The document describes a Collision Avoidance System (CAS) that uses sensors to detect potential collisions and takes actions to prevent or mitigate crashes. It analyzes 2012 crash statistics showing the need for such a system. The CAS is intended to detect collisions 10 seconds before impact, warn drivers at 8 seconds, and actively intervene via braking at 4 seconds. It would use ultrasonic sensors to detect objects, then compute time to impact using vehicle speed and acceleration data to time its responses. The system has challenges with sensor range and response time that need addressing to provide effective collision prevention.

1. Collision Avoidance System (CAS)
By Adnan Khan

2. Crash Statistics and Proposed Solution
• 2012: 5.6 million accidents, 33,561 deaths, 2.3
million injuries.
• Most collisions caused by human error. Machines
should play a more active role (explain ABS)
• CAS detects collision threat and acts to prevent
collision or reduce injuries during collision.

3. CAS System Requirements
1. CAS shall detect an incoming collision threat and act
preemptively to avoid it.
2. CAS shall warn the driver 10 seconds before predicted
impact.
3. CAS shall adjust vehicle settings to mitigate occupant
injury 8 seconds before predicted impact.
4. CAS shall intervene by actuating the vehicle’s chassis
and brake components to perform an avoidance
maneuver 4 seconds before predicted impact.

4. Functional Analysis
1. Detect object/person using ultrasonic range
sensor.
2. Use acceleration and speed inputs from vehicle
control modules to formulate time-based
response.
3. Use data to compute time until collision.
4. Warn driver via warning buzzer 10s prior.
5. Change vehicle settings to mitigate/avoid injury
if collision imminent 8s prior.
6. Actuate ABS pump to prevent collision 4s prior.

5. Component Architecture
• Ultrasonic range sensor reads distance from
object.
• Thermistor measures tire temperature; used for
early brake activation in the event of cold tires
which reduce braking performance.
• Warning buzzer alerts driver.
• Illumination of yellow LED simulates command to
close windows, sliding roof and adjust seats.
• Red LED illumination simulates ABS pump
actuation signal.

7. Issues Encountered
• Sensor range is too low to be used for this
purpose (hence multiplier).
• Sample rate of range sensor decreases as
output signals are increased, lowering system
response as the object approaches.

8. Simulated demonstration

9. Simplified demonstration
• Simplified demonstration:
– Warning is distance based. No acceleration or
vehicle speed input.
– Shows operation as the vehicle is moving.

10. What I Would Do Differently In The
Future
• Use a radar sensor.
• Determine a method to simulate an
acceleration and speed input to perform
a true system test.
• Code a more progressive braking
sequence (threshold braking discomfort).

11. Mercedes-Benz PRE-SAFE

12. Questions?
Discuss use of time-dependent vs. dependent
operation:
-need to account for system dynamics such as
speed and acceleration.
-prevention of false operation. 10 feet at 80mph
accelerating vs. 10 feet at 3mph decelerating.

13. Kinematics equation
-demonstration of kinematics equation used:
Time until collision = [-V0 + (V0
2 + 2ax)1/2 ]/a
Vo = Vehicle speed.
a = acceleration.
x = distance

14. Some real inputs and outputs
• Inputs :
-rain/light sensor
-range sensor (radar)*
-camera
-vehicle speed sensor*
-vehicle acceleration sensor (lateral) *
-brake position sensor/switch
-tire pressure sensor
-tire temp sensor*
-steering wheel angle sensor
-seat recognition sensor sensor
-seatbelt sensor
• outputs:
-warning buzzer
-body control module signals
-ABS actuation signal