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Brake squeal has been a chronic customer complaint, often appearing high on the list of items that reduce customers' satisfaction with their vehicles. Brake squeal can emanate from either a drum brake or a disc brake even though the geometry of the two systems is significantly different. A drum brake generates friction within a cylindrical drum interacting with two semi-circular linings. A disc brake consists of a flat disc and two flat pads. The observed squeal behavior in a vehicle differs somewhat between drum and disc brakes. A drum brake may have a loud noise coming from three or more squeal frequencies, whereas a disc brake typically has one or two major squeal frequencies making up the noise. A good understanding of the operational deflection shapes of the brake components during noise events will definitely aid in design to reduce squeal occurrences and improve product quality.

Utilization of statistical methods can improve vehicle stopping-distance projections and reduce the complexity of brake deceleration models. These techniques can be very useful in the course of ascertaining whether an untested vehicle conforms to the applicable Federal Motor Vehicle Safety Standard (FMVSS), but they have much broader uses in the design of brake systems.

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

This paper presents an advanced yaw stability control system that uses a sensor set including an inertial measurement unit to sense the 6 degrees-of-freedom motions of a vehicle. The full degree of the inertial measurement unit improves and enhances the vehicle motion state estimation over the one in the traditional electronic stability controls. The addition of vehicle state estimation leads to the performance refinement of vehicle stability control that can improve performance in certain situations. The paper provides both detailed system description and test results showing the effectiveness of the system.

This paper proposes a low-cost but indirect method for occupancy detection and occupant counting purpose in current and future automotive systems. It can serve as either a way to determine the number of occupants riding inside a car or a way to complement the other devices in determining the occupancy. The proposed method is useful for various mobility applications including car rental, fleet management, taxi, car sharing, occupancy in autonomous vehicles, etc. It utilizes existing on-board motion sensor measurements, such as those used in the vehicle stability control function, together with door open and closed status. The vehicle’s motion signature in response to an occupant’s boarding and alighting is first extracted from the motion sensors that measure the responses of the vehicle body. Then the weights of the occupants are estimated by fitting the vehicle responses with a transient vehicle dynamics model.

Wheel slip control is crucial to active safety control systems such as Traction Control System (TCS) and Anti-lock Braking System (ABS) that ensure vehicle safety by maintaining the wheel slip in a stable region. For this reason, a wide variety of control methods has been implemented by both researchers and in the industry. Moreover, the use of new electro-hydraulic or electro-mechanical brakes, and in-wheel electric motors allow for a more precise wheel slip control, which should further improve the vehicle dynamics and safety. In this paper, we compare two methods for wheel slip control: a loop-shaping Youla parametrization method, and a sliding mode control method. Each controller is designed based on a simple single wheel system. The benefits and drawbacks of both methods are addressed. Finally, the performance and stability robustness of each controller is evaluated based on several metrics in a simulation using a high-fidelity vehicle model with several driving scenarios.

As part of determining the circumstances of a crash, sometimes components or component assemblies are evaluated to identify if they were damaged as a result of the crash or if they lost function prior to the crash. What role the loss of function may have contributed to the crash is useful in determining if they lost function prior to the crash. The causes and conditions for a brake rotor hub separation from the spindle of a vehicle with tapered roller bearing designs are analyzed through both component level testing and full vehicle testing. Laboratory tests were performed on component assemblies where loads were applied to the wheel assembly and the residual damage to the components was documented. In addition, full vehicle testing was conducted to evaluate the effects of a hub and rotor separation on vehicle control and to document evidence on the components. Real world case studies of hub and rotor separations are presented.

It is desirable to find methods to increase electric vehicle (EV) driving range and reduce performance variability of Plug-in Hybrid Electric Vehicles (PHEV). One strategy to improve EV range is to increase the charge power limit of the traction battery, which allows for more brake energy recovery. This paper applies Big Data technology to investigate how increasing the charge power limit could affect EV range in real world usage with respect to driving behavior. Big Data Drive (BDD) data collected from Ford employee vehicles in Michigan was analyzed to assess the impact of regenerative braking power on EV range. My Ford Mobile (MFM) data was also leveraged to find correlation to drivers nationwide based on brake score statistics. Estimated results show incremental improvements in EV range from increased charge power levels. Subsequently, this methodology and process could be applied to make future design decisions based on the dynamic nature of driving habits.

This paper discusses the technical importance of measuring disc brake caliper stiffness, seal performance, and fluid displacement. The paper then presents a method for measuring brakes and calculating these parameters during routine friction dynamometer testing. Finally, results of this testing from multiple production calipers are presented and discussed.

The brake pedal is the brake system component that the driver fundamentally has contact and through its action wait the response of the whole system. Each OEM defines during vehicle conceptualization the behavior of brake pedal that characterizes the pedal feel that in general reflects not only the characteristic from that vehicle but also from the entire brand. Technically, the term known as Pedal Feel means the relation between the force applied on the pedal, the pedal travel and the deceleration achieved by the vehicle. Such relation curves are also analyzed in conjunction with objective analysis sheets where the vehicle brake behavior is analyzed in test track considering different deceleration conditions, force and pedal travel. On technical literature, it is possible to find some data and studies considering the hydraulic brakes behavior.

To reduce warranty cost due to brake squeal and provide guidance for brake design, it is important to understand the contributions of key brake design parameters to brake noise. In this paper, a new technique, which employs the nonlinear transient finite element method as well as Taguchi method, is proposed as a design tool for improving the quality of brake systems. This DOE technique has been implemented to a car program. The final results identified the major parameters associated with the brake noise and also led to an optimal design by selecting appropriate levels of those parameters.

