wing0766
09-07-2010, 02:36 AM
The theory behind the ultrasound sensor is based on echo-location (like SONAR, the same thing bats use to navigate). The frequency of the sound is so high that humans cannot detect it, which is useful because it provides accuracy and remains inconspicuous. As sound hits a solid object, it is reflected back creating an echo. Since the speed of sound is known and constant for similar conditions, (such as wind or humidity to name a few), it is possible to determine the distance of the object you hear an echo from by multiplying the speed of sound by half the time it takes to hear the echo (because the echo time is actually the time it takes the sound to go there and back).
http://farm5.static.flickr.com/4106/4963707194_6fe9450e4e.jpg
A sensor is placed on the rear bumper of the car, which is capable of both emitting and detecting ultrasound. As it pulses, a computer measures the time it takes for the sound it emits to be heard again. Parking sensors operate at a close range and some sensors have a minimum operating range. When the user set distance threshold is passed, the sensor will emit an audible sound alerting the driver that it is getting close to an object. The distance threshold is useful for those who may want to leave more room behind their vehicles, and those who like to squeeze in as tight as possible. Some more expensive models may also have an extra unit inside the car which can also visually alert the driver.
http://farm5.static.flickr.com/4108/4963707330_b0bd529282.jpg
Parking sensor systems use ultrasonic proximity detectors embedded in the front and/or rear bumpers, to measure the distances to nearby objects at low level. The sensors measure the time taken for each sound pulse to be reflected back to the receiver.
http://farm5.static.flickr.com/4105/4963108293_dd2459362a.jpg
Depending on the speed of the vehicle and the distance to the obstacle, the system will warn the driver by visual and/or audible means about the risk of collision. The feedback to the driver will generally indicate the direction and proximity of the obstacle. Warnings are deactivated when the vehicle exceeds a certain speed, and can be switched off for situations such as stop-and-go traffic.
Audible feedback
The most common form of feedback to the driver in a car with parking sensors is audible "beeps" and/or tones. Generally, the frequency of the beep indicates distance from an obstruction, with the beeps becoming faster the closer the vehicle moves to an object. A continuous tone may be heard when the vehicle is extremely close, often warning a driver to stop immediately to avoid collision.
System indicates obstacles by giving 5 different intervals of sound according to distance
http://farm5.static.flickr.com/4109/4966525664_4e375d719c.jpg
Visual feedback
Some systems use visual aids as well as or instead of audible tones, such as LED or LCD readouts to indicate distance from an object. The direction and distance to the obstacle is indicated by the location and strength of the warning symbols.
Installation
http://farm5.static.flickr.com/4128/4963108543_31d8fde98d.jpg
http://farm5.static.flickr.com/4129/4963108723_22201d588a.jpg
http://farm5.static.flickr.com/4106/4963707194_6fe9450e4e.jpg
A sensor is placed on the rear bumper of the car, which is capable of both emitting and detecting ultrasound. As it pulses, a computer measures the time it takes for the sound it emits to be heard again. Parking sensors operate at a close range and some sensors have a minimum operating range. When the user set distance threshold is passed, the sensor will emit an audible sound alerting the driver that it is getting close to an object. The distance threshold is useful for those who may want to leave more room behind their vehicles, and those who like to squeeze in as tight as possible. Some more expensive models may also have an extra unit inside the car which can also visually alert the driver.
http://farm5.static.flickr.com/4108/4963707330_b0bd529282.jpg
Parking sensor systems use ultrasonic proximity detectors embedded in the front and/or rear bumpers, to measure the distances to nearby objects at low level. The sensors measure the time taken for each sound pulse to be reflected back to the receiver.
http://farm5.static.flickr.com/4105/4963108293_dd2459362a.jpg
Depending on the speed of the vehicle and the distance to the obstacle, the system will warn the driver by visual and/or audible means about the risk of collision. The feedback to the driver will generally indicate the direction and proximity of the obstacle. Warnings are deactivated when the vehicle exceeds a certain speed, and can be switched off for situations such as stop-and-go traffic.
Audible feedback
The most common form of feedback to the driver in a car with parking sensors is audible "beeps" and/or tones. Generally, the frequency of the beep indicates distance from an obstruction, with the beeps becoming faster the closer the vehicle moves to an object. A continuous tone may be heard when the vehicle is extremely close, often warning a driver to stop immediately to avoid collision.
System indicates obstacles by giving 5 different intervals of sound according to distance
http://farm5.static.flickr.com/4109/4966525664_4e375d719c.jpg
Visual feedback
Some systems use visual aids as well as or instead of audible tones, such as LED or LCD readouts to indicate distance from an object. The direction and distance to the obstacle is indicated by the location and strength of the warning symbols.
Installation
http://farm5.static.flickr.com/4128/4963108543_31d8fde98d.jpg
http://farm5.static.flickr.com/4129/4963108723_22201d588a.jpg