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As software (SW) becomes more and more an important aspect of embedded system development, project schedules are requiring the earlier development of software simultaneously with hardware (HW). In addition, verification has increasingly challenged the design of complex mixed-signal SoC products. This is exacerbated for automotive safety critical SoC products with a high number of analogue interfaces (sensors and actuators) to the physical components such as an airbag SoC chipset. Generally, it is widely accepted that verification accounts for around 70% of the total SoC development. Since integration of HW and SW is the most crucial step in embedded system development, the sooner it is done, the sooner verification can begin. As such, any approaches which could allow verification and integration of HW/SW to be deployed earlier in the development process and help to decrease verification effort, (e.g.: accelerate verification runs) are of extreme interest.

In the automotive industry, FMEA occurrence ranking is made to a standard such as SAE J1739. The SAE J1739 standard, as does other comparative standards, provides numerical probability criteria to aid ranking. Problems arise when the part or system under analysis is new, and there is no field data to estimate the probability of failure occurrence. Attempts to use qualitative verbal criteria or to go by the “feel” often result in inconsistency or large variability across and within FMEA projects. This paper presents a case study in which this problem was solved by the development of a tool that enables consistent - and efficient - FMEA occurrence rankings. The tool takes input from the user in the form of multiple-choice answers and calculates the final solution.

The ISO TC22/SWG2 - Brake Lining Committee established a task force to determine and analyze root causes for variability during dynamometer brake performance testing. SAE paper 2010-01-1697 “Brake Dynamometer Test Variability - Analysis of Root Causes” [1] presents the findings from the phases 1 and 2 of the “Test Variability Project.” The task force was created to address the issue of test variability and to establish possible ways to improve test-to-test and lab-to-lab correlation. This paper presents the findings from phase 3 of this effort-description of factors influencing test variability based on DOE study. This phase concentrated on both qualitative and quantitative description of the factors influencing friction coefficient measurements during dynamometer testing.

Two methods are allowed in ISO 26262-5 for hardware analysis of random hardware failures. The 1st method is called “Evaluation of Probabilistic Metric for random Hardware Failures”. The 2nd method is called “Evaluation of each cause of safety goal violation”. Advantages of the 2nd method during development of ASIL D Generation 3 Electric Power Steering are presented in this paper. A reliability analysis is one of the important prerequisite for the hardware analysis and this paper shows the best practice for hardware part failure rate estimation using industry standards such as IEC TR 62380. The equally important focus is on a diagnostic coverage of each safety mechanism with respect to residual faults and with respect to relevant dual/latent point faults because any safety design can either benefit from low failure rates or from high diagnostic coverage of safety mechanism to mitigate faults. FMEA is highly recommended by ISO 26262-5 as a part of hardware analysis.

While much research has focused on improving terrain mobility, energy and fuel efficiency of terrain trucks, only a limited amount of investigation has gone into analysis of power distribution between the driving wheels. Distribution of power among the driving wheels has been shown to have a significant effect on vehicle operating characteristics for a given set of operating conditions and total power supplied to the wheels. Wheel power distribution is largely a function of the design of the driveline power dividing units (PDUs). In this paper, 6×6/6×4 terrain truck models are analyzed with the focus on various combinations of PDUs and suspension systems. While these models were found to have some common features, they demonstrate several different approaches to driveline system design.

Electrically Powered Hydraulic Steering (EPHS) was developed in the early 90s and previously applied to vehicle segments B and C (small and medium-sized passenger cars). Till now more than 10 million vehicles are in the field. The advantages consist of the well known power density coming along with the flexible package. Value is added due to the consequent development and usage of electronic control realized in compact physical units. As a result key features for chassis control systems like controllability, high dynamic performance, and low energy consumption are achieved while maintaining mature and robust hydraulic components. Recent market requirements in other segments, e.g. Sport Utility Vehicles (SUV) and Light Commercial Vehicles (LCV) require higher powered motor pump units and lead to the decision to develop products in this direction.

A new system reliability allocation methodology was applied on a steering product. The methodology makes use of design failure modes and effects analysis (DFMEA) and allows the allocation percentages to reflect differences in the criticality levels of the subsystems or components. The methodology was applied in conjunction with system reliability target setting. The paper first explores existing reliability allocation methods. It then introduces the new methodology. Finally, a real-life case is presented to show how the methodology was adopted and how and why it was modified. The approach presented here is one more way to make full use of the analytical efforts that have gone into the DFMEA.

This paper reports the progress that has been made to date on a research program that has as its focus to describe the mechanism of metal pick-up generation on passenger car disc brake pads in correlation with deep rotor scoring. In contrast to other existing generation theories, the new investigation considers other aspects of the initial onset of the metal pick-up.

One of the most important means used for suppressing squeal noise in disc brakes is the application of shims on the pad backplates. In many cases this proves a very efficient tool depending on the type of shim applied in the specific cases. Building up knowledge on the effects of shims have been ongoing for several years, and measuring the important parameters characterizing the shims is crucial for understanding how to develop and implement the shims in an optimal way. Several methods are described in literature for measuring the constrained layer damping effect and one method is described for direct measurement of the shear stiffness and shear damping properties. However, up to now no method has been available that can measure and characterize the normal stiffness and damping properties of shims. This is one of the most important properties of shims as it controls the de-coupling effect in the direction of the normal forces.

