-system approach that includes more sensors and advanced controls is helping design teams reduce component counts without sacrificing performance. The multifaceted design challenges of today's equipment are forcing engineers to take a broad view of the vehicle and its systems in order to get the most from valves, electronics, pumps and other equipment. Customer expectations and regulatory requirements are both rising, forcing engineers and planners to examine every element of a design.
Costlow, Terry
The Rodney Dangerfield of Automated-Driving Sensors19AVEP07_067/1/2019
Radar and lidar get all the attention, but Inertial Measurement Units are the backbone of sensor fusion. Suppliers are scrambling to make IMUs more accurate-and much less expensive. The emerging era of highly-automated driving comes courtesy of much-vaunted sensor technology-spinning lasers, penetrating radar, sonar blips. But the sensor that gets the least respect in the technology stack could be the lynchpin for the mass roll-out of self-driving vehicles: the inertial measurement unit (IMU). “IMUs are the glue that binds everything together,” said Mike Horton, chief technology officer at Aceinna, a Boston-based company that develops sensing solutions for automotive applications. “An IMU can help bring different types of data together from GNSS (Global Navigation Satellite System), lidar and cameras to make everything consistent and smooth.”
Berman, Bradley
Target Setting Process for Hybrid Electric Drives Using TPA, Jury Study, and Torque Management2019-01-14536/5/2019
The idea of improved efficiency without compromising the “fun to drive” aspect has renewed the auto industry’s interest toward electrification and hybridization. Electric drives gain from having multiple gear ratios which can use advantageous operating set points thus increasing range. Furthermore, they benefit significantly from frequent decelerations and stopping as is experienced in city driving conditions. To recuperate as much energy as possible, deceleration is done at high torque. This presents an interesting but serious sound quality issue in the form of highly tonal whine harmonics of rapidly changing gears that do not track with vehicle speed thus being objectionable to the vehicle occupants. This paper presents an NVH target setting process for a hybrid electric transmission being integrated into two existing vehicles, one belonging to the premium segment and another aimed at enthusiasts with off-road applications. The demand for power has shifted from mechanical domain into electrical domain, and as such, the solution to electric drive NVH issues also lay partly, in the way these drive systems are calibrated. A time-domain Transfer Path Analysis (TPA) model was developed for both vehicles, by virtually installing the hybrid transmission into the vehicle, thus predicting interior noise in several gears and simulating the brake regen coast downs at varying torque levels. Road and wind noise masking was added to these predictions taking care that the summations were correctly done at same vehicle speeds for which a program was written using a commercially available numerical computing tool. Extensive jury studies were then conducted to determine NVH no-fly zones and the torque management strategy for the two vehicles during brake regen events. Requirements and strategy for the two vehicles were different since they presented different levels of road and wind noise masking. To validate the NVH targets, another jury compared the finalized strategy with a premium target vehicle fitted with a similar hybrid system. This target-setting approach was useful in getting an upfront idea of the NVH risks without any system modifications. It then circumvented the need of re-developing expensive acoustic package and/or gear optimization that would be otherwise needed to mitigate the risks, with co-operation from calibration teams, while still being able to meet their regenerative braking targets in every gear for the two vehicles.
Singh, Vinod, Parbat, Aniket, Charan, Anil
Jeep revives its pickup mojo with 2020 Gladiator19AUTP05_155/1/2019
Get ready for the fractionalization of the U.S.'s raucous pickup-truck market. Launching what's surely one of the year's most-anticipated and potentially significant new models, Jeep engineers and planners insist they went out of their way to ensure the 2020 Gladiator was developed as a genuine pickup and not “a Wrangler with a bed.” But everyone knows Jeep would've been crazy to stray too far from the radiant demand for the new JL-generation Wrangler, so excuse us if the Gladiator does, well, at least look like just that: a 4-door Wrangler Unlimited-with a bed.
Visnic, Bill
The CAN Bus: Driving the Future of Autonomous Military Vehicles19AERP05_025/1/2019
It's a crisp November day in Michigan, and a convoy of British and American resupply vehicles are rumbling along at a comfortable 25 miles per hour. In the lead is a British Army Rheinmetall MAN Military Vehicles (RMMV) HX-60 truck, trailed closely by two U.S. Army Oshkosh Light Medium Tactical Vehicles (LMTVs). In total, there are zero humans operating this convoy. This was the scene in November 2017, when the US-UK Coalition Assured Autonomous Resupply (CAAR) demonstration took place at Camp Grayling, Michigan - the result of three years of research and engineering to examine the use of unmanned ground vehicles (UGVs) in resupply situations, to tackle so-called “last mile” issues regarding supplying troops on the front lines of active conflicts around the world.
