PRESENTATION

Collision Avoidance System (CAS)By Adnan Khan

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.

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.

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.

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.

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.

Simulated demonstration

Simplified demonstration

• Simplified demonstration:– Warning is distance based. No acceleration or

vehicle speed input.– Shows operation as the vehicle is moving.

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).

Mercedes-Benz PRE-SAFE

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.

Kinematics equation

-demonstration of kinematics equation used: Time until collision = [-V 0 + (V0

2 + 2ax)1/2 ]/aVo = Vehicle speed. a = acceleration. x = distance

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