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Virtual reality

Jean-Michel Prima - 23/05/2012

Lean and Go in Virtual Worlds

Maud Marchal and Julien Pettré testing the Joyman in Immersia VR room, Rennes

Scientists from Inria and Insa Rennes come up with a trampoline-like innovative VR interface for pedestrian navigation. Making a joystick of the human body as a whole is what Joyman is all about.

When Hong Kong schoolboys came across the Joyman, in December 2011, the Siggraph Asia Emerging Technologies Exhibition turned to a funfair. “Our stand was crowded all right the whole week long, researcher Julien Pettré marvels. This hefty enthusiasm was shared by laymen and pros alike.”  At first sight, the Joyman looks like a trampoline. But no bouncing is involved. It suffices for the user to lean and he will be navigating accordingly in a virtual scene displayed either on a screen or on a head mounted display. A safeguard prevents any fall and allows to lean unhesitatingly. “An inertial sensor measures the central board inclination, co-inventor Maud Marchal explains. Control laws then retrieve these parameters and transform the angle of the platform into virtual walking.” Et voilà.
“The Joyman is slightly peripheral to our research, Pettré comments. It was born from the need to interact with pedestrian simulation. We wanted to enable the user to walk in a virtual world and amble through the crowd realistically. In this field, science is still a lot of work away from reaching the perfect match between virtuality and reality. "

In the course of their experiments, the two scientists hit upon a  stumbling block. “Our VR room is obviously too small for accomodating any lengthy real walk in connection to a simulation.” One possible solution is the treadmill. “Some are pretty cutting edge. In Germany, the Cyberwalk is a omni-directional treadmill that even compensates for lateral walk and systematically brings back the walker plum in the middle. But this is a 11-tonne outfit whereas our aim is to come up with a much simpler device” ...and a lighter price tag.
Things clicked one day when Pettré and Marchal saw a Segway rolling through campus. “The light went on as we came to realize that this was precisely what we needed for navigating into virtual worlds. Indeed, this machine moves forward when the user shifts his weight forward on the platform. Those who have tried it find it to be a very intuitive way of moving. In addition, it is a balance-based device. Human walk has been much studied by neuroscience. It relies on three senses. Vision. Proprioception  —which the sense of body efforts. And lastly the sense of balance. Also known as equilibrioception. These senses mobilize three sensory systems, e.g., visual, somatosensory and vestibular. The human body mixes all three in order to control the walk. Most interfaces use proprioception. Say joysticks for instance. But they are not immersive at all.Treadmills preserve the perception of the walk. But perception of acceleration is lost. There was simply a lack of an interface that would preserve the sens of balance.”
Can Joyman help to deliver realistic locomotion trajectories in the virtual environment? “Despite of its simplicity, there are good reasons to think that yes indeed.”   Why? “Because the user really moves his own body to control his virtual movement,” Pettré supplies.
“Having said that, the control laws that govern the interface can be modified according to the targeted use, Marchal adds. We can stick to a realistic restitution if we solely aim at validating our research on human locomotion. But we might as well want to deliver additional sensory illusions, like the feeling of a fast acceleration in the context of a ski simulator for instance.”

Market savvy

Is it to say that the Joyman will hit the game stores next to the Wii shelves? “Obviously, that's the first idea that comes to mind, Pettré remarks. The interface is well suited for that. Nevertheless, it might not be the best target for a technology transfer as the game scene is a highly competitive play ground. By the way, this is why having an industrial partner becomes all the more interesting. Thanks to their market expertise, vendors are better positioned to find the ideal outlet.”
In order to give their invention a future, the Rennes-based scientists are teaming up with Immersion. “This French company is a major international player both in terms of distribution and conception of VR interfaces. They already have had an experience of working with Inria through researcher Martin Hachet and Bordeaux 1 University. Mutual trust prevails. For us, they are the ideal partner.”
Among other possible applications, physiotherapy might also be of interest. “For instance, the Joyman could be used to help cure patients with balance disorder. We would like to explore this avenue through a collaborative project that remains to be mapped out.”

Keywords: Joyman Insa Rennes Interface Joystick INRIA Rennes - Bretagne Atlantique Virtual reality Maud Marchal Julien Pettré