The document discusses an anti-lock braking system (ABS) for four-wheel vehicles. It describes ABS as a system that prevents wheels from locking up during braking, allowing the driver to maintain steering control. The key components of ABS are electronic control units, hydraulic modules, wheel speed sensors. ABS works by continuously monitoring wheel speed and adjusting brake pressure to keep wheels rotating just before the point of locking up. This allows for shorter braking distances and maintained vehicle stability and steerability during emergency braking situations.

1. ANTILOCK BRAKING SYSTEM
IN FOUR WHEELER
SUBMITTED BY:
GAJENDRA MEENA
(K10945)
ANTILOCK BRAKING SYSTEM 1

2. INTRODUCTION
• Anti-lock braking system (ABS) is an automobile safety system that allows
the wheels on a motor vehicle to maintain tractive contact with the road surface
according to driver inputs while braking, preventing the wheels from locking up
and avoiding uncontrolled skidding.
• ABS generally offers improved vehicle control and decreases stopping distances
on dry and slippery surfaces.
• ABS modulates the brake line pressure independent of the pedal force, to bring
the wheel speed back to the slip level range that is necessary for optimal
braking performance.
ANTILOCK BRAKING SYSTEM 2

3. PROJECT OUTLINE
• Objectives ofABS
• Components ofABS
• Working ofABS
• Results
• Conclusion
• References
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4. OBJECTIVES OFABS
• To reduce stopping distance
1. The road surface type and conditions can be inferred from the vehicle's
braking pressure, wheel slip measurements, and deceleration rate
comparisons.
2. The wheel slip is regulated so that the road adhesion coefficient is
maximized. By keeping all of the wheels of a vehicle near the maximum
friction coefficient,
force
an antilock system can attain maximum fictional
3. In turn, this strategy leads to the minimization of
distance.
the vehicle stopping
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5. • Stability
1. A locked-up wheel generates a reduced braking force, smaller than the peak
value of the available adhesion between tires and road. A locked-up wheel
will
loss
The
also lose its capability to sustain any lateral force. This may result in the
of vehicle stability.
2. basic purpose of a conventional ABS system is
in
thus to prevent any
wheel from locking and to keep the longitudinal slip an operational range
by cycling the braking pressure.
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6. • Steerability
1. Good peak frictional force control is necessary in order to achieve
satisfactory lateral forces and, therefore, satisfactory steer-ability.
2. If an obstacle appears without warning, emergency braking may not be
sufficient. When the wheels are
steering intention.
WithABS car remains steerable
locked, car no longer respond to the driver’s
3. even during emergency braking, and thus the
obstacle can be safely avoided.
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7. COMPONENTS OFABS
The primary components of theABS braking system are:
• Electronic control unit (ECU)
1. It receives signals from the sensors
pressure at the road wheels according
in the circuit and controls the brake
to the data analysed by the Unit.
2. ECU assists the vehicle operator to prevent wheel lockup by regulating the
wheel slip.
• Hydraulic control unit or modulator
1. It receives operating signals from the ECU to apply or release the brakes
underABS conditions.
It executes the commands using three solenoid valves connected in series2.
with the master cylinder and the brake circuits- one valve for
wheel hydraulic circuit, and one for both of the rear wheels. Thus
be actuated by controlling hydraulic pressure.
each front
brakes can
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8. • Power booster and master cylinder assembly
1. It is activated when the driver pushes down on the brake pedal. The master
cylinder transforms the applied pedal force into hydraulic pressure which
is transmitted simultaneously to all four wheels.
It provides the power assistance required during braking.2.
• Wheel sensor unit
1. Speed sensors are comprised of a magnet wrapped in a coil and a toothed
sensor ring. An electrical field given off by the contact between the magnet
and the toothed ring creates aAC voltage.
2. The voltage frequency is directly proportional to the wheel's rotational
speed.
It monitors the rotational speed of the wheel and
ABS control module.
3. transmits this data to the
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9. WORKING OFABS
• If a wheel-speed sensor signals a lock up - the ECU sends a current to the
hydraulic unit. This energizes the solenoid valve. The action of the valve
isolates the brake circuit from the master cylinder. This stops the braking
pressure at that wheel from rising, and keeps it constant. It allows wheel
velocity to increase and slip to decrease.
When the velocity increases, ECU re-applies the brake pressure to restrict
the wheel slip to a particular value.
•
• Hydraulic control unit controls the
based on the inputs from the system
speed.
brake pressure in each wheel cylinder
sensor. This in result controls the wheel
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10. RESULTS
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11. VEHICLE SPEEDAND WHEEL SPEED
(WITHOUT ABS)
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12. VEHICLE SPEED AND WHEEL SPEED
(WITH ABS)
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13. CONCLUSION
•
•
•
It is inferred thatABS improves the braking performance.
The stopping distance after usingABS system has considerably reduced.
The error in slip and desired slip is used to manipulate brake pressure in brake
cylinder.
ANTILOCK BRAKING SYSTEM 24

14. REFERENCES
• Tianku Fu,“Modelling and performance analysis of ABS system with non-linear control”,
2000.
• Tobias Eriksson,“Co-simulation of full vehicle model in Adams and anti-lock brake system
model in Simulink”, 2014.
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15. THANK YOU!
ANTILOCK BRAKING SYSTEM 26