Browse Topic: Vehicle deceleration

Items (383)

Estimation parameters of braking of vehicles category M1 at definition of circumstances road accidents

2022-01-116609/19/2022

The study of the distribution of the deceleration of vehicles of category M1 when performing various maneuvers is intended to develop methods for assessing the parameters of maneuvering of cars in the study of the circumstances of the occurrence of road accidents. Experimental studies were carried out on passenger cars, which are equipped with automated braking force control systems, for various driving styles. M1 category vehicles were maneuvered on dry asphalt pavement in the range of speeds from 11 to 25 m / s, which is typical for most road traffic accidents. It was found that when braking a vehicle of category M1, longitudinal deceleration increase according to a second-order polynomial dependence in the range of deceleration variation from 1.39 to 5.86 m/s2. This fact is well explained by the peculiarities of the operation of automated brake force control systems that are equipped a vehicle , and the psychological behavior of the driver, who carries out the process of braking the

Kashkanov, Andrii, Kashkanova, Anastasiia, Podrigalo, Mikhail, Klets, Dmytro, Saraiev, Oleksii, Mikhalevich PhD, Mykola, Andrey, Korobko

An Affordable Tool Based on a Pedestrian-Vehicle Collision Model to Support the Fieldwork and Reconstruction

2022-01-505808/03/2022

A free access tool based on a pedestrian-vehicle collision model is presented. The model allows for the qualitative and quantitative description of the entire dynamics of an event through pre-collision, collision, and post-collision segments. Furthermore, it enabled the determination of the magnitude of the initial speed of the vehicle before collision with a pedestrian and the location of the point of impact on the road where the accident occurred. The model inputs correlate to evidence collected at the scene, providing a platform checklist to assist investigators in their fieldwork. Additionally, the pre-collision segment allowed the investigators to develop an avoidability study to evaluate road safety. The model was validated by comparing the results with experimental cases developed with dummies, bodies, and reconstructed cases using statistical methods. It is shown that there is no significant difference, thus verifying its functionality. In addition, the tool is available as a

Martínez, Ezequiel, Vargas, Juan Pablo, Baena, Alejandra

Wear Test Procedure on Inertia Dynamometer for Brake Friction Materials

J2707_202106 (Current)

06/10/2021

This SAE Recommended Practice (RP) specifies a dynamometer test procedure to characterize wear rates of automotive service brake linings (brake shoes) and disc brake pads.

Brake Dynamometer Standards Committee

Wear Test Procedure on Inertia Dynamometer for Brake Friction Materials

J2707_202106-TEST-REC (Historical)06/10/2021

Brake Dynamometer Standards Committee

Occupant Restraint Dynamic System Evaluation - Frontal Impact Heavy Trucks

J2418_202011 (Current)

11/09/2020

This SAE Recommended Practice describes the test procedures for conducting frontal impact restraint tests for heavy truck applications. Its purpose is to establish recommended test procedures that will standardize restraint system testing for heavy trucks. Descriptions of the test set-up, test instrumentation, photographic/video coverage, and the test fixtures are included.

Truck Crashworthiness Committee

Maximum Sound Level Potential for Motorcycles

J47_202006 (Current)

06/05/2020

This SAE Recommended Practice establishes the test procedure, environment, and instrumentation for determining the maximum sound level potential for motorcycles under wide open throttle acceleration and closed throttle deceleration.

Motorcycle Technical Steering Committee

Quantifying Engine Braking for Various Common Street Motorcycles

2020-01-088004/14/2020

Motorcycle engine braking was measured in each forward gear for a cross-section of typical street motorcycles. Using GPS data acquisition and video, deceleration relative to speed was examined. Motorcycle characteristics included various engine displacements and types of motorcycle. The data acquired will give more insight into the extent which engine braking is a factor for deceleration, a topic which has not been addressed in a peer-reviewed journal article to this date.

Jansen, Henricus, LeBlanc, Beau, Wilhelm, Christopher, Shaw, Tyler, Lowi, Alvin

A Smart Measuring System for Vehicle Dynamics Testing

2020-01-106604/14/2020

A fast measurement of the car handling performance is highly desirable to easily compare and assess different car setup, e.g. tires size and supplier, suspension settings, etc. Instead of the expensive professional equipment normally used by car manufacturers for vehicle testing, the authors propose a low-cost solution that is nevertheless accurate enough for comparative evaluations. The paper presents a novel measuring system for vehicle dynamics analysis, which is based uniquely on the sensors embedded in a smartphone and therefore completely independent on the signals available through vehicle CAN bus. Data from tri-axial accelerometer, gyroscope, GPS and camera are jointly used to compute the typical quantities analyzed in vehicle dynamics applications. In addition to signals such as yaw rate, lateral and longitudinal acceleration, vehicle speed and trajectory, normally available when working with Inertial Measurement Units (IMU) equipped with GPS, in the presented application the

