Hazbot you are right mobility is important. I personally like the wheel, track design. Easier to work with and they can move about faster. I'd eventually like a Bipedal but too slow and complicated for me right now.

Now this did all start cause the boyfriend wanted to build a quad rotor. I had an idea to turn SPykee into a quad copter then he could move on ground too.

First off, Tracks are just plain cool! They are more difficult to build and require more power to operate, and they are louder. But they can really cover ground and move on most surfaces. I think a good alternative to tracks is a 4 wheel design. You can drive the two wheels on one side with a single motor, but there is less resistance than with tracks so better energy consumption and less power usage for the same output. This is what the omnibots use. You can also do a double wheel drive with a "tail dragger caster" for balance. I think a lot of it depends on how you want to use the bot - indoor/outdoor, smooth/rough surfaces, etc.

When we first started we used the 360 degree rotation servos from the Kit for wheel turning. That was fine - servos are light and can be powerful but they are not good for connecting direct to wheels as they have a very narrow connection (a narrow nylon male cog - no shaft). After a while the wheels would work loose, seperate and drop off. Also the tail dragger caster on the back would mean fine power tuning to the front drive wheels otherwise, while the bot could spin on a dime, his forward direction could be slightly off to the left or right. We then tried electric screw driver motors and all of a sudden we had a lot of extra weight, the additional requirement of a H-bridge and battery issues (more volts and amps needed). A seperate issue was having wheels capable of getting over carpet or bumps in the floor without the robot shuddering. One answer to this is bigger wheels but as soon as you take that option you need more leverage, more torque, more power. To reach our multi-surface goal we ended up where we are now, waiting to apply 1/16 tank tracks to the robot. I've seen toy bots with 3-4 wheels each side but not sure how they work or what the advantages are, also seen cone type wheels that are super flexible but I think would be limited by weight.

These guys are developing a single wheel robot.

single wheel robot

Check out this neat design. Could make a robot like Rosie on The Jetsons cartoon

Omg I want to make a ball balancing robot!

Absolutely - WOW - There must be an infinite number of applications for a ball Robot like that..

I need that!!!!

Ok, so you think you've seen it all - check out how this robot gets around !!

Whilst the flying ball robot looks amazing, I'd question how long it fly around, it must draw a truck load of power !!

They for sure do , but imagine if it could recharge itself

it allmost could if you rewound it added some magnets and palsed its power at a high rate that could do it or atleast cause it to have a c.o.p in the 90s

I'm sure the military are working on that gadget - anything that can roll and fly can just about go anywhere.

na thay not interested in toys like that as it dont cost enuff for them lol

I think the military are working on nanobots (tiny insect type robots) and sand slither robots that discover mines (prototypes used in Iraque). I read that's where the guy that developed Robosapien - Mark Tilden - came up with his snake bot to discover mines and ironically also makes up his collection of commercial toys (not the military version - of course). Mark Tilden is worth reading up on for ideas on how robots move and how he believes they should be as simple as possible. He was a real pioneer in robots both for NASA and the Wow Wee Toy Company (Robosapien and several others).