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					Headrest Whiplash
    Reducer

             Bo Huang
          Danish Nagda
    CREATION OF WHIPLASH




 Initial Head-     Completely         Completely
Neck Position        Forward           Backward
before vehicle   Extended Head-     Extended Head-
   collision      Neck Position      Neck Position
                 during collision   during collision
           BACKGROUND
           INFORMATION
 Causes of Whiplash
 Parts of the body affected
 Prevention measures already in place
 The Long Term effects
   Allergy
   Breathing, Digestive, and Cardiovascular
    Disorders
   Hypertension, and Low Back Pain
BACKGROUND STATISTICS

 Case-control study of 700+ people
 with neck injuries
   Examined attribution of MVC to chronic
    neck pain
      45% attributed neck injury to whiplash
BACKGROUND STATISTICS

 Study of 1,133 random people in Quebec
   Determined number of neck injuries due to
    MVC
      15.9% reported history of neck injury from MVC
   Associated illness with history of MVC
      Disabling neck pain – 9.9 % MVC, 3.9 % no MVC
      Headaches – 33 % MVC, 15.2 % no MVC
      Depression – 32.8 % MVC, 19.3 % no MVC
    Problem Statement:

It is possible to reduce the level of neck
    injury in a Motor Vehicle Accident by
        varying different parameters.
              Parameters
 Distance between Neck Headrest
 Speed of forward and backward
  movement
 Height of headrest
 Seat angle
 Velocity of Car
       RANGE OF MOTION
 Minimize backward motion of the
  head/neck
 Direct correlation between range of motion
  and whiplash
 Movement of headrest to reduce range of
  motion
 Movement of headrest determined by IR
  sensor
            Flexible design
 Accounts for adult male or female
 Passengers as well as driver
 Different Vehicle Types can utilize this
  system
             CIRCUIT LAYOUT
 Many different designs were tried and
  implemented for this project
     Ultrasound with FPGA, buffer circuit
     IR with FPGA, PICC, low-pass filter circuit
     IR with FPGA, A/D converter, low-pass filter
     IR with FPGA, Comparator, low-pass filter
        POSSIBLE DESIGNS
Ultrasound with FPGA, buffer circuit
 Disadvantages
   The output from the ultrasound sensor was
      Variable according to surface of object
      Greatly affected by movement
      Bad-input range – 24V
      Detecting distance inaccurate
         POSSIBLE DESIGNS
IR with FPGA, PICC, low-pass filter circuit
 Disadvantages
   The PICC was to be used for a/d conversion and
    pre-processing
      Very inaccurate results when comparing the two signals
       digitally
         POSSIBLE DESIGNS
IR with FPGA, PICC, low-pass filter circuit
 Disadvantages
   The PICC was to be used for a/d conversion and
    pre-processing
      Very inaccurate results when comparing the two signals
       digitally
        POSSIBLE DESIGNS
IR with FPGA, A/D converter, low-pass filter
  Disadvantages
   A/D converter logic was too complex for our
    project needs
   FPGA would have to have a complicated state
    machine
            FINAL DESIGN
IR with FPGA, Comparator, low-pass filter
 Advantages
   IR output is stable and variable with distance
   Comparator allows for easy analog threshold
    comparison
   Motor input is clear and accurate
            EQUIPMENT

 Infrared Sensor
 Microprocessor
 Low-Voltage Stepper Motor
 Stepper Motor Driver
      INFRARED SENSOR

 Utilized to detect the
  distance between the
  headrest and head
 Variable output voltage
    inversely proportional to
     distance
    Range: 2-3V
 Distance range
    4 - 30 cm
       INFRARED SENSOR
 ADVANTAGES
  Less influence on the color of reflective
   objects – Works for all surfaces
  Distance output type – Analog
  Detecting Distance – 4 to 30 cm
  External control circuit was unnecessary
  Steady, controlled output
           COMPARATOR

 Comparator compares the sensor input
  to a controlled threshold value
   Takes in variable
    sensor input
   Compares it to
    threshold value set
    through testing
   Outputs a digital high
    when the value is
    larger than threshold
         MICROPROCESSOR
 FPGA XSA-100 was used to run the motor
 with digital input
     System is triggered
     Input comparator data
     Digital input is processed
     Motor is sent an impulse to turn 7 ½ degrees
      per negative edge trigger
LOW-VOLTAGE Stepper MOTOR
     LOW-VOLTAGE STEPPER
           MOTOR
 Unipolar Stepper Motor (PF55-48C5) by
  Alltronics
 12VDC, 7.5 Degrees per step, 48
  steps/revolution, single phase, two phase,
  or half-step
 Ran in two phase mode in our project
   Best compromise of startup torque and
    maximum speed.
       Motor Driver




 Each “step” energizes different
  windings to advance the motor
 Allows precise control over both
  motor Speed and Total
  Rotations
SYSTEM OUTLINE
 Trigger Point


               Deceleration

Acceleration         Trigger point
                ANALYSIS
 Rise time is critical to the functionality of
  the system.
 Stepper motor used: ~100 ns rise time
 Torque decreases as speed increases
 To achieve our torque requirements, max
  motor speed was only 3 turns/sec
  (9cm/sec)
         IMPROVEMENTS
 Inputs in more than one axis
 Flexible Headrest
 Connected to Accelerometer in the car
 More powerful motor
 More efficient mechanical power transfer
            Improvements
 Real vs. Miniature
 Real-life testing
 Using Ultrasound Sensor
 Design taking into account air bags
 Pressure sensor on headrest
               Conclusion
 A variation of this type of system is the
  future in whiplash injury prevention. Our
  system was a much simplified model and
  took in a lot less inputs in comparison to
  an a real-life model

				
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posted:12/11/2008
language:English
pages:30