Galvagno, Enrico, Mauro, Stefano, Pastorelli, Stefano, Tota, Antonio

Optimization of Braking Strategy for Automatic Emergency Braking System in Vehicle-Pedestrian Accidents

07-12-02-000903/23/2020

Braking strategy is the core of the automatic emergency braking (AEB) system. How to make the braking strategy of the AEB system more suitable for real traffic conditions and more acceptable to drivers is a very important research. This article carries out the braking strategy optimization for the AEB system. From the vehicle-pedestrian accidents collected by the National Automobile Accident In-depth Investigation System (NAIS) of Songjiang Station, this article selects typical cases equipped with event data recorder (EDR) and then analyzes the EDR data. On this basis, the strategy for the optimization of the AEB system is formed. The optimized strategy is simulated in the test scenario specified in the European New Car Assessment Programme (Euro-NCAP) and compared with the real vehicle test results. The result illustrates that the optimized braking strategy is more effective to avoid or mitigate collisions.

Qian, Yubin, Yang, Xueyan, Xiao, Lingyun, Zhu, Yican

More than a brake

2019-36-002001/13/2020

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

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

Study on Vehicle Spin Tendency during Braking on Differential mu Surfaces in Four Wheeled Automobile Vehicle

2019-01-211409/15/2019

A four-wheeled automobile during braking event in which left and right wheels of the vehicle are on different mu surfaces, has high chances of experiencing spin, which may lead to stability issues on vehicle. This paper intends to provide a mathematical approach to predict the deceleration at which vehicle will spin during braking in a differential mu surface, and determine the effect of influencing parameters on the extent of the vehicle spin tendency. This paper also provides a correlation between theoretical vs actual decelerations for vehicles to exhibit vehicle spin tendency. This paper helps in providing sufficient aid/tool for system designer to predetermine the vehicle spin at early level of system designs and make necessary amendments at initial stage of prototype development rather than late changes, to create a product which gives safe driving experience.

Nedunuri, Kartheek, K, Rajakumar, Lalasure, Santosh

Research on Integrated Performance Design for the Braking System

2019-01-212009/15/2019

Medium or higher commercial vehicles weight will be increased by 5 to 6 times compared to kerb weight depending on their load carrying capacity. Therefore, a pneumatic braking device is used that produces a greater braking force than hydraulic pressure. Pneumatic braking system is a device that performs mechanical braking using air pressure and shall be designed to an appropriate level, taking into account the multi-physics of air and mechanical phenomena. In addition, the dynamics of the vehicle during braking should be considered due to different vehicle behavior depending on the load carrying capacity. This study utilizes SIL(Software In the Loop) for a comprehensive review of the pneumatic braking performance of vehicles.

Han, Wookhyun, Yang, Kee-Young

Probabilistic Method for Assessing the Stability of Multi-Axle Vehicles When Braking

2019-01-214609/15/2019

The solution to the problem of stability of a multi-axle vehicle during braking is connected with the determination of the dynamic distribution of normal road reactions between the axles. To assess the stability of the vehicle is used as an indicator of the stability factor representing the ratio of the stabilizing moment to moment, the perturbing skid. When the values of the stability coefficient is greater than or equal to unity, the movement is stable, and otherwise it is unstable. For a multi-axle vehicle, determining the dynamic normal road reactions on the axles is possible after disclosing the static uncertainty of the physical model of the car, which is a multi-support beam. The solution to this problem involves the use of the "three sigma" rule. The maximum possible value of the stability coefficient is realized with the most favorable distribution of the total normal road reactions between the axles, ensuring the maximum value of the stabilizing moment and the minimum value

Podrigalo, Mikhail, Klets, Dmytro, Yatsenko, Kostiantyn, Abramov, Dmytrii, Kurenko, Oleksandr, Rohozin, Ihor, Abramova, Tetyana, Rudzinskyi, Volodymyr, Rudzinska, Olha, Voskobiinyk, Olena

