Browse Topic: Vehicle deceleration

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Wear Test Procedure on Inertia Dynamometer for Brake Friction MaterialsJ2707_202106 (Historical)6/10/2021
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
Occupant Restraint Dynamic System Evaluation - Frontal Impact Heavy TrucksJ2418_202011 (Current)11/9/2020
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 MotorcyclesJ47_202006 (Current)6/5/2020
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
A Novel Velocity Planner for Autonomous Vehicle Considering Human Driver’s Habits2020-01-01334/14/2020
In automatic driving application, the velocity planner can be considered as a key factor to ensure the safety and comfort. One of the most important tasks of the velocity planner is to simulate the velocity characteristics of human drivers. In this paper, two Driver In-the-Loop (DIL) experiments are designed to explain velocity characteristics of human drivers. In the first experiment, static obstacles are placed on both sides of the straight road to shorten the cross range that vehicles can driver across. Moreover, different cross ranges are set to study the influence of the steering wheel error. In the second experiment, velocity characteristics are investigated under the condition of different road widths and curvatures in a U-turn road contour. In both tests, different drivers’ preview behavior is analyzed through the operation of throttle, braking, and steering. From the results we could see the change of vehicle speed depends largely on the traffic environment at the driver’s preview point. On this basis, a novel velocity planner is proposed. Firstly, a target velocity in preview terminal point is calculated. The calculation of the velocity is based on two indicators-the driver’s driving & operating ability, and the degree of visual restriction. The former refers to the ability of the driver to maintain the driveway as well as the control ability of the vehicle stability, and the latter is related to the uncertainty of the environment. Subsequently, the smooth velocity profiles that connect the initial point and the preview terminal point are generated based on the convex optimization. Finally, the simulation results show that this velocity planner possesses good human-like performance, considering the human-vehicle-road coordination. This study is useful to customize velocity planning for autonomous vehicle so as to improve the acceptability of the specific human driver.
Cui, Zongwei, Guo, Xuexun, Pei, Xiaofei
Simulation of Curved Road Collision Prevention Warning System of Automobile Based on V2X2020-01-07074/14/2020
The high popularity of automobiles has led to frequent collisions. According to the latest statistics of the United Nations, about 1.25 million people worldwide die from road traffic accidents each year. In order to improve the safety of vehicles in driving, the active safety system has become a research hotspot of various car companies and research institutions around the world. Among them, the more mature and popular active security system are Forward Collision Warning(FCW) and Autonomous Emergency Braking(AEB). However, the current active safety system is based on traditional sensors such as radar and camera. Therefore, the system itself has many limitations due to the shortage of traditional sensors. Compared to traditional sensors, Vehicle to Everything (V2X) technology has the advantages of richer vehicle parameter information, no perceived blind spots, dynamic prediction of dangerous vehicle status, and no occlusion restriction. In order to overcome the many shortcomings of the existing anti-collision warning system and strategy, this paper proposes a curved road collision prevention warning strategy based on V2X technology. Through V2X technology, the state information released by the neighboring car and the road environment information issued by the roadside unit are obtained. Using the above information and the state information of the vehicle, the relative positional relationship between the car and the neighboring car is dynamically predicted in real time, and then a two-degree-of-freedom dynamic collision time model and a two-degree-of-freedom collision time threshold model are proposed and designed. Finally, based on the output parameters of the above model, a two-degree-of-freedom curved road collision prevention warning system of automobile based on V2X technology is proposed, and a layered early warning mechanism is established. Through the PreScan environment, the typical working conditions and early warning strategy models are built by Matlab & Simulink, and the simulation of the early warning strategy is completed.
