Browse Topic: Anti-lock braking (ABS)

Items (382)

SAE-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 Definition

J1698/1A_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

Integrated Regenerative Braking System and Anti-Lock Braking System for Hybrid Electric Vehicles & Battery Electric Vehicles

2020-01-08464/14/2020

Yao, Yixin, Zhao, Yanan, Yamazaki, Mark

Research on Compensation Redundancy Control for Basic Force Boosting Failure of Electro-Booster Brake System

2020-01-02164/14/2020

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

New Integrated Vehicle Dynamics Control System Based on the Coordination of AFS, DYC, and ED for Improvements in Vehicle Handling and Stability

10-04-02-00091/27/2020

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

Brake System Thermal Performance for Brazil Market Battery Electric Vehicles

2019-36-00191/13/2020

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 brake

2019-36-00201/13/2020

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

Regenerative Braking Cooperative Control of Hybrid Electric Vehicle Based on System Efficiency Optimization

2019-01-508911/19/2019

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 Technology

2019-01-503811/4/2019

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

Information on Brake-By-Wire (BBW) Brake Control Systems

AIR5372A (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

Braking Requirements for Optimizing Autonomous Emergency Braking Performance

2019-01-21279/15/2019

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 EYE

19AUTP09_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.

The CAN Bus: Driving the Future of Autonomous Military Vehicles

19AERP05_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 Vehicles

TBMG-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.

Development and Control of Four-Wheel Independent Driving and Modular Steering Electric Vehicles for Improved Maneuverability Limits

2019-01-04594/2/2019

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

Influence Mechanism of Electromechanical Parameters on Transient Vibration of Electric Wheel System

2019-01-04624/2/2019

Electric wheel systems of in-wheel motor driven vehicles consist of the motor controller, in-wheel motor and tire-suspension assembly. The coupling between the electromagnetic excitation and elastic structure gives rise to electromechanical dynamic issues. As for the structural layout of the electric wheel system, the driving motor is directly connected to the wheel without torsion dampers or transmission in the driveline, thus making the electric wheel structure a weak damping system. Moreover, the driving torque of electric wheel can change rapidly in various conditions of vehicle. As a result, the transient vibration problem becomes one of the key electromechanical dynamic issues in the electric wheel system. To investigate this problem, the electromechanical coupling model of the electric wheel system is established first. Then the transient responses of the electric wheel under abrupt changes of the driving torque are simulated. The results indicate that the tire mainly suffers from longitudinal shocks in the anti-phase rotational mode at 95 Hz and vibration in the in-phase rotational mode at 44Hz successively, while the motor vibrates in the in-phase rotational mode at 44Hz. As the electric wheel system is electromechanically coupled, the influence mechanism and rules of electromechanical parameters on the transient vibration are studied. The results show that the permanent magnet flux linkage increases damping ratio of the in-phase rotational mode in virtue of the electromagnetic stiffness and damping, thus further weakening transient vibration of motor. The anti-phase rotational mode is sensitive to tire’s stiffness. It is effective to optimize tire’s shock by adjusting tire’s stiffness. This paper reveals the electromechanical coupling mechanism of the electric wheel system, and provides reference for parameter design from the perspective of improvement in dynamic characteristics.

Feng, Zhaoyang, Zuo, Shuguang, Mao, Yu

Reconstructing Vehicle Dynamics from On-Board Event Data

2019-01-06324/2/2019

Modern vehicles record dynamic data from a number of on-board sensors for events that could precede a crash. These data can be used to reconstruct the behavior of a vehicle, although the accuracy of these reconstructions has not yet been quantified. Here, we evaluated various methods of reconstructing the vehicle kinematics of a 2017 and a 2018 Toyota Corolla based on Vehicle Control History (VCH) data from overlapping events generated by the pre-collision system (PCS), sudden braking (SB) and anti-lock brake (ABS) activation. The vehicles were driven towards a stationary target at 32-64 km/h (20-40 mph) and then after the pre-collision alarm sounded the vehicle was steered sharply right or left and braked rapidly to rest. VCH data for PCS event were recorded at 2 Hz and for the sudden braking and ABS activation events at 6.7 Hz. The steering wheel angle and the vehicle’s longitudinal acceleration, lateral acceleration, and angular rate data were extracted and used to predict the vehicle position and heading over the duration of the VCH data record preceding the vehicle coming to rest. These predictions were generated by directly integrating the VCH data and by using the VCH data as inputs to PC-Crash simulations. The predicted positions and headings were then compared to the actual position and heading data measured using differential GPS synchronized to the VCH data record. The results of these analyses provide insights into the best methods for reconstructing vehicle kinematics from VCH data and estimates of the errors associated with different reconstruction techniques.

Tsuge, Brandon, Yang, Mike, Flynn, Thomas, Xing, Peter, Lawrence, Jonathan, Heinrichs, Bradley, Siegmund, Gunter

Regenerative Braking Pedal Decoupling Control for Hydraulic Brake System Equipped with an Electro-Mechanical Brake Booster

2019-01-11084/2/2019

Electrification and intelligence are the important development directions of vehicle techniques. The Electro-Mechanical Brake Booster (Ebooster) as a brake booster which is powered by a motor, can be used to replace the traditional vacuum booster. Ebooster not only improves the intelligence level of vehicle braking and significantly improves the braking performance, but also adapts to the application in new energy vehicles and facilitates coordinated regenerative braking. However, Ebooster cannot complete pedal decoupling independently. It needs to cooperate with other components to realize pedal decoupling. In this paper, a pedal decoupling control algorithm for regenerative brake, which is based on the coordination control of Ebooster and ESP, is proposed. First, regenerative braking strategy is designed to distribute the hydraulic brake force and regenerative braking force. Then, the coordinated control strategy of Ebooster and ESP is proposed, and the decoupling of brake pedal and brake wheel cylinder is realized. Finally, series of simulations are carried out under regenerative braking condition. The results show that the control algorithm introduced in this paper can achieve the decoupling of brake pedal and brake wheel cylinder.