The CAN Bus: Driving the Future of Autonomous Military VehiclesTBMG-343435/1/2019
It’s a crisp November day in Michigan, and a convoy of British and American resupply vehicles are rumbling along at a comfortable 25 miles per hour. In the lead is a British Army Rheinmetall MAN Military Vehicles (RMMV) HX-60 truck, trailed closely by two U.S. Army Oshkosh Light Medium Tactical Vehicles (LMTVs). In total, there are zero humans operating this convoy.
Parameter Design of a Parallel Hydraulic Hybrid Vehicle Driving System Based on Regenerative Braking Control Strategy2019-01-03684/2/2019
In this paper, hydraulic driving system parameters of a parallel hydraulic hybrid vehicle are designed based on the regenerative braking requirement. Torque, speed and power demands during typical driving cycles are analyzed. The braking control strategy is designed considering both the braking safety and braking energy recovery efficiency. The hydraulic braking torque is determined by the braking control strategy. The proportional relationship of hydraulic pump/ motor output torque and its working pressure is considered. Through simulation with typical city driving cycles, most braking energy can be recovered by the proposed hydraulic driving system and braking control strategy.
Zhou, Shilei, Walker, Paul, Tian, Yang, Zhang, Nong
Vehicle E/E Architecture and Its Adaptation to New Technical Trends2019-01-08624/2/2019
With the ever-increasing requirements on vehicle performance, as well as the trend of vehicle becoming an integral part of a much bigger ecosystem involving automated driving, intelligent transportation and smart city, more and more electrical/electronic (E/E) systems are integrated in vehicles. Vehicle E/E architecture being the fundamental organization of E/E components, the relationship among the components and with the environment, as well as the principles guiding the design and evolution, has essential influences on vehicle E/E system functions and performance. This paper gives the definition of vehicle E/E architecture and provides different views. The guidelines, contents and process of E/E architecture design are discussed. The evolution of E/E architecture, influence of the latest technical trends including electrification, automated driving, and connectivity functions on E/E architecture, and how vehicle E/E architecture adapts to the technical trends are studied.
Jiang, Shugang
Study on a Method for Evaluating the Safety of the Braking Control Algorithm for Automated Driving System When Following2019-01-10154/2/2019
The purpose of this study is to develop a method for evaluating the safety of the braking control algorithm for automated driving under mixed traffic flow of automated driving system and vehicles driven by drivers. We consider that the automated driving system should be controlled such that it blends in with mixed traffic. Therefore, in evaluating the safety of braking control for the automated driving system when following, the influence of the automated driving system on the driver of the following vehicle is an important evaluation index. First, we analyzed past traffic accidents in Japan to determine a suitable traffic environment for evaluating the safety of the braking control algorithm for the automated driving system when following. Second, the driver’s braking operations were measured using actual vehicles in this situation. We developed a method of generating sample algorithms of braking control based on the driver’s braking operations. Finally, we developed a method of identifying the most suitable range of parameters of braking control algorithms by evaluating these sample algorithms based on the results of actual experiments. This evaluation method uses a driving simulator. The automated driving system in which the sample algorithm of braking control is installed runs ahead of the vehicle driven by a subject in the driving simulator. The subject evaluates the sense of danger for braking by the automated driving system.
Gokan, Masato, Tanaka, Nobuhisa, Furukawa, Yoshimi, Iwase, Tunetoshi, Hirowatari, Taichi
GPU Implementation for Automatic Lane Tracking in Self-Driving Cars2019-01-06804/2/2019
The development of efficient algorithms has been the focus of automobile engineers since self-driving cars become popular. This is due to the potential benefits we can get from self-driving cars and how they can improve safety on our roads. Despite the good promises that come with self-driving cars development, it is way behind being a perfect system because of the complexity of our environment. A self-driving car must understand its environment before it makes decisions on how to navigate, and this might be difficult because the changes in our environment is non-deterministic. With the development of computer vision, some key problems in intelligent driving have been active research areas. The advances made in the field of artificial intelligence made it possible for researchers to try solving these problems with artificial intelligence. Lane detection and tracking is one of the critical problems that need to be effectively implemented. The ability of a self-driving car to successfully drive from point A to point B without going off track is dependent on lane tracking. Lane tracking in self-driving cars is a computationally intensive task and a fast implementation is needed to help a self-driving car track lanes in real-time to make the right decision at the right time. Lane tracking in self-driving cars is also dependent on the visibility of lane markings on the road. It will be difficult for a self-driving car to track lanes if the lane marking has faded, blocked by an object, or there were no lane markings on the road. Most available lane tracking implementations in the literature do not give account to these two problems. Our implementation is to solve these two problems by using artificial intelligence techniques to track lanes in all conditions and using GPU computing on NVIDIA Jetson TX2 to speed-up the process.
