Vehicle Safety ModificationsDesign Review Presentation

May06-21

ClientSenior design

Faculty AdvisorDr. Gary Tuttle

Team MembersJoshua Bruening EEMei-Ling Liew EEFei Liu EEBrian Phillips CprEAdams Sutanto EE

December 8, 2005

Blind Spots

• Driver vision can be restricted by vehicle architecture, mirror image resolution, the driver's field of vision, and the driver's personal mobility, thereby creating blind spots.

• Vehicle structure and visibility constraints are two factors that create blind spots and cause lane change accidents.

Common Mirrors

• Adjusting mirrors correctly

• Minimizing the blind-spots not eliminating

Blind-spot Eliminators

• Improved the driver’s view of what is in front of, to the side of, and behind the vehicle

• Eliminated the potential danger for accidents when entering freeways and backing up

• Solved lane-changing problem

Blind-spot Eliminators

• The blind-spot mirror is an angled add-on mirror that attaches to an existing side mirror to increase the blind spot visibility range by 75% without distortion.

Technology A

• Driver presses a button

• The exterior mirror moves slightly outward, reflecting the blind spot

• Releases the button, and the mirror returns to its standard field-of-view.

• Simple and safe

Technology B

• A red LED directional arrow into the mirror glass.

• Additional warning to traffic when the driver wants to make lane change.

• Not a distraction when driving at night.

Technology B

• Drivers are not subjected to the full brightness of the LED technology.

Technology C

• Two digital cameras and advanced computer software

• When another vehicle enters the zone – an area of 9.5 meters by 3.0 meters – a yellow warning light comes on beside the appropriate door mirror in the driver's

peripheral view

Technology C

• The system will not function in conditions of poor visibility, for instance in fog or flying snow

• Too expensive

Technology D

• A single radar sensor on each side of the vehicle continuously scans the adjacent lane of traffic from the rear view mirror to about one or more car length behind the rear bumper.

• Drivers are notified of potential risks by a lighted icon warning light in the outside rear-view mirror and can be augmented by an audio tone inside the vehicle, at the driver's option.

Technology E

• The easy-to-apply lens is 6 "x 8" and designed for the inside of the back window on SUVs, VANs and MiniVANS, Station Wagons and Trucks with rear-windowed shells. Made of optical grade PVC (polyvinyl Chloride), it can

be peeled off and re-applied at your discretion. • The lens is made from a clear, flexible PVC material. The lens is soft and

may be damaged and discolored by harsh cleansers.

A driver's blind spot is that corner of where your peripheral vision is cut off and yourrear view mirror does not spread wide enough to see.

Diagram showing the angle of incidence (i) and angle of reflection (r).

Car manufacturers are required to provide flat, unit magnification mirrors on the driver's side of the car. Even the inside rear-view mirror also is flat and shows objects without distortion.

• Engineers have found out that the convex side-view mirror on passenger-side affords drivers a much clearer view of the passenger-side of the car. This is because of the advantage of convex mirrors - they allow a much wider angle of vision.

• The average radius of curvature not be less than 35" and no greater than 65".

The blind spot eliminator will be a simple 3 inch x 3 inch convex panel mirror added directly on top of the preexisting side view mirror. The mirror will be paced so that the angle of incidence is set to pick up objects picked up by the original mirror as well as objects in the preexisting blind spot. The final product will look similar to the figure below.

Other sensor types considered:1. Infrared - They can be affected by humidity and water, they can be

expensive and dust and dirt can coat the optics and impair response. We want sensors that can operate in all weather.

2. Inductive proximity – They are ideal for virtually all metal sensing applications, including detecting all metals or non-

ferrous metals only. We want to detect any type of object.

3. Capacitive proximity – These are used to detect change in the environment rather than to detect the absolute presence or absence of an object. They do not give a direct indication of how far away the detected object is.

4. Magnetoresistive – These are the type of sensors found in a metal detector. We want to detect any type of object.

Fundamental Ultrasonic Properties

• Ultrasonic sound is a vibration at a frequency above the range of human hearing, usually >20 kHz. The microphones and loudspeakers used to receive and transmit the ultrasonic sound are called transducers.

• Most ultrasonic sensors use a single transducer to both transmit the sound pulse and receive the reflected echo, typically operating at frequencies between 40 kHz and 250 kHz.

• A variety of different types of transducers are used in these systems.

 • Variation in the speed of sound as a function of both temperature and the composition of the transmission medium, usually air, and how these variations affect sensor measurement accuracy and resolution

  • Variation in the wavelength of sound as a function of both sound speed and frequency, and how this affects the resolution, accuracy, minimum target size, and the minimum and maximum target distances of an ultrasonic sensor

  • Variation in the attenuation of sound as a function of both frequency and humidity, and how this affects the maximum target distance for an ultrasonic sensor in air

  • Variation of the amplitude of background noise as a function of frequency, and how this affects the maximum target distance and minimum target size for an ultrasonic sensor

  • Variation in the sound radiation pattern (beam angle) of both the ultrasonic transducer and the complete sensor system, and how this affects the maximum target distance and helps eliminate extraneous targets

  • Variation in the amplitude of the return echo as a function of the target distance, geometry, surface, and size, and how this affects the maximum target distance attainable with an ultrasonic sensor

Choosing an Ultrasonic Sensor for Proximity or Choosing an Ultrasonic Sensor for Proximity or Distance MeasurementDistance Measurement

Background Noise

• The level of background ultrasonic noise diminishes as the frequency increases.

• The reason is that less noise at the higher frequencies is produced in the environment, and the noise that is produced is greatly attenuated as it travels through the air.

Target Range Measurement

• For each application, it is important to select a sensor that will detect the desired targets when they are located within a specified area in front of the sensor, but ignore all targets outside this area.

• A lower frequency sensor should be selected for longer ranges of detection and a higher frequency sensor should be used for shorter range, higher resolution measurements.

• Sensor beam angles should be selected to cover the desired detection geometry, and to reject unwanted targets.

*The major benefit of ultrasonic sensors is their ability to measure difficult targets such as solids, liquids, powders and even transparent and highly reflective material.

Limitations• Ultrasonic devices do have some limitations. Foam and other

attenuating surfaces may absorb most of the sound, significantly decreasing measuring range.

• Extremely rough surfaces may diffuse the sound excessively, decreasing range and resolution. However, an optimal resolution is usually guaranteed up to a surface roughness of 0.2 mm.

• Ultrasonic sensors emit a wide sonic cone, limiting their usefulness for small target measurement and increasing the chance of receiving feedback from interfering objects.

• Some ultrasonic devices offer a sonic cone angle as narrow as 6º, permitting detection of much smaller objects and sensing of targets through narrow spaces such as bottle necks, pipes, and ampoules

Ultrasonic sensors• A picture of two ultrasonic sensors is shown below:

• Two sensors work in unison, one as the transmitter and one as the receiver.  The transmitter typically sends out a constant beam of sound at a frequency of 40KHz (note that the human hearing barely goes above 17KHz). 

• The receiver detects any sounds coming in and gives us a voltage out.  So, what happens is the transmitter sends out a signal.  If there isn't an object in front of it, then the sound wave will carry on (note there is a limit to the distance here!).  If, and only if, there is an object in the way, the sound waves will bounce back along the same path, and so be picked up by our receiver