Zhao, Jian, Hu, Zhiqiang, Zhu, Bing

Information on Electric Brakes

AIR5937 (Current)2/15/2019

This SAE Aerospace Information Report (AIR) describes the design, operation, and attributes of electrical braking systems for both military and commercial aircraft. At this time, the document focuses only on brakes utilizing electromechanical actuators (EMAs), as that is the present state of the art. As such, the discussions herein assume that EMAs can simply replace the hydraulic actuation portion of typical brake system leaving things such as the wheel and heat sink unchanged. Furthermore, the document provides detail information from the perspective of brake system design and operation. The document also addresses failure modes, certification issues, and past development efforts. Details on the design and control of electric motors, gear train design, ball or roller screw selection are available in the reference documents and elsewhere, but are outside the scope of this document. Other all-electric technologies such as piezoelectric actuation or more exotic methods of applying drag to a rotating wheel may be included at a later time. Important: Electric braking systems for aircraft are at the early stages of production implementation. There are also a variety of control schemes that may be used to provide acceptable EMA performance. As a result, many of the details involved in the design of electric brake systems are proprietary or competition sensitive to the brake system OEMs. This AIR attempts to provide a basic technical overview of electric brakes without compromising any particular manufacturer's intellectual property concerns.

A-5A Wheels, Brakes and Skid Controls Committee

Challenges in High Current Measurements Using Magnetic Flux Concentrator and Hall Effect Current Sensor

2019-26-01061/9/2019

Accurate and safe current measurement in electric and hybrid electric vehicles impose several challenges in conventional shunt-based measurement technique due to presence of high voltages coupled with very high currents. In this paper, we have proposed a low cost and practical contactless current sensing method based upon Hall effect using magnetic flux concentrators and Hall effect sensor for DC current sensing. We aimed at developing a low power sensor having high sensitivity, and flexibility to accommodate in small size for DC currents ranging from ±100 amperes. In this paper, we have modelled the vital properties of the magnetic flux concentrator such as core dimension, air gap, core material and hysteresis. We achieved simulation results showing performance of sensor with respect to varying core material, air-gap, dimensions and temperature. Four different core materials with two geometries were created for benchmarking against simulations results. The modelling was performed in finite element method (FEM) and ANSYS Maxwell 3D Design (Magneto-static) software. The simulation and experimental results were compared for influence of above parameters for accurate and optimum sensor design.

Gambhir, Ameya, Newaskar, Abhishek, Desai, Tushar

Movement Prediction Hypotheses for Pedestrians and Trajectory Planning for Cooperative Driving Systems

12-02-01-000212/19/2018

It is a challenge to find a safe trajectory for automated vehicles in urban environments with pedestrians. The prediction of future movements with 100% certainty is impossible, if the intention is unknown. A Gaussian process approach is used to formulate future movement hypotheses of the pedestrian based on historical movements. A mixed integer linear programming (MILP) optimization approach is used for the trajectory planning of the vehicle. The collision probability between the ego-vehicle and pedestrian is used as constraints in the optimization. This approach is useful for cooperative vehicle systems, with historical movement data in a fixed urban environment (e.g., intersection) and the premise that pedestrians follow typical movement data.

Hartmann, Michael, Stolz, Michael, Watzenig, Daniel

Tire Side Force Characteristics with the Coupling Effect of Vertical Load and Inflation Pressure

10-03-01-000211/9/2018

The tire vertical load and inflation pressure have great influence on tire steady- and non-steady-state characteristics and, consequently, on the vehicle handling and stability. The objective of this article is to reveal the coupling effect of tire vertical load and inflation pressure on tire characteristics and then introduce an improved UniTire side force model including such coupling effect through experimental and theoretical analysis. First, the influence of the tire vertical load and inflation pressure on the tire characteristics is presented through experimental analysis. Second, the theoretical tire cornering stiffness and lateral relaxation length model are introduced to study the underlying mechanism of the coupling effect. Then, an improved UniTire side force model including the coupling effect of tire vertical load and inflation pressure is derived. Finally, the proposed improved UniTire side force model is validated through tire steady-state and transient data. The coupling effect of tire vertical load and inflation pressure on tire cornering stiffness and lateral relaxation length is decided by the variation of the half length of tire contact patch and the carcass stiffness caused by the tire vertical load and inflation pressure changes.

Guo, Konghui, Chen, Ping, Xu, Nan, Yang, Chao, Li, Fei

Open-Loop Characteristics Analysis and Control of High Speed On-Off Valve

2018-01-186810/5/2018

In the process of ABS control, the Anti-lock braking system (ABS) of the vehicle adjusts the wheel cylinder brake pressure through the hydraulic actuator so as to control the movement of the wheel. The high-speed on-off valve (HSV) is the key components of the Anti-lock braking system. HSV affects the performance of the hydraulic actuator and the valve response characteristics affects the Anti-lock braking system pressure response as well as braking effect. In this paper, the electromagnetic field theory and flow field theory of HSV are analyzed, and simulation analysis of electromagnetic field characteristics of HSV is done by ANSYS. Combined with the ANSYS analysis results, a precise physical model of HSV is constructed in AMESim. Meanwhile, the valve response characteristics are analyzed. Moreover, the influence of different wheel cylinder diameter and PWM carrier frequency on hydraulic braking force characteristics are analyzed. The open-loop control methods of hydraulic braking force based on Look-up tables and T-S fuzzy structure are comparatively analyzed. The results show that T-S fuzzy controller can be more direct and rapid training to obtain buck-boost surface without fitting and interpolation of data surface, it is more adaptable. The single-wheel model and ABS sliding mode control module are established in Simulink. The inner ring of the module is hydraulic brake force controller, it is used to control hydraulic braking force precisely. The outer ring of the module is a sliding mode controller to control the wheel slip rate. Based on the above two open-loop control strategies, ABS control can be better achieved to realize anti-lock control of the vehicle in the emergency braking conditions.

