Tank Cam

Line Follower Robot

The Tank Cam

(click here to see a video clip of the tank cam probing under my deck for a lost baseball)

Building a robot from scratch is a daunting task. A lot of disciplines are necessary. Electronics is hard enough without adding to it mechanical engineering. For me the mechanics are the hard part. I have a decent selection of tools but even still it's tough to build something elaborate. My solution very often is to hack a toy. Toys are great bases for robots. Motors and gear boxes, wheels, frame - all that stuff is solved for you. You just have to hack into it and corrupt it to your own fell purposes.

Toys R Us is one of my favorite stores to visit. Look for a battered, returned, marked down bulldozer or tank for $20 or so. I bought the tank there for $30 new. But still $30 to save hours of hair pulling trying to build a tank base myself? I'll take that deal.

Here is the tank in its box. The remote is accessible for testing while still in box, so you can run the motors, shoot the guns, all that while it's still in the box.

That's a good looking tank all right. But it will look even better in pieces. I started by removing some screws on the bottom of the chassis allowing me to lift the top section off. You can see in the bottom section the main drive (white plastic box to left), the main circuit board (middle of rats nest of wire) and the speaker (cool engine and gun firing sounds). The top section has a gear box for the rotating turret and control wires for the main and machine gun lights. The IR receive module is visible on top section at back (to left)

The main drive gearbox is a compact little unit in the back of the tank. For the most part it is fully enclosed to keep out dirt and dog hair, the nemesis of hobby robots. The gear box and track system alone is worth $30 to me.

Main circuit board. The black things are transistors making up the H bridge for driving the motors. Presumably, you could use this board and just put in digital signals from a microcontroller. I haven't experimented to see how practical this is yet.

The top of the tank has an enclosed turret that was not condusive to easy mounting. Too curvy aand rounded. So I removed it. I still left the rotating turret base on, just took off the gun and the hatch and all that. This was a bit more difficult. The screws for this are not really accessible that I could find. So I rotated the turret until I could see one of the screws and then marked inside the top cover the radius where that screw would rotate. I then drilled a hole and used my screwdriver on first one, then the other screws and voila, off came the top.

I took an X-10 wireless camera I have and mounted it to the top (duct tape special) along with a portable battery power supply to run it. I hooked up the camera reciver to my TV and then sent the tank to find a baseball. The remote control is IR and thus line of sight. So if you lose line of sight with the tank you're in trouble. I got lucky as you can see in the video clip.

Click here for a video clip of the tankcam on its first mission. This clip is pretty big (4.5Megs) so don't try downloading it if you don't have a fat connection. I made a smaller size one but the resolution is so bad you can't see what's going on so I left it large.

IR is not the way to go for remote control though. So I'm going to convert it over to a radio link. I want two way so it can send me data. Big plans for this baby.