F3NR1R is a little shoulder-mounted robot based on a fennec fox, one of the most adorable creatures I know. His AI brain consists of a Raspberry Pi 3 with a Neural Compute Stick 2, running OpenVINO. (Here's my guide for setting that up!)Design
I chose to laser-cut F3N's pieces, first out of cardboard, because it's much faster than 3D printing pieces, and going into the office is a very rare luxury under quarantine.
I compiled a bunch of pictures of fennecs, and used OnShape, paper, and my trusty mm ruler to draw a few layers that would sandwich the camera and servos in F3N's head. The Assembly tab allows me to place all the layers in space, see how the sizes match up, and adjust the design before sending it to the laser.
The servos are mounted diagonally, so that with a single motor for each ear, I can get the multi-axis movement required to make the ears perky or droopy – a key mode of expression for these little guys. :)
I figured I'd give him three eyes, with the third one being the artificially intelligent camera, but for now I'm just trying to get him up and running with the one. :)
All together, F3N has 13 laser-cut parts: two back legs, two front legs, his torso (tapered toward the back), two parts per ear (to sandwich the servo horns), and four face layers (including the tiny nose nubbin). I might add more nose nubbins to give him a longer snout.
For this prototype, I've used hot glue and double-sided foam tape to attach parts together.
The body is encased in a sleeve cut from an old pair of tights. He'll have a little fox tail as well, which the cables will run through.Electronics
F3N's brain is set inside his torso. It consists of a RasPi 3 Model B running Raspbian Buster, connected to a Neural Compute Stick 2 running OpenVINO.
There are a couple more pieces stacked on top, for hardware and audio interfacing. Back in the day, we got these Snips + Seeed Voice Interaction kits, and I never really got to use them before Snips was acquired by Sonos and readied for shutdown. But the hardware setup was beautiful. The ReSpeaker 2-Mics Pi HAT provides stereo microphones, as well as two Seeed Grove expansion ports, a mini speaker, and audio out, so it'll be a snap to add extra functionality: servos, relays, an informational LCD, or anything else I can dream up.
On one of those Grove ports, I've put a 16-channel PWM expansion board, which shoudl be able to drive F3N's servo motors.
This is all going to be fairly hard for me to program, as I'm usually more about the hardware components! But if I can get it working, it'll be a great little platform that could power a huge variety of companion bots.Power
I always try and provide separate power to my robot's brain and servo motors, for a couple of reasons: it's easier to troubleshoot, and I can unplug the motors if I want them to shut up for a second. :)
I like being able to hack on my bots at my desk, connected to wall power, but when I wear them, they need to run off batteries. F3N's brain (the Pi) has power broken out from its 5V and GND pins, because if he had a USB cable sticking out of his side, that would look... rather messy. I used an XT60 connector on the other end of the cable, and put its mating connector on a wall plug capable of 5V/4A for plenty of juice. I also made a USB-A cable with the complementary connector, which I can plug into my high-amperage 5V USB battery for portability.
That battery has two ports, and can also supply the USB cable feeding independent power to the 16-channel PWM driver.Behavior / Programming
To be continued!Fun fact
F3NR1R is named after one of my family dogs. He's a beautiful, floppy terror. :)