Zhuo, Guirong, Shen, Huadong, Xue, Ruonan, Wu, Shenchen

Coordinated Control under Transitional Conditions in Hybrid Braking of Electric Vehicle

2018-01-186910/5/2018

In the hybrid brake system of electric vehicle, due to the limitation of the motor braking force when the motor is at high speed and the failure of the regenerative braking force when the motor is at low speed, there are three transitional conditions in hybrid braking: the hydraulic brake system intervenes the braking, the hydraulic brake system withdraws the braking and the regenerative braking force withdraws the braking. Due to the response speed of the hydraulic system is slower than that of the motor, there is a large braking impact (the derivative of braking deceleration) in the transitional conditions of hybrid braking, which deteriorates the smoothness and comfort in braking. Aiming at the impact caused by the poor cooperation between the hydraulic braking force and the motor braking force, a coordinated strategy of double closed-loop feedback and motor force correction is proposed in this paper. The double closed-loop feedback strategy relies on the motor force to compensate the tracking error of hydraulic pressure of the hydraulic brake system. The purpose of the motor force correction strategy is to allow the motor to consistently have the compensation capability under all transitional conditions. Simulation and hardware in-loop test were carried out based on Integrated-electro-hydraulic brake system (I-EHB). The HIL test results show that the proposed strategy can greatly reduce the impact degree when the two kinds of braking force switch. The impact degree of hydraulic braking force intervention decreased from the initial 28.26 m/s3 to 18.39 m/s3, decreased by 34.9%, the impact degree of regenerative braking withdrawal reduced from the initial −60.94 m/s3 to 16.84 m/s3, reduced by 72.3%, which improved the comfort in vehicle braking and provided a reference for the practical application of the strategy.

Yu, Zhuoping, Shi, Biaofei, Xiong, Lu, Han, Wei

Inertia Calculation for Single-Ended Inertia-Dynamometer Testing

J2789_201809 (Historical)9/26/2018

This procedure provides methods to determine the appropriate inertia values for all passenger cars and light trucks up to 4540 kg of GVWR. For the same vehicle application and axle (front or rear), different tests sections or brake applications may use different inertia values to reflect the duty-cycle and loading conditions indicated on the specific test.

Brake Dynamometer Standards Committee

Characterization of the brake system of a Formula SAE vehicle

2018-36-01489/3/2018

SAE Formula vehicles are required under extreme braking conditions during the race, where four-wheel braking is required. The brake assembly is composed of mechanical and hydraulic systems, which depending on the assembly of the components, can be subject to losses, causing a variation of the expected behavior. During braking situations, it is important to consider the load transfer in order to configure the braking distribution between the front and rear axles of the car with the best setup desired. The main objective of this work is to formulate a numerical model using the empirical data from the brake system of a SAE Formula vehicle to ensure that, after force is applied to the pedal, and the corresponding load is transferred to the front axle, the vehicle can lock the four wheels. Experimental data was acquired through static tests carried out on the bench and prototype vehicle, controlling the change of pressure and force between the front and rear axles through the balance bar mechanism. These tests were performed using low cost instrumentation, based on the Arduino platform. These analyses ensures that a vehicle with a brake distribution configured by the balance bar will lock the four wheels during the brake tests.

da Silva, Pedro Henrique Moraes, Idehara, Sérgio Junichi

Travelling Resistance Estimation and Sandy Road Identification for SUVs

2018-01-05784/3/2018

The mechanical properties of sandy road are quite different from those of hard surface road. For vehicle control systems such as EMS (engine management system), TCU (transmission control unit) and ABS (antilock brake system), the strategies and parameters set for solid surface road are not optimal for driving on sandy road. It is an effective way to improve the mobility of all-terrain vehicles by identifying sandy road online and shifting the control strategies and parameters of control systems to sandy sets. In this paper, a sandy road identification algorithm for SUVs is proposed. Firstly, the vehicle signals, such as engine torque and speed, gear position, wheel and vehicle speed, are acquired from EMS, TCU and ESP (electronic stability program) through CAN (controller area network) bus respectively. Based on the information and longitudinal force equilibrium equation, the travelling resistance of vehicle is estimated. The hydraulic torque converter is divided into several parts to calculate the acceleration resistance instead of using the rotational inertia coefficient. Then, the sandy road identification algorithm is proposed mainly based on the travelling resistance. Finally, real vehicle tests are carried out on different road conditions. After cone index penetrometer and soil hygrometer are used to measure the sandy test fields, performances of the travelling resistance estimation method and sandy road identification algorithm are validated. The results show that the identification algorithm designed in the paper can identify the sandy terrain effectively.

