Former NASA engineer scores a bullseye with moving dartboard
YouTuber Mark Rober, a former NASA engineer, has built a robotic dartboard that ensures that you always hit a bullseye, wherever you throw the dart. The system uses infrared detectors placed around the room to track the flight of the dart; a computer collates the data and predicts the flightpath of the dart within 200 milliseconds and adjusts the position of the dartboard accordingly, within the space of a further 200 milliseconds.

Playing darts is tough. Reliably hitting a bull’s-eye requires practice, skill, and some serious hand-eye coordination to pull off, something that can take a lifetime to truly master. Or, you could do what former NASA-engineer-turned-popular-YouTuber Mark Rober did, and build a custom dartboard system that can track a dart through the air and perfectly position itself to let the dart hit a bull’s-eye no matter where it’s thrown, as spotted by Gizmodo. To paraphrase Francis Bacon: if the dart won't come to the bull’s-eye, then the bull’s-eye must go to the dart.

Of course, actually building the perfect automatic dartboard took Rober over three years of work to put together. In the video, Rober describes the two parts to putting the project together: tracking the dark to predict exactly where it will land, and moving the dartboard to be there to catch it.

According to Rober, the average dart throw takes about 400 milliseconds to travel from the regulation throwing distance to the board. In that time, a six-camera Vicon motion capture system tracks the dart using IR LEDs that bounce off tiny retro-reflectors attached to the dart, determining the exact location of the dart in 3D space. Then, using some physics equations, the trajectory of the dart can be calculated to figure out exactly where the dart will hit.

Then, the board needs to move to that location. To accomplish that, the dartboard is on two sliders that allow it to pan anywhere on a 2D plane, using a system of six stepper motors to push and pull it around. Once the bull’s-eye location has been found using the motion tracking system, a connected computer can apply some trigonometry to figure out where the bull’s-eye needs to be, and will then send instructions to the motor to move the board there. The impressive thing is that the system is constantly tracking and updating the prediction — up to 100 times in the less than half a second it has before the dart hits.