24th July , 2004- Munroe

Munroe is the name of my first home made robot. My first real robot was actually a cybug, from Dick Smith electronics. The main aim for this robot was to do some physical work, eg lifting and moving things.

When a robot isn’t actually a robot
Although I like to call this a robot, it isn’t actually a robot. Technically, robots have to be able to sense their surroundings and make their own decisions based on the results they find; they have to have some Artificial Intelligence before they are truly a robot. Since this is completely human-controlled at the moment, it can’t really be a robot. It’s an interesting that I like to call a robot nonetheless.

The base
… is made from aluminum sheet, chosen for it’s easy cutting and drilling. The drive system is based on a differential drive, similar to carpet rovers and the like. 2 modified servos attached to model airplane landing wheels at the front provide the power. I won’t tell you here how to modify the servos to rotate continuously; there are plenty of others on the net, and perhaps the most official one is from Lynxmotion’s website.
A small caster wheel bolted to the back provides the ability to spin on it’s own circle.

The shoulder and arm
The shoulder is made from yellow acrylic and has 2 spacers at the back to keep the assembly rigid. The shoulder is attached to the base via “L” shaped aluminium extrusion.
The arm is made so the hand at the end will always be parallel with the ground. One mistake I made here was drilling the holes for the arm with the angle of the front of the shoulder. I should have drilled them at right angles with the base, so now the hand is always pointing upwards slightly. I suppose I could fix this with some new holes.
The motor to lift the arm is one salvaged from an old VCR. After several very expensive (both in time and money) gearboxes, this one was the only one that had just enough grunt to lift the arm. I could fix this by scaling down the shoulder and arm so the length of the arm doesn’t amplify the weight so much. I’ll do it, once I get it fully functional and working.

The hand
This hand is based on Lynxmotion’s design. Once I got the idea, I painstakingly designed it on paper, made countless cardboard models and finally got the perfect design. I then cut it out of yellow acrylic and spent hours getting it to mesh properly and filed it to a nice finish. The motor was a beautiful little gearhead motor supplied by the Berri Office Shop. It has lots of power and is just the right speed.

By the time I had finished all the construction work I was so tired. It took almost a year of construction in my spare time, and I am just about to get serious on the programming work.

The controller
Is based around on a picaxe 18X, on a nice Oatley picaxe board. I am using a little joystick assembly taken from an old computer joystick to control motion. It basically has a pot for each axis. I plan to use the ADC pins to tranfer this to the two servos. I use spring-return centre-off DPDT switches to control the hand and arm motors.

So, as you can see, it still requires a lot of work. There is much to be improved once I get it working and I would like to make it autonomous eventually. All of my new progress will be put up on this page.