Wu, Weixiang, Zhang, Jian, Zhao, Jian, Zhu, Bing

Active Suspension Control of Electric Vehicle Driven by Switched Reluctance Motor Based on Vibration Absorbing Structure

2018-01-14014/3/2018

Active suspension control for in-wheel switched reluctance motor (SRM) driven electric vehicle with dynamic vibration absorber (DVA) based on robust H∞ control method is presented. The mounting of the electric drives on the wheels, known as in-wheel motor (IWM), results in an increase in the unsprung mass of the vehicle and a significant drop in the suspension ride performance and road holding stability. Structures with suspended shaftless direct drive motors have the potential to improve the road holding capability and ride performance. The quarter car active suspension model equipped with in-wheel SRM is established, in which the SRM stator serves as a dynamic vibration absorber. The in-wheel SRM is modelled using an analytical Fourier fitting method. The SRM airgap eccentricity is influenced by the road excitation and becomes time-varying such that a residual unbalanced radial force is induced. This is one of the major causes of SRM vibration. Current chopping control (CCC) and pulse width modulation control (PWM) are adapted to suppress motor vibration. Moreover, a robust H∞ controller is developed for the active suspension with DVA to further enhance vehicle ride performance. A comparison of passive suspension with conventional SRM, passive suspension with DVA, active suspension with DVA on vehicle suspension and SRM dynamic responses are presented. Simulation results under bump road excitation and random road excitation demonstrate the effectiveness of DVA structure active suspension system with proposed control method in enhancing suspension and motor performance.

Shao, Xinxin, Naghdy, Fazel, Du, Haiping

A Comparison of Motorcycle Braking Performance with and without Anti-Lock Braking on Dry Surfaces

2018-01-05204/3/2018

This paper analyzes motorcycle braking characteristics during stops at various speeds on a dry, asphalt surface with and without the use of the anti-lock brake system (ABS). To characterize the braking performance of the motorcycle, threshold brake stops were performed on a motorcycle of the superbike category at various speed increments. Motorcycle and brake system outputs consisting of brake pressures, wheel speeds, accelerations and yaw rates were measured and analyzed to highlight the different characteristics between a motorcycle with an integrated anti-lock brake system and multiple anti-lock brake system rider modes. Three different brake input strategies were used to brake the motorcycle; a front only brake application, a front and rear brake application, and a rear only brake application. The anti-lock brake system rider modes consist of a sport setting, a race setting and a setting that deactivates the anti-lock brake system. Each of the rider modes are tailored to the road surface conditions and rider driving style. Motorcycle stopping distances and deceleration levels were correlated with brake performance and longitudinal stability. This paper highlights the differences in braking performance between a motorcycle with and without the use of anti-lock brakes to help better understand what a rider might encounter in a limit braking situation on a dry, asphalt surface.

Dinges, Jeffrey, Hoover, Todd

The Influence of Autonomous Driving on Passive Vehicle Dynamics

2018-01-05514/3/2018

Traditional vehicles are designed to be inherently stable. This is typically obtained by imposing a large positive static margin (SM). The main drawbacks of this approach are the resulting understeering behavior of the vehicle and, often, a decrease in peak lateral grip due to oversized rear tire characteristics. On the other hand, a lower SM can cause a greater time delay in the vehicle’s response which hardens the control of a vehicle at limit handling for a human being. By introducing advanced autonomous driving features into future vehicles, the human factor can be excluded in limit handling manoeuvers (e.g., obstacle avoidance occurrences) and, consequently, the need for a high SM (i.e., high controllability for human drivers) can be avoided. Therefore, it could be possible to exploit the passive vehicle dynamics and enhance the performance, both in terms of peak grip and transient response. The goal of this article is to explore if a decrease in SM can lead to a performance advantage on an obstacle avoidance manoeuver when the vehicle is driven by a robotic controller. This is achieved by analyzing the behavior of various vehicle models with different SMs and peak lateral acceleration on a nonstandard double lane change manoeuver. After having characterized the dynamic response of the various models in both steady-state and unsteady-state, several tests are run on a Driver-in-Motion (DiM) dynamic driving simulator driven by human drivers. The same tests are run again in a Model-in-the-Loop (MiL) simulation where the vehicle is controlled by means of a nonlinear model predictive control (NMPC). The results show that the robotic controller outperforms a human driver and poses interesting design challenges for autonomous vehicles in terms of passive stability and active controllers to modify vehicle stability online.

Novi, Tommaso, Liniger, Alex, Capitani, Renzo, Fainello, Marco, Danisi, Giacomo, Annicchiarico, Claudio

Analysis of Berla iVe Acquisitions of Vehicle Speed Data from Ford Sync Systems

2018-01-14424/3/2018

Many modern automobiles’ infotainment/navigation systems store vehicle telematics and user-supplied infotainment data. This data is useful in a wide variety of analyses but is not available through traditional OEM tools. The necessity to access the infotainment module data for forensic analysis can be satisfied by utilizing the Berla iVe system. Similar to CDR/EDR technology, Berla iVe is a hardware and software tool that is used to acquire and analyze stored automotive data. However, CDR/EDR systems are generally developed in partnership with manufacturers or OEM suppliers. Berla iVe is a privately developed forensic system analogous to traditional forensic tools used to interrogate computer hard drives and smartphones. The technology is privately developed and tested. The data is then parsed using recognized forensics practices. This research was focused on assessing the accuracy of speed data recorded in certain modules and the resulting translations reported by the Berla iVe system. While a number of manufacturers’ vehicles store a variety of infotainment data, this project was limited to Ford Sync Generation 2 (SG2) and Generation 3 (SG3) systems. A series of controlled tests were conducted under a variety of operational conditions to create GPS-based and wheel speed-based (SG3 only) vehicle speed data. The Berla iVe-obtained speed data was compared to reference instrumentation without any smoothing or matching of recording latencies. Within each data set, the maximum error was 9 kph (the largest errors were associated with rapid speed change maneuvers), the average error was less than 1 kph, the correlation coefficient was 0.98 kph or higher, and the root mean square error (RMSE) was generally 2 kph or less. As such, the Berla iVe-obtained GPS- and wheel-based speed data are sufficiently accurate for a number of applications, including traffic accident reconstruction.

