How to Get Ahead in Robotics

Those with a hobby in just about any area of technology will eventually find an irresistible urge within themselves to build their own robot. And why not? Robots are just plain cool, and building one takes skills in mechanical engineering, software development, artificial intelligence, and much more — so whatever you are into, building a robot is a great way to practice your craft and further your education.

YouTuber allen's lab is a techie that recently decided to go down the long and sometimes frustrating, yet always rewarding, path of robotics design. A few months ago, allen's lab built the torso and arms for a robot butler that is named IO. After finishing that, he moved on to the head — mainly because after all the hard work of making the arms, he needed a breather. I mean, how hard could the head be?

That, of course, depends on the requirements. Since the inspiration for IO’s head came from a robot in the video game NieR: Automata that is capable of spinning its head in any direction — like a ball sitting on top of the body — it actually ended up being a very challenging design to perfect. But hey, that just means there is more to learn, right? And anyway, the pain of the difficulties experienced during the build will fade over time (probably).

The robot’s spherical head was 3D-printed simply enough, and some LEDs were used to light up the eyes. But the difficulties really started to rear their head when it came to attaching the head to the body. Permanent attachments just would not cut it since the sphere needs to be able to rotate in any direction. But allen's lab found that with some magnets to hold things together, and ball bearings to make movement smooth, the head would stay in place and was completely free to move.

With a successful attachment, the next problem to solve was the actuation mechanism — how can this thing be made to move? The solution was quite clever. A set of three electric motors, each attached to an omni wheel, were attached to the base of the robot, with the wheels contacting the bottom of the head. By applying different velocities to each wheel, relative to the others, the head could be made to rotate in any direction. The math required to make it work was not easy, but in the end, it did work perfectly.

That just left one more issue. For the head to rotate to a specific position, one needs to know exactly what position the head is actually in. After trying to make dead reckoning work, and then struggling with an inertial measurement unit, allen's lab found that little errors introduced over time eventually got the measurements way out of whack. That led to the development of a new device that attaches to the magnetic base and that makes use of a pair of rotary encoders to capture the measurements. It is not perfect, but at least the errors do not accumulate over time, so it will do the job well enough.

To test the head out, a face tracking algorithm — running on a nearby smartphone — was used to control IO’s head. Keeping eye contact is a fun trick, but IO is going to need some hands and legs before it can do anything really interesting. Stay tuned to see how this project develops!