Brake Rotor Corrosion and Friction Cleaning Effect on Vehicle Judder Performance

2019-01-211509/15/2019

Brake disc corrosion has emerged as an important field of study within the automotive industry due to the wide range of lining materials that are currently used worldwide, and their inherent rust-cleaning properties. The presence of oxide layers irregularly deposited on the cast iron disc surfaces usually leads to a forced, braking-induced vibration that can reach the driver’s position as a pronounced annoyance. Hence, the friction material composition directly impacts on the judder performance during the early corrosion-removal stage. This study incorporates both dynamometer and vehicle tests into the definition of a predictive methodology that allows corrosion-induced vibrations to be investigated at both system and vehicle levels. The oxide film is artificially generated by means of a salt spray chamber under steady-state climate conditions in order to guarantee a repetitive and robust procedure. The vibration response of the system is objectively evaluated in the form of caliper

Molina Montasell, Narcís, Ferrer, Bernat

Research on Constant Speed Control Strategy of Water Medium Retarders for Heavy-Duty Vehicles

2019-01-130404/02/2019

Hydraulic retarders are extensively used in heavy-duty vehicles because of their advantages, such as their large braking torque and long continuous operating hours. They can reduce the vehicle velocity by converting the kinetic energy of a traveling vehicle to the thermal energy of the working fluid. The water medium retarder is a new type of hydraulic retarder with the characteristics of high power density and simple structure. It uses the engine's coolant as the working medium, and the heat is directly taken away by the vehicle cooling system. Therefore, the heavy-duty vehicle can achieve long-term continuous braking during the downhill process. One of the main functions of water medium retarder is driving downhill at a constant speed which determines whether the vehicle drives stably and safely. Therefore, studying the constant-speed control strategy during downhill driving is particularly important. In this paper, the structure and working principle of water medium retarder and the

Lei, Yulong, Song, Pengxiang, Fu, Yao, Wang, Yuhai, Zhang, Yuchen

Learning from Human Naturalistic Driving Behavior at Stop Signs for Autonomous Vehicles

2019-01-102104/02/2019

Despite public expectations that autonomous vehicles should be able to avoid most accidents, the existing fleet of autonomous test vehicles has demonstrated this is simply not the case. An explanation for some of these accidents has been that these vehicles do not drive like humans and therefore do not exhibit certain driving patterns expected by human drivers. With the high likelihood of a gradual integration of autonomous vehicles into our traffic system in the future, there will be a need for such vehicles to adapt to, and mimic, human driving. Although much work has been done to understand human behavior and performance in driving, it has been mostly geared towards defining human capabilities and limitations. Little work has been done on the interactions between human-driven and autonomous vehicles. In previously published work, we described a large-scale, on-road eye tracking study conducted in instrumented test vehicles to understand and assess human behavior in a naturalistic

Tavassoli, Abtine, Cymbalist, Niccolo, Dunning, Amber, Krauss, David

Model-Based Pitch Control for Distributed Drive Electric Vehicle

2019-01-045104/02/2019

On the dual-motor electric vehicle, which is driven by two electric motors mounted on the front and rear axles respectively, longitudinal dynamic control and electro-dynamic braking can be achieved by controlling the torque of front and rear axle motors respectively. Suspension displacement is related to the wheel torque, thus the pitch of vehicle body can be influenced by changing the torque distribution ratio. The pitch of the body has a great influence on the vehicle comfort, which occurs mainly during acceleration and braking progress. Traditionally active suspension is adopted to control the pitch of body. Instead, in this paper an ideal torque distribution strategy is developed to limit the pitch during acceleration and braking progress. This paper first explores the relationship between the torque distribution and the body pitch through the real vehicle test, which reveals the feasibility of the vehicle comfort promotion by optimizing the torque distribution coefficient. A two

Yu, Yize, Xiong, Lu, Yu, Zhuoping, Yang, Xing, Hou, Yuye, Leng, Bo

Analysis of Changes in Disc-Brake Squeal Characteristic due to Regenerative Braking Simulation on Brake-Inertia-Dynamometer

2019-26-020301/09/2019

Brake is very crucial functional part of automobile, therefore need a robust testing for validation in order to ensure its failsafe functionality under harsh circumstances. For performance testing and foundation brake system design optimization purpose Brake-Inertia-Dynamometer (BID) being used extensively since its inception, and from last two decades for optimization of brake Noise, Vibration, and Harshness (NVH) performance too. In brake NVH the major issue is brake squeal or squeak generation, which is very difficult to predict its occurrences and standardized its prerequisite conditions. Since, brake is the only device which is designed for power absorption in automobile and therefore the regenerative braking concept come to the picture for energy conservation. The loss of energy in braking in case of Hybrid Electric Vehicle (HEV) and Electric Vehicle (EV) is more crucial and hence implementation of regenerative-braking is more discernible in HEVs and EVs to enhance the efficiency

Chilbule, Chaitanya, Weiss, Dieter

Performance and Comfort Optimization from ABS/CBS/Motor Regenerative Braking in an Electric Two Wheeler during Heavy and Mild Braking Respectively