Vandiver, Wesley, Anderson, Robert

Automotive Stability Enhancement Systems

J2564_201711 (Current)11/14/2017

The purpose of this SAE Information Report is to describe currently known automotive active stability enhancement systems, as well as identify common names which can be used to refer to the various systems and common features and functions of the various systems. The primary systems discussed are: a ABS - Antilock Brake Systems b TCS - Traction Control Systems c ESC - Electronic Stability Control The document is technical in nature and attempts to remain neutral regarding unique features that individual system or vehicle manufacturers may provide.

Vehicle Dynamics Standards Committee

Performance Improvement of Regulator Rectifier for 2-Wheeler Engine with Respect to Upcoming Stringent Regulations in Emerging Market

2017-01-242510/8/2017

On two wheelers, magneto/alternator generates either single/three phase AC power and Regulator Rectifier Unit (RRU) does regulated rectification to charge the battery. In order to face the requirements of 2-wheeler engine with respect to upcoming stringent regulations like electronic fuel injection (EFI), anti-lock braking system (ABS), automatic headlamp on (AHO) in emerging markets like India; vehicles demand more electrical power from batteries. This demands higher power from alternator and consequently from RRU. Requirement of higher output power presents challenges on regulator rectifier unit in terms of size, power dissipation management and reliability. In this paper, improved performance of MOSFET based RRU is discussed in comparison to Silicon Controlled Rectifier (SCR) based RRU. The motivation/benefits of MOSFET based design is described along with the thermal behavior and temperature coefficient performance of RRU with test results. The second topic discussed is how the MOSFET based RRU helps to improve performance by respecting form factor and total power dissipation compared to SCR based design.

Verma, Ramit, R Ugale, Ramdas

Tuning of Brake Force Distribution for Pickup Truck Vehicle LSPV Brake System During Cornering Maneuver

2017-01-24919/17/2017

Automotive industry has led to constant production innovation among manufactures. This has resulted in the reduction of the life cycle of the design philosophies and design tools. One of the performance factors that have continues to challenge automotive designer is to design and fine tune the braking performance with low cost and short life cycle. Improvement in braking performance and vehicle stability can be achieved through the use of braking systems whosebrake force distribution is variable. Braking force distribution has an important and serious role in thevehicle stopping distance and stability. In this paper a new approach will be presented to achieve the braking forcedistribution strategy for articulated vehicles. For this purpose, the virtual optimization process has beenimplemented. This strategy, defined as an innovative braking force distribution strategy, is based on the wheel slips.The simulation results illustrate proposed strategy can significantly improve the vehicle stability in curved braking fordifferent levels of vehicle deceleration.

Anthonysamy, Baskar, Prasad, Arun Kumar, Shinde, Babasaheb

Longitudinal and Lateral Dynamics Evaluation of an Anti-Lock Braking System for Trail Snowmobiles

2017-01-25129/17/2017

Anti-lock braking systems are one of the most important safety systems for wheeled vehicles. They reduce the braking distance and, most importantly, help the user maintain controllability and steerability of the vehicle. This paper extends and adapts the concept of Anti-lock braking systems to tracked vehicles, specifically to snowmobiles. Snowmobiles are an interesting development platform for two main reasons: 1) track dynamics, despite being analogous to tire dynamics, present important differences that help understanding the features of the control algorithm and 2) snowmobiles are simple and rugged vehicles with a limited set of sensors, making the design of an effective control system challenging. The paper designs a track-deceleration based ABS algorithm and tests it both in straight riding and cornering. The analysis shows that, on snowmobiles, Anti-lock braking systems have negligible advantages in term of stopping distance, but are beneficial in terms of steerability and stability, during cornering.

Corno, Matteo, Roselli, Federico, Onesto, Luca, Savaresi, Sergio, Molinaro, Frank, Graves, Eric, Doubek, Andrew

Pressure Following Strategy for Conventional Braking Control Applied to a HIL Test Bench

2017-01-24969/17/2017

Brake systems represent important components for passenger cars since they are strictly related to vehicle safety: Anti-lock Braking Systems (ABS) and Electronic Stability Control (ESC) are the most well-known examples. The paper is focused on the characterization of the braking hydraulic plant and on the design of a pressure following control strategy. This strategy is aimed at pursuing performances and/or comfort objectives beyond the typical safety task. The low-level logic (focus of the paper) consists of a Feedforward and Proportional Integral controller. A Hardware In the Loop (HIL) braking test bench is adopted for pressure controller validation by providing some realistic reference pressure histories evaluated by a high-level controller. Results prove that innovative control strategies can be applied to conventional braking systems for achieving targets not limited to braking issues, i.e., comfort or NVH tasks.

Galvagno, Enrico, Tota, Antonio, Vigliani, Alessandro, Velardocchia, Mauro

3D Printing Enables Customized Magnets

TBMG-270226/1/2017

Polymer-bonded magnets are valuable for many sensor applications that require the production of unique and reproducible field profiles, not necessarily fields with the highest strength.

Active Safety Concept to Mitigate Slippery Road Conditions

2017-01-50025/30/2017

Antilock braking systems (ABS) are inherently limited by the static coefficient of friction (µ) between a vehicle’s tires and the road surface. This paper explores a unique active safety concept, Integrated Coefficient Enhancement (ICE), which works to improve ABS well beyond their present limits. The ICE concept was developed using a basic physics principle: to change µ between two surfaces, at least one of the surfaces must be altered in some way. By quickly deploying a specially designed tractive medium (TM) to aid in directional stability and braking, hazardous situations can be greatly mitigated. This paper describes the features and testing results of this TM and its aerodynamic-mechanical-electronic deployment apparatus. Under all slippery road conditions tested, the developed TM mitigated skidding, with improvements that ranged from 20% to several hundred percent, depending on conditions and deployment rates.

