Introduction: Web Controlled Surveillance Camera
The purpose of this work is to show, how to build surveillance system with the web-page interface. The webcam can be turned in the vertical or horizontal direction throught the interface, but only in the area that border sensors will allow. The control page is secured with login system, where the user types in an username and a password.
On the control page the user can control how the webcam will turn and how many steps it will run. The user can also turn the webcam on and off via web interface. Information about the states will immediately update to screen. User can also turn the motion detector online, if the camera detectd motion, it will automatically save the frames. Naming of the pictures is done with "timestamps", so it is possible to find out when the picture was taken.
The camera interface is coded by using PHP and XHTML programming languages. The micro controller is programmed by using C-language. System works on Linux operating system.
Step 1: Step Motors
You can find the step motors from the old printer. Printer usually contains two step motors. The step motor can be bipolar or unipolar.
Step 2: Making the Box
Polystrol is cheap and easy to modify. You can bend it to right shape with (hot air) aerophone. Hot glue is good when you stick parts together.
Step 3: Assembly
I have used lot of parts from the Lego kit. These are really useful =). Rest of the parts are taken from the old printer. Only the switches and wires are from the electronic shop.
Step 4: Motor Driver for the Bipolar Step Motor
To control the step motors we have to build a motor driver. There is difference between bipolar and unipolar motor drivers. Bipolar motor driver is little bit harder to do, than unipolar.
- 12MHz crystal
- 2x 27 pF capacitors
- L7805CV regulator with 100 nF and 4,7uF/35V capacitors
- L7808CV regulator with 100 nF and 4,7uF/35V capacitors
- 1N5408 diode
- 2x Dual-H-Bridge (model L293B)
- TTL-RS transducer (model ST232ACN) with five 0,1 nF capacitors
- 2,1mm DC connector
- screw terminals
L293B Dual-H-bridge does not contain internal diodes !
Model L293D contains diodes.
Step 5: Micro Controller Board
Solder the components on the board and that's it. About the wiring.. there is nothing to say =)
Step 6: Done
System is ready to use.
Step 7: Easy Motion Detector Program
This works only under Linux!
1. Install your webcamera.
2. Install capture software called Xawtv. It creates file called .webcamrc
3. Open the file with your favorite editor.
4. Delay defines how often the still-picture is sent to server. I used 7 seconds.
Dir defines location folder where the picture goes. Something like: /usr/webcam/pictures/
File defines name of the picture. Something like caption,jpgor what you want to use.
5. Save and exit.
6. Now you can try the command webcam & . The program start updating the picture on every 7 second to
the defined dir folder. & option, put it to run on background.
Install ImageMagick software.
Under Fedora command is: yum install ImageMagick
Software contains function called compare and this is what we need.
Now you have to code a Shell script. Use your editor to do that.
cp $PATH/caption.jpg $PATH/tmp/caption2.jpg
compare -metric PSNR $PATH/caption.jpg $PATH/tmp/caption2,jpg null > result
result2=`head -c 4 result`
if test $result2 -lt 300
cp $PATH/caption,jpg $PATH/save/$time.jpg
Now you can run your script with command: sh gived_script_name
If the picture contains difference, it will be saved to defined folder. In my example it goes to /usr/webcam/pictures/ save/
About the ImageMagick and the compare function you will find more information from here http://www.imagemagick.org/script/compare.php
Step 8: Codes
Codes are commented in Finnish.