Li, Xuanhe, Wu, Jian, He, Rui, Zhu, Bing, Zhao, Jian, Zhou, Hang
An Experimental Methodology for Measuring Resistance Forces of Light-Duty Vehicles under Real-World Conditions and the Impact on Fuel Consumption2020-01-03834/14/2020
A vital element of any vehicle-certification test is the use of representative values for the vehicle resistance forces. In most certification procedures, including the WLTP recently adopted by the EU, the latter is achieved mainly through coast down tests. Subsequently, the resistance values measured are used for setting up the chassis-dyno resistances applied during the laboratory measurements. These reference values are obtained under controlled conditions, while a series of corrections are applied to make the test procedure more repeatable and reproducible. In real driving, the actual vehicle road loads are influenced by a series of factors leading to a divergence between the certified fuel consumption values, and the real-world ones. An approach of calculating representative road loads during on-road tests can help to obtain a more unobstructed view of vehicle efficiency and, when needed, confirm the officially declared road loads. This approach is also essential for validating simulations and achieving better estimates of the actual fuel consumption, a requirement introduced by the new policy adopted in the EU. In this study, a series of on-road experiments were conducted, under real-world conditions, on three vehicles, belonging to different vehicle body-categories, a supermini, a B segment cross-over city car, and a light-duty commercial vehicle. A wheel rim torque-measurement system (strain gauge torque sensors) was used to record the torque at the wheels accompanied by a wheel rotational-speed sensor. The present paper presents the results and investigates the capacity of such kind of tests to measure road loads with precision and accuracy. The calculated resistance forces are compared against the ones officially declared at type approval or measured via dedicated coast down tests. Results show satisfactory accuracy and repeatability, ranging within a ±3-7% range for the aerodynamic resistance, and point out margins for improvement. Simulation models are subsequently used to quantify the impact on real-world fuel consumption and CO2 emissions. The road loads measured using the method lead to similar fuel consumption simulation results as the official road loads with deviations in total simulated CO2 emissions remaining within ±6% of the measured values in the majority of the cases.
Komnos, Dimitrios, Fontaras, Georgios, Ntziachristos, Leonidas, Pavlovic, Jelica, Ciuffo, Biagio
Optimization of Braking Strategy for Automatic Emergency Braking System in Vehicle-Pedestrian Accidents07-12-02-00093/23/2020
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 brake2019-36-00201/13/2020
The automotive world is battling every day to provide innovation and product development without compromising the environment. The electrification of the engines can be a factor that divides eras into the market. The conventional brake system links the act of apply the brake pedal with the stop or deceleration of the vehicle. This is now possible thanks to the long-term use of the vacuum generated by the combustion engine or by auxiliary equipment (vacuum pump). New brake system technologies provides, without a vacuum source, more efficient and safer braking than the current power brake system. Embedded in technological developments, these systems interacts with other vehicle components (cameras, radars, ABS, ESC) bringing the driver advanced safety conditions.
Batagini, Emerson
Braking Control Strategy Based on Electronically Controlled Braking System and Intelligent Network Technology2019-01-503811/4/2019
In order to solve the coupling problems between braking safety, economical efficiency of braking and the comfort of drivers, a braking control strategy based on Electronically Controlled Braking System (EBS) and intelligent network technology under non-emergency braking conditions is proposed. The controller utilizes the intelligent network technology’s characteristics of the workshop communication to obtain the driving environment information of the current vehicle firstly, and then calculate the optimal braking deceleration of the vehicle based on optimal control method. The strategy will distribute the braking force according to the ideal braking force distribution condition based on the EBS according to the braking deceleration; the braking force will be converted to braking pressure according to brake characteristics. Computer co-simulations of the proposed strategy are performed, the strategy is verified under different initial speeds. The results show that the strategy enables the vehicle to stop within a safe distance, keeps the brake deceleration as smooth as possible for better braking comfort while at the same time obtaining better braking economy by increasing braking efficiency under different initial speeds.
Zheng, Hongyu, Li, Rui
Information on Brake-By-Wire (BBW) Brake Control SystemsAIR5372A (Current)10/25/2019
This SAE Aerospace Information Report (AIR) describes the design approaches used for current applications of aircraft Brake-by-Wire (BBW) control systems. The document also discusses the experience gained during service, and covers system, ergonomic, hardware, and development aspects. The document includes the lessons that have been learned during application of the technology. Although there are a variety of approaches that have been used in the design of BBW systems, the main focus of this document is on the current state of the art systems.
A-5A Wheels, Brakes and Skid Controls Committee
Brake Rotor Corrosion and Friction Cleaning Effect on Vehicle Judder Performance2019-01-21159/15/2019
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 accelerations and pressure (BPV) / torque (BTV) oscillations throughout a reduced rust-removal test sequence composed of 30 snubs; basic spectral and order analyses are conducted with the gathered data. Furthermore, vehicle-based results are correlated with the subjective ratings that an expert driver gives to the different vibrations perceived at chassis level. The in-service roughness of the oxide layer, on the other hand, is indirectly monitored by using a couple of non-contacting capacitive sensors that measure the variation in disc thickness (DTV). Ultimately, this paper is intended to characterize the inherent corrosion-cleaning capability of different friction materials -paying special attention to the presence of copper-, as well as revealing their impact on the vehicle judder subsequently induced during the actual removal of the oxide layers.
