Let's Make Robots!

Which will work better modified servo or stepper motor

I want to build a simple robot system to do the following:

I want three 3 modes to run off a toggle switch or cycle the modes through a push button and an activation (run program mode) button

Mode 1

What I need it to do is when the "run" button is pressed the motor (servo or stepper) rotates "x" degrees 1 time to triggar a mechanical gear / lever


Mode 2

What I need it to do is when the "run" button is pressed the motor (servo or stepper) rotates "x" degrees 5 times is say 1 second to triggar a mechanical gear 5 times


Mode 3

What I need it to do is when the "run" button is pressed the motor (servo or stepper) rotates "x" degrees 30 times in 1 second to triggar a mechanical gear 


Id also like to build the system as cheap as possible

What would be a good setup to use Im not to sure exacly what to use I was thinking of the Solarbotics Ardweeny

for a small package but not sure if it would work the way I want it

any help or sugestions or alternate ideas will be greatly appriciated 



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after some more research on this site a cheap way to start is with a

picaxe 08M to start kit with?

Your choice of microcontroller is up to you. If you are more comfortable with a Basic-like language, then go with a Picaxe. If you are OK with a C++ like language, an Arduino is a fine choice. There are others as well, both those are both affordable and accessible to most hobbyists.

The exact model to use depends. You only need one digital output to control a servo. You need an input for your control switch or button. You may also want to use another input to monitor the state of the lever mechanism.

Hey, there.

Either idea might work , depending on your mechanical set up. You may want to provide a sketch of that for our reference.

An unmodified servo could turn up to about 180 degrees. With a microcontroller, you can command it to any position within that range, at any time you want. That might be perfect for your needs.

If you need more than 180 degress, you could add some gearing to the servo. You would sacrafice some granularity of control (how small the step sizes are) for greater range of motion.

I don't think that a servo modified for continous rotation is a good approach for your application at all. With a continous servo, you can control speed and direction, but not position.

A stepper motor is also another good choice. With a stepper, you are not limited to 180 degress, since it can rotate continously. You will have a set step size (how many degrees/step). You will need a driver circuit to send a sequence of pulses. Jones on steppers is the best reference I can provide for learning about steppers.