This tiny spy robot can send audio and video and includes night vision
After building my two large video controlled robots (Oberon and Goober) as well as the small sized all terrain spy robot, I wanted to take the militarization process as far as I could using inexpensive components. A spy robot needs to have a rock solid video link that is good for at least 500 feet, crystal clear amplified sound pickup, silent motor operation and night vision, so that is a lot of stuff to pack into a small area. Also note that this project was built in 2004, when affordable miniature cameras and video transmitters were kind of a rare thing to find.
I decided to build this project when I finally found a source for an ultra tiny composite video camera with a low lux CCD element that would be good for night vision. I also had a tiny 250mw audio and video transmitter that was hacked from a security system into its absolute minimum size, so the project could finally come together. This version is just a simple proof of concept prototype and will eventually be made less than half the size and have the ability to survive a throw through a window into the target location for stealthy surveillance missions in a hostile environment. The final version will also have some onboard autonomous intelligence so once it is dropped or thrown into the target location it can quickly sneak into a dark hiding spot much like the way a fleeing insect.
Since I now had the small video camera and the tiny gearbox drive motors
on order, I could experiment with some possible layouts and battery
pack sizes using a computer CAD program. I originally planned to use
very small lithium batteries, but it was found that the current draw
from all of the subsystems made the video drop out when the motors were
activated, so I decided to go with sub-AA sized rechargeable nickel
batteries as these were commonly available for small RC aircraft use.
The next version will use a custom made lithium ion battery pack similar
to the ones used in cell phones for much smaller and extended run
times, but for now the goal was cheap and simple.
I also intended to have a four wheel transmission system with possible a
track drive, but in later experimentation it was found that only two
wheels were needed as the little motors had more than enough power to
just drag the back of the robot along. The final version will probably
have a custom track drive though, as the two wheels would sometimes fail
to pull the tiny robot over large carpet runners due to slipping easily
on the smooth surfaces.
I originally made my own small video transmitter but it lacked audio and
was very unstable as the robot moved around or when the batteries began
to drain. This video transmitter is the output block of a small
security camera reduced to its absolute minimal components, allowing it
to send 900MHz audio and video back to a down converter. The small
transmitter was very stable for several hundred feet, had very clear
audio, and ran just fine from any DC power source from 6 volts to 12
volts. Having the video transmitter on a high frequency band will also
help stop interference between it and the drive remote controller, which
operates on the low 49MHz band.
Figure 2 - This is a tiny half inch square audio and video transmitter
It was very difficult to find a suitable micro video camera in 2004 for
this project. The camera had to be black and white for use with the
invisible infrared night vision LEDs, have a CCD imager rather than CMOS
for clarity, and also output a standard NTSC composite signal rather
than a serial bit stream. I eventually found this extremely small high
resolution black and white composite camera and did a little hacking in
order to remove the onboard power supply, which was 4x the size of the
actual camera. This camera was perfect for this spybot now that it was
reduces to only 1/4 inch square and able to run from 8 to 12 volts DC
power.