Molina Montasell, Narcís, Ferrer, Bernat
Research on Integrated Performance Design for the Braking System2019-01-21209/15/2019
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
Study on Vehicle Spin Tendency during Braking on Differential mu Surfaces in Four Wheeled Automobile Vehicle2019-01-21149/15/2019
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
Learning from Human Naturalistic Driving Behavior at Stop Signs for Autonomous Vehicles2019-01-10214/2/2019
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 driving environment. Here we describe one condition from that study, approaching and proceeding through stop-sign-controlled intersections, in the context of applying our work to the development of autonomous vehicles. We investigated naturalistic driver behavior at stop signs based on vehicle dynamics. In particular, we obtained deceleration rates, stopping/slowing speeds, stopping/slowing durations and acceleration rates while participants drove specific routes in Los Angeles. We also found and quantified clear evidence of “California Rolls” for many drivers. We suggest that data such as that presented in this paper can be incorporated into autonomous systems such that they behave more like human drivers (e.g. to avoid rear-end accidents), as well as to better predict human driving behaviors (e.g. “California Rolls” and very short stops).
Tavassoli, Abtine, Cymbalist, Niccolo, Dunning, Amber, Krauss, David
Research on Constant Speed Control Strategy of Water Medium Retarders for Heavy-Duty Vehicles2019-01-13044/2/2019
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 dynamic characteristic are analyzed. The dynamic models of vehicle and water medium retarder are established based on dynamic analysis during downhill process. The braking process that involves the water medium retarder is divided into three stages. Then the constant speed controller of water medium retarder which include three control algorithms is designed, respectively, PID algorithm, fuzzy algorithm and fuzzy-PID algorithm. The vehicle dynamic model and the constant speed control model of water medium retarder are established using MATLAB/SIMULINK. The simulation has been carried out and the comparative analysis of three algorithms mentioned above is conducted. The simulation results show that three controllers designed in this paper can quickly and accurately calculate the target filling ratio, fuzzy controller has better constant torque control performance, and the vehicle speed error is significantly reduced, which improves the stability of the vehicle during downhill process.
Lei, Yulong, Song, Pengxiang, Fu, Yao, Wang, Yuhai, Zhang, Yuchen
Model-Based Pitch Control for Distributed Drive Electric Vehicle2019-01-04514/2/2019
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-degree-of-freedom semi-vehicle model is established according to the actual vehicle parameters. Based on the vehicle model, the control system is established to minimize the pitch motion during the acceleration and braking process by means of a model predictive control technique. The control effect is verified by simulation experiments.
Yu, Yize, Xiong, Lu, Yu, Zhuoping, Yang, Xing, Hou, Yuye, Leng, Bo
Optimized Braking System Sizing by Means of a Parametric 1D Brake Model2019-26-03551/9/2019
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
Performance and Comfort Optimization from ABS/CBS/Motor Regenerative Braking in an Electric Two Wheeler during Heavy and Mild Braking Respectively2019-26-01221/9/2019
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 optimizing the vehicle pitch and pitch-rate, this gives an analysis/control on rider comfort. Model based simulation helps in precise analysis of corner cases like slip-ratio, suspension bump-stop etc. and gives an overall objective analysis on system design.
