I'm strugling for a while with soft-hardware to do all the movements as close as with my graphical GUI controler. (kinematic movements)
The problem, most servos have a range of 180°, no feedback. If you want to have full 360° you have to get another servo 'continues rotation' here you cannot change the speed. And lots of other anoying things happen when I got further in designing the software.
I searched the web for a few houres and found some intelligent servos, lot of them where to expensive and had some bigger dimensions. But after a couple of houres later I found something that could be the solution! A good price, almost the same dimensions as a normal servo, very smart and 320° degrees of freedom or software changeable to continues rotation. choice between two types of motors 12Kg/cm or 24Kg/cm for this project.
The 12Kg/cm will be the cheapest one and has all the same features like the other one.
Even when you take two of them for the same work it is a lot cheaper so I decided to go for this product, I ordered a few to do some tests, if they will solve all my problems I will change the design with these boys!
I want a robot arm not to expensive, something where you almost can compete with a real robot arm! Something more than a piece of plastic that moves without any precision.

See ya when I got my parts and played with it :-)

It's super easy to connect up to 200 servo on one serial bus.

some specs

I made a preview of the robot arm with master slave servos to get more power, it has 8 servos DRS-0101(12kg/cm) and for the base 1 servo DRS0201 (24kg/cm)
The benefit of these motors, you can set the torck on and off so you can move the arm yourself and record the feedback position.

This could be the new 'SMARTrobo' 8-) when I'm satisfied with the results!

Another fine feature is the rgb light on the back of the servo that you can command through the serial bus.

A small movie shows the driving of 8 motors with 1 serial cable connected.