The last 3D printing

After several tries we finally printed a triangle with the right size for the led strip.

Several tries : 3D priting (black) and laser cutter(brown)

I also used a laser cutter but the led strip could not fit within holes again. To use the laser cutter we need someone trained to insure the safety so it was simpler for us to use the 3D printing. The main issue was the fact that we didn’t have accurate enough data. I measured with caliper and re-written the placement of holes algorithme on openscad. After several tries I printed a triangle with the right size and the data were to be very accurate (~20 micron). I took some times because each printing took 2 hours.

The last triangle (orange because orange is the New Black) 

Lucas soldered the led strip, tied the triangle and the led strip together and we have our prototype.

Now I am working on the programming of the AHRS. We use Ultimate Sensor Fusion Solution designed by Pesky Product. It is made up of EM7180 Sensor Hub coupled with the MPU9250 IMU. The EM7180 uses a Kalman filter and provides in output quaternions.

[bouLED] 3D printing

After we made a model of our icosahedron’s one equilateral triangle using openscad. This is the first time I used 3D printer. After two hours, the first print has finished.

The first version

As you can see, the main issue was the led strip can not fit within holes because widening holes I didn’t change the spacing’s dimension between two LEDs and two rows. So the alignment doesn’t match with our LED strip. I fixed it and I tried a new print. After two other hours, the second version is here.

The second version

The alignment is more appropriate, but it’s still not perfect. The reason remains to be determined I think we should to have more accurate data (below millimeter) and if it’s possible with 3D printer available. Tomorrow I will fix and retry another 3D printed triangle.

[bouLED] Visualization shenanigans and 3D modeling

A new simulator

I was trying to replace the cube in Lucas’ simulator (see here) by an icosahedron and add some kind of clue of the icosahedron’s orientation, but the Python 3D library we used, VTK, was getting on my nerves. Adding an icosahedron worked fine, but I wasn’t able to change its colors, and what’s worse, even when using the default colours (blue everywhere), one of the model’s facets stayed red, which was pretty jarring. I also added an axes widget that was supposed to rotate with the icosahedron, but to no avail: it wouldn’t rotate. One of us had to go, and it wasn’t going to be me.

Alexis sent us a script 11 days ago that displayed a colorful icosahedron with PyQtGraph, which provides a light abstraction over OpenGL. It made a nice starting point for a new simulator, with a rotating icosahedron, a fixed grid and axes. Behold !

Granted, it’s still ugly, but it works and PyQtGraph is way nicer to deal with than VTK.

3D modeling

We’d like our icosahedron to have 13cm equilateral triangles, which would make it fit snugly inside a 25cm transparent spherical shell for protection.

At first, we wanted to build the icosahedric display with triangular PCBs, but last week, our teachers suggested trying to 3D print a facet and put a LED strip (one the ubiquitous APA102 strips) on it, to check density, and if triangular PCBs are really necessary: perhaps we could have a PCB inside the isocahedron control LED strips glued to the facets.

Hichem and I made a model using OpenSCAD to understand how to lay the LEDs out. It’s a pretty neat piece of software for 3D declarative modeling. I really appreciated that because in this case, we had to be explicit and think about our constraints. So far, here’s what we’ve got:

The LED strips are meant to go under this. Using this model, we see that with the strips and dimensions we chose, there’s 111 LEDs per facet, so 2220 LEDs overall. That’s huge, and we’ll have to discuss whether having that many LEDs is feasible (or desirable, for that matter).