1.
ACOUSTICPARKING
SENSORS
(APS)
Seminar Links

2.
ACOUSTIC PARKING SENSORS
Parking sensors are proximity sensors for road vehicles designed to
alert the driver to obstacles while parking. These systems, which use
either electromagnetic or ultrasonic sensors, are marketed variously by
vehicle manufacturers under proprietary brand names such as Park
Distance Control, Park Assist or Parktronic.
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3.
ULTRASONIC PARKING SYSTEMS
These systems feature ultrasonic
proximity detectors to measure
the distances to nearby objects
via sensors located in the front
and/or rear bumper fascias or
visually minimized within
adjacent grills or recesses.

4.
ULTRASONIC PARKING SYSTEMS: WORKING
• The sensors emit acoustic pulses, with a
control unit measuring the return interval of
each reflected signal and calculating object
distances.
• The system in turns warns the driver with
acoustic tones, the frequency indicating
object distance, with faster tones indicating
closer proximity and a continuous tone
indicating a minimal pre-defined distance.
• Systems may also include visual aids, such as
LED or LCD readouts to indicate object
distance.
• A vehicle may include a vehicle pictogram
on the car's infotainment screen, with a
representation of the nearby objects as
coloured blocks.

5.
If an object is detected, the sensor beeps. Faster beeps indicate the car is coming closer to the obstacle.
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6.
ULTRASONIC PARKING SYSTEMS: WORKING
• Rear sensors may be activated when
reverse gear is selected and deactivated as
soon as any other gear is selected.
• Front sensors may be activated manually
and deactivated automatically when the
vehicle reaches a pre-determined speed —
to avoid subsequent nuisance warnings.
• As an ultrasonic systems relies on the
reflection of sound waves, the system may
not detect flat objects or object
insufficiently large to reflect sound — e.g., a
narrow pole or a longitudinal object
pointed directly at the vehicle or near an
object.
• Objects with flat surfaces angled from the
vertical may deflect return sound waves
away from the sensors, hindering detection.

7.
• The main characteristics of ultrasonic sensors for rear sonar are directivity,
ringing time, sensitivity and sound pressure.
• Directivity of an ultrasonic sensor corresponds to the size and shape of the
vibrating surface (that is emitting the ultrasound) and the frequency at which it
vibrates.
• Figure(Below) indicates directivity of a disc type transducer.
• Narrower directivity can be achieved at higher frequency when the size remains
the same, or at larger size when the frequency remains the same. Difference in
detection distance with varying frequency at the same size is indicated on next
slide.

8.
FREQUENCY (DIRECTIVITY) AND INFLUENCE OF THE GROUND
• By using higher frequency and selecting an appropriate amplifier (gain), we
can increase the influence of ground objects, such as wheel stoppers.
• While narrower vertical directivity improves sensor usability, wider horizontal
directivity can provide wider coverage with fewer sensors. 'Asymmetric'
ultrasonic sensors are used in such situations.

9.
DIRECTIVITY TYPE FOR ULTRASONIC SENSORS
• Since rear sonar ultrasonic sensors handle both sending and receiving of ultrasound,
unless the emitting sound wave dissipates without ringing quickly, it cannot start
receiving its reflection.
• The shorter the ringing time, the closer the detection range can be.

10.
ADVANTAGES ULTRASONIC PARKING SENSORS
• The ultrasonic backup sensors have difficulty to detect inclined
surfaces or slightly reflective obstacles as shrubs and wire mesh.
• They also only detect objects directly behind or in front of the car,
and may not work if the sensors are dirty or out of alignment.
• Fitting usually requires drilling the bumper, but stick-on sensors are
available (though unattractive).
• Ultrasonic parking sensors not be suitable for use with a tow bar.
DISADVANTAGES OF ULTRASONIC PARKING SENSORS
• The cheapest form of parking aid.
• Sensors detect objects even when the car is stationary.

11.
ELECTROMAGNETIC PARKING SYSTEMS
• Electromagnetic sensors rely on the vehicle
moving slowly and smoothly towards the
object to be avoided.
• Once detected, the obstacle, if the vehicle
momentarily stops on its approach, the
sensor continues to give signal of presence
of the obstacle.
• If the vehicle then resumes its manoeuvre
the alarm signal becomes more and more
impressive as the obstacle approaches.
• Electromagnetic parking sensors are often
sold as not requiring any holes to be drilled
offering a unique design that discreetly
mounts on the inner side of the bumper
preserving the 'new factory look' of your
vehicle

12.
ELECTROMAGNETIC PARKING SYSTEMS: WORKING
• A system provides an alarm indicative of a
presence of an obstacle in a vicinity of a vehicle.
• The system operates by electromagnetic
detection, and generates an oscillating
radiofrequency signal.
• A transmitter transmits the generated oscillated
radiofrequency signal to create, all around the
transmitter, an electromagnetic radiofrequency
near field.
• A receiver receives the electromagnetic
radiofrequency near field.
• A detector is connected to the receiver and
detects a perturbation resulting in a reduction of
an oscillation amplitude of the electromagnetic
radiofrequency near field, and an indicator
indicates the detected perturbation of the
received electromagnetic radiofrequency near
field.
• Based on this operation, an obstacle in a vicinity
of the vehicle can be detected.

13.
ADVANTAGES OF ELECTROMAGNETIC PARKING SENSORS
• Suitable for use with tow bars, cycle racks, etc.
• Capability to approach the obstacle up to few centimetres.
• Electromagnetic sensors are mounted inside the bumper, so there's
no need for drilling.
DISADVANTAGES OF ELECTROMAGNETIC PARKING SENSORS
• Electronic parking sensors are more expensive –The factory-fitted
cost is about the same as ultrasonic sensors.
• Electromagnetic sensors only detect objects once the car has started
moving."

14.
CONCLUSION
• In a country like India where the parking space is always less than desired,
sometimes due to heavy traffic and sometimes due to the irrational
parking of others, such a parking assist system can be of great help.
• The only thing that repels the consumer from buying these systems is the
heavy cost they have to pay for them.
• A vehicle with these systems can cost the buyer anywhere between 30k to
50k more in comparison to the ones which don’t have them.
• Indians, who are more comfortable with their “simple” cars than in paying
the hefty price, often try to avoid the installation of these systems.
• If the cost is reduced and the people are convinced by the car
manufacturers of the benefits of these systems, they may consider buying
them for the sake of their vehicle’s safety.

15.
REFERENCES
•Newelectronics
•Mechanics.Stackexchange
•Telematicswire
•Toyotaownersclub
•Proxel
•Parkingdynamics
•Self.Gutenberg

16.
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