The document discusses various vehicle safety systems, categorizing them into active safety measures like collision avoidance and passive safety measures like airbags and seat belts. It details braking mechanisms, including hydraulic brakes, anti-lock brakes, and the functioning of electronic stability control for improved vehicle control. Additionally, advanced safety systems such as adaptive cruise control and collision avoidance technologies are explored, emphasizing their roles in enhancing driver safety and vehicle performance.

1. Vehicle safety systems
Done by,
J.Karthickraja-15E117,
S.Praveenkumar-15E137,
Ranjithkumar-15E143.

2. Safety domain
• Active-letting off a warning before a crash
• Active safety refers to avoiding or minimizing an accident and
systems such as braking systems, ABS, TCS, ESP,lane keeping, etc.
• Adaptive cruise control and collision warning/avoidance systems that
contribute to the concept of advanced driver assistance.
• Passive Safety
• acting after a crash- Seat belts and airbags
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3. BRAKES
• For slowing and stopping the vehicle.
• Most of the kinetic energy of the car is dissipated by the brakes
during deceleration and stopping
• Drum brake
• Disk brakes
• Hand brake.
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4. Typical hydraulic brake
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5. Master cylinder
• It has the main purpose of transferring and amplifying the force input
from the brake pedal to the individual wheels
• Since the force transmission from the brake pedal to the wheels has
to take place with the shortest amount of delay possible, the brake
fluid used is incompressible.
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6. Proportioning valves
• During braking a vehicle undergoes a shift in dynamic load from rear
to front. Thus in a straight line deceleration the front wheels will
experience a higher normal force while the rear wheels will
experience an equal reduction in the normal force.
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7. Disc brakes VS Drum brake
• There are two basic types of disc brakes: fixed caliper and floating
caliper.
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8. Anti-lock brakes-need?
• Under poor braking conditions (e.g., wet or slippy roads), if one or
more of the vehicle wheels locks (begins to skid), and results in a
number of consequences.
• Braking distance increases.
• Steering control is lost.
• Abnormal tyre wear.
• The obvious result is that an accident is far more likely to occur.
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9. Units
• Wheel-speed sensors: It detects the speed of rotation of the wheels
and pass the electrical signals to the control unit.
• Electronic control unit(control algorithms): It regulates braking force
to an optimum for any given low-friction condition. The results of
these calculations form the basis for the triggering signals sent to the
hydraulic modulator.
• Hydraulic modulator: The hydraulic modulator incorporates a series of
solenoid valves that can open or close the hydraulic circuits between
the master cylinder and the wheel-brake cylinders.
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10. Antilock brake system (ABS)
• pressure build-up
• maintain pressure
• pressure release
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11. Hand brake
• The parking or hand brake is a lever mechanism that is applied to hold
a vehicle in a parked position.
• The emergency brake cable runs directly to the brake shoes,
Bypassing the hydraulic brake system.
• When activated the brake shoe is firmly pushed towards the brake
drum or disc, thereby holding the wheels.
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12. Electronic stability control
• ESC intervenes only when it detects a probable loss of steering
control, i.e. when the vehicle is not going where the driver is steering
• ABS and Traction Control only work in the driving (longitudinal)
direction. ESC can help drivers to cope with sideways (lateral)
movements which create instability using them.
• Unlike ABS and TCS, ESC is a holistic system that can control a car’s
entire movements far better than human capability.
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14. Working
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15. Scenario
• Spin control is achieved by, introducing a correlation between the
steering angle, individual wheel speed, and engine power to optimize
trajectory control in bends.
• To avoid understeering and oversteering by applying the brakes to
individual wheels asymmetrically in order to create torque about the
vehicle's vertical axis, opposing the skid and bringing the vehicle back
in line with the driver's commanded direction.
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 inner rear wheel to counter
understeer,
 the outer front wheel during
oversteer

16. AIRBAG
• An airbag is a type of vehicle safety device. Used in combination with
seat-belt pre-tensioners and other safety systems
• This will restrain the body if the driver or passenger is endangered by
a severe impact to the front of the vehicle.
• If an impact whose magnitude exceeding the preset value is applied
to the vehicle, the airbags inflate immediately to prevent the driver
and front seat passenger being hit.
• inflates fully at speeds > 320mph within 0.05s of crash.
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17. DRIVER’S SEAT AIRBAG MODULE
• The driver’s seat airbag module assembly consists of an
inflator(igniters and gas generating agents in a metal container) and
airbag, and a steering wheel pad.
• The inflator outputs power suitable for the severity of collision
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18. Actual Working
Airbag Before Collision Airbag After Collision

19. Seat belt pre-tensioner
• The seat belt pre-tensioner improves efficiency of body restraint
by retracting the seat belt immediately if the driver or passenger is
endangered. The airbag control module controls the operation of
the seat belt pre-tensioner.
• When sensors detect the abrupt deceleration of an accident the
piston is driven. This in turn, rapidly drives the spool around which
the fabric strap of a seatbelt is wrapped.
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20. Belt pre-tensioners
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Once the seat belt pre-tensioner
has been activated, the seat belt
retractor remains locked.

21. Advanced safety systems
• Cruise control
• ACC
• Lane detection
• Collision Avoidance & Crash detection
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22. Cruise control
• Maintain a speed as set by the driver.
• For example, a car entering a long, relatively steep downgrade may
accelerate due to gravity even with the throttle closed.
• When the driver wants to go faster than the cruising speed for a short
time, he can override the system by pushing the accelerator pedal.
This overdrive phase will end when the driver releases his foot from
the pedal.
• The driver can also at any time take over the system by pushing the
brake pedal.The system is then deactivated.
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23. ACC
• Maintain a speed as set by the driver.
• Adapt this speed and maintain a safe distance from the vehicles in
front. Provide a warning if there is a risk of collision.
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24. ACC
• For cars equipped with a conventional cruise control system, the
driver has to apply braking to hold speed.
• The ACC controller regulates the throttle (as explained above for a
conventional cruise control) as well as the brake system via electrical
output signals and in response to inputs, including the vehicle speed
sensor and set cruise speed switch
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25. Collision Avoidance Radar Warning System
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• Detection of vehicles in front of the equipped car,
and distance regulation with the relevant targets.

26. References
• Bosh automotive electrics and automotive electronics by various
authors
• Intelligent vehicle technologies - theory and applications by Ljubo
vlacic
• Automobile electrical and electronics systems by Tom Denton
• Understanding automotive electronics by William Ribbens
• Automotive embedded systems hand book by Nicholas Navet

27. END OF SLIDE SHOW
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