Soni, Lokesh, Venkateswaran, Shivaram, Ramachandran, Vijeta
FMVSS 105 Inertia Brake Dynamometer Test Procedure for Vehicles Above 4540 kg GVWRJ2684_201812 (Current)12/5/2018
This Recommended Practice is derived from the FMVSS 105 vehicle test and applies to two-axle multipurpose passenger vehicles, trucks, and buses with a GVWR above 4540 kg (10000 pounds) equipped with hydraulic service brakes. There are two main test sequences: Development Test Sequence for generic test conditions when not all information is available or when an assessment of brake output at different inputs are required, and FMVSS Test Sequence when vehicle parameters for brake pressure as a function of brake pedal input force and vehicle-specific loading and brake distribution are available. The test sequences are derived from the Federal Motor Vehicle Safety Standard 105 (and 121 for optional sections) as single-ended inertia-dynamometer test procedures when using the appropriate brake hardware and test parameters. This recommended practice provides Original Equipment Manufacturers (OEMs), brake and component manufacturers, as well as aftermarket suppliers, results related to brake output, friction material effectiveness, and corner performance in a laboratory-controlled test environment. The test sequences include different dynamic conditions (braking speeds, temperature, and braking history as outlined in the FMVSS 105); inertia loads equivalent to the vehicle’s LLVW and GVWR; fully operational, partial failure, and failed system conditions. All applicable sections of the FMVSS 105 are included. Optional sections include: parking brake output, water recovery, TP-121D dynamometer retardation, and 32 km/h (20 mph) stops to simulate Federal Motor Carrier Safety Administration (FMCSA) requirements. This recommended practice does not evaluate or quantify other brake system characteristics such as wear, noise, judder, ABS performance, or braking under extreme temperatures or speeds. Minimum performance requirements are not part of this recommended practice. Consistency and margin of pass/fail of the minimum requirements related to stopping distance or equivalent deceleration levels of the FMVSS 105 vehicle test can be assessed as part of the project in coordination with the test requestor when using the appropriate vehicle information and vehicle dynamics modeling. Nevertheless, this procedure and its results do not replace the vehicle-level test to demonstrate compliance to FMVSS (105 for hydraulic brake systems, or 121 for air-over-hydraulic brake systems), or other mandatory regulations (like ECE R13 or equivalents).
Truck and Bus Hydraulic Brake Committee
Comparison of Different Variable Braking Force Systems2018-01-186510/5/2018
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 variable braking force system. In this research work, three different variable brake force systems are compared. The different braking force systems are obtained by varying the effective disc radius or varying the pedal leverage or varying the area of piston. Simulation on the vehicle stopping distance is performed to compare the stopping distance of conventional braking system to Variable braking force system.
Subramanian, Chidambaram, Vinayaga Sundaram, Ganesh
Cementitious-Based Brake Pads Technology: Performance, Low Energy Consumption, Emission Drop2018-01-186710/5/2018
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 AM material according to ECE R90 regulation (road test on vehicle). The energetic evaluation of the employed technology in term of prototypal manufacturing process and employed raw materials has been established, demonstrating the advantages of this new system compared to the standard one. Our investigation finally reports selected thermo-chemical analysis (TG-EGA and pyrolysis PY-GC/MS) devoted at identifying the key organic compounds potentially/eventually emitted during braking at various temperatures. Our material shows a dramatic drop of the volatile hazardous/organic compounds (VHCs/VOCs) released by a standard phenolic homologous, thus increasing the favorable characteristics of such inorganic hydraulic-binder brake pads and related technology.
Sanguineti, Alessandro, Samela, Alessandro, Rampinelli, Flavio, Bottalico, Luca, Ranza, Luigi, Romeo, Marco, Bonfanti, Andrea
Coordinated Control under Transitional Conditions in Hybrid Braking of Electric Vehicle2018-01-186910/5/2018
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 TestingJ2789_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
Sizing of anti-lock braking system for Formula SAE vehicles2018-36-02019/3/2018
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 the desired output of the system. Simulation results are used to estimate contributions in straight braking time during typical events of Autocross and Endurance of FSAE. Thus, a quantitative analysis about overall placement contribution of the device implementation is presented.
Boere, Lucas Dickow, Silva, André Luis da
Commercial Truck and Bus SAE Recommended Procedure for Vehicle Performance Prediction and ChartingJ2188_201807 (Current)7/25/2018
This SAE Recommended Practice takes into account modern standardized methods for collecting and summarizing data that has an effect on vehicle steady-state performance, such as engine output (gross and net), transmission losses, drivetrain efficiency, vehicle aerodynamic devices for various vehicle and body configurations, as well as road surface variations and air density variations resulting from altitude and barometric effects. The procedure does not address vehicle transient performance (acceleration, braking, and cornering), because of the considerable amount of additional data required such as moment of inertia of all the rotating parts. Nor does it address vehicles with torque converters and automatic transmissions. This document is, therefore, intended for vehicles having fixed-ratio type transmissions and positive engagement clutches. Metric and ISO unit conversions are provided in the metric conversion tables at the end of this procedure (see Appendix B). Some modern vehicles with electronic engine controls have the ability to vary the maximum engine revolutions for each gear, as well as permitting the power or rpm to increase if more time is spent in the lower gears, as when climbing a grade. These special cases can be handled by this procedure, just by customizing the data for each transmission ratio and superimposing the long-term data on top of the instantaneous data. All of the equations are written in a form suitable for programming into a mainframe or desk-top computer, using a spreadsheet/database or a higher level language, such as Basic, Fortran, Pascal, C or Unix, etc. However, they are simple enough, to be performed on a hand-held calculator.
