Forward-looking: The US Patent and Trademark Office recently approved a patent for motorized shoes submitted by Google. The device is intended to be used in a virtual reality environment to give the user a sense that they are walking. The shoes would continually work to keep the user in the center of the play area.

Virtual reality developers are always looking for ways to make the VR experience more immersive. We've covered various haptic gloves that allow you to "feel" objects. Realistically walking around in VR, however, is more difficult to pull off requiring either an expensive and bulky omnidirectional treadmill, or tons of play space.

Google filed a patent for motorized shoes that simulate walking, but can be used in a confined space like your living room. The footwear would use small wheels that gently roll the user back toward the center of the room as he or she walks in any direction.

UploadVR reports that the idea is based on "infinite redirected walking" that is under development by other companies. Dynamic Saccadic Redirection (DSR) is one technique to achieve this. Developed by Nvidia, DSR tricks the user's eyes and causes them to walk in different directions even though the VR is telling them they are walking straight. Thus the user can be redirected to avoid walking into walls and even physical and virtual obstacles.

However, Nvidia's technique requires at least a 20-square-foot play area. Since Google's shoes would redirect the users physically back toward the center of the play space by rolling the wheels opposite the player's direction of movement, the space required would be significantly less.

Japanese startup Cybershoes has a similar approach using strap-on shoes with slick bottoms. Rollers on the soles register distance-traveled data, which is relayed to the VR computer for rendering. The disadvantage here is that to use the Cybershoes users must be seated on a stool to keep them stationary. Google's method proposes to eliminate this necessity.

The patent reads:

"A physical position of motorized footwear in a physical environment may be tracked, and movement of the footwear may be transmitted into corresponding movement in a virtual environment. When a distance between the motorized footwear and a boundary of an operational zone defined in the physical environment is less than or equal to a threshold distance, a motor of the motorized shoe may be actuated. Actuation of the motor may in turn actuate a locomotion device of the motorized footwear, to move the motorized footwear back into a return zone defined within the operational zone. This may allow the user to walk, seemingly endlessly in the virtual environment, while remaining within a defined physical space in the physical environment."

At this time the motorized shoes are only a concept that has been approved by the US Patent and Trademark Office. There is no official word from Google on how far into development the shoes are.