Pov led hula hoop

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Pixelatedraverrabbit
 
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Pov led hula hoop

Post by Pixelatedraverrabbit »

I have been going through the information on the website but I'm hoping I may be able to get some additional guideience in regards to a 'smart led hoop' or a pov led controllable hoop. I understand that I would want to get the dotstar LEDs, I would prefer to be able the change the batteries but if I had to I could use a rechargeable one that remained in the hoop while charging.... But what would be the best micro controller, and I gave seen allot of info on different led pov projects, but I'm unsure how to proceed like .... With an accelerometer and a gyroscopic sensor.... I was hoping you could help!!!

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adafruit_support_mike
 
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Re: Pov led hula hoop

Post by adafruit_support_mike »

Pixelatedraverrabbit wrote: Wed Sep 28, 2022 9:30 pm But what would be the best micro controller
The main concern will be physical size: you'll want something small enough to fit inside the hoop.

The actual microcontroller is less of a concern because our 32-bit boards have more than enough programming resources for your project, and they come on small PCBs. I'd suggest the SAMD21 ItsyBitsy or QT Py:

https://www.adafruit.com/product/3727
https://www.adafruit.com/product/4600

Both are 0.7" wide, and the QT Py (0.8") is about half as long as the ItsyBitsy (1.4"). The main difference is the number of GPIO pins available for you to use.
Pixelatedraverrabbit wrote: Wed Sep 28, 2022 9:30 pm I would prefer to be able the change the batteries but if I had to I could use a rechargeable one that remained in the hoop while charging
That will be a major design issue. LEDs can use a lot of power, depending on how many you have lit at any moment.

More generally, all battery-powered systems force a design tradeoff between the size of the battery and how long the battery lasts. The process is to decide how much power you need, design the battery system, then fit everything else around that.

Replaceable battery systems usually require more space than non-replaceable ones. At minimum you need a path to get the battery in and out, including covers and mechanical closures. It's generally doable, but takes more work. Non-replaceable batteries can be buried wherever is convenient for the design, and can be glued in place with less than a millimeter of clearance beyond the battery itself. You do need to run a charger connection to non-replaceable batteries, but that can also be done in a compact way.
Pixelatedraverrabbit wrote: Wed Sep 28, 2022 9:30 pm I'm unsure how to proceed like .... With an accelerometer and a gyroscopic sensor.
That's mostly a code problem, though I'd suggest that you do use both an accelerometer and a gyro. You'll probably need one of each at multiple points around the hoop.

A hula hoop has no fixed center, and generally rolls around a central body.

For simple rolling, one point on the hoop is stationary. That point feels no linear acceleration, only rotation. The point at the opposite side feels more linear acceleration than any other point on the hoop.

To make things more fun, the circumference of the body inside the hoop is smaller than the circumference of the inner hoop itself. For one swing around the body, the hoop makes less than one rotation around its own center.

A hula hoop is even more complicated because the central body is moving. The point of contact between the hoop and the body feels linear acceleration at an angle to the surface of the hoop, which pushes the hoop to rotate faster.

Your first programming problem will be to capture a description of the motion. The most effective way to do that will be to compare the rotation and linear acceleration at opposite sides of the hoop. Ideally you'd have sensors at every point on the hoop, but that isn't feasible. What you'll have to do is capture readings from sensors spaced around the hoop, and extrapolate the motion of the hoop from those numbers.

As with all design problems, that will be easier if you break it down into smaller pieces. Start by taping sensors to the outside of a hoop and moving it on the floor to see what acceleration and rotation readings you get. As you do, you'll develop a better intuitive feel for how the readings fit the motion.

Once you can describe the motion of the hoop, you'll need to map that onto a set of coordinates for the POV display. Rotating systems are usually easiest to describe using polar coordinates (angle from a 'forward' direction and distance from a center point), but you'll have to decide where to put 'center' in a system where everything moves. That will take some experimentation to see what looks best.

Fortunately, once you've chosen a center, it will be easier to define and keep track of a 'forward' direction, and to calculate distance from that center.


Overall you've chosen a project that's more complex than the hoop itself. It will take research, probably some study, and a lot of trying things out.

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