[1] Univ Ljubljana, Fac Elect Engn, User Adapted Commun & Ambient Intelligence Lab, Trzaska Cesta 25, Ljubljana 1000, Slovenia
[2] Univ Washington, Dept Ind & Syst Engn, Seattle, WA 98105 USA
[3] Colorado State Univ, Dept Mech Engn, 400 Isotope Dr, Ft Collins, CO 80521 USA
[4] Univ Ljubljana, Fac Elect Engn, Lab Informat Technol, Trzaska Cesta 25, Ljubljana 1000, Slovenia