Virtual worlds are infinite environments in which users can move freely. But there is a catch: the real world in which the user walks is usually limited.
At CHI 2019 (ACM CHI Conference on Human Factors in Computing System),Stefan Schneegaß' team (Human-computer Interaction Group) presented an approach with electrical muscle stimulation (EMS) allowing an unlimited walking experience in limited real space. The researchers use a trick: they let the VR user walk in a circle without him noticing. To do this, they stimulate his/her Sartorius muscle, which extends from the hip to the shinbone. The muscle stimulation causes the user's leg to move outwards. The user automatically deviates from the straight route and walks in circles while walking straight ahead in the virtual world.
In the video, you can see the of the developed "Infinite Walker System". A study with test persons showed that the required space can be significantly reduced with this system. The test persons walked in the VR through an infinitely long, straight avenue. In fact, they moved in a limited space. The least space was required when muscle stimulation was combined with a vision shift. This technique slightly shifts the user's view in one direction, so that the user automatically takes a curve to correct this shift.
EMS and vision shift might be used as components of VR systems that create a perfect illusion of infinite environments.
The CHI is the largest and most important conference in the field of human-computer interaction. The paper has been published as: Around the (Virtual) World: Infinite Walking in Virtual Reality Using Electrical Muscle Stimulation by Jonas Auda, Max Pascher and Stefan Schneegaß: https://doi.org/10.1145/3290605.3300661
A summary has been published on: https://medium.com/acm-chi/around-the-virtual-world-719c0270f325.