More pics and ramblings I was going to do a full write up but then realised I had told you pretty much everything in the last post.

The actual construction of Cheapo is not that interesting and I could have done it with any bits of plastic or metal I had lying around. The cool thing about using the plastic covered foam is that it is a) so cheap and b) so easy to work with. To cut it I just used a Stanley knife and a metal ruler.

As long as it is layered correctly the plastic foam is fairly strong. I could still rip it into pieces easily (say if it became self aware and started chatting up my fiance ) but in normal use I think the frame will hold together nicely as long as I don’t drop it! I am interested in eventually constructing robot frames that are a little bit different from the usual box with wheels and this foam has intrigued me simply because it is so cheap I can easily construct various things without it costing an arm and a leg. I would probably get the design laser cut out of HDPE (a type of plastic) for the final version. I just used double sided foam tape to stick it all together.

I must admit I cheated slightly (or was ‘more efficient’) by using a couple of pre-modified Parallax Continuous Rotation Servos I had bought previously for the drive system. Servos are just too convenient to not use for a robot of this size. No driver circuitry to add, automatic speed and direction control, all by connecting a couple of pins. I am using my Arduino to control the bot currently but will switch to the Boarduino (an Arduino clone) that I bought a month or so ago as soon as I build it. The Boarduino is smaller and I will need to test it anyway.

Small robot dev using the Arduino couldn’t be easier. I don’t like the dev environment it self much (I am going to have to write a replacement one of these days) but the way they have set it up is easy to get going with and you can still code using AVR studio or one of the alternatives if you wish. To get the servos running on the arduino I simply connected the right pins then imported the ‘Servo’ lib that some guy had written. From there it was as simple as running the test program and punching in the right numbers to calibrate the servos.

Speaking of which, the Parallax Contiuous servos expose the (normally internal) pot to allow you adjust the point at which the servo will stop moving. To calibrate the servos I first uploaded the ‘Servo’ lib test program to the Arduino then typed the command that would normally center the servo if it had not been modified for continous rotation – In this case "90s" (without the quotes). This cause the Servo to start rotating.

I then used a small philips head screwdriver to turn the pot until the wheel stopped turning. This was now the dead area of the servo. To move one way I send the servo commands that are greater than 90. To move the other way, I send commands that are less than 90. To stop I send 90 exactly.

So what now? Well now I need some proper power and sensors to allow Cheapo to become untethered. I need some 3 pin JST connectors for the Sharp Infrared sensors I bought because the cheapskates at Hobby Engineering were too cheap to supply me with cables. Also I mistakenly bought and attached two AAA battery holders instead of AA! Hahahahaa! Damn.

Stay tuned for more adventures of Cheapo… As soon as he/it gets a brain!