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Short Summary
Main recommendation: Mark Rober's video is a showcase rather than a how-to, presenting a motion-tracked dartboard that either guarantees bullseyes or sabotages throws depending on which dart is used. The system works by predicting where a dart will land using a Vicon motion capture rig and then moving the board with stepper motors within roughly 400 milliseconds total.
Key Points
- The dartboard is built around a retroreflective dart tracked by a six-camera Vicon motion capture system, which sees the dart in 3D by bouncing infrared light off tiny reflectors on it.
- Landing prediction relies on physics: a thrown dart follows a parabola, so the vertical position comes from a side-view parabola fit, while the horizontal position comes from a linear fit (y = mx + b) in the bottom view.
- Movement is handled by two linear sliders carrying the board, driven by six stepper motors that spool fishing line attached to the center of the back of the board.
- The team spent the first two years trying to build their own motion capture system with Nvidia TX1 boards but found it too complex, so they switched to the turnkey Vicon system; the overall project took over three years.
- The board refines its position guess 10 to 100 times, achieving sub-millimeter precision, which explains the visible jitter as it settles.
Details Worth Noting
- Concrete instructions: The video gives no build steps, parts list, or setup instructions for the viewer to follow. The only actionable element is the system's own operating sequence: track the dart's XYZ position in flight, fit the trajectory with MATLAB code, compute the trigonometry for the motor movements, and send commands through an Arduino-compatible board, preamps, and stepper motor drivers, all within under half a second.
- The dart is the control variable: the video says a special dart makes the thrower a near-perfect player, and a different dart makes them the worst by moving the board opposite to the predicted landing spot.
- Power flows from the wall through an AC/DC converter to the stepper motor drivers, which combine it with control signals to produce the motor steps.
- The team also tested the board with the public in a bar.
- Parabolic motion applies to anything thrown without air resistance, and the video notes that a high jumper's center of mass follows a parabola as well.
Bottom Line
The project is primarily a demonstration of applied physics and motion tracking, and its real lesson is that predicting trajectory and moving hardware fast enough can make a dartboard feel almost magical.