Skarie, James Bradley

Effects of Active Aerodynamic Wings on Handling Performance of High-Speed Vehicles

2017-01-15923/28/2017

In this research, active aerodynamic wings are investigated using numerical simulation in order to improve vehicle handling performance under emergency scenarios, such as tight cornering maneuvers at high speeds. Air foils are selected and analyzed to determine the basic geometric features of aerodynamic wings. Built upon the airfoil analysis, the 3-D aerodynamic wing model is developed. Then, the virtual aerodynamic wings are assembled with the 3-D vehicle model. The resulting 3-D geometry model is used for aerodynamic analysis based on numerical simulation using a computational fluid dynamics (CFD) software package. The CFD-based simulation data and the vehicle dynamic model generated are combined to study the effects of active aerodynamic wings on handling performance of high-speed vehicles. The systematic numerical simulation method and achieved results may provide design guidance for the development of active aerodynamic wings for high-speed road vehicles.

Cai, Jingdong, Kapoor, Saurabh, Sikder, Tushita, He, Yuping

Integrated Safety and Security Development in the Automotive Domain

2017-01-16613/28/2017

The replacement of safety-critical mechanical components with electro-mechanical systems has led to the fact that safety aspects play a central role in development of embedded automotive systems. Recently, consumer demands for connectivity (e.g., infotainment, car-2-car or car-2-infrastructure communication) as well as new advances toward advanced driver assistance systems (ADAS) or even autonomous driving functions make cybersecurity another key factor to be taken into account by vehicle suppliers and manufacturers. Although these can capitalize on experiences from many other domains, they still have to face several unique challenges when gearing up for specific cybersecurity challenges. A key challenge is related to the increasing interconnection of automotive systems with networks (such as Car2X). Due to this connectivity, it is no longer acceptable to assume that safety-critical systems are immune to security risks. Consequently novel automotive systems require appropriate systematic approaches to support security and safety aware development. Traditionally, safety and security have been treated separately, however due to increasing awareness of the mutual impacts, an integrated view based on cross domain knowledge becomes more important. The recently released SAE J3061 guidebook for cyber-physical vehicle systems provides high-level principles for automotive organizations for identifying and assessing cybersecurity threats and for designing cybersecurity aware systems in close relation to the ISO 26262 standard for the functional safety of road vehicles. The focus of this paper is set on addressing system safety and cybersecurity in combination rather than independently, and thereby raise the awareness of their mutual impacts. Therefore, we examine appropriate threat modeling and hazard analysis techniques in order to quantify the security impact on dependable safety related system development on a system level. Furthermore, we investigate systematic approaches to supporting the identification of trust boundaries and attack vectors for the safety- and cybersecurity-related aspects of complex automotive systems.

Macher, Georg, Messnarz, Richard, Armengaud, Eric, Riel, Andreas, Brenner, Eugen, Kreiner, Christian

A System for Autonomous Braking of a Vehicle Following Collision

2017-01-15813/28/2017

This paper presents two brake control functions which are initiated when there is an impact force applied to a host vehicle. The impact force is generated due to the host vehicle being collided with or by another vehicle or object. The first function - called the post-impact braking assist - initiates emergency brake assistance if the driver is braking during or right after the collision. The second function - called the post-impact braking - initiates autonomous braking up to the level of the anti-lock-brake system if the driver is not braking during or right after the collision. Both functions intend to enhance the current driver assistance features such as emergency brake assistance, electronic stability control, anti-brake-lock system, collision mitigation system, etc.

Lu, Jianbo, Hammoud, Hassen, Clark, Todd, Hofmann, Otto, Lakehal-ayat, Mohsen, Farmer, Shweta, Shomsky, Jason, Schaefer, Roland

Experimental and Simulation Studies on Instability of a Two Wheeler Vehicle

2017-01-15633/28/2017

Two and three wheeler vehicles are largely used in many developing and under developing countries because of their lower cost, better fuel economy and easy handling. Although, the construction of them is simpler than the four wheeler vehicle, they pose some problems related to instability. Wobbling is the main cause of instabilities in two wheeler and three wheeler vehicles. In this study, a mathematical model was proposed and developed to determine wobble instability of a two wheeler. Nonlinear equations were formulated by using kinematics and the D’Alembert’s principle with the help of multi body formalism. The non-linear equations found in the study were linearized with respect to rectilinear and upright motion, considering no rolling. It led to formation of matrix. The real part of the Eigen value of the matrix was found to be negative, implication of whose was an asymptotic stable motion. It was observed that, the above real part of Eigen value was a function of different parameters such as Tire stiffness, Frame compliance, Steering angle and Rider’s way of handling. These parameters play an important role in determination of wobble frequency. Further, a model was developed using the Lotus Suspension Software, and dependency of above parameters on wobble frequency was studied. Further, experiments were conducted to verify the dynamics behaviour of these parameters included in the proposed mathematical model. The simulation and experimental results are presented in this paper.

