Collision Mitigation break system (CMS)

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Collision Mitigation break system (CMS)

• What is CMS?
• How it works
• System Configuration
• Warning Devices
• Collision Avoidance Maneuvers
• Conclusions

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References

• Honda Motor Science Education. Trends in Japan
  2003
• Autoweb.com.au Honda Develops New Collision
  Avoidance Safety System. 2003
• Francois Granet, Rosella Picado, Lauren Smith
  Longitudinal Avoidance. 2003

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What is CMS?

• CMS is the world's first Collision Mitigation
  Brake System (CMS). The technology predicts
  rear-end collisions and assists brake operation
  to reduce the impact.
• CMS anticipates a collision based on driving
  conditions, distance to the vehicle ahead and
  relative speeds. It then uses visual and audio
  warnings to prompt the driver to take
  preventative action and also initiates braking if
  the driver fails to respond to the warnings.

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How it Works?

• First, the radar measures the distance between
  the car and other vehicles up to 100 meters ahead
  and any differences in speed, and an onboard
  computer judges the risk of a collision based on
  this information and on data about the course of
  the car.
• Then if the system judges that there is a risk of
  a crash, such as when the car gets too close to
  the vehicle in front, it alerts the driver by
  sounding an alarm and lighting up a BRAKE
  warning on the dashboard. This is the first
  warning stage, aimed at alerting the driver to
  the danger and encouraging the driver to slow
  down.

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• The system works in conjunction with the
  "E-Pretensioner" seatbelt retraction system. If
  the car continues to get closer to the other
  vehicle and the computer decides that it will be
  hard to avoid a collision, it tightens the
  seatbelt more firmly and applies the brakes
  forcibly and hard.
• The CMS has three staged modes
• An audible warning,
• An audible warning, light braking and light
  seat-belt retraction.
• An audible warning, strong braking and strong
  seat-belt retraction.

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CMS configuration

• Millimeter-wave radar Detects vehicles within a
  range of about 100 meters ahead, in a 16-degree
  arc.
• Sensors The system determines driving conditions
  using a range of sensors that detect factors such
  as yaw rate, steering angle, wheel speed, and
  brake pressure.
• CMS Electronic Control Unit (ECU) Based on
  distance to the vehicle ahead and relative speed
  obtained from radar information, the ECU
  calculates the likelihood of a collision, and
  warns the driver, and in some cases activates the
  braking function.

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• E-Pretensioner ECU Sends instructions to the
  motorized E-Pretensioner to retract the seatbelt,
  based on braking instruction signals from the CMS
  ECU and electronically controlled brake assist
  signals.
• E-Pretensioner Retracts the seatbelt using an
  internal motor, based on instructions from the
  E-Pretensioner ECU. Used in combination with
  conventional pretensioners.
• Meter unit Receives signals from the CMS ECU,
  and warns the driver of potential danger using a
  buzzer and a visual warning.

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Figure Autoweb.com.au, CAS 2003
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CMS Warning Devices

• Visual head-up displays warnings are displayed
  on the windshield in the driver's field of view.
• Audio/Voice signals auditory signals appear to
  be less intrusive on driving tasks.

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CMS Collision Avoidance Maneuvers

• Headway distance control the system warns the
  driver whenever his/her car is following the
  leading car too closely
• Hazard warning the system warns the driver of an
  object within its projected path, so that the
  driver has sufficient time to avoid a crash.
• Automatic vehicle control the system controls
  the vehicle's brakes and steering wheel

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Precise breaks Actuator Systems depend a lot on
sensors

• Sensors fulfill the tasks of headway control and
  obstacle detection, which are the basis of
  Collision Avoidance Systems (CAS) Sensing.

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Indicators

• Sensing range the maximum range over which the
  technique can be used 
• Resolution the relative change in distance that
  can be measured 
• Directionality the width of the beam over which
  the sensor is sensitive 
• Response time how quickly the sensor can respond
  to a change in distance 

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Conclusion

• Automatic braking systems can detect an obstacle
  and bring the car to a complete halt just before
  impact. The technology has reached the level
  where the systems can even detect the speed of a
  vehicle in front, compare it with the speed of
  the user's car, and stop the car to avoid an
  accident. Honda and Toyota are applying and
  testing these Automatic braking systems nowadays
  and will continue improving this type of
  technology.