hackaday.com: [Pete] needed a rotary encoder for one of his project so he set out to build his own. As the name implies, a rotary encoder measures rotation by encoding “steps” into electrical signals which can be measured by a microcontroller (or used in numerous other ways). Knowing the degrees of movement for each step will allow you to calculate precise distance traveled in applications like robot wheels. Or you can simply use the rotating shaft as an input device which navigates menus or settings.
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There are all sorts of encoders and feedback devices available today, and all of varying styles and complexities. The rotary encoder is one of the more popular types used in stage machinery. These encoders can range some simple contrast sensing readers like this one that monitor a single motion, to stacks of disks within a housing, all with different patterns that define a motion. These encoders can even be located in different places within a system. We can and often, place one on the winch itself. We can even do something similar on a turntable, by strategically placing the photo-metric sensors and a corresponding contrast tape, we can define the motion of the unit and its actual travel onstage, reducing any errors that might occur.
I never knew how rotary encoders were able to sense direction. I've used rotary encoders for projects before to get an analog input. I originally wanted to use a potentiometer, however I needed a full 360 degrees of input in order to control exactly where a motor was turned. The use of encoders was a game changer, I not only used it for input, but also to control the out put. With the use of the encoder, I was able to turn a simple DC motor into a step motor more or less.
This reminds me of one time during my senior year of high school when one of our color scrollers became dysfunctional. Basically it wasn't responding properly to the data we were sending it from the console, and it became apparent that the issue was with the encoder on the motor that wound through the scroll. For a long while we fussed with trying to both clean this encoder as well as realign the sensors so that they could function in the way described by the article. I think that the kind of ingenuity that goes into figuring out how to accurately control rotation is something that we should all look at as problem solvers. These types of mechanisms are things that a majority of society takes for granted, most people don't care how the machines that make their lives so much easier work as long as they do.
This is really cool! I love how simple the solutions are to some seemingly complex problems. Rotary encoders are extremely useful, and they work in fairly simple manner. But using two readers to determine direction of travel is ingenious, simple, and elegant.
This is actually a really useful article for anybody looking to understand encoders in a practical and down-to-earth way. Especially with current projects I am working on, this article has clarified and broken down some really key concepts for me.
The demo device seemed to be constructed fairly easily. And from what I’m seeing, the whole assembly costs about 1/5 of the cost just a single, inexpensive encoder. It makes me wonder what kind of low-res applications we might find for it on stage: Positional information for manual follow spots, tracking wagons, or anything that has any sort of rough position information.
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