Precision mini winch (with position feedback) for kinetic lighting?

Question

I am trying to create a kinetic lighting installation for my home, above the dining table (see example here https://www.youtube.com/watch?v=-DZ18DNbjTQ ). Obviously I will use max around 20 lights.

The solutions I have found either cost above 100K (!) or are based to huge, theatrical stage oriented fixtures from China.

So I have decided to attempt to create such a system by myself (with the help of an experienced friend).

The first thing I would need is a DC servo motor / winch which would give some form of position feedback (so that I can keep the lights in sync) or even better a winch that will allow me to roll down the light by 20 cm or to a specific position and do it accurately. The whole idea is to have a system where I will be able to set the position of each light with ease and accuracy. The weight of the light will be slow - in essence a led strip within a 15 cm glass bowl.

Any ideas where I could find parts that could help me implement this? I am open to any control methodology - e.g. dmx, custom arduino control etc.

Many thanks!

ORBIS-FLY - the inspiration:

Answer 1

Radio Controlled Model sailing boats use "Servo Winches" that can be driven with standard servo interface libraries from something like Arduino mega. The Arduino should have enough outputs to drive all the servos separately. Servos have the advantage of being able to control their position directly, with the electronics inside the servo taking care of any error.

If the servos are too noisy, they could be located remotely from the display using using something like fishing line. This an interesting project.

Answer 2

The simplest option to do this will be to use a stepper motor. Get yourself some cheap 3d printer stepper motors, stepper drivers, something like an arduino to control them (or maybe multiple Arduinos).

Basically the steppers take a "step" signal which turns them 1/200th of a turn in either direction. You can count the steps to keep track of where they are. As long as you don't overload the motor it will keep position perfectly over time.

Now for the downsides: the steppers only "step up" and "step down", so they won't know where they are if you power-cycle the system. To fix that you'll need to create some kind of switch that triggers when the lamp is retracted all the way. You can use this to "home" the lamps at startup. These are typically called limit switches.

The other downside is that the steppers will not hold their position when powered off, so the steppers will have to be constantly energized. This is sort of wasteful, but it's only going to add up do a 10-20 watts for your whole system so you might find that to be acceptable.