Nuts and Volts - August 2012

Design a Customized Security System Using RobotBASIC

By John Blankenship and Samuel Mishal

Nowadays, home security systems are commonplace, but often have limited capabilities. If you could design your own system, it could meet your specific needs and perhaps even save you money. If your home could call your cell phone when a violation occurs, for example, you might be able to dispense with monthly monitoring fees. If you travel a lot, imagine the piece of mind you would have if you received an email every day telling you everything is secure.

Assume that in addition to the standard window and door sensors, your home has motion sensors mounted outside the house to give an early warning so the system can react before a break-in actually happens. When outside motion is detected, lamps and perhaps a radio could be turned on to give the impression that someone is home. Furthermore, the times of the outside movements could be logged and included in an email report.

Consider what you could do if your system could interface with a camera. Instead of just saying that the house is secure, the daily emails could actually include one or more pictures as proof that everything is okay. And, should an intrusion actually occur, the system could take a picture of the intruder and immediately email it to you.

Once the system has the ability to interface with a camera, imagine the added functionality you would have if it could be mounted on a motorized turret. You might even want the ability to point the camera from a remote laptop and request pictures in real time. If you need more flexibility, imagine mounting the camera on a mobile robot that can be controlled over the Internet from anywhere in the world.

Remember, the whole idea is to create a custom system that meets your needs. You may or may not want all these features, and you probably have additional requirements we haven’t even considered. With all these complexities, you might be wondering how difficult it would be to implement such a robust design. The software for such a project — especially if it grows over time — could eventually become quite complex. For that

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reason, the language we choose for implementation should have strings, floating-point math, arrays, and a significant amount of memory which would be beyond the capabilities of most microcontrollers.

If we center the hardware portion of the project around a PC, we can take advantage of low cost web cams, and memory will certainly not be a problem. With Microsoft’s constant pressure to make Windows more stable, though, many PC languages cannot even handle basic I/O operations any more, let alone our more advanced needs. Just capturing images from a web cam, for example, is difficult (if not impossible) to do in many languages, and support for Internet communication and the sending of emails is even less common.