Truck and Bus Powertrain Committee
Considerations for ISO 26262 ASIL Hazard ClassificationJ2980_201804 (Historical)4/28/2018
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 practice. ISO 26262:2011 [1] has a wider scope than SAE J2980, covering other functions and accidents (not just motion control or collisions as in SAE J2980).
Functional Safety Committee
Development of a Torque-Based Control Strategy for a Mode-Switching Hydraulic Hybrid Passenger Vehicle2018-01-10074/3/2018
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 development of a new controller for the mode-switching hydraulic hybrid prototype. A uniform torque-based control strategy is proposed, which, along-with a supervisory controller decides on the usage of the high-pressure accumulator, thereby switching the vehicle mode from hydrostatic to series hybrid, among others. The supervisory controller analyzes the driving scenario, the system states and the user power demand to select the optimum vehicle-driving mode. This improved control strategy allows the vehicle to operate in higher efficiencies and the uniform control type results in a better “driver-feel”. The development of the control strategies, their implementation on the prototype vehicle and the test results are discussed in this paper.
Banerjee, Pranay, Ivantysynova, Monika
A Lane-Changing Decision-Making Method for Intelligent Vehicle Based on Acceleration Field2018-01-05994/3/2018
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 in this article. As the simulation results showed, adopting the lane-changing decision-making method based on acceleration field, the lane-changing measurements such as starting position, span and driving speed can be optimized with driver’s habits involved. At the same time, the vehicle safety can be well ensured.
Zhu, Bing, Liu, Shuai, Zhao, Jian
Estimation of Injury Risk of the Cervical Spine of Car Occupants after Emergency Braking2018-01-05414/3/2018
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 neck injuries and neck pain (whiplash disorders) for car occupants who experienced a full braking maneuver. This applies for the specific individual measured data of the test subjects compared to the known maximum load from the literature. But the authors of the study have to point out that special individual psychological and physiological frame conditions can lead to symptoms in terms of minor whiplash associated disorders like muscle tension symptoms.
Otte, Dietmar, Facius lng, Thorsten, Johannsen, Heiko, Hüfner, Tobias
Combined Hill Descent Braking Strategy for Heavy Truck in the Featured-Slope2017-01-25359/17/2017
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 temperature decreases by 69.9°C and reaches 193.1°C after the heavy truck goes down the chosen slope with the combined braking strategy. The brake thermal decay of the brake drum could be avoided and the brake safety could be ensured after using the combined hill descent braking strategy.
Xu, Yongbing, Mei, Binyu, Xiao, Longjie, XIA, Wanyang, Tan, Gangfeng
Longitudinal and Lateral Dynamics Evaluation of an Anti-Lock Braking System for Trail Snowmobiles2017-01-25129/17/2017
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
A Comparison of Braking Behavior between an IC Engine and Pure Electric Vehicle in Los Angeles City Driving Conditions2017-01-25189/17/2017
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 by the chosen set of brake components overlaid to a set of vehicle attributes. Brake system sizing has generally converged on typical sizing choices based on market forces and the typicality of vehicles in their associated segment. As a result, the general sizing of brakes systems tends to revert to a mean within a segment. Tradeoffs between, noise, wear, dust and other performance attributes are made with the selection of the friction material. Where, by example, a brake designer may tradeoff the attributes of higher dust, lower lining and rotor life in LACT for higher performance in extreme fade testing to achieve a desired market differentiation. The need for the work presented is motivated by the relatively recent entry to the market of pure electric vehicles. Many of the Pure EV’s offer significant capability to employ regenerative braking, which allows the conversion of vehicle kinetic energy to electrical energy. Therefore, the potential exists to significantly affect the amount of energy input to a vehicle’s friction braking system. As the performance in a LACT is highly dependent on the energy input the brake system must manage, it is important to objectively understand how this may change with the contribution of regenerative braking. If it is determined that the energy input to the friction brake system is significantly different in pure EV’s, then the potential exists to design fundamental brake system attributes differently with the potential to realize an improved totality of associated metrics by altering many of the traditional tradeoff balances commonly constraining brake system designers. This paper will provide an analysis by comparison between an exemplar IC engine based vehicle and a pure electric vehicle during a typical “day in Los Angeles”. The paper will provide an assessment of how regenerative braking influences the energy the brake system must manage, as well as any changes to the usage profile of the brake system in these driving conditions. Finally, this paper will offer some thoughts on how this could affect future design of brake systems of pure electric vehicles
Hall, Thomas J.
Estimation of Brake Friction Coefficient for Blending Function of Base Braking Control2017-01-25209/17/2017
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 both brake performance and active safety. The achievement of a compensation mechanism requires the estimation of relevant vehicle states. Hereunto, a novel technique based on a linear Kalman observer is proposed for the online estimation of the brake friction coefficient by relying upon the wheel speed sensors and inertia measurement unit (IMU). Such a tool enables a more efficient use of the frictional brakes aimed at minimizing losses of friction coefficient by keeping them in the optimal operational conditions. A simulation analysis will be carried out using the commercial vehicle dynamics simulation software IPG CarMaker to test the functionality of the developed estimator in the real-time mode. Experimental results from brake dynamometric test rig will be considered in the vehicle dynamics simulation software to reproduce the real behaviour of brake linings friction coefficient. The resulting improvements in brake control functions will be analysed against longitudinal base braking cases involving blending functions also in presence of failure of the electric motors.
Ricciardi, Vincenzo, Savitski, Dzmitry, Augsburg, Klaus, Ivanov, Valentin
Performance Comparison between ABS 4S/4M and ABS 4S/3M2017-36-00015/24/2017
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 the proposed system would be capable to keep its performance. A discussion regarding feasibility of ABS 4S/3M on 6x2 or 6x4 trucks is also presented.
de Souza, Luís Fernando Nuss, de Oliveira, Antônio Carlos, Vetter, Narã Vieira
Aerospace Landing Gear Systems TerminologyAIR1489C (Current)5/9/2017
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 and definitions, each term is followed by a code in parenthesis which indicates which basic functional area or major component to which the term is most applicable. Codes indicating basic functional area or major component are as follows: a Landing Gear Systems 1 Landing Gear (General) (L/G) 2 Tire (Tire) 3 Wheel (Whl) 4 Brake (Brk) 5 Nose Wheel Steering (NWS) 6 Shock Absorber (S/A) 7 Brake Control (B/C) b Related Systems 1 Air Vehicle/Aircraft (A/V) 2 Arresting Gear (A/G) 3 Operating Base & Equipment (Base) 4 Catapult (Cat)
A-5 Aerospace Landing Gear Systems Committee
Model Predictive Control for Feasible Region of Active Collision Avoidance2017-01-00453/28/2017
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 with yaw moment. The result shows applying the additional yaw moment can assist the vehicle to steer when the steering input reaches the limit value. Finally, the feasible collision avoidance regions based on the braking/steering are built under the conditions that the front car is stationary, in constant speed or in constant deceleration.
Zhuo, Guirong, Wu, Cheng, Zhang, Fengbo
Modeling, Simulation and Experimental Analysis of Brake Pedal Feel for Passenger Car2017-01-13713/28/2017
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 analyzed in detail. Finally, based on the evaluation system of BFI, the influence degree of different factors in different levels on the brake pedal feel are discussed through the orthogonal experiment design. The optimal scheme of brake pedal feel is put forward based on the sensitivity of various factors and validated by experiment. This study can serve as important reference for obtaining the best brake pedal feel, and also provides the theoretical basis for pedal simulator design and braking intention recognition in Brake-by-wire.
Pan, Hao, Guo, Xuexun, Pei, Xiaofei, Dong, Xingzhi
Deceleration Rates of Vehicles with Disabled Tires2017-01-14273/28/2017
Tire disablement events can cause a drag force that slows a vehicle. In this study, the magnitude of the deceleration was measured for different phases of 29 high speed tire tread separation and air loss tests. These deceleration rates can assist in reconstructing the speed of a vehicle involved in an accident following a tire disablement.
Koch, Daniel, Beauchamp, Gray, Pentecost, David
The Tunnel Climbing Acceleration Reminder System Based on Vehicle Dynamics2017-01-00793/28/2017
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 deceleration reasons is explored. The judgement criterion for the driver's unconscious behavior is determined. The geometric data and traffic flow data of the Wuhan Yangtze River Tunnel is used to verify the function of this system. The study shows that, during the start of morning rush and the end of evening peak, this on-board system could allow the average traffic congestion time dropped by 5-30%, which means higher traffic efficiency and comfort driving experience.
