TRB Special Report 308: The Safety Challenge and Promise of Automotive Electronics Insights from Unintended Acceleration (2012) / Chapter Skim
Currently Skimming:
1 Background and Charge
1 Background and Charge
Pages 23-42
The Chapter Skim interface presents what we've algorithmically identified as the most significant single chunk of text within every page in the chapter.
Select key terms on the right to highlight them within pages of the chapter.
From page 23... ...
While NHTSA has investigated complaints of unintended acceleration for many decades, an unusually large number of such complaints have been made in recent years, particularly by owners of Toyota vehicles.1 Many complaints have involved high-power acceleration, which NHTSA's investigators concluded was attributable to drivers applying the accelerator pedal by mistake and to certain other mechanical causes, including sticking pedal assemblies and pedals becoming obstructed or entrapped.2 Pedal misapplication, entrapment, and sticking have often been identified by NHTSA as causes of unintended acceleration, along with various other mechanical causes such as throttle icing and damage to the physical linkages between the pedal and throttle assemblies.3 However, the proliferation of electronics systems, and particularly the introduction of 1 According to data presented to the committee by NHTSA, about 35 percent of the complaints it received between 2004 and 2010 alleging unintended acceleration were by drivers of Toyota vehicles. Presentation by Daniel C
|
From page 24... ...
In subsequent recalls, Toyota reshaped the accelerator pedal to make it less prone to floor mat interference and to install software that causes brake application to override the throttle on vehicles equipped with pushbutton ignition systems. The latter step was taken as evidence emerged that some drivers were unfamiliar with how to turn off the engine by holding down the start–stop button during an emergency while the vehicle is in motion.5 Even as these multiple recalls proceeded, questions persisted about the adequacy of Toyota's remedies and whether its ETC technology was to blame, particularly after media reports of more cases of Toyota vehicles exhibiting unintended acceleration, some involving fatalities.6,7 ETCs were mass introduced beginning about 10 years ago.
|
From page 25... ...
In NHTSA's view, cases in which alleged immediate and profound brake loss could not be explained were consistent with pedal misapplication. The latter cases of unintended acceleration involving degraded braking capacity were believed to be caused by pedal entrapment, pedal sticking, and other identifiable mechanical problems.
|
From page 26... ...
The committee's task was to inform a broader examination of the safety assurance challenges arising from the proliferation and growing complexity of automotive electronics and their implications for NHTSA's vehicle safety programs. In performing its task, the committee was to consider the pending results of the ODI and NASA investigations as well as the results of past NHTSA investigations.
|
From page 27... ...
The first category covers vehicle capabilities essential to preventing a crash, such as minimum capabilities for braking, visibility, and 9 More details on the laws establishing NHTSA and its vehicle safety mission are given in Chapter 4. 10 The FMVSSs, along with other NHTSA regulations, are incorporated into Chapter 5 of Title 49, Code of Federal Regulations.
|
From page 28... ...
The third specifies requirements for maintaining vehicle integrity after a crash has occurred, such as fire resistance. NHTSA sets and enforces several other standards that are not contained within these three categories of FMVSSs, such as requirements for vehicles equipped with event data recorders and mandated reporting to NHTSA of certain safety-related data.
|
From page 29... ...
NHTSA officials explained to the committee that its neutrality with respect to the technologies used by manufacturers to meet the FMVSSs does not mean that the agency can afford to neglect technological developments taking place in the automotive sector. Accordingly, NHTSA's Office of Vehicle Safety Research is charged with keeping abreast of existing and emerging technologies that may create safety assurance challenges or that may provide opportunities to make driving safer.
|
From page 30... ...
ODI analysts regularly screen and analyze consumer complaints to detect vehicle behaviors and conditions indicative of defects or other vehicle-related problems that present a safety concern.17 Such concerns may prompt ODI to investigate further by examining more complaints, reviewing warranty repair records submitted by manufacturers, inspecting and testing vehicles and their parts, interviewing drivers and repair technicians, and consulting with and seeking more detailed information from manufacturers.18 When a deeper investigation of a suspect problem establishes that a vehicle safety deficiency exists and is sufficient in magnitude and scope to pose an unreasonable safety risk, ODI has authority to compel the manufacturer to issue a product recall. In practice, most recalls are initiated by the manufacturer before ODI even opens an investigation, and nearly all are initiated without ODI having to take an enforcement action.19 eARlieR NHTSA iNiTiATiveS oN uNiNTeNded AcceleRATioN The committee learned that ODI has fielded and investigated driver reports of unintended acceleration for more than 40 years.20 More than three dozen investigations of such concerns were conducted by ODI during the 1980s alone, resulting in a number of manufacturer recalls (Pollard and Sussman 1989)
|
From page 31... ...