2019-26-012201/09/2019

Reducing the number of traffic accidents is a declared target of most governments leading to mandating Combined Braking System (CBS) or Anti-lock Braking System (ABS) in two wheelers. Traditional friction braking torque and motor braking torque can be used in braking for electric 2wheeler. Use of CBS and ABS helps in active control of vehicle braking leading to better deceleration, prevention of tire locking, control on vehicle pitch etc. A braking model (friction braking + motor regenerative braking) along with battery dynamics is developed in Matlab/Simulink and validated with real vehicle response. This paper presents an analysis on vehicle braking separately for heavy and mild braking in various vehicle load conditions. During heavy braking a feedback control algorithm is used to maintain optimal slip ratio both at the front and rear tire, active control on CBS and ABS+Regen is done and performance is compared. Similarly, during mild braking rider’s comfort is addressed by

Soni, Lokesh, Venkateswaran, Shivaram, Ramachandran, Vijeta

Optimized Braking System Sizing by Means of a Parametric 1D Brake Model

2019-26-035501/09/2019

This paper presents a methodology that incorporates a 1D (non-geometric) brake model, together with conventional vehicle tests, into the solution of problems associated with the sizing of a braking system. The 1D tool is aimed at predicting the main braking attributes, such as pedal feel or thermal capacity under repeated snubs, and the fulfilment of the legislative requirements -service, emergency and parking brake performance. The model recreates a parametric brake system, and thus allows engineers to understand the impact a parameter (e.g. a specification) might have on the overall performance when it is altered. This calculation provides valuable assistance when sizing a braking system. The methodology presented succeeds in reducing the number of vehicle test iterations throughout the brake sizing stage, thus being more cost-effective and less time-consuming than the usual trial and error approach to select the off-the-shelf components available from suppliers.

Molina Montasell, Narcís, Santosh, Raunak

FMVSS 105 Inertia Brake Dynamometer Test Procedure for Vehicles Above 4540 kg GVWR

J2684_201812 (Current)12/05/2018

Truck and Bus Hydraulic Brake Committee

Coordinated Control under Transitional Conditions in Hybrid Braking of Electric Vehicle

2018-01-186910/05/2018

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

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

A Mathematical Model of the Braking Dynamics of a Car

2018-01-189310/05/2018

The braking efficiency of a vehicle is its most important operational property. However, in practice, researchers utilize simplistic physical-mathematical models for the process of vehicle braking that leads to accuracy reduction of these models predictions. The literature data show that the error in assessing braking efficiency can reach 30%. One of the main indicators of the efficiency of a braking system is deceleration. Most accurately, this value can be determined by experimental measurements. However, this is not always possible due to various technical reasons. The existing models typically ignore the impact of the car design and its speed on deceleration. They also either neglect air resistance completely or account only for its horizontal component. This paper presents an improved mathematical model written in the differential form that takes into account the impact of the lifting or downforce components of the aerodynamic forces. The proposed model accounts for the dependence

Saraiev, Olexii, Gorb, Yuliya

Comparison of Different Variable Braking Force Systems

2018-01-186510/05/2018

An automobile braking system has a crucial role in the safety of the passengers and riding quality of the vehicle. The braking force mainly depends on the normal reaction on the wheel and the coefficient of adhesion between the tire and the road surface. The required braking force for a vehicle varies with the load on the vehicle. If the applied braking force is greater than the required brake force, wheel gets locked which results in increased stopping distance. In order to prevent the wheel lock at low load conditions or deficient braking force at extremely high load conditions, a variable braking force system is developed. Whenever a motorcycle is loaded, the normal reaction on the rear wheel is increased. Thus, the amount of braking force required to halt the motorcycle with minimum stopping distance and stability of the motorcycle is based on the pillion load on the motorcycle. Hence, the amount of braking force developed between the road surface and the tire is varied in the

Subramanian, Chidambaram, Vinayaga Sundaram, Ganesh

Cementitious-Based Brake Pads Technology: Performance, Low Energy Consumption, Emission Drop

2018-01-186710/05/2018

Brake pads employing innovative hydraulic inorganic binders in place of common state-of-the-art thermosetting phenolic resins have been produced by means of a unique prototypal equipment and a distinctive manufacturing process. The unicity of the process enables us to exclude completely any thermal cycle in the manufacturing steps, with a considerable positive energy balance compared to the standard counterpart. Realized brake pads have indeed been successfully tuned to meet the braking performances of phenolic counterparts. In the present work our latest efforts in this field are illustrated, focusing our attention to three main areas of interest: performance, energy consumption, volatile organic emissions. One selected exponent of our cementitious-based material is reported, demonstrating its capability of matching both standard OE and AM braking performances (investigated through a full scale brake dynamometer by SAE J2522 procedure), and its feasibility to be released as an actual

