Embedded Computers in Automobiles

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Embedded Computers in Automobiles
Sunggu Lee Electrical Engineering
Department Pohang Univ. Science
Technology June 4, 2008
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Embedded Computers in Automobiles

• While automobile production is likely to increase
  slowly in the coming years, the embedded
  electronics component (of total automobile cost)
  is expected to growing Navet 2006
• Cost of electronic systems was 37 billion in
  1995 and 60 billion in 2000 (annual growth rate
  of 10)
• In 2006, electronic embedded systems represented
  25 of the total cost of a car (and more than 35
  in high-end models)
• Typical modern automobile contains 20-50 Embedded
  Control Units (ECUs)

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Automotive Embedded Intelligence Wallentowitz
2008

• Embedded System
• A special-purpose computer system designed to
  perform one or a few dedicated functions
• Constraints minimal cost, minimal required
  space, minimal use of energy and minimal memory
• Automotive Embedded Intelligence
• Mechanical components have been replaced by
  electric/electronic components
• Mechatronic components enable new functions using
  both hardware and software
• Example individual control of the rotation of
  each of the tires on a car

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Automotive Networks (1/2)

• Controller Area Network (CAN)
• Most widely-used in-vehicle network
• Design by Bosch in early 1980s for multiplexing
  the increasing number of ECUs in a car
• Became an OSI standard in 1994
• Priority-based bus that provides bounded
  communication delay for each message
• Different bounds for each priority level
• MAC protocol of CAN uses CSMA
• Uses NRZ (non-return-to-zero) coding
• A maximum of 1 Mbps is specified for a CAN bus
  not exceeding 40m
• TTCAN (time-triggered CAN) and high-rate CAN are
  newer versions of CAN

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Automotive Networks (2/2)

• Time-Triggered Protocol (TTP/C)
• Developed at Vienna University of Technology
  commercialized by TTTech
• At the MAC layer, TTP/C implements synchronous
  TDMA
• Has strong emphasis on fault tolerant and
  deterministic real-time features
• Todays available TTP/C C2 chips support data
  rates of up to 25 Mbps in synchronous mode
• Main purpose of this protocol is to support
  X-by-Wire
• FlexRay
• Currently being developed by a consortium of
  major automobile companies
• Main purpose is to support X-by-Wire applications
• At MAC level, FlexRay defines a communication
  cycle as the concatenation of a time-triggered
  window (using TDMA) and an event-triggered window
  (using Flexible TDMA)
• Local Interconnect Network (LIN)
• Low cost serial communication system designed for
  low-cost SAE class A applications (which have a
  lower reliability requirement)

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Software Development Trends

• Model-based development
• Trend in which software is created automatically
  based on a specification of how the software
  should behave
• Unified Modeling Language (UML)
• A lot more emphasis is placed on validation
• Automotive Open System Architecture for
  Automobile Companies (AUTOSAR)
• Based on component modules
• Components communicate through a Virtual
  Functional Bus (VFB)

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Existing Automotive Electronic Systems

• Safety-related systems
• Anti-lock braking system (ABS)
• Electronic stability program (ESP)
• Trace control system (TCS)
• Airbag control sytem
• Drowsiness monitoring system
• Convenience features
• Navigation systems (using GPS modules)
• Cruise control
• Parallel parking systems
• Performance and efficiency features
• Engine fuel injection control
• Etc.

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Systems Under Development

• Active cruise control (ACC)
• Brake-assist (BA)
• Electro-hydraulic brake (EHB)
• Electro-mechanical brake (EMB)
• Cornering-assist
• Intersection-assist
• Electrical power-steering (EPS)
• Automated parking
• Active steering

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Active Cruise Control

• State-of-the-art system in which a safe distance
  is maintained with the car in front
• Already present in a few of the luxury model cars
• Braking occurs in the area of comfortable
  deceleration only. In the future, in critical
  driving situations, severe braking could be
  applied.
• Autonomous railway vehicle
• Feasibility demonstrated by RWTH Aachen
• Applied time gap lt 2s
• Maximal test velocity 80 km/h
• Driverless operation

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Electro-Hydraulic Brake

• Tire footprint increase during braking, reduced
  swell time, wheel individual control of brake
  pressure
• Used to reduce the braking distance while
  stopping the car in a smooth manner
• An alternative is the Electro-Mechanical Brake
  (EMB), which has no hydraulics
• Electronic wedge brake

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Cornering Assist

• Example system Siemens VDO 24 GHz close-up range
  radar sensor system
• Monitors right side of truck
• Warning strategy all objects within distance lt
  2m and all objects that are approaching from the
  rear
• Warnings occur in two stages visually and
  visually/acoustically

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Intersection Assistant with Car to Car
Communication (Using WLAN)

• Collisions at street intersections can be avoided
  with Intersection Assistant
• Cornering and Intersection Assistant
• Radar and laser sensors enable the monitoring of
  surroundings of cars
• Obstacles are identified. Cars can be braked
  automatically
• Intersection Assistant can be realized with
  currently commercially available WLAN. Up to now,
  it is only used in driver assist mode.

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Active Electrical Power Steering, Automated
Parking, Active Steering

• Active electrical power steering
• The steering gear box is controlled by the
  electronics to achieve smoother, more accurate
  steering
• Automated Parking
• BMW Park-Assist uses sensors to detect an empty
  parking and parallel-park the car
• Commonly-used sensor Lidar (light detection and
  ranging technology) laser-based range detection
• Active Steering
• Superposition steering (BMW)

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Steering Systems

• Automated parking and disturbance control (e.g.,
  from side wind) will be the next development
  steps
• To realize the accident-free vehicle, more
  near-field information will be necessary
• After so-called collision avoidance, automated
  driving can be realized
• The next development steps will need to
  concentrate on camera vision

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Automotive Electronics Research (1/2)

• Image processing systems for traffic sign
  identification
• Autonomous driving
• Stanford and Volkswagen America project
• Steering is carried out by a drive-by-wire system
• Controlled by seven Pentium M computers
• Navigation uses GPS, four laser distance sensors,
  a radar system, a stereo camera system and a
  video camera
• It won the 132-mile DARPA Grand Challenge
  Competition. Stanley needed 6 hours 54 minutes
  (average speed more than 19 miles per hour)

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Automotive Electronics Research (2/2)

• Convoy-driving with 10m distance
• Electronic coupling of 2 or more trucks
• Fuel reduction of the convoy by slipstream
  driving
• Reduction of traffic space
• Relaxed driving in the vehicles following the
  lead vehicle
• Vehicle-to-vehicle communication
• For emergency situations (e.g., stopped cars),
  lane changes, intersections
• Infrastructure-based extended driver-assistance
  systems

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Summary

• Without embedded intelligence, the car would
  never have become so functional, safe and
  energy-efficient
• Challenge control of the complexity
• Several projects to develop driver-assistance
  systems have been started
• The development occurs in cooperation with
  industry and research institutions
• Activities provide a basis for technology-developm
  ent and, at the same time, the improvement of
  driving safety and driving comfort

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References

• Henning Wallentowitz, Now and future prospects
  of intelligent automobiles, Proc. 3rd
  International Symposium on Embedded Technology
  (ISET), Daegu, Institute of Embedded Engineering
  of Korea, pp. 49-90, May 2008.
• Nicolas Navet and Francoise Simonot-Lion,
  Fault-tolerant services for safe in-car embedded
  systems, (pp. 42-1 - 42-15) in Embedded Systems
  Handbook, Ed Richard Zurawski, CRC Press, Boca
  Raton, 2006.