However, in testing the Audi 5000, TSC investigators found that some versions of the vehicle had an electronically controlled idle stabilizer prone to defects that could intermittently cause high engine idling and unexpected increases in engine power, which the investigators characterized as "surging."24 The idle stabilizer was composed of an electronic control unit and an 21 From 1978 to 1987, Audi's complaint rate for unintended acceleration was 586 per 100,000 vehicles in the fleet. 22 The November 1986 broadcast of "Out of Control" by the CBS news program 60 Minutes interviewed individuals who had allegedly experienced sudden acceleration by Audi vehicles and were suing the importer (Volkswagen)
|
From page 32... ...
On the basis of the measurements taken, the control unit selected the appropriate engine idle RPM. 26 The TSC investigators were not the first to associate pedal misapplication with unintended accelera tion, although the TSC work provided a clearer model for how to identify such cases.
|
From page 33... ...
However, one conclusion of the TSC investigators remains relevant: sudden acceleration commencing in a vehicle that had been stationary or moving slowly should be controllable by brake application. Referring to testing that showed the stopping effectiveness of brakes and their independence from the throttle,27 the TSC investigators could not offer a credible explanation, apart from pedal misapplication, for how drivers claiming to have applied the brakes promptly would not have been able to stop a vehicle during the onset of acceleration or how the alleged complete brake failure would not be accompanied by physical evidence of a malfunction.
|
From page 34... ...
For example, ODI reported to the committee that a number of complaints by drivers of Toyota vehicles alleging unintended acceleration involved a loss of braking capacity after a prolonged effort by the driver to slow the vehicle through brake application.30 According to ODI, these complaints stood out from the more common complaints alleging the simultaneous occurrence of high-power acceleration and complete brake loss.31 Further investigation of these complaints led ODI to conclude that their cause was not pedal misapplication, but rather entrapment of the accelerator pedal by the floor mat.32 NHTSA requested that this committee assess the continued relevance of the Silver Book in identifying and investigating incidents involving unintended acceleration. Such an assessment is offered in this report, but not for every aspect of the Silver Book's investigations.
|
From page 35... ...
Thus, this is the aspect of the Silver Book that was examined by the committee for continued relevance. THe RevoluTioN iN AuTomoTive elecTRoNicS The 1980s-era vehicles discussed in the Silver Book were not devoid of electronics, but the state of technology marked the beginning of the electronics revolution that is now well under way.
|
From page 36... ...
According to this model, OEMs retained responsibility for overall vehicle design and assembly but depended on specialized suppliers for the development and engineering of the many individual vehicle components and subsystems. Suppliers were thus able to specialize in production and achieve scale economies by selling their electronics systems to multiple manufacturers, and the need for OEMs to invest in increasingly specialized and fast-changing areas such as electronics design and manufacturing was reduced.
|
From page 37... ...
How automotive manufacturers are meeting these safety assurance challenges is discussed in this report. STudy GoAlS ANd RepoRT oRGANizATioN The full charge to the committee is contained in the statement of task in Box 1-1.
|
From page 38... ...
In accordance, the study committee shall: A Conduct a broad review and assessment of electronic vehicle controls, systems, and UA across the industry and safeguards used by manufacturers and suppliers to ensure safety.
|
From page 39... ...
The study committee shall review the 1989 "Silver Book" to analyze its continued relevance with respect to technologies, possible defects, and failure modes associated with UA. The committee shall report on the current understanding of pos sible causes of UA and how the increasing prevalence of electronic throttle controls, other electronic vehicle control systems (e.g.
|
From page 40... ...
The committee does not know all of NHTSA's safety priorities and their associated resource requirements. The report therefore offers suggestions on relevant research topics and recommends a means by which NHTSA can make more strategic choices with regard to allocating its resources to meet the safety oversight challenges arising from automotive electronics.
|
From page 41... ...
RefeReNceS Abbreviations NHTSA National Highway Traffic Safety Administration NTSB National Transportation Safety Board Bereisa, J
|
From page 42... ...
1988. Study of Mechanical and Driver-Related Systems of the Audi 5000 Capable of Producing Uncon trolled Sudden Acceleration Incidents.
|
Key Terms
This material may be derived from roughly machine-read images, and so is provided only to facilitate research.
More
information on Chapter Skim is available.