TRB Special Report 308: The Safety Challenge and Promise of Automotive Electronics Insights from Unintended Acceleration (2012) / Chapter Skim
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2 The Electronics-Intensive Automobile
2 The Electronics-Intensive Automobile
Pages 43-70
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From page 43... ...
As discussed in Chapter 1, today's electronics-intensive vehicle is fundamentally different from the mostly mechanical vehicle of the 1970s and 1980s. The electronics in the contemporary automobile contain hundreds of sensors, drive circuits, and actuators that are connected to scores of microprocessors running on increasingly complex software and exchanging information through one or more communications networks (Krüger et al.
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From page 44... ...
(Source: Clemson University Vehicular Electronics Laboratory.)
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From page 45... ...
to adjust headway limits depending on the vehicle's proximity to a highway exit ramp. These systems provide one or more capabilities for the following, among others: • Entertainment, information, and navigation assistance -- radios, satel lite radio, CD and DVD players able to interpret a wide array of data formats, USB and other multimedia ports, Wi-Fi and Internet con nectivity, GPS navigation, travel advisories; • Convenience -- seat and mirror position memory, remote and key less entry and ignition, automatic lights and wipers, embedded and Bluetooth-connected mobile phones; • Comfort and ease of use -- suspension adjustment, brake and steer ing assist, heated and cooled seats, cabin temperature control, inte rior noise and vibration suppression, parking assist, hill hold, mirror and light dimming; • Emissions, energy, and operating performance – Concerted control of fuel flow, air intake, throttle position, and valve timing; cylinder deactivation; transmission control; trac tion and cornering control; tire pressure monitoring; regenera tive braking; – Power train and battery charging control for hybrid and electric drive vehicles;
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From page 46... ...
Communications Networks and Protocols All electronics systems that control vehicle functions consist of a control module containing one or more computer processors. The control module receives input for its computations from a network of sensors (e.g., for engine speed, temperature, and pressure)
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From page 47... ...
The protocols are accompanied by a variety of physical media to provide the required connections among system components on the network, including single wires, twisted wire pairs, fiber-optic cables, and communication over the vehicle's power lines. Many automotive manufacturers are seeking a standard protocol, but none has emerged.
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From page 48... ...
Because a typical vehicle will have a variety of networking speed and capacity needs, it will have multiple networks and will often host different control units and use different protocols and physical media. The networks are often intended to be isolated from one another for various reasons, including bandwidth and integration concerns (e.g., entertainment network isolated from the network containing the engine controller)
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From page 49... ...
; • Inertial sensors, accelerometers, yaw-rate sensors (e.g., stability con trol, air bag deployment, suspension control, noise and vibration suppression) ; • Radar and light detection and ranging (lidar)
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From page 50... ...
For years automakers have been leveraging the power of networked controllers and advances in software development to introduce active safety features, many of which are described below. Between 2,000 and 3,000 individual vehicle functions are estimated to be performed with the aid of software in a premium-class car (Charette 2009)
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From page 51... ...
An exhaust gas oxygen sensor provided a signal to the engine control unit so that it could regulate fuel levels to achieve an even more precise air–fuel mixture. As emissions standards were tightened and electronic fuel injectors were introduced, additional functions were added to the engine controller for such purposes as more precise and consistent spark timing and regulation of the flow of fuel during a cold start.
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From page 52... ...
Brake Power Assistance and Lockup Control Brakes continue to rely fundamentally on hydraulic lines that transmit the pressure at the brake pedal to actuators at the wheels to force the brake pads into contact with a drum or disc on the wheel. The generated friction slows and eventually stops the vehicle.
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From page 53... ...
Power train control in electric Vehicles All electric-drive vehicles require sophisticated power train control to manage power flow from the battery to the motor and from the motor/generator to the battery during regenerative braking and, in the case of parallel hybrids (either HEV or PHEV) , to coordinate the sharing of loads between the engine and the electric motor.
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From page 54... ...
In compari son, EV power train control is simple since there is no concern over emissions and the only processes that need to be controlled are those involving the transmission from the battery to the motor and from regenerative braking back to the battery. Because switching large current either in the charger or in the power electronics for propulsion is done quickly to minimize losses, the potential for transients to be created in wiring harnesses that could cause electromagnetic interference and malfunctioning microprocessors is an area of design concern.
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From page 55... ...
The ABS was introduced widely in the 1980s. A typical system uses an electronic control unit and speed sensors in the wheels.