Sanguineti, Alessandro, Samela, Alessandro, Rampinelli, Flavio, Bottalico, Luca, Ranza, Luigi, Romeo, Marco, Bonfanti, Andrea

Inertia Calculation for Single-Ended Inertia-Dynamometer Testing

J2789_201809 (Historical)09/26/2018

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

Sizing of anti-lock braking system for Formula SAE vehicles

2018-36-020109/03/2018

The anti-lock braking system (ABS) has the purpose of controlling the wheel slip, in order to maintain steering and stability during braking. Due to the increasing search for safety and performance in competition vehicles, it is sought to minimize braking distances for the purpose of reduce track time. It is known that a slip control task is not trivial, where one of the main reasons is the high amount of uncertainties involved. Thus, the present paper aims to simulate a SAE vehicle with and without ABS using reliable experimental data of friction interfaces. The performance of the system is evaluated by a longitudinal vehicle model, supported by principles of vehicular dynamics, dynamometric test and track data. The model has a feedback control system with two proportional, integral, derivative (PID) loops. A sensor monitors wheel slip and feed it to the controller. This, actuates the hydraulic modulator operated by the opening or closing of the valves, with the objective of maintain

Boere, Lucas Dickow, Silva, André Luis da

Commercial Truck and Bus SAE Recommended Procedure for Vehicle Performance Prediction and Charting

J2188_201807 (Current)07/25/2018

Truck and Bus Powertrain Committee

Considerations for ISO 26262 ASIL Hazard Classification

J2980_201804 (Historical)

04/28/2018

This SAE Recommended Practice presents a method and example results for determining the Automotive Safety Integrity Level (ASIL) for automotive motion control electrical and electronic (E/E) systems. The ASIL determination activity is required by ISO 26262-3:2011 [1], and it is intended that the process and results herein are consistent with ISO 26262:2011 [1]. The technical focus of this document is on vehicle motion control systems. It is limited to passenger cars weighing up to 3.5 metric tons. Furthermore, the scope of this recommended practice is limited to collision-related hazards associated with motion control systems. The recommended practice focused on motion control systems since the hazards they can create generally have higher ASIL ratings, as compared to the hazards non-motion control systems can create. Because of this, the Functional Safety Committee decided to give motion control systems a higher priority and focus exclusively on them in the SAE J2980 recommended

Functional Safety Committee

Considerations for ISO 26262 ASIL Hazard Classification

J2980_201804-TEST-REC (Historical)04/28/2018

Functional Safety Committee

A Lane-Changing Decision-Making Method for Intelligent Vehicle Based on Acceleration Field

2018-01-059904/03/2018

Taking full advantage of available traffic environment information, making control decisions, and then planning trajectory systematically under structured roads conditions is a critical part of intelligent vehicle. In this article, a lane-changing decision-making method for intelligent vehicle is proposed based on acceleration field. Firstly, an acceleration field related to relative velocity and relative distance was built based on the analysis of braking process, and acceleration was taken as an indicator of safety evaluation. Then, a lane-changing decision method was set up with acceleration field while considering driver’s habits, traffic efficiency and safety. Furthermore, velocity regulation was also introduced in the lane-changing decision method to make it more flexible. Afterwards, the polynomial trajectory planning method was matched up with this lane-changing decision-making method and simulations based on Matlab/Simulink were finally conducted to verify the method presented

Zhu, Bing, Liu, Shuai, Zhao, Jian

Development of a Torque-Based Control Strategy for a Mode-Switching Hydraulic Hybrid Passenger Vehicle

2018-01-100704/03/2018

An increase in the number of vehicles per capita coupled with stricter emission regulations have made the development of newer and better hybrid vehicle architectures indispensable. Although electric hybrids have more visibility and are now commercially available, hydraulic hybrids, with their higher power densities and cheaper components, have been rigorously explored as the alternative. Several architectures have been proposed and implemented for both on and off highway applications. The most commonly used architecture is the series hybrid, which requires an energy conversion from the primary source (engine) to the secondary domain. From he re, the power flows either into the secondary source (high-pressure accumulator) or to the wheels depending upon the state of charge of the accumulator. A mode-switching hydraulic hybrid, which is a combination of a hydrostatic transmission and a series hybrid, was recently developed in the author’s research group. This paper focuses on the

