running 49 motors???

How could you get an arduino to control the the individual movement of 49 motors. Or is there a better way to do it. I'm looking to do something very similiar to the link in the post below.

thanks,

http://www.i-m-a-d-e.org/morpholuminescence/comment-page-1#comment-889

If you're wanting a way to control a lot of servo motors from the Arduino, probably the best way is to use some form of serial servo controller.

This is a controller that (generally) hooks up via a digital pin, and you send TTL serial commands to it (using either the hardware serial port if it is available for use, otherwise you can use a software serial library for other pins), and it will position the servos (and keep them positioned - it has its own microcontroller built in for this).

The controllers generally handle from 8-16 (sometimes 32) servos at once, and can be typically set up to be daisy-chained in an addressable manner so that only the single digital pin is used. This generally allows them to control up to 256 servos.

Different places sell them, but the two you will likely run into are the Scott Edwards Serial Servo Controller, as well as the Pololu line of serial controllers (they make both servo as well as regular DC motor controllers; almost all of their controllers can be daisy-chained on the same bus, and their servo controllers understand the simpler Scott Edwards protocol in addition to the Pololu protocol, which is more feature-rich).

The action is slow enough that you could do it with shift registers feeding the motor drivers. Not clear whether they are using simple DC gear motors or stepper motors (or maybe servos?)

Richard, the article linked to mentioned specifically "servos"; nothing more than that, though, which is why I mentioned the serial servo controllers. Since such controllers tend to be relatively cheap, they are the best method to use to keep you from pulling you hair out trying to figure out why things aren't so stable when you add more servos and shift-registers to expand the system.

I don't exactly know the limits of how many shift-registers one could use to control how many servos (it seemed to me the servo controllers made better sense from a processing perspective on the master microcontroller), but to me it would seem low before you started seeing jitter and other timing issues, unless you had fast registers and tight code.

:)

I didn’t read the whole article carefully and missed the mention of the specific kind of motors.

No problem - there was only one blurb, and it was buried at that. It only mentioned “servos”, so I am making a big assumption that they meant “hobby servos”.

There seems to be more “petals” in that project than what even two Arduinos could control, unless they are using Megas, or some other variant - or if they are “doubling up” the number of servos being controlled by each pin.

So that would be something to keep in mind as well; I could see building a smaller version of this using a single Arduino, the Servo library, and having each pin control more than one servo (though the multiple servos being controlled on the pin would move the same amount). The same could be applied to the LEDs or other light behind the petals. If you could build this smaller version, and could group the petals and lights into useful units, then it could work out well - which may be what the artists were doing.

:slight_smile:

For smooth slow servo movement, a servo controller with speed control would be needed. Below is a possible servo to use for very light weight construction. At only $2 each they tend to be backordered often.

http://www.hobbycity.com/hobbycity/store/uh_viewItem.asp?idProduct=9549

First off thanks a lot, I'm really new to this stuff so its been really hard to find this kind of information.

They article doesn't mention it but one of their diagrams below show stepper motors, I'm not quite sure which would be better servo or stepper motors. What i do know is that when i look for servo motors they are more expensive. Would there be a benefit of using these over servos?

What i need to do is similar in that i need to move many strings individual distances, what would be best for that? Cr0sh's comment about a serial servo controller seem very promising. For 49 motors would I need many arduinos to control these motors? Are there any tutorials off the top of your head that cover doing this?

Thanks again guys,

The below pix look like stepper motors are used, possibly with an arduino board and controller. I think the bottom wooden mirrors probably use servos.

http://flickr.com/photo.gne?id=3543063187 http://flickr.com/photo.gne?id=3543856122 http://flickr.com/photo.gne?id=3543062079

http://www.youtube.com/results?search_query=wooden+mirror&aq=f

does that mean they need an ardunio, controller, and motor per piece? Ouch that could get expensive real fast. do you happen to know what the wooden mirror uses to run its processes?

does that mean they need an ardunio, controller, and motor per piece?

No.

You can control many motors from the same arduino. You can make each arduino output control 1 servo.