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From page 56... ...
Electronic traction control systems, which were first introduced in the early 1990s, use the same wheel speed sensors as the ABS to detect wheel spin. These systems reduce the throttle opening and perhaps apply the brake to the spinning wheel to help restore traction.
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From page 57... ...
Electric power steering was introduced in the 1990s, primarily to reduce the amount of energy that had been used by the hydraulic pump and thus to improve vehicle fuel economy.5 The torsion bar modifies compliance to facilitate stability, but an electrical sensor determines the angular displacement. The power assist is provided by an electric motor controlled by a microprocessor.
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From page 58... ...
More recent systems for active lane-keeping use the ESC and electric power steering to assist the driver in maintaining lane position by applying light brake pressure or countersteering forces. Parallel Parking Assistance Some automobile manufacturers have recently introduced systems that automatically control the power train and steering so that the vehicle can parallel park itself.
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From page 59... ...
On the basis of the sensor information, the control unit can calculate the angle of impact and the force of the crash to determine which air bags to deploy and to what degree and activate additional measures such as seat belt pretensioning. Every time a vehicle is started, the air bag control module selfchecks the sensors and the state of the system.
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From page 60... ...
The recorders typically capture a few seconds of vehicle data before a crash, including vehicle speed, accelerator pedal position, throttle position, and brake switch position. The recorded information can be retrieved by investigators through the OBD port to help determine the causes of the crash.
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From page 61... ...
Steer-by-Wire and Brake-by-Wire In steer-by-wire systems, the mechanical link between the steering wheel and the vehicle wheels is removed, and the driver's intent is translated into signals to a motor or motors that turn the wheels. Among possible advantages, steer-by-wire would reduce vehicle weight, eliminate the safety hazard presented by the protruding steering column, offer greater flexibility in designing the car interior, and enable customizable driver interfaces since the steering mechanism could be designed and installed as a modular unit.
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From page 62... ...
Because V2V would require a substantial number of vehicles equipped with transponders and V2I would require intelligent highway infrastructure, the emergence of these systems will depend not only on further technological advances but also on many safety assurance, institutional, and economic factors. Partly and Fully Automated Vehicles In contrast to systems that provide the driver with a warning or assume temporary control over the vehicle in an emergency situation, partial or fully automated systems would provide assistance for routine driving tasks.
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From page 63... ...
Among them are stability control and blind spot, lane-keeping, and headway surveillance. Even after a crash occurs, electronics allow more effective air bag deployment and faster emergency response through automatic emergency responder notification of crash location.
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From page 64... ...
in the event of some unforeseen and potentially unsafe vehicle operating condition is a critical goal for automotive manufacturers. This will remain the case, since software in future vehicles can be expected to become even more complex.
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From page 65... ...
Whether the nature and level of this testing have kept pace with the changing electromagnetic environment and increased safety assurance required for the expanding electronics content in vehicles has not been the subject of extensive research in the public domain. In addition, the effectiveness of controlled network gateways and firewalls is coming into question as a result of recent research and testing.
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From page 66... ...
and those using remote means such as cell phones, other short range wireless devices, and tire pressure monitoring systems. The committee was briefed by the researchers, who described in more detail the many possible means by which an adversary could attack a vehicle in the manner outlined above and the implications for the safe operation of a vehicle.1 In the briefing and published papers cited above, the researchers surmise that automotive manufacturers have designed their networks with
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From page 67... ...
and because of the incremental nature by which these networks have been expanded, interconnected, and opened to external communication channels. Recognizing that high levels of interconnectedness among vehicle control units are necessary for desired functionality, the researchers did not propose the creation of physically isolated networks.
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From page 68... ...
Intelligent vehicle concepts that now appear to be far out on the horizon, such as V2V and V2I, may progress even faster than expected and add further to the safety assurance and oversight challenge. The next chapter discusses how automobile manufacturers are attempting to meet these various safety and cybersecurity challenges through their product design, development, and production processes.
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From page 69... ...
A critical aspect of this challenge is to ensure that the complex software programs managing and integrating these electronics systems perform as expected and avoid unsafe interactions. Another is to ensure that the electronics hardware being embedded throughout the vehicle is compatible with the demanding automotive operating environment, including the electromagnetic environment, which may be changing as electronics devices and accessories are added to automobiles.
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From page 70... ...
1998. Special Report 253: National Automated Highway System Research Program: A Review.
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