Liu, Hao, Tan, Gangfeng, Yang, Mengying, Zhou, Xiaoxiao, Tang, Yu
Constant Speed Control Method of Hydraulic Retarder Based on Fuzzy PID2017-01-11133/28/2017
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 stages. Then the common PID algorithm is improved, the PID parameters are optimized by using fuzzy reasoning method based on the change of vehicle speed error and the rate of error, a fuzzy PID constant-speed controller is designed. The vehicle dynamic model and the constant-speed control model of hydraulic retarder are established using MATLAB/SIMULINK and the simulation has been carried out. The simulation results show that compared with common PID controller, the fuzzy PID controller designed in this paper has better constant-torque performance and anti-inference performance that enable the vehicle to travel at a constant-speed in either a constant or a changing slope.
Lei, Yulong, Song, Pengxiang, Zheng, Hongpeng, Fu, Yao, Liu, Zhenjie, Fu, Xuanyi
Method to Optimize Key Parameters and Effectiveness Evaluation of the AEB System Based on Rear-End Collision Accidents2017-01-01123/28/2017
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 trajectories preceding the collision point to evaluate the potential effectiveness of different combinations of TTC according to the collision velocity reduction effectiveness and the excessive avoidance performance. After the simulations of 4284 run with 51 combination of the parameters based on 84 accidents, the results show that among the four desirable combinations, TTC1 = 1.0 s and TTC2 = 0.6 s is suitable for collision avoidance while TTC1 = 0.9 s and TTC2 = 0.5 s has satisfactory excessive collision avoidance.
Zhao, Mingming, Wang, Hongyan, Chen, Junyi, Xu, Xiao, He, Yutong
Strength and Durability Testing for Automotive Hydraulic Brake ComponentsJ2995_201703 (Current)3/13/2017
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 applications, or vehicles up to 7 tons of GVWR. Except for the AK load collectives, which have proven correlation to customer usage, the damage content of other procedures requires (a) the quantification with actual laboratory testing to develop the corresponding S/N curves, and (b) the calculation of the equivalent damage at the test conditions for a given load collective. The hydraulic components covered by this RP include: a Non-vacuum apply system (brake booster and master cylinder) b ABS modules c Service, IPB, and EPB calipers d Proportioning valves e Wheel cylinders This RP has an accompanying electronic appendix with the tabular presentation as a spreadsheet of different test procedures by type and by component.
Hydraulic Brake Components Standards Committee
Development of Advanced Braking System for Hybrid Sports Cars2016-01-19239/18/2016
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 CompartmentJ2956_201608 (Historical)8/23/2016
This SAE Recommended Practice describes the test procedures for conducting side impact occupant restraint and equipment mounting integrity tests for ambulance patient compartment applications. Its purpose is to describe crash pulse characteristics and establish recommended test procedures that will standardize restraint system and equipment mounting testing for ambulances. Descriptions of the test set-up, test instrumentation, photographic/video coverage, and the test fixtures are included.
Truck Crashworthiness Committee
Occupant Restraint and Equipment Mounting Integrity - Rear Impact Ambulance Patient CompartmentJ3044_201608 (Historical)8/17/2016
This SAE Recommended Practice describes the test procedures for conducting rear impact occupant restraint and equipment mounting integrity tests for ambulance patient compartment applications. Its purpose is to describe crash pulse characteristics and establish recommended test procedures that will standardize restraint system and equipment mount testing for ambulances. Descriptions of the test set-up, test instrumentation, photographic/video coverage, and the test fixtures are included.
Truck Crashworthiness Committee
Occupant Restraint and Equipment Mounting Integrity – Frontal Impact Ambulance Patient CompartmentJ2917_201608 (Historical)8/17/2016
This SAE Recommended Practice describes the test procedures for conducting frontal impact occupant restraint and equipment mounting integrity tests for ambulance patient compartment applications. Its purpose is to describe crash pulse characteristics and establish recommended test procedures that will standardize restraint system and equipment mounting testing for ambulances. Descriptions of the test set-up, test instrumentation, photographic/video coverage, and the test fixtures are included.
