Ahmad Rana's Engineering Log

Projects: Multilingual Watchman






Engineering Log

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Inventors: Ahmad and Sal


Meet Kayamat Singh, the multilingual Watchman.  He greets and communicates with you in multiple languages. You’ll have to go through multiple security steps, like fingerprint scanning, enter code on touch-screen etc. for him to open the front door for you and let you inside the house. All the way, he will guide you in his pleasant voice. You can even look through his eyes inside your house (or even remotely if you’re not at home) on a computer through your internet browser, and open the door for your visitors. But wait. That’s not all. For a limited time, we’re including the feature where if you see your mother-in-law on your doorstep, you can instruct him to politely tell her that nobody’s at home. You can always claim machine error later on.


The scope of this project is to build an interactive and configurable home-security system to operate the entrance to home either automatically if security checks pass, or by notifying the home owner, who can remotely operate the entrance door. Commercial off-the-shelf components will be used to interface with an embedded SBC (Single Board Computer) to build the system. The focus will be on providing an interactive experience to the user by using a combination of sound and video streams. Since it is a hobby project, the price tag will be kept to a minimum by utilizing components from the inventor’s stash.


1.      Motion should be sensed in front of the entrance to activate the system, and at night, turn on the light.

2.      Welcome audio message should be played at activation, and instructions should be played at every level to instruct user how to proceed in multiple languages.

3.      Biometric (fingerprint) sensor and keypad entry code should be provided for automatic access.

4.      The user should be able to interact with the system through a touchscreen.

5.      Visual image should be provided to the home-owner by connecting to the web server through web browser on any computer connected to the network.

6.      Control should be provided to the home-owner to remotely open the door.

7.      Instruction sets in multiple languages should be configurable by the home owner, so as to choose which instruction set to play to the user. The home-owner should be able to record and choose an instruction set in a new language.


Figure 1. Block Diagram of the Multilingual Security System.

The PIR motion sensors available in the market (approx $7) provide TTL output, which can be sensed on GPIO port of the computer. The motion can be sensed, and a welcome message played through Speaker (an audio amplifier might be required, price speaker + audio amplifier $15) connected to the Audio interface of the SBC. The graphical user interface can be provided through a touchscreen LCD. This need not be purchased, since a 3M capacative touchscreen (serial interface) and 10” LCD is already available from inventor’s hobby collection.  Web interface to other computers in the house can be provided through wireless bridge. This also will come from the inventor’s collection from a previous project. A relay interface will be used to turn on the light, or operate the actuator to open the door. Material for this will also come from the inventor’s collection. A webcam ($15) connected through USB interface will provide visual image. The fingerprint scanner is the sticking block. Scanning type fingerprint scanners are available for $75 upwards, whereas swipe-type scanners are available for $15. If a good deal is not obtained on scanning-type scanners, then swipe-type will be used. However, the recognition quality of these is lower. The SBC is to be provided by Microsoft Embeddedspark Competion if the project goes through round 1. Software development will be done on Windows Embedded Standard 7 platform using .NET framework. The total cost of the project for the inventor will be $55 - $75.  If the SBC doesn’t support certain interfaces (e.g. RS-485 or GPIO), then an Arduino microcontroller will be used to provide USB interface to control the devices currently planned to be operated through these interfaces. This controller will also come from the inventor’s collection, and will not incur any additional cost.

Multilingual Watchman in Action: