This presentation on the applications of embedded systems in automobiles focusses on the two most prevalent and sought about technologies- ABS and ACC with collison avoidance, the biggest motivation being that these technologies save lives.

1. An overview of
EMBEDDED SYSTEMS
IN AUTOMOBILES
By Amber Deep Singh
EN. No-22/10
Dept. of Electronics and Communication
NIT Srinagar

6. What is ABS?
“An anti-lock brake system is a feedback control
system that modulates brake pressure in response to
measured wheel deceleration, preventing the
controlled wheels from becoming fully locked.”
It’s main functions are that it
• Reduces stopping distance.
• Maintains steerability.
• Maintains lateral stability.

7. The Operation of ABS

8. Typical ABS Components
 Wheel Speed Sensors (up to 4)

Electronic Control Unit (ECU)

Brake Master Cylinder, Hydraulic
Modulator Unit with Pump and
Valves
 Vehicle’s Physical Brakes

9. Wheel Speed Sensor (WSS)
Magnetic field changes as
toothed gear wheel
rotates, resulting in a signal
with frequency related to the
angular velocity of the axle.

10. Electronic Control Unit
• The signal from the WSS is
proportional to angular
velocity. By differentiating this
signal, acceleration of each
wheel is known. If a wheel is
decelerating too quickly the
brake pressure is modulated.
• A fifth input to the ECU is from
a brake pedal switch. This
signal can shift program
execution from a standby to an
active state

11. Hydraulic Modulator Unit
The hydraulic modulator
unit contains the ABS pump
as well as solenoid valves
for each brake line.
The fifth line - far right - is
from the brake master
cylinder, which is
connected to the brake
pedal.

12. Valves and Brakes
The Solenoidal valves
modulate the brake pressure
up to 20 times per second,
effectively realizing the ideal
tire slip percentage.
ABS ‘pumps’ the brakes
much faster than any driver
could.

15. Adaptive Cruise Control(ACC)
with Collision Avoidance

16. What is ACC?
• Adaptive Cruise Control (ACC) is an automotive
feature that allows a vehicle's cruise control
system to adapt the speed to the traffic
environment.
• ACC allows cars to keep safe distances from
other vehicles on busy highways. The driver
can set the speed of his car and the distance
between his car and others. When traffic
slows down, ACC alters vehicle speed using
moderate braking.

17. PRINCIPLE OF ACC
ACC works by detecting the distance and speed
of the vehicles ahead by using either a Lidar
system or a Radar system .The time taken by
the transmission and reception is the key of the
distance measurement while the shift in
frequency of the reflected beam by Doppler
Effect is measured to know the speed. The
brake and throttle controls are done to keep
the vehicle in a safe position with respect to
the other.

18. CONSTITUENTS OF AN ACC SYSTEM
• A sensor (LIDAR or RADAR) usually kept
behind the grill of the vehicle to obtain the
information regarding the vehicle ahead. The
relevant target data may be velocity or
distance.
• A controller which receives the sensor data
and process it to generate the commands to
the actuators of brakes, throttle or gear box.

19. Working of ACC