Robot Goalie Has Sub-Millimeter Accuracy Optical Tracking
Mark Rober’s latest engineering video pitches legendary Portugal soccer player Cristiano Ronaldo against a robot goalie. See who’s up to the challenge.
Edited by EE Staff
Feb 16, 2026
Mark Rober, a former NASA engineer, has an innovative and entertaining approach to science, technology, engineering, and math (STEM) education, which is a global inspiration for him. He records and uploads his adventures regularly on Youtube to get the word out. He’s also the founder of CrunchLabs, an exciting and impactful STEM brand.
Recently, Rober partnered with OptiTrack, a designer and manufacturer of precision motion capture technology. He used the company’s PrimeX 120 camera system to power a high-speed, high-G tracking behind his newest project where Cristiano Ronaldo fired high speed penalty kicks at a robot goalie capable of accelerating at 10 Gs.
To track an 80 mph (120 km/h) ball launcher, full-speed professional strikes, and a robot moving fast enough to tear its own mechanical components apart, OptiTrack deployed a 20-camera volume of PrimeX 120 cameras running at 500 FPS, combined with passive retroreflective markers placed on the ball. The PrimeX 120 features customed designed ultra-low distortion “fast glass” lenses for optimal tracking. The PrimeX 120 is an 18mm lense with wide-band anti-reflective coating for greater light transmission, larger volumes, and more precise 3D data.
The capture volume was engineered around the penalty box, with the system configured to track anything entering the strike zone with sub-millimeter fidelity. OptiTrack participated with a full on-site engineering team that supported both the Portugal shoot and earlier development testing performed in California. According to Rober, “OptiTrack’s tracking is so accurate and so fast that it let us push this experiment way further than I thought was possible. It’s the only system that could keep up with Ronaldo’s shots.”
Unlike traditional sensor systems, OptiTrack’s optical motion capture allowed Rober’s team to calculate the ball’s predicted path in real time. With that data, the system calculated ball trajectory data and streamed it directly from OptiTrack’s system to the robot. This enabled the robot to not only anticipate where the ball would cross its line but to move to the exact location with extreme speed—fast enough to stop the kick.
When Mark approached OptiTrack with the idea, the company knew that their PrimeX camera system was the right product to deliver the data needed fast enough to block the kick. The 500 frames per second required for the experiment was comfortably within the normal operating range of the technology. Sidney Rittenbert Jr., CEO of OptiTrack said, “We’re proud to support ambitious engineering projects like this with the reliability our customers depend on every day.”
The video is available on the Mark Rober YouTube channel and has additional approved behind-the-scenes footage and technical breakdowns you can find showcased on OptiTrack’s social media channels.
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*Lead image courtesy of DepositePhotos.com.