YouTube star Mark Rober, best known for his DIY science videos, has been helping Apple develop virtual reality for entertainment in self-driving cars, according to patent filings that were first reported by Variety.

Rober, who has more than 3.4 million YouTube followers, left stints at NASA and Morph Costumes to take a job in 2015 at an unknown company, according to his LinkedIn. Variety reports he's been working as a product design engineer for Apple since then.

Two patent applications filed by Apple in late March bear Rober's name, and give a hint as to just what the company has been working on.

The two patents, for "immersive virtual display," and "augmented virtual display," describe virtual reality systems that could be used by passengers of self-driving cars, or by a passenger in a conventional car. Among other things they entail "methods that address problems with vehicles in motion that may result in motion sickness for passengers." Although the patents specifically pertain to use in autonomous vehicles, they could have a wide range of other applications, as well.

Apple’s work on virtual reality and autonomous vehicles have long been related. In 2015, for example, Apple acquired augmented reality startup Metaio, which had been working with car manufacturers Audi, BMW and Ferrari. Apple has since scaled back its autonomous vehicle efforts.

Read more about Rober and Apple from Variety.