Behera, Abhijeet, Sivalingam, Murugan

Research on Vehicle Stability Control Strategy Based on Integrated-Electro-Hydraulic Brake System

2017-01-15653/28/2017

A vehicle dynamics stability control system based on integrated-electro-hydraulic brake (I-EHB) system with hierarchical control architecture and nonlinear control method is designed to improve the vehicle dynamics stability under extreme conditions in this paper. The I-EHB system is a novel brake-by-wire system, and is suitable to the development demands of intelligent vehicle technology and new energy vehicle technology. Four inlet valves and four outlet valves are added to the layout of a conventional four-channel hydraulic control unit. A permanent-magnet synchronous motor (PMSM) provides a stabilized high-pressure source in the master cylinder, and the four-channel hydraulic control unit ensures that the pressures in each wheel cylinder can be modulated separately at a high precision. Besides, the functions of Anti-lock Braking System, Traction Control System and Regenerative Braking System, Autonomous Emergency Braking can be integrated in this brake-by-wire system. A sliding mode variable structure vehicle dynamics stability controller based on hierarchical control framework is built in MATLAB/Simulink. The I-EHB actuator model and vehicle dynamic model with 15 degrees of freedom are built in simulation package AMESim through a parameterized and modularized method. Simulations are conducted via co-simulation platform using MATLAB/Simulink and AMESim under scenarios of the typical braking and NHTSA FMVSS 126 standard-Sine With Dwell. Simulation results show that hydraulic braking forces are coordinated well during typical braking process, verifying the feasibility and effectiveness of the models built and the control strategy proposed. Under Sine With Dwell maneuver, compared with the base systems equipped without/with the conventional ESP, the proposed stability control system has a good improvement on the vehicle dynamics.

He, Xiangkun, Yang, Kaiming, Ji, Xuewu, Liu, Yahui, Deng, Weiwen

Longitudinal Vibration Analysis of Electric Wheel System in Starting Condition

2017-01-11263/28/2017

Due to coupling of in-wheel motor and wheel/tire, the electric wheel system of in-wheel motor driven vehicle is different from tire suspension system of internal combustion engine vehicle both in the excitation source and structural dynamics. Therefore emerging dynamic issues of electric wheel arouse attention. Longitudinal vibration problem of electric wheel system in starting condition is studied in this paper. Vector control system of permanent magnet synchronous hub motor considering dead-time effect of the inverter is primarily built. Then coupled longitudinal-torsional vibration model of electric wheel system is established based on rigid ring model and dynamic tire/road interface. Inherent characteristics of this model are further analyzed. The vibration responses of electric wheel system are simulated by combining electromagnetic torque and the vibration model. The results indicate that abrupt changes of driving torque will cause transient vibration of electric wheel system. To be specific, vehicle body mainly undergoes longitudinal shake in 4Hz and unsprung mass suffers from longitudinal shock in 38Hz; the transient vibration of electric wheel system is most remarkable at zero velocity and decreases with vehicle speed. In addition, torque ripple will arouse 6pth order vibration, which is centralized in 40Hz and 100Hz and becomes noticeable in certain speed range due to resonance. The longitudinal vibration of electric wheel system in starting condition is highlighted and deserves attention. The detailed features and characteristics of this vibration are studied in this paper, which is favorable for design and analysis of in-wheel motor driven vehicle.

Mao, Yu, Zuo, Shuguang, Wu, Xudong

Anti-Lock Braking System Control Design on An Integrated-Electro-Hydraulic Braking System

2017-01-15783/28/2017

Two control strategies, safety preferred control and master cylinder oscillation control, were designed for anti-lock braking on a novel integrated-electro-hydraulic braking system (I-EHB) which has only four solenoid valves in its innovative hydraulic control unit (HCU) instead of eight in a traditional one. The main idea of safety preferred control is to reduce the hydraulic pressure provided by the motor in the master cylinder whenever a wheel tends to be locking even if some of the other wheels may need more braking torque. In contrast, regarding master cylinder oscillation control, a sinusoidal signal is given to the motor making the hydraulic pressure in the master cylinder oscillate in certain frequency and amplitude. Hardware-in-the-loop simulations were conducted to verify the effectiveness of the two control strategies mentioned above and to evaluate them. The simulation platform consists of the I-EHB hardware and software including CarSim and MATLAB/Simulink as well as LabVIEW serving as the communication tool. Conclusions can be reached in the light of testing results that both control strategies were able to achieve anti-lock braking under emergency situations. Compared with safety preferred control, master cylinder oscillation control performed better on the functionality of avoiding braking lock and the reduction of braking distance. Also, it is capable of working with electronic stability control systems (ESC) while safety preferred control cannot.

Liu, Tianyang, Yu, Zhuoping, Xiong, Lu, HAN, Wei

Using Generic Tyre Parameters for Low Friction Surfaces in Full Vehicle Simulations

2017-01-15063/28/2017

An intervention of vehicle stability control systems is more likely on slippery surfaces, e.g. when the road is covered with snow or ice. Contrary to testing on dry asphalt, testing on such surfaces is restricted by weather and proving grounds. Another drawback in testing is the reproducibility of measurements, since the surface condition changes during the tests, and the vehicle reaction is more sensitive on slippery surface. For that, simulation enables a good pre-assessment of the control systems independent from testing conditions. Essential for this is a good knowledge about the contact between vehicle and road, meaning a good tyre model and a reasonable set of tyre model parameters. However, the low friction surface has a high variation in the friction coefficient. For instance, the available lateral acceleration on scraped ice could vary between 0.2 and 0.4 g within a day. These facts lead to the idea of using generic tyre parameters that vary in a certain range. Benefit would be the robust testing of the stability control systems. Generic tyre parameters could also cover a high variety of available tyres on the market. Furthermore the model can be used to evaluate changing surface conditions. The extreme case of this situation are then the µ-slip manoeuvres, e.g. braking with asphalt on one lane and snow or ice on the other side.