Customers of new vehicles expect their vehicle to provide reliable operation. One path vehicle manufacturers have chosen to meet this expectation is to offer their customers advanced braking systems. Antilock Brakes (ABS) and Traction Control (TC) are two advanced braking systems that have evolved to a point at which many OEM's offer them as standard equipment. Size, weight, and performance have also improved to the point of near transparent operation in many cases. The current direction of braking system evolution is in making Vehicle Stability Control (VSC) widely available as well. VSC adds the ability to assist the driver in negotiating understeer and oversteer, by adding corrective braking and engine torque to the vehicle as appropriate. A large percentage of VSC system modeling is related to the sensors chosen to provide driver and vehicle dynamic information to the system's electronic control unit (ECU).

The continuous decrease in background noise levels inside vehicles has made other noise sources easily noticeable. Specifically, foundation brake rattle noise is a growing concern to the customer. This brake rattle is primarily due to rigid body impact between brake components. Currently, vehicle and brake manufacturing companies use different testing procedures to evaluate brake rattle that include laboratory vibration shakers, full vehicle shakers (four post), chassis dynamometers and vehicle road testing. These evaluations are subjective in most cases. A method is needed to replicate and quantify vehicle brake rattle in the laboratory to help determine the acceptability of a brake system at a component level. This approach would also help to identify the root cause for brake rattle and evaluate design changes to address that rattle. Some guidelines for better quantifying brake rattle using shakers will be proposed in this paper.

This paper reviews the state of the art of CAE simulation and analysis methods on disc brake squeal. It covers complex modes analysis, transient analysis, parametrical analysis, and operational simulation. The advantages and limitations of each analysis method are discussed. This review can help analysts to choose right methods and decide new lines of method development. For completeness, analytic methods dealing with continuum models are also briefly covered. This review was made from those papers that the authors are familiar with. It is not meant to be all-inclusive even though the best possible effort has been attempted.

It is always a challenging task for the braking industry to maintain consistent friction material behavior during brake system development. Lack of consistency in friction behavior causes significant disruptions in efforts to integrate friction material with the foundation brake system. This is especially true when new friction formulations and/or manufacturing processes are introduced during an application program. Furthermore, every new program has new requirements that introduce new challenges and issues to the brake and friction manufacturers. As issues arise during the Application development, engineers devise countermeasures that often entail new engineering techniques and methods. Sometimes, such countermeasures amount to inventions to cover the inadequacy of lining behavior during brake integration.

Recently, during the course of different experimental problem-solving activities on automotive vehicles, several examples have been found in which the identification of the cause of a particular vibration problem related to a specific component or subsystem involves detecting the presence of an impulsive effect on measured time signals. The difficulty in identifying such an effect arises due to the fact that the vibrational response signals measured during operation are dominated by relatively high amplitude harmonics which tend to mask the impulsive component. This article describes two case studies for this type of identification problem, a servo-assisted steering system and a front suspension shock absorber strut.

The noise problem in a multiple-piston hydraulic pump was investigated through computer simulation combining lumped and distributed parameter models (CFD). Analysis results have shown that the source of noise is the turbulence flow and pressure perturbation in the pump gallery caused by check valve flow interference. It was identified that this flow induced noise can be reduced by modifying the check valve characteristic and its flow profile without compromising pump performance.

Interaction of the human arm and deploying airbag has been studied in the laboratory using post mortem human subjects (PMHS). These studies have shown how arm position on the steering wheel and proximity to the airbag prior to deployment can influence the risk of forearm bone fractures. Most of these studies used older driver airbag modules that have been supplanted by advanced airbag technology. In addition, new numerical human body models have been developed to complement, and possibly replace, the human testing needed to evaluate new airbag technology. The objective of this study is to use a finite element-based numerical (MADYMO) model, representing the human arm, to evaluate the effects of advanced driver airbag parameters on the injury potential to the bones of the forearm. The paper shows how the model is correlated to Average Distal Forearm Speed (ADFS) and arm kinematics from two PMHS tests.

This paper reports the progress that has been made to date on a research program that has as its focus extracting the full spectrum of friction material performance. In contrast to existing friction test specifications, the new program considers the rise of coefficient of friction at each application by using a statistical evaluation. The statistical evaluation allows also a batch to batch control by monitoring statistical values.

Today's newer friction materials and brake systems are able to operate under extreme conditions that are not normally evaluated with the standard squeal rig procedures. This could cause some discrepancy between the squeal rig test results and the vehicle test results like Los Angeles City Traffic Test (LACT). In some cases the noise behavior of brake systems could change dramatically and take us by surprise with new squeal frequencies being uncovered or get flagged due to high occurrences. This discrepancy could also be a major handicap with respect to developing a noise fix in the lab if the squeal cannot be reproduced. In this paper, we evaluated some case studies where some extreme conditionings especially related to thermal inputs drastically changed the squeal behavior of the brake system.

Steer-By-Wire will be the steering technology of the future. The mechanical connection between the hand wheel and the front axle will become obsolete. Independent electronically controlled actuators will set the road wheel steering angles and will provide force feedback to the driver. This paper presents the approach to establish a production intended steer-by-wire solution in two steps. In a first step a fail safe steer-by-wire system with a mechanical backup is developed which meets the functional and performance requirements of today's passenger vehicles. In the second step this concept is expanded to a future fault tolerant system architecture without any mechanical backup.

The paper focuses on various important decisions of verification and testing plans of the product during its design and production stages. In most of the product and process development projects, decisions on verification and testing are ad-hoc or based on traditions. Such decisions never guarantee the performance of the product as planned, during its whole life cycle. We propose an analytical approach to provide the concrete base for such crucial decisions of verification planning. Accordingly, a mathematical model is presented. Also, a case study of an automotive Electro-mechanical product is included to illustrate the application of the model.