Truck Crashworthiness Committee
Development of an Electronically Controlled Brake System for Fuel-efficient Vehicles2016-01-16644/5/2016
To solve various environmental problems, fuel-efficient vehicles that reduce CO2 emissions as well as exhaust gas emissions have been developed. In such vehicles, a regenerative brake is used to further reduce fuel consumption. Because the market size for such vehicles is expanding, a brake system is required that can be used in a wide range of vehicles extending from internal combustion engine vehicles (ICEVs) to electric vehicles (EVs). In addition, issues such as deceleration fluctuation and brake pedal fluctuation arise because the regenerative brake force is dependent on the vehicle speed. This paper presents a brake system configuration and its element technologies that can replace existing brake systems in different vehicles ranging from ICEVs to EVs. The proposed system can realize a regenerative cooperative brake not only by replacing the brake booster unit but also without replacing the modulator. The advantages of this system are the maximization of regenerative efficiency, assurance of system reliability, and better brake feel.
Masuda, Yoshio, Yamasoe, Yosuke, Kuki, Yosuke, Okano, Takahiro, Uchida, Kiyoyuki
Evaluation of the Effectiveness of Volvo’s Pedestrian Detection System Based on Selected Real-Life Fatal Pedestrian Accidents2016-01-14504/5/2016
The objective of this work is to test the potential benefit of active pedestrian protection systems. The tests are based on real fatal accidents with passenger cars that were not equipped with active safety systems. Tests have been conducted in order to evaluate what the real benefit of the active safety system would be, and not to gain only a methodological prediction. The testing procedure was the first independent testing in the world which was based on real fatal pedestrian accidents. The aim of the tests is to evaluate the effectiveness of the Volvo pedestrian detection system. The in-depth accident database ZEDATU contains about 300 fatal pedestrian traffic accidents in urban areas. Eighteen cases of pedestrians hit by the front end of a passenger vehicle were extracted from this database. Cases covering an average traffic scenario have been reconstructed to obtain detailed model situations for testing. Simulations of accidents have been made in PC Crash 10.0 using a multibody object and a mesh model of vehicles. An active safety testing scenario was built on the basis of the reconstructed accidents with a Volvo V40 cc and a new dummy simulating a pedestrian. Before the tests the dummy was evaluated in anechoic room to gain required radar reflection properties which would be the same as those of a human body. The movement of the dummy was driven by the autonomous ultraflat overrunable robot (UFO) for experimental ADAS testing and synchronized with the Volvo’s motion by D-GPS with high accuracy. Experts that solves traffic accident involving a vehicle with a fully autonomous braking in a critical situation, encounter the problem of taking into account the impact of this system on the course of a traffic accident. Experts do not have enough information about the behavior of autonomous braking system. The implementation of such active safety systems has not yet been described and studied. Benefit of active safety systems to prevent road accidents can be achieved, for example, early warning driver of a potential collision situation sufficiently in advance to reaction and post-maneuver (braking, yaw,..). Professional community of traffic accident experts have lack of information about the general behavior of autonomous braking systems. From the perspective of traffic accident experts on following problems is study focused: How weather conditions affected to the operation of the system? In what speeds the system can prevent or reduce the risk of an accident? What type of pedestrian motion can system recognize? What period of time prior to the collision situation the system is warning the driver? How is the deceleration of the vehicle during autonomous braking?
Vertal, Peter, Steffan, Hermann
A Study on Vehicle Crash Pulse Severity in Frontal NCAP Tests2016-01-15364/5/2016
In this study, the available metrics to evaluate the crash pulse severity are reviewed and their assessability is investigated by using frontal New Car Assessment Program (NCAP) test data. Linear regression analysis and sled test simulations are conducted. In addition, a new approach is proposed to measure the crash pulse severity and restraint system performance separately and objectively.
Park, Chung-Kyu, Kan, Cing-Dao
GPGPU-Based High Performance Parallel Computation Method for Valve Body Failure Mode2016-01-13534/5/2016
The method that enables a Simulink model to execute parallel computation by using GPGPU technology is introduced. The GPGPU, General-purpose computing on graphics processing units, is a technology to accelerate program by using graphic card instead of CPU computation. This method was developed to reduce the time to detect failure mode of automatic transmission’s valve body. The valve body is the major part of automatic transmission. It is extremely important to confirm the functional safety of automatic transmission in the case that any parts of valve body failed. We have developed Simulink-based valve body failure mode simulator, and made a considerable contribution for this work. However, the number of failure mode is increasing recently. Therefore, we made the simulator to compute at a high-speed using GPGPU technology. We have sharply reduced the computation time and strengthened the computing ability to support the detection for an increasing amount of failure modes. In addition, we have automated almost a whole detection process and have made the simulator easier to use and scalable from now.
Suzuki, Tomonori, Mani, Tsutomu, Tsuchida, Kenichi, Yamaguchi, Masamichi
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