Positive Technology Journal

Via Science Daily

I was fashinated by this physics experiment, which is the first attempt to create a linked virtual/real system.  Vadas Gintautas and Alfred Hübler of the Center for Complex Systems Research at the University of Illinios achieved this result by coupling a real-world pendulum with a virtual version that moved under time-tested equations of motion. In their "mixed reality" system, the two pendulums swing as one. To get the two pendulums to communicate, the physicists fed data about the real pendulum to the virtual one, and information from the virtual pendulum is transferred to a motor that affects the motion of the real pendulum.

Mixed reality can occur only when the two systems are sufficiently similar, but a system having unknown parameters could be coupled to a virtual system whose parameters are set by the experimenters. The unknown variables in the real system could then be determined by adjusting the virtual system until the two systems shift from dual reality to mixed reality, enabling good estimates for the values of the unknown parameters.

Here is the study abstract: 

Experimental evidence for mixed reality states in an interreality system.

Phys Rev E Stat Nonlin Soft Matter Phys. 2007 May;75(5-2):057201

Authors: Gintautas V, Hübler AW

We present experimental data on the limiting behavior of an interreality system comprising a virtual horizontally driven pendulum coupled to its real-world counterpart, where the interaction time scale is much shorter than the time scale of the dynamical system. We present experimental evidence that, if the physical parameters of the simplified virtual system match those of the real system within a certain tolerance, there is a transition from an uncorrelated dual reality state to a mixed reality state of the system in which the motion of the two pendula is highly correlated. The region in parameter space for stable solutions has an Arnold tongue structure for both the experimental data and a numerical simulation. As virtual systems better approximate real ones, even weak coupling in other interreality systems may produce sudden changes to mixed reality states.