License Plate Recognition (LPR) Auto-gate System

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2 Νοε 2013 (πριν από 3 χρόνια και 9 μήνες)

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License Plate Recognition (LPR) Auto
-
gate System


April 14
th
, 2009

Danny Choi (President and CEO)

Jaehoon Shin (CMO and CFO)

Wook Sun Shim (CTO and COO)


Introduction


Motivation


System Overview


Hardware


Metal Detector


Microcontroller


Communication Module


LPR System


Camera Module


License Plate Locator


Letter Recognition


Finances


Timeline


Final Thoughts


Questions and Answers


License Plate Recognition System


Convert the license plate number to ASCII










245 AFC


License Plate uniquely identifies vehicle.


Various police forces


Electronic toll Collection


Pay per use roads


Monitoring traffic activity


Auto Theft


On an average day in B.C.


37 vehicles are stolen


62 vehicles are broken into



One third occurred in the private residences


Underground parking lots with Auto gate


“Stop until the gate close”


No physical barrier !


Auto
-
gate Parking Lot


Must carry key entry devices


Could be lost, stolen, or no battery



RF signals can be stolen


RF (radio frequency) remote control analyzer



Following after vehicles


Walk
-
ins

No Physical barrier !


LPR Auto
-
gate system: Virtual Barrier


The system recognizes the vehicle and checks
for verification


Following
-
after vehicles or walk
-
ins are
controlled


Alerting a trespassing and save the image for
further crime investigation and enforcement.



Conveniences


Eliminating the use of key entry device.


Simply “come and enter”



No need to wait for the gate to close!


Registering for guest vehicles:


Type in the plate number



Block Diagram

Metal

Detector

LPR

System

Microcontroller

Board (LCD & LED)


Logic Diagram




Capture

&

Image

Processing

Green

LED

Start

Vehicle?

Verified?

Green?

Red

LED

Red

LED & Alarm

Y

Y

Y


N

N

N


The Concept of Mutual Inductance








Main Components


TL072 (Dual Operational Amplifier), NE555
(Timer), a couple of Inductors


Microcontroller (Atmel ATmega168)


High density of various features (ADC, PWM, LCD
driver, and etc)


GNU Complier Collection (GCC) supported


Voltage Regulator (L7805)


9V battery to 5V


LCD


2x24 characters display


HD44780 protocol


Outputs (
piezoelectric buzzer and LEDs)


Vehicle detection


Road tube, Magnetometer sensor, Weigh
-
In
-
Motion
(WIM) , Piezoelectric sensor, and etc


Microcontroller



Atmel

ATmega
168

Zilog

Z
86
E
3416
VSC

Speed

20
MHz

16
MHz

Memory

16
K

16
K

Ram

1
Kb

512
b

I/O

pin

23

24

ADC

Yes

No

Package

DIP
-
28

DIP
-
28

Price

$
4
-
5

$
11


RS232 serial I/O port


Cheaper and Simpler solution than USB!


Use CSerial source code










Baud Rate

115200

Data Bits

8

Parity

None

Stop Bits

1

Flow Control

None


Brain of the overall system.


OpenCV


Computer Vision library by Intel.


Module:


Camera Module


License Plate Locator


(Skew Correction Module)


Letter Recognition Module


Verification Module


Grab a frame from a webcam


Refresh the frame every 0.5 seconds


If signal comes in from microcontroller, save
current frame.


Erosion:


Dilation:


Original:


Erosion after Dilating the image:


Dilation:


Original:


Dilation:


Grey Scaled:


Erosion after Dilation:


Dilation:


Subtract:


Threshold and Noise Filter


Canny Edge Detection


Not integrated with the overall system.


Not every input image had detectable edges.


Assumption: the camera is in its fixed position,
almost perfectly parallel to the ground.


System can also recognize the letters from license
plate with tilt angle of ~10
°



Other Possible Solutions:


Hough Transform


Radon Transform









Localized Plate



Invert Image



Paint out margins



Binary Image



Cropped plate



Character Segmentation


Character Segmentation

Template Matching !

Not a character !



Ratio is not valid

~

~



Template Matching



I, O, Q, U, Y, Z



Identification



SIX



Identification



B!


616BBL

_

Equipment

Estimated Cost

Actual Cost

Camera

$100

$0

Microcontroller & development kit

$300

$20

Metal detector

$50

$0

Miscellaneous (LCD, cable, case, alarm,
etc)

$50

$80

Total

$500

$100

Equipment

Market price

Project Cost

Camera

$150

$0

Microcontroller & development kit

$20

$20

Metal detector

$800

$0

Miscellaneous (LCD, cable, case,

alarm, etc)

$400

$80

Total

$1370

$100


We learned:


Team dynamics


Digital Image Processing techniques


Programming in C/C++


Circuitry


Microcontroller



Challenges


A group of three members


Localization



Possible Future Works


Improve skew correction


Implement with actual gate (or motor)


Finer resolution camera


User Interface


More accurate LPR algorithm


“The complexity of each of these subsections of the
program determines the accuracy of the system”
(en.wikipedia.org/wiki/Automatic_number_plate_recog
nition)



Dr.
Parvaneh Saeedi


Jun Kim


Steve Whitmore


Patrick Leung, P. Eng


Jamie Westell


Jason Lee


Insurance Corporation of British Columbia (ICBC). 2008.
Stop Auto Crime in Multi
-
Residential and Mixed
-
Use
Buildings.


Insurance Corporation of British Columbia (ICBC). 2007.
Auto Crime and Fraud.


Mia Dauvergne. Statistics Canada. 2008.
Motor Vehicles
Theft in Canada, 2007
.


Statistics Canada. 2008.
Motor Vehicle Theft
.


G. Baridski and A. Kaehler. 2008.
Learning OpenCV:
Computer Vision with the OpenCV Library
.



C. WU, L. C. ON, C. H. WENG, T. S. KUAN, K. NG. August
2005.
A Macao License Plate Recognition System
.