I am very new to Arduino and this topic in general but have come up with a project that will utilize motorized faders (as many as possible) that are controlled by an Arduino. I know that you would run out of pins very quickly if you were trying to control them directly from the board, so what products are out there that would allow you to control lots of dc motors and faders (potentiometers) from a single Arduino board? Is there a particular Arduino board that would be better suited for this project? This might be similar to a large scale motorized fader MIDI setup.
I'm thinking [u]analog multiplexer[/u] chips. But, you'd need inputs & outputs (for the positional feedback) and it might get tricky if you need to move more than one fader at a time.
FYI - The Arduino ATmega chip has multiple analog input pins, but internally there is only one (multiplexed) analog-to-digital converter. Under "normal conditions" it runs fast enough that it appears to be reading the inputs simultaneously.
So why have you taken such a huge and complex task as trying to control 100 motorised faders!
Electronics, like many other things does not simply scale up to such large numbers without a lot more engineering skill. Mind you it seems a common thing these days of over ambitious projects tackled by beginners. What tends to happen is they spend a lot of money and give up.
Forget the scaling up until you have the skills to control and understand what is needed for controlling just one, that will be challenging enough.
The biggest problem is making sure they do not hunt, that is buzz when they are still. Then the next problem is to disengage the Motors when you detect a touch on the fader by the operator. This normally involves a capacitive touch sensor on each fader.
Then you have got the things that maybe you have thought of already like reading the position of the slider and moving it to the required spot.their is hardware control of the motor with a h-bridge and the algorithm to move it at such a speed that you don’t get overshoot and yet it doesn’t take forever to get to the right place.
Then their is the analogue electronics in the circuit of what ever the fader is going to control. You have to make sure that the digital noise doesn’t get into those circuits.
It is a complex process controlling just one let alone 100 of the buggers, so please get some skills first before committing to such a large and expensive project.
You are right that it is definitely an ambitious topic. The first goal would not be to get 100 faders moving at once, but to start smaller. Many of the tutorials online that I have seen have examples of moving one or two faders at once. The problem arises when I want to scale the schematics that they used up to more pillars. I would not be buying 100 faders off the bat, but am more looking for products and schematics that can grow as the project does. But the complexity is a concern for my experience level.
Thank you for your thoughts on the project, and I will definitely look into what you brought up!
Very thought through and personalized project. Watching the videos from the project website, I liked how the team tried hard to incorporate her original workflow and techniques into the new device. Impressive!
To spare everyone details at the start of the thread, I didn't really describe what I was planning to use the motorized faders for. Coming on about a year ago now, I had the idea to make a table which displayed a 3D raised relief map from pillars that could be raised to various heights. The landscape would be approximated by the pillars and they could be programmed so that the table would be able to first display Mount Everest, China and then morph into Crater Lake, USA or something like that. This project was well beyond my reach since I would describe myself as a beginner programmer (Python). Over the last few months, I have begun assembling a team and the project seems to be getting closer, though is still a very long term goal with opportunity for setbacks. I have created a program which converts DEM files (GIS elevation files) into a readable format for something like an Arduino or small computer to read, and am now headed towards more of the hardware side of the project. We have been searching for the best way to drive the display of the table, and have gone through many different theoretical variations, though have not put many into practice. We came to the motorized faders because of a project out of MIT Tangible Media Group that seems somewhat similar to what we are looking to accomplish.
If you or anyone else has better solutions for the motion of the table, the team is very receptive to suggestions. Or if you are interested in learning more about the project, you can PM me. I will attach the project from MIT and some of our projects designs to this post.
Scaling up in engineering is often tricky indeed. You'd be surprised.
There's operating one motorised fader, then there's the scaling up to 100 of them. The latter is not just the sum of the parts, it's more than that.
You may get power supply issues, timing issues in the microcontroller you have to take into account when writing your code, and even the practical issue of coming up with a wiring scheme that does not make the final product look like a pile of spaghetti (or a breadboard that can't be routed on less than five layers - but which with some rearrangements suddenly barely needs the second layer). Devices may start to interfere in all kinds of unexpected ways. And when you think you got it all under control your sketch has grown too big...
Now reading your further project description, I wonder whether a motorised fader is what you need. You don't need the additional complexity of having to react to and record people making adjustments to your fader settings. This sounds much more like a job for some kind of linear actuator.
To operate hundreds of them is still not too easy, but it's going to be a lot easier than motorised faders - and these actuators have the power (they can get really powerful) and the range (can be seriously long) to push up the liner that forms the surface of your mountain range.
Thanks for that.
I would not use a motorised fader for that I would use a liner actuator. Their are many types of design and some can be expensive however you can make then yourself. Their are a few designs but this one is the hackiest, their are a few variations of that as well.
Our team has discussed pneumatic versus electric actuators before and that was the original idea for the project. My personal worry with pneumatics is that until the number of actuators is increased to something like a 60x60 table, the cost of getting everything started might be higher, whereas with electric actuators, the scaling itself would become expensive. But maybe it is time to revisit some of those ideas again. And I definitely see the point now of the unneeded touch sensitivity of motor faders.
Thank you all for the advice that you have. Really is helping me think through this project. There is not a deadline for the project, and is something that I enjoy working on in my spare time. Brings together a lot of fields that I haven't worked with in the past (GIS, programming, Arduino, design, etc). Definitely learning a lot!
