Getting more throttle resolution from an old RC Controller.

I have been flying my tricopter around lately, and have been getting a bit better at not running it into things. However, one thing in particular has been bugging me about the my controller for the tricopter. The throttle stick resolution has felt really low, especially when compared to a friend's newer and nicer controller. When flying it around at the Makery there was about one notch of difference between it barely skidding around the floor, and heading straight to the ceiling.

So, tonight I took it apart to see what I could do about getting finer control out of it.  It turns out there is just a small spring arm with a bump at the end riding on notches molded on the back of the joystick. I believe this is pretty standard from what I’ve seen online.

This is one of the times where having a 3D printer, and knowing how it works pays off. I needed a very specialized piece with several notches running up a curved surface. This immediately reminded me of the surface that 3D printers make as they lay down each layer of an object. So I took a few measurements, fired up the 3D modeling software and made a “cap” that will sit on top the current notches, so that the spring rides on it instead. You will notice that the 3D model has a perfectly smooth surface, but we get the ridges that it needs by setting the layer height for the printer.  I measured the old notches at .5mm on center, so I set the layer height to .3mm for the first try.

After trying to print one by itself, and having it end up all blobby and malformed, I remembered to turn the “cool” setting on in Slic3r,  and put five of them on a plate to make sure they have time to cool between layers. I also turned the fan on, which I believe is why they all came detached from the build platform halfway through the print. After turning that off and trying it again, 3 out of the 5 finished properly, and I was able to test it out. It worked great! The new piece fit right over the top of the old piece and the spring lined up perfectly on top.

It turned out to be a great improvement over the original. The ridges were smaller and more rounded, which gave it a lighter feel, but the spring was compressed more, so it still felt like it was strong enough to hold position. And most importantly, it had better resolution, and I can fly it around without worrying so much about it running into the ceiling while indoors.

All in all it took about an hour from idea to completion. I would say it’s definitely worth trying this if your controller is like mine.

 

April 5th – Tricopters and SCADA

The next regular meeting will be at the space on Tuesday, April 5th at 7pm. We’ve got two presentations:

Brandon will be showing his progress on the remote controlled Tricopter he’s been working on (as seen on this site); If you’re unfamiliar with exactly what a Tricopter is, it’s like a quadcopter with just 3 rotors.

Nick will be pre-presenting his paper on SCADA, an acronym used to describe the systems used to control the supply of electricity, water, gas, and so much more. Because of their high profile status, SCADA systems have been garnering a lot more attention from unsavory elements. This talk represents an introduction to SCADA systems and attempts to look at the challenges in securing them.

The space will be open starting around 5:30 on Tuesday through whenever people leave after the meeting. (Though the meeting typically runs from 7 to 8 or so). See you all then!