newby servo question

[greywanderer012345]

I'm very new to robotics. I just got most of my materials to build a version of the $50 robot. It was the Lego Mindstorms robot that got me interested in robots in the first place, and most of the Lego robot parts are very similar to regular robot parts(IR sensors etc) except the lego parts are meant to be mounted on other lego parts and are more expensive. Let me get to the point though... I've been reading about hacking servos so that they can rotate continuously. The concept makes sense, but I'm suprised to not see more servos that can rotate continuously AND give angle feedback. The Lego Mindstorms servos are able to do this. Is it possible to modify servos to do this?

[rbtying]

As far as I know, the LEGO Mindstorms "servos" are really motors with encoders attached, not a potentiometer like in a hobby servo.  Generally it's more effort than is really necessary to go and add an encoder to the servo shaft, most people just add it to the wheel (tutorial: http://www.societyofrobots.com/sensors_encoder.shtml) for the same functionality. 

[waltr]

The standard hobby servos have a huge market so can be produced fairly cheep. Hacking them for continuous rotation allows us to obtain an easily controlled gear motor for a low cost.

not see more servos that can rotate continuously AND give angle feedback

These have a much smaller market thus are available but more expensive.

[greywanderer012345]

Thanks.