Banerjee, Pranay, Ivantysynova, Monika

Estimation of Injury Risk of the Cervical Spine of Car Occupants after Emergency Braking

2018-01-054104/03/2018

This study deals with the question whether or not a “braking with maximum deceleration” represents a specific physical load situation for the occupants of a car. For this purpose, a literature study was performed to determine the relevance of symptoms concerning whiplash-associated disorders (WAD) of car occupants who were involved in traffic accidents with low accident severity. Additionally, test drives with full braking cars were conducted to determine the load situation of the neck for human test persons. Dummies were used too, which were equipped with measuring components at the head and thorax to identify the effective acceleration/deceleration and to compare these values to scientific approved characteristic deceleration values and to the existing neck injury criteria. Finally, the likelihood of occurrence of symptoms in terms of a neck injury was evaluated from the medical and biomechanical point of view. The study shows that there is basically no risk for the occurrence of

Otte, Dietmar, Facius lng, Thorsten, Johannsen, Heiko, Hüfner, Tobias

Estimation of Brake Friction Coefficient for Blending Function of Base Braking Control

2017-01-252009/17/2017

The brake architecture of hybrid and full electric vehicle includes the distinctive function of brake blending. Known approaches draw upon the maximum energy recuperation strategy and neglect the operation mode of friction brakes. Within this framework, an efficient control of the blending functions is demanded to compensate external disturbances induced by unpredictable variations of the pad disc friction coefficient. In addition, the control demand distribution between the conventional frictional brake system and the electric motors can incur failures that compromise the frictional braking performance and safety. However, deviation of friction coefficient value given in controller from actual one can induce undesirable deterioration of brake control functions. The main objective of the presented study is to propose a method to compensate disturbances induced by variations of brake linings friction coefficient through modifications of the brake torque demand for the enhancement of

Ricciardi, Vincenzo, Savitski, Dzmitry, Augsburg, Klaus, Ivanov, Valentin

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

2017-01-251209/17/2017

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

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

Combined Hill Descent Braking Strategy for Heavy Truck in the Featured-Slope

2017-01-253509/17/2017

The continuous braking for the brake drum will cause the brake thermal decay when the heavy truck is driving down the long slope in the mountain areas. It reduces the heavy truck’s braking performance and the braking safety. The engine braking and the hydraulic retarder braking both consume the kinetic energy of the heavy truck and can assist the truck driving in the mountain areas. This research proposes a combined hill descent braking strategy for heavy truck based on the recorded information of the slopes to ensure the braking safety of the heavy truck. The vehicle dynamic model and the brake drum temperature rising model are established to analyze the drum’s temperature variation during the downhill progress of the heavy truck. Then based on the slope information, the combined braking temperature variation is analyzed considering the characteristics of the engine braking, the drum braking and the hydraulic retarder braking. The research result shows that the brake drum’s

Xu, Yongbing, Mei, Binyu, Xiao, Longjie, XIA, Wanyang, Tan, Gangfeng

A Comparison of Braking Behavior between an IC Engine and Pure Electric Vehicle in Los Angeles City Driving Conditions

2017-01-251809/17/2017

The Los Angeles City Traffic Brake Test Schedule has been an established procedure used almost universally for generations by vehicle manufacturers to evaluate and validate braking systems for the attributes of NVH and brake wear behavior. The Los Angeles driving route, commonly known as the Los Angeles City Traffic Test (LACT), has long been considered an effective and “quasi” extreme set of real world driving conditions representative of the US passenger vehicle market and have been covered in other analysis including SAE Technical Paper 2002-01-2600 [1] The performance of a vehicle, relative to braking, in LACT conditions is typically influenced by basic vehicle and brake system attributes including the ratios of vehicle mass to brake sizing attributes, friction material selection, and the acceleration, drag, and cooling behavior of the vehicle. The general character of the LACT Route and typical driving behavior establishes an energy input to the braking system that must be managed

Hall, Thomas J.

Performance Comparison between ABS 4S/4M and ABS 4S/3M

2017-36-000105/24/2017

After the anti-skid brake system (ABS) introduction, mandatory for all vehicles in the Brazilian market, manufacturers have given increasing attention to optimized systems which meet legal and safety requirements. For commercial vehicles, an alternative for the ABS, which presents feasibility, is the configuration 4S/3M (4 wheel-speed sensors and 3 modulator valves) in substitution to the configuration 4S/4M. In other words, application of just one modulator valve to control the brakes of the same axle, front or rear, instead of independent control per each brake of the vehicle. The aim of this paper is to present a performance comparison between a brake system fitted with ABS configuration 4S/3M and an ABS configuration 4S/4M. To this end, both configurations were tested on the same vehicle application in accordance with the Brazilian legislation, CONTRAN 519/15. In addition, a test on which the vehicle was prepared with an unusual load distribution was performed in order to verify if

