How would the Servos Work?

The follow spot that I plan use, like most follow spots, has a colour magazine attached to the front of the light. This magazine allows colour filters to be moved in front of the light, consequently changing the colour.

Unfortunately this system is a manual system and cannot be controlled by a computer. As a result I have decided to construct a method of controlling the motors using servo motors. I have already highlighted how a servo motor works; pulse coded modulation controls how far the motor will move. In order to harness this ability I will have to send a pulse to the servo every 20 milliseconds. I am uncertain however that the computer that I am using will be able to generate pulses that quickly. This is something that will have to be tested. If the computer is able to generate pulses this rapidly I will be able to control the length of the pulse that is sent to the servo thus controlling how it moves. If this can be controlled, I will then be able to attach a metal arm, which can be attached to the colour filters. As I have tried to highlight on the picture below the colour filters rotate around a central point, moving into place in an arcing motion (represented by the arrow).



I will then be able to attach an arm to the motor that will move the colour filter into place and back again. In order for such a system to work each arm would have to a motor attached to it. Although I will need to make a final decision about the colour scheme I am currently thinking that I will use red, green and blue. If I stick to this plan I will have to have four motors for every light, which will amount to twelve. There will be four motors per light as I also plan to utilize the metal sheet at the front of the magazine, which will make the little appear to turn on or off. This may prove to be a problem, as the experimental interface board that I am using to detect the signals from the PIR detectors only has 8 digital outputs, so I would need to purchase another one in order for this plan to work. As you can see there are several potential problems with this idea that will have to be tested. I will also have to test how the arms can be attached to the motor, and if I can gain the necessary movement from them. If this system cannot be implemented properly I will have to find another solution to control the colour filters.