Considering that the most part of commercial vehicles are equipped with air brakes it is very important assure specific technical requirements for air brake system and its components. In addition, the effects of brake system failure are more critical for commercial vehicles which require more attention on their requirements details. Historically, the development of air brakes technology started on North America and Europe and consequently two strong and distinct resolutions were structured: FMVSS 121 and ECE R.13, respectively. For passenger cars were developed the ECER.13H to harmonize North American and European resolutions. However, for commercial vehicles regional applications, culture and implementation time must be considered. These commercial vehicles peculiarities must be understood and their specific requirements harmonized to attend the global marketing growth.

It is very important and unquestionable that we need to have a clear technical requirement for Air Brake Systems and its components, since it is one of most important regarding safety. Looking to heavy commercial vehicles and possible air brake system failures, everything becomes clearly to pay total attention for these normative and regulatory requirements. Historically, the development of Brakes technology has started on EUA and Europe and consequently two strong and distinct requirements were structured: FMVSS 121 and ECE-R13. From decades people are trying to harmonize these requirements and for passenger cars, the evolution was faster. However, for commercial vehicles there are more peculiarities considering regional applications and some of them cultural and implementation time. As globally market is growing so fast as well new markets around the world, become fundamental the clearly understanding of these similarities, variants, peculiarities and correlated requirements.

High mileage NVH performance is one of the major concerns in vehicle design for long term customer satisfaction. Elastomeric bushings and brake rotors are key chassis components which tend to degrade as vehicle mileage accumulates with time. The degradation of these components normally causes the overall degradation of vehicle NVH performance. In the current paper two categories of problems are addressed respectively: road-induced vibration due to bushing degradation, and brake roughness due to rotor wear. A system integration approach is used to derive the design strategies that can potentially make the vehicle more robust in these two NVH attributes. The approach links together bushing degradation characteristics, brake rotor wear characteristics, the design of experiment (DOE) method, and CAE modeling in a systematic fashion. The concept and method are demonstrated using a production vehicle.

The brake pedal is the brake system component that the driver fundamentally has contact and through its action wait the response of the whole system. Each OEM defines during vehicle conceptualization the behavior of brake pedal that characterizes the pedal feel that in general reflects not only the characteristic from that vehicle but also from the entire brand. Technically, the term known as Pedal Feel means the relation between the force applied on the pedal, the pedal travel and the deceleration achieved by the vehicle. Such relation curves are also analyzed in conjunction with objective analysis sheets where the vehicle brake behavior is analyzed in test track considering different deceleration conditions, force and pedal travel. On technical literature, it is possible to find some data and studies considering the hydraulic brakes behavior.

Analysis of road accidents has shown that an important portion of fatal crashes involving Commercial Vehicles are caused by rollovers. ESC systems in Commercial Vehicles can reduce rollovers, severe understeer or oversteer conditions and minimize occurrences of jackknifing events. Several studies have estimated that this positive effect of ESC on road safety is substantial. In Europe, Electronic Stability Control (ESC) is expected to prevent by far the most fatalities and injuries: about 3,000 fatalities (-14%), and about 50,000 injuries (-6%) per year. In Europe, Electronic Stability Control Systems is mandatory for all vehicles (since Nov. 1st, 2011 for new types of vehicle and Nov. 1st, 2014 for all new vehicles), including Commercial Vehicles, Buses, Trucks and Trailers.

An average luxury car contains more than 50 sensors connected, to over 28 microprocessors, through multiple communication networks. What makes these complex machines diagnosable at a dealership, is the ability of sophisticated diagnostics algorithms. Besides use of diagnostics in service, diagnosing a failure is also key for functional safety and vehicle availability. Safety related diagnostic functions such as loss of Brake fluid and leaky fuel system detection are critical. Once a failure is detected, Vehicle availability functions extend vehicle operation, so that one could reach the dealership without being stranded. The number of failure modes in a car could far exceed tens of thousands, thereby identifying key failure modes that require diagnostics can be a challenge.

Pedal feel is one of the first customer touch points during a driving experience, and as such can be an important contributor to quality perception and customer appeal. Many brake system design characteristics contribute to pedal feel, and although not the largest contributors, the brake linings play a role. Friction material properties that influence pedal feel include: friction level, in-stop friction rise, ambient compressibility and hot compressibility. These properties have been measured on a series of commercial friction materials intended for passenger cars and light trucks. Vehicle tests have also been performed to compare objective and subjective evaluations of pedal feel for the different linings on the same vehicle brake system. The testing was designed to identify the contribution of the linings to the brake system's responsiveness and feel. This paper will discuss the correlation between friction material properties and vehicle tests for pedal feel.

Brake system development and testing is spread over vehicle manufacturers, system and component suppliers. Test equipment from different sources, even resulting from different technology generations, different data analysis and report tools - comprising different and sometimes undocumented algorithms - lead to a difficult exchange and analysis of test results and, at the same time, contributes to unwanted test variability. Other studies regarding the test variability brought up that only a unified and unambiguous data format will allow a meaningful and comparative evaluation of these data and only standardization will reveal the actual reasons of test variability. The text at hand illustrates that a substantial part of test variability is caused by a misinterpretation of data and/or by the application of different algorithms.

This paper presents the development of a hardware in the loop (HIL) simulation system for evaluating and optimizing the interactions of the brake system with the vehicle. This unique HIL set-up consists of an inertial brake dynamometer with a brake corner module, an electronic control unit, a real time 3D total vehicle model and a computer system with a high-speed operating platform. The HIL system simultaneously confers advantages of both computer modeling and hardware testing. It offers the capability to do upfront design and assess performance of the foundation brake hardware and the chassis controls, as well as their interactions, in advance of testing and tuning a vehicle. This powerful tool enables reduction in development time and cost. A simple example of applying the brake dynamometer HIL system will be presented.