Wiessalla, Johannes, Mao, Yiqin, Esser, Frank

Conversion of Drum Brake System to Disc Brake with CAE and CFD: Resulted in Optimized Brake Rotor Design and Improved Performance

2017-26-02611/10/2017

Paper explains conversion of existing drum brake system to disc brake system with complete digital validation at structural as well as thermal level to make sure First Time Right Design before physical part development. To provide leverage to quick design, modification and selection of brake system according to vehicle configuration, a virtual computational fluid dynamics (CFD) simulation process is developed and validated with test results. Temperature variation over brake drum and disc in internal standard braking cycle is measured virtually and correlated with test results. Also Fade testing criteria’s were considered during CFD analysis. This up gradation is must considering technology enhancement trend and safety in automotive segment. In current competitive market scenario and as per customer requirements, front disc brake module is becoming necessary not only for passenger segment but also for commercial segment vehicle. Brake system design is challenging task as it deals with safety norms and also required to meet stringent performance. Brake Rotor is very important component in brake system which is expected to withstand high braking torque and dissipate heat during braking event. Hence proper design and selection of braking system is very important before implementing on vehicle. Also rigorous testing process to measure the temperature rise of disc, calliper and hub of brake system is very important along with physical testing at vehicle level. Brake rotor is major part of disc brake system and First step of development is design calculation, followed up with CAD model preparation and later on CAE. All vehicle level structural loads considered during digital/CAE validation and post structural analysis, CFD analysis is completed. Detailed brake thermal loading cycle in terms of braking heat flux, meshing methodology and simulation processes revealed in paper. A transient simulation of three different types of disc profile performed. In transient thermal simulation of brake system, maximum temperature rise over disc and pads at different location are monitored and evaluated. These were compared with similar case of drum brake system. Based on conduction heat loss and convection heat loss calculation, the brake cooling effect is evaluated. Finally after confirmation from CFD analysis Brake rotor/ Brake system design frozen. All digital simulation results co-related with physical rig level and vehicle level testing, and results were acceptable. Finally weight optimized disc brake system meeting all performance criteria implemented in 8 × 2 commercial vehicle at all wheel ends. It resulted in customer delight with 20% payload increment and performance improvement from drum brake system to Disc brake system.

Anil Shah, Ashesh, Patidar, Ashok

Investigating the Parameterization of Dugoff Tire Model Using Experimental Tire-Ice Data

2016-01-80399/27/2016

Tire modeling plays an important role in the development of an Active Vehicle Safety System. As part of a larger project that aims at developing an integrated chassis control system, this study investigates the performance of a 19” all-season tire on ice for a sport utility vehicle. A design of experiment has been formulated to quantify the effect of operational parameters, specifically: wheel slip, normal load, and inflation pressure on the tire tractive performance. The experimental work was conducted on the Terramechanics Rig in the Advanced Vehicle Dynamics Laboratory at Virginia Tech. The paper investigates an approach for the parameterization of the Dugoff tire model based on the experimental data collected. Compared to other models, this model is attractive in terms of its simplicity, low number of parameters, and easy implementation for real-time applications. The relations correlating tire forces with slip ratios were identified by applying zero-phase filtering techniques to the raw test data. Next, an optimization procedure was utilized to extract parameters for the Dugoff tire model from the tire-on-ice drawbar pull coefficient versus slip ratio at certain levels of normal load and inflation tire pressure.

He, Rui, Jimenez, Emilio, Sandu, Corina, Savitski, Dzmitry, Ivanov, Valentin, He, Rui, Jimenez, Emilio, Sandu, Corina

Verification of Non-ABS Vehicle Performance with Real Time Suspension Deflection

2016-01-19349/18/2016

Fierce competition in India’s automotive industry has led to constant production innovation among manufactures. This has resulted in the reduction of the life cycle of the design philosophies and design tools. One of the performance factors that have continues to challenge automotive designer is to design and fine tune the braking performance with low cost and short life cycle. Braking performance of automotive vehicle is facilitated by the adhesion between the tyre and the ground. Braking force generated at the wheels of a vehicle have to appropriately match to the adhesion. Antilock braking system (ABS) is used for this purpose. ABS is a modern braking system which could significantly improve directional stability and reduce stopping distance of a vehicle. However this system still too complicated and expensive to use in low end compact car and pickup truck. In this research, the adaptation of a load sensing valve on the subject vehicle along with the real time performance is evaluated and compared with the simulation results using MSC.ADAMS/CAR software. Close correlation is established between actual testing and the simulation. The results show that load sensing valve actuation with respect to spring deformation could control the fluid pressure in order to reach equal time lock between front and rear wheels. A combination of load sensing valve and spring system could develop significant effect of ABS which is simple and economic enough to use low end car and pickup truck.

Prasad, Arun Kumar, Anthonysamy, Baskar, Gopalakrishn, V.A., Pahwa, Gurdeep Singh

Novel Disc Brake System Leading towards Payload Increment and Maintenance Improvement

2016-01-19369/18/2016

Brake system for any vehicle plays an important role, as safety comes at highest level, also domestic and international safety norms for commercial vehicles are getting stringent. In current scenario of highly competitive commercial market, Payload advantage comes at peak level in customer demand list, also maintainability plays an important role to make sure least vehicle downtime, linked to customer profitability. Finally, if product has less complexity (reducing no. of parts), then it will provide add on benefit to any organization. Considering these customer oriented perspectives, mainly payload & maintenance, along with regulation compliance. We have proposed new Disc brake system for heavy duty commercial vehicle providing maximum payload benefit, along with enhancement in maintainability. It has also enhanced performance and meeting all legislative criteria at vehicle level.

Anil Shah, Ashesh, Raj, Kshitiz

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