Yusuf, Ayomide, Alawneh, Shadi
A Novel Torque Distribution Strategy for Distributed-Drive Electric Vehicle Considering Energy Saving and Brake Stability2019-01-03344/2/2019
This paper presents a novel torque distribution strategy (TDS) and a modified regenerative braking strategy (MRBS) for distributed-drive electric vehicle (DDEV) considering energy saving and brake stability. The presented TDS minimizes the energy consumption from battery in driving process. In order to overcome the shortcomings by using polynomial approximation for motor efficiency and the local minima problem, an exhaustive search method (ESM) is proposed to obtain the optimal front-rear torque distribution ratio. First, the power summation of four in-wheel motors is selected as the cost function of the optimization problem. Second, the ESM is designed to obtain the optimal torque distribution ratio according to current torque demand and motor speed based on motor efficiency map. Maximum motor torque and tire-road conditions are taken as constraints. Third, a MRBS is proposed to improve energy recovery performance by take ECE R13 and motor efficiency into account. In order to improve computational efficiency, the optimized ratio for every achievable motor operation point is stored as a 3-dimension look up table. Finally, simulation experiments based on MATLAB/Simulink are carried out to verify the effectiveness of the proposed torque distribution strategy under NEDC and UDDS driving cycle. The simulation results show that the proposed TDS can improve the energy efficiency by 5.3% under NEDC and 5.5% under UDDS than even-drive strategy.
Liu, Jingxing, Zhong, Hong, Wang, Liangmo, Chen, Hejuan
Development and Control of Four-Wheel Independent Driving and Modular Steering Electric Vehicles for Improved Maneuverability Limits2019-01-04594/2/2019
Electric vehicles are capable of more flexible drivetrain configurations, such that driving dynamics of each wheel could be controlled independently to increase its stability and maneuverability bounds. We hereby propose a configuration consisting of four wheel independent driving and front and rear axle modular steering. The vehicle implements drive-by-wire technology, which means the control program running on vehicle control computer will have direct control authority of the vehicle under normal driving conditions, based on inputs of higher level systems such as human drivers and autonomous driving programs. Both the torque allocation on four wheels and the steering allocation on axles are completely independent on the mechanical hardware level, thus the vehicle is able to harness adverse contact conditions with confidence. A slip-aware model-free control method for torque allocation and steering is proposed and inspected in the paper, with digital model of a modified SUV simulated for validation, and the vehicle responses with and without such controller are compared to elaborate its strengths. Such control method has more safety margin under close-to-limits driving conditions with presence of tire slip. The control method along with drive-by-wire features also enhance driving safety by correcting excessive inputs by human drivers. Additionally, a comprehensive index reflecting the stability and maneuverability of the vehicle is also introduced and based on which a model-based controller is designed and compared.
Yang, Haoguang, Liu, Chen, Shi, Jiongming, Zheng, Gangtie
Safety and Lateral Dynamics Improvement of a Race Car Using Active Rear Wing Control2019-01-06434/2/2019
As the forward speed of a car increases, the safety of the vehicle and the driver becomes a more significant concern. Active aerodynamic control can effectively enhance the lateral stability of high speed vehicles over tight cornering maneuvers. A split rear wing has been proposed. By means of manipulating the attack angles for the right and/or left parts of the split rear wing, a favorable yaw moment may be achieved to ensure the lateral stability of the vehicle. However, active control of the split rear wing has not been adequately explored. This paper proposes a novel active split rear wing, which can improve the lateral stability over tight cornering maneuvers, and will not degrade the longitudinal dynamics of the vehicle. A Linear Quadratic Regulator (LQR) based controller for the active split rear wing is designed using a linear vehicle model. In order to examine the performance of the active split rear wing, Numerical simulation is carried out using the LQR based controller and a yaw-plane vehicle model designed in MATLAB. The effectiveness of the proposed active split rear wing is demonstrated by the results derived from the numerical simulation.
Hammad, Mohammed, Qureshi, Khizar, He, Yuping
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