How to rotate a servo continously?

[kampi]

Hello!

I am beginner with robotics. I bought a simple arduino compatible robot (http://www.robotshop.com/en/dagu-mini-robots-kit.html). This little robot has 4 little servos (http://www.jameco.com/1/1/3861-rs001a-dagu-micro-servomotor-8g-1-5kg-cm.html). I rebuilt this robot, how i want it(i "gave" him wheels and arms), but right now, i am having trouble to rotate a servo continously. As i see it, this servo rotates only 180 degrees. After that it starts to rotate backwards. Which is bad, because, i used two of these servos to attach wheels to the robot. So now i cant get my robot to roll.

Is this behaviour normal? Or am i doing something wrong? Is there maybe an other, so i can rotate my servo continously?

Thanks in advance! (And merry christmas!)

[jkerns]

Much of this sort of thing can be found by clicking on the "Robot Tutorials" link on the upper right corner of this page.

http://www.societyofrobots.com/actuators_modifyservo.shtml

[Inigo Montoya]

Hello, nice to see someone run into the same problem I had, it means I can help.  My entry into the world of servos and micro controllers was similar.

Servos, straight from the store, work in roughly a 180 degree sweep, and the signal from the micro controller controls the POSITION.

Many servos can be modified for "continuous rotation" but there is a sacrifice.  Position becomes unknown, the signal instead controls SPEED and DIRECTION of rotation.  To have all of the above is a very expensive device.  The best way to see if your specific servo can be modified (this is usually permanent), you will have to consult Google.