I’m currently squirming in excitement in my command chair in the Pleasure Dome (my office) because I’ve just seen something that made me want to squeal in excitement. I’ll tell you about this in a moment, but first let me briefly set the scene.
Earlier this year, as described in my SMAD: Steve and Max’s Awesome Displays blog, my chum Steve Manley and I decided to create a small display board with 45 tricolored LEDs. These SMADs can be augmented with 3D printed shells to provide 29 or 45 segment displays.
I used my SMADs as the “eyes” in two pseudo robot heads — one with two 29-segment SMADs, and the other with two 45-segment SMADs. In this video we see my two heads “talking” to each other in Morse code by flashing their SMADs.
In my later Don’t Mess with My Head! blog, I explained how Steve had created modified facias (face plates) for the front of our SMADs. These new facias have a slight curve to them to make them more “eye-like.” Although this curve is only 5 mm tall in the center, it really provides an interesting effect, especially since the diffuser remains behind the facia, thereby allowing the viewer to see the segment partitions as shown in the first image (this image also reflects the new SMADs presented as part of a larger “eyeball” assembly).
In my more recent blog, I also mentioned that someone — we’ll call him Matt (because that’s his name) — had suggested that I create a new head with pan-and-tilt servos associated with each of its SMAD eyes and also pan-and-tilt servos to control the head as a whole. Since I’d been cogitating and ruminating along these lines already, this was all the encouragement I needed to leap into action.
My first thought was to use something like the Mini Servo-Driven Pan-and-Tilt Kits from Adafruit. In fact, I’ve purchased two of these to be playing with (I’ll be waffling about these more in a future column).
The term gimbal refers to a pivoted support that permits rotation of an object about an axis. Take a close look at the pan-and-tilt kit image. This is the way I’ve always seen this sort of thing implemented before, with the two motions isolated and separated from each other.
We start with a sub-assembly that consists of a gimbal with an associated servo that performs one of the motions such as tilting. This entire sub-assembly is then mounted on top of a second sub-assembly that consists of its own gimbal-servo combo that performs the other motion such as panning.
The thing is that Steve has implemented this pan-and-tilt functionality in a way I’ve never seen before. Take a look at the third image (the back of the SMAD eye will be attached to the blue ring at the far side of the image).
The light-gray arms attached to the servos are known as “horns” (don’t ask me why). The way I’ve often seen these horns connected to the things they are controlling is via thin pieces of relatively rigid steel wire, with the end attached to the horn simply being bent into a loop that’s threaded through a hole in the horn. By comparison, Steve has used thicker, more rigid steel bars with each end screwed into a sophisticated little ball joint (item number 253796473328 on eBay) with a brass ball imbedded in a tough black plastic surround. These brass balls, which have a 2 mm diameter mounting hole in the center, can smoothly rotate through 360 degrees in any direction.
What Steve has omitted from this image is the bolts attaching the ball joints to the servo arms and to the back of the SMAD eye assembly so that we see the holes in the brass balls and better understand how everything works.
Steve also sent me an animation illustrated in this video, along with his kind permission for me to post it on my Cool Beans Blog YouTube channel.
To be honest, when Steve first told me what he was intending to do, I simply couldn’t wrap my poor old noggin around how this was going to work. Whenever I tried to visualize how one servo would perform one of the pan or tilt motions without fighting the servo performing the other motion, my brains would start to leak out of my ears.
Now that I’ve seen this animation, I for one am blown away by Steve’s innovative solution to this problem! How about you? Have you ever seen anything like this before?