de Souza, Luís Fernando Nuss, de Oliveira, Antônio Carlos, Vetter, Narã Vieira

Aerospace Landing Gear Systems Terminology

AIR1489C (Current)05/09/2017

This report has been compiled by the Landing Gear Systems Terminology Panel of SAE Committee A-5 (Aerospace Landing Gear Systems). It represents an effort to gather together those terms commonly used within the discipline. Some terms are of course common to other disciplines as well. Others, however, are unique in form and/or meaning to the landing gear discipline. The need has been noted to set these terms down and provide a standard definition in order that communication within the discipline may be conducted with a common understanding. Full use has been made of available published information, and a list of references is provided. See also References (a) to (e). Terms listed are usually applicable to a general functional area of landing gear disciplines. These general functional areas include; landing impact, directional ground control, velocity control (acceleration, retardation, and arrestment), structural support, ground flotation, and ground maintenance. In the listing of terms

A-5 Aerospace Landing Gear Systems Committee

Method to Optimize Key Parameters and Effectiveness Evaluation of the AEB System Based on Rear-End Collision Accidents

2017-01-011203/28/2017

Rear-end accident is one of the most important collision modes in China, which often leads to severe accident consequences due to the high collision velocity. Autonomous Emergency Braking (AEB) system could perform emergency brake automatically in dangerous situation and mitigate the consequence. This study focused on the analysis of the rear-end accidents in China in order to discuss about the parameters of Time–to-Collision (TTC) and the comprehensive evaluation of typical AEB. A sample of 84 accidents was in-depth investigated and reconstructed, providing a comprehensive set of data describing the pre-crash matrix. Each accident in this sample is modeled numerically by the simulation tool PC-Crash. In parallel, a model representing the function of an AEB system has been established. This AEB system applies partial braking when the TTC ≤ TTC1 and full braking when the TTC ≤ TTC2. Lastly, the AEB system’s model is coupled to the kinematic of the vehicle in simulation for virtual

Zhao, Mingming, Wang, Hongyan, Chen, Junyi, Xu, Xiao, He, Yutong

Model Predictive Control for Feasible Region of Active Collision Avoidance

2017-01-004503/28/2017

Vehicle active collision avoidance includes collision avoidance by braking and by steering. However, both of these two methods have their limitations. Therefore, it is significant to establish the feasible region of active collision avoidance to choose the optimal way to avoid traffic accidents. This paper focuses on the steering control of an autonomous vehicle to track the planned trajectory and to perform an emergency collision avoidance maneuver. Meanwhile, the collision avoidance effect of steering control is compared with that of braking control. The path tracking controller is designed by hierarchical control structure. The upper controller includes model predictive control allocation and speed controller, and the lower is designed by weighted least-squares control allocation for torque allocation. Besides, seven order polynomial is used for path planning. In this paper, two kinds of steering collision avoidance measures are compared, including steering without yaw moment and

Zhuo, Guirong, Wu, Cheng, Zhang, Fengbo

Automated Electrified Powertrain Robustness Testing Tool

2017-01-168203/28/2017

The FMEA and DV&PV process of developing automotive products requires identifying and repeatedly testing critical vehicle attributes and their response to noise factors that may impair vehicle function. Ford has developed a new automated scripting tool to streamline in-vehicle robustness testing and produce more accurate and repeatable results. Similar noise factors identified during the FMEA process are grouped together, condensed, and scripts are developed to simulate these noise factors using calibration parameters and vehicle controls. The automated testing tool uses the API of a calibration software tool and a graphical scripting interface to consistently simulate driver inputs with greater precision than a human calibrator and enable more sophisticated controls, which would have previously required experimental software builds. The noise factor scripts are executed with minimal intervention from a human operator, and the collected data is analyzed to determine robustness. The

von der Lippe, Matthew, Waterbury, Mark, Ortmann, Walter J., Nefcy, Bernard, Thompson, Scott

Constant Speed Control Method of Hydraulic Retarder Based on Fuzzy PID

2017-01-111303/28/2017

Hydraulic retarders have been widely used in heavy-duty vehicles because of its advantages such as large braking torque and long operating hours. They can be used instead of service brakes in non-emergency braking conditions and can also reduce frequency and time of driver’s actions in braking process, thereby minimizing heat-related problems. In order to accurately produce braking torque needed for the vehicle in time by using hydraulic retarder, which enable the vehicle to travel stably and safely during downhill driving, aiming at the constant-speed function of hydraulic retarder, the research of constant-speed control method is conducted in this paper. The structure and working principle of hydraulic retarder is introduced and the dynamic characteristic is analyzed. And the theoretical model of vehicle and hydraulic retarder are established based on dynamic analysis of the vehicle downhill driving. The braking process that involves the hydraulic retarder is divided into three

Lei, Yulong, Song, Pengxiang, Zheng, Hongpeng, Fu, Yao, Liu, Zhenjie, Fu, Xuanyi

The Tunnel Climbing Acceleration Reminder System Based on Vehicle Dynamics

2017-01-007903/28/2017

Road traffic congestion sometimes happens at tunnel exit even without high traffic flow. One reason is that the deceleration process is imperceptible when the vehicle is driving to the tunnel exit with gradual upgrade slopes. Nowadays regulations are more concentrated in transport sectors, and control measures are applied to vehicles through the tunnel. This process is careless of vehicles’ specific characteristics and easily distract the driver attention. In this paper, a tunnel climbing acceleration reminder system is introduced. When the speed drop is detected and the analysis show this is due to the driver's unconscious behavior, the system will remind the driver to speed up. Based on the dynamic model and the tunnel properties, the relationship between the throttle opening degrees and the duration with the speed change is studied. Then, the engine braking is considered for the variation of speeds and slopes. Then combining the tunnel lighting effects on drivers, unconscious

Liu, Hao, Tan, Gangfeng, Yang, Mengying, Zhou, Xiaoxiao, Tang, Yu

Modeling, Simulation and Experimental Analysis of Brake Pedal Feel for Passenger Car

2017-01-137103/28/2017

Brake pedal feel plays an important role in the driver's comprehensive subjective feeling when braking, which directly affects the active safety and riding comfort of passenger car. A systematical mathematical model of the vehicle brake system is built in according with the structure and system characteristics of hydraulic servo brake system. A complete hydraulic servo brake system simulation model composed of brake pedal, vacuum booster, brake master cylinder, brake pipe, brake wheel cylinders, brake calipers is established in AMESim. The effects of rubber reaction plate stiffness, rubber valve opening, brake master cylinder piston, brake caliper, brake pipe deformation and friction liner deformation on brake pedal feel are considered in this model. The accuracy of this model is verified by real road vehicle tests under static and dynamic two different conditions. The influence of six structural parameters of vacuum booster, brake pipe and brake caliper on brake pedal feel are

Pan, Hao, Guo, Xuexun, Pei, Xiaofei, Dong, Xingzhi

Strength and Durability Testing for Automotive Hydraulic Brake Components

J2995_201703 (Current)

03/13/2017

To assess the strength and durability for hydraulic brake components as a function of test conditions. These conditions may include: braking torque, hill-holding, braking forces, hydraulic pressure, brake temperatures, environmental and corrosion effects, vibration, and time. This RP includes a systematic reference to other test methods and provides new test methods for durability life prediction based on the VDA 311 for operating strength for brake calipers. When using AK load collectives from vehicle testing for life prediction, the nominal vehicle life corresponds to 300000 km. Braking torques and forces take into account inputs from non-ABS, ABS, EPB, and ESC systems. It also applies to gasoline, diesel, hybrid, and electric vehicles. This RP applies to vehicles below 4540 kg of GVWR. With the appropriate engineering review and assessment for a given test program, this RP can apply (or be used) to scale the duty cycle (or special collective) to reflect regional, on-road special

Hydraulic Brake Components Standards Committee

Strength and Durability Testing for Automotive Hydraulic Brake Components

J2995_201703-TEST-REC (Historical)03/13/2017

Hydraulic Brake Components Standards Committee

Development of Advanced Braking System for Hybrid Sports Cars

2016-01-192309/18/2016

An advanced braking system had to be developed for a next-generation hybrid sports car with Sport Hybrid Super Handling All-Wheel Drive to achieve an intuitive brake feeling in a variety of driving conditions, ultimate track performance and reduction of CO2 emissions per vehicle. This paper outlines the integration of brake-by-wire with traditional high-performance braking hardware and describes the technology needed to achieve these goals. Key focus areas to generate these results were: brake feeling control, corner hardware specification considerations and brake cooling.

Dyar, Lorne R., Akita, Yuichiro, Paul, Scott, Lepito, Joseph, Ishikawa, Yoshio, Watanabe, Tomohiro

Occupant Restraint and Equipment Mounting Integrity – Side Impact Ambulance Patient Compartment

J2956_201608 (Historical)08/